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64db4cff PM |
1 | /* |
2 | * Read-Copy Update mechanism for mutual exclusion | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
17 | * | |
18 | * Copyright IBM Corporation, 2008 | |
19 | * | |
20 | * Authors: Dipankar Sarma <dipankar@in.ibm.com> | |
21 | * Manfred Spraul <manfred@colorfullife.com> | |
22 | * Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical version | |
23 | * | |
24 | * Based on the original work by Paul McKenney <paulmck@us.ibm.com> | |
25 | * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. | |
26 | * | |
27 | * For detailed explanation of Read-Copy Update mechanism see - | |
a71fca58 | 28 | * Documentation/RCU |
64db4cff PM |
29 | */ |
30 | #include <linux/types.h> | |
31 | #include <linux/kernel.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/spinlock.h> | |
34 | #include <linux/smp.h> | |
35 | #include <linux/rcupdate.h> | |
36 | #include <linux/interrupt.h> | |
37 | #include <linux/sched.h> | |
c1dc0b9c | 38 | #include <linux/nmi.h> |
8826f3b0 | 39 | #include <linux/atomic.h> |
64db4cff | 40 | #include <linux/bitops.h> |
9984de1a | 41 | #include <linux/export.h> |
64db4cff PM |
42 | #include <linux/completion.h> |
43 | #include <linux/moduleparam.h> | |
44 | #include <linux/percpu.h> | |
45 | #include <linux/notifier.h> | |
46 | #include <linux/cpu.h> | |
47 | #include <linux/mutex.h> | |
48 | #include <linux/time.h> | |
bbad9379 | 49 | #include <linux/kernel_stat.h> |
a26ac245 PM |
50 | #include <linux/wait.h> |
51 | #include <linux/kthread.h> | |
268bb0ce | 52 | #include <linux/prefetch.h> |
64db4cff | 53 | |
9f77da9f | 54 | #include "rcutree.h" |
29c00b4a PM |
55 | #include <trace/events/rcu.h> |
56 | ||
57 | #include "rcu.h" | |
9f77da9f | 58 | |
64db4cff PM |
59 | /* Data structures. */ |
60 | ||
b668c9cf | 61 | static struct lock_class_key rcu_node_class[NUM_RCU_LVLS]; |
88b91c7c | 62 | |
4300aa64 | 63 | #define RCU_STATE_INITIALIZER(structname) { \ |
e99033c5 | 64 | .level = { &structname##_state.node[0] }, \ |
64db4cff PM |
65 | .levelcnt = { \ |
66 | NUM_RCU_LVL_0, /* root of hierarchy. */ \ | |
67 | NUM_RCU_LVL_1, \ | |
68 | NUM_RCU_LVL_2, \ | |
cf244dc0 PM |
69 | NUM_RCU_LVL_3, \ |
70 | NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \ | |
64db4cff | 71 | }, \ |
af446b70 | 72 | .fqs_state = RCU_GP_IDLE, \ |
64db4cff PM |
73 | .gpnum = -300, \ |
74 | .completed = -300, \ | |
e99033c5 PM |
75 | .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname##_state.onofflock), \ |
76 | .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&structname##_state.fqslock), \ | |
64db4cff PM |
77 | .n_force_qs = 0, \ |
78 | .n_force_qs_ngp = 0, \ | |
4300aa64 | 79 | .name = #structname, \ |
64db4cff PM |
80 | } |
81 | ||
e99033c5 | 82 | struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched); |
d6714c22 | 83 | DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); |
64db4cff | 84 | |
e99033c5 | 85 | struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh); |
6258c4fb | 86 | DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); |
b1f77b05 | 87 | |
27f4d280 PM |
88 | static struct rcu_state *rcu_state; |
89 | ||
b0d30417 PM |
90 | /* |
91 | * The rcu_scheduler_active variable transitions from zero to one just | |
92 | * before the first task is spawned. So when this variable is zero, RCU | |
93 | * can assume that there is but one task, allowing RCU to (for example) | |
94 | * optimized synchronize_sched() to a simple barrier(). When this variable | |
95 | * is one, RCU must actually do all the hard work required to detect real | |
96 | * grace periods. This variable is also used to suppress boot-time false | |
97 | * positives from lockdep-RCU error checking. | |
98 | */ | |
bbad9379 PM |
99 | int rcu_scheduler_active __read_mostly; |
100 | EXPORT_SYMBOL_GPL(rcu_scheduler_active); | |
101 | ||
b0d30417 PM |
102 | /* |
103 | * The rcu_scheduler_fully_active variable transitions from zero to one | |
104 | * during the early_initcall() processing, which is after the scheduler | |
105 | * is capable of creating new tasks. So RCU processing (for example, | |
106 | * creating tasks for RCU priority boosting) must be delayed until after | |
107 | * rcu_scheduler_fully_active transitions from zero to one. We also | |
108 | * currently delay invocation of any RCU callbacks until after this point. | |
109 | * | |
110 | * It might later prove better for people registering RCU callbacks during | |
111 | * early boot to take responsibility for these callbacks, but one step at | |
112 | * a time. | |
113 | */ | |
114 | static int rcu_scheduler_fully_active __read_mostly; | |
115 | ||
a46e0899 PM |
116 | #ifdef CONFIG_RCU_BOOST |
117 | ||
a26ac245 PM |
118 | /* |
119 | * Control variables for per-CPU and per-rcu_node kthreads. These | |
120 | * handle all flavors of RCU. | |
121 | */ | |
122 | static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task); | |
d71df90e | 123 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status); |
15ba0ba8 | 124 | DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu); |
5ece5bab | 125 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); |
d71df90e | 126 | DEFINE_PER_CPU(char, rcu_cpu_has_work); |
a26ac245 | 127 | |
a46e0899 PM |
128 | #endif /* #ifdef CONFIG_RCU_BOOST */ |
129 | ||
0f962a5e | 130 | static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu); |
a46e0899 PM |
131 | static void invoke_rcu_core(void); |
132 | static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp); | |
a26ac245 | 133 | |
4a298656 PM |
134 | /* |
135 | * Track the rcutorture test sequence number and the update version | |
136 | * number within a given test. The rcutorture_testseq is incremented | |
137 | * on every rcutorture module load and unload, so has an odd value | |
138 | * when a test is running. The rcutorture_vernum is set to zero | |
139 | * when rcutorture starts and is incremented on each rcutorture update. | |
140 | * These variables enable correlating rcutorture output with the | |
141 | * RCU tracing information. | |
142 | */ | |
143 | unsigned long rcutorture_testseq; | |
144 | unsigned long rcutorture_vernum; | |
145 | ||
fc2219d4 PM |
146 | /* |
147 | * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s | |
148 | * permit this function to be invoked without holding the root rcu_node | |
149 | * structure's ->lock, but of course results can be subject to change. | |
150 | */ | |
151 | static int rcu_gp_in_progress(struct rcu_state *rsp) | |
152 | { | |
153 | return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum); | |
154 | } | |
155 | ||
b1f77b05 | 156 | /* |
d6714c22 | 157 | * Note a quiescent state. Because we do not need to know |
b1f77b05 | 158 | * how many quiescent states passed, just if there was at least |
d6714c22 | 159 | * one since the start of the grace period, this just sets a flag. |
e4cc1f22 | 160 | * The caller must have disabled preemption. |
b1f77b05 | 161 | */ |
d6714c22 | 162 | void rcu_sched_qs(int cpu) |
b1f77b05 | 163 | { |
25502a6c | 164 | struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu); |
f41d911f | 165 | |
e4cc1f22 | 166 | rdp->passed_quiesce_gpnum = rdp->gpnum; |
c3422bea | 167 | barrier(); |
e4cc1f22 | 168 | if (rdp->passed_quiesce == 0) |
d4c08f2a | 169 | trace_rcu_grace_period("rcu_sched", rdp->gpnum, "cpuqs"); |
e4cc1f22 | 170 | rdp->passed_quiesce = 1; |
b1f77b05 IM |
171 | } |
172 | ||
d6714c22 | 173 | void rcu_bh_qs(int cpu) |
b1f77b05 | 174 | { |
25502a6c | 175 | struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); |
f41d911f | 176 | |
e4cc1f22 | 177 | rdp->passed_quiesce_gpnum = rdp->gpnum; |
c3422bea | 178 | barrier(); |
e4cc1f22 | 179 | if (rdp->passed_quiesce == 0) |
d4c08f2a | 180 | trace_rcu_grace_period("rcu_bh", rdp->gpnum, "cpuqs"); |
e4cc1f22 | 181 | rdp->passed_quiesce = 1; |
b1f77b05 | 182 | } |
64db4cff | 183 | |
25502a6c PM |
184 | /* |
185 | * Note a context switch. This is a quiescent state for RCU-sched, | |
186 | * and requires special handling for preemptible RCU. | |
e4cc1f22 | 187 | * The caller must have disabled preemption. |
25502a6c PM |
188 | */ |
189 | void rcu_note_context_switch(int cpu) | |
190 | { | |
300df91c | 191 | trace_rcu_utilization("Start context switch"); |
25502a6c PM |
192 | rcu_sched_qs(cpu); |
193 | rcu_preempt_note_context_switch(cpu); | |
300df91c | 194 | trace_rcu_utilization("End context switch"); |
25502a6c | 195 | } |
29ce8310 | 196 | EXPORT_SYMBOL_GPL(rcu_note_context_switch); |
25502a6c | 197 | |
90a4d2c0 | 198 | DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { |
4145fa7f | 199 | .dynticks_nesting = DYNTICK_TASK_NESTING, |
23b5c8fa | 200 | .dynticks = ATOMIC_INIT(1), |
90a4d2c0 | 201 | }; |
64db4cff | 202 | |
e0f23060 | 203 | static int blimit = 10; /* Maximum callbacks per rcu_do_batch. */ |
64db4cff PM |
204 | static int qhimark = 10000; /* If this many pending, ignore blimit. */ |
205 | static int qlowmark = 100; /* Once only this many pending, use blimit. */ | |
206 | ||
3d76c082 PM |
207 | module_param(blimit, int, 0); |
208 | module_param(qhimark, int, 0); | |
209 | module_param(qlowmark, int, 0); | |
210 | ||
a00e0d71 | 211 | int rcu_cpu_stall_suppress __read_mostly; |
f2e0dd70 | 212 | module_param(rcu_cpu_stall_suppress, int, 0644); |
742734ee | 213 | |
64db4cff | 214 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed); |
a157229c | 215 | static int rcu_pending(int cpu); |
64db4cff PM |
216 | |
217 | /* | |
d6714c22 | 218 | * Return the number of RCU-sched batches processed thus far for debug & stats. |
64db4cff | 219 | */ |
d6714c22 | 220 | long rcu_batches_completed_sched(void) |
64db4cff | 221 | { |
d6714c22 | 222 | return rcu_sched_state.completed; |
64db4cff | 223 | } |
d6714c22 | 224 | EXPORT_SYMBOL_GPL(rcu_batches_completed_sched); |
64db4cff PM |
225 | |
226 | /* | |
227 | * Return the number of RCU BH batches processed thus far for debug & stats. | |
228 | */ | |
229 | long rcu_batches_completed_bh(void) | |
230 | { | |
231 | return rcu_bh_state.completed; | |
232 | } | |
233 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); | |
234 | ||
bf66f18e PM |
235 | /* |
236 | * Force a quiescent state for RCU BH. | |
237 | */ | |
238 | void rcu_bh_force_quiescent_state(void) | |
239 | { | |
240 | force_quiescent_state(&rcu_bh_state, 0); | |
241 | } | |
242 | EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); | |
243 | ||
4a298656 PM |
244 | /* |
245 | * Record the number of times rcutorture tests have been initiated and | |
246 | * terminated. This information allows the debugfs tracing stats to be | |
247 | * correlated to the rcutorture messages, even when the rcutorture module | |
248 | * is being repeatedly loaded and unloaded. In other words, we cannot | |
249 | * store this state in rcutorture itself. | |
250 | */ | |
251 | void rcutorture_record_test_transition(void) | |
252 | { | |
253 | rcutorture_testseq++; | |
254 | rcutorture_vernum = 0; | |
255 | } | |
256 | EXPORT_SYMBOL_GPL(rcutorture_record_test_transition); | |
257 | ||
258 | /* | |
259 | * Record the number of writer passes through the current rcutorture test. | |
260 | * This is also used to correlate debugfs tracing stats with the rcutorture | |
261 | * messages. | |
262 | */ | |
263 | void rcutorture_record_progress(unsigned long vernum) | |
264 | { | |
265 | rcutorture_vernum++; | |
266 | } | |
267 | EXPORT_SYMBOL_GPL(rcutorture_record_progress); | |
268 | ||
bf66f18e PM |
269 | /* |
270 | * Force a quiescent state for RCU-sched. | |
271 | */ | |
272 | void rcu_sched_force_quiescent_state(void) | |
273 | { | |
274 | force_quiescent_state(&rcu_sched_state, 0); | |
275 | } | |
276 | EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state); | |
277 | ||
64db4cff PM |
278 | /* |
279 | * Does the CPU have callbacks ready to be invoked? | |
280 | */ | |
281 | static int | |
282 | cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) | |
283 | { | |
284 | return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]; | |
285 | } | |
286 | ||
287 | /* | |
288 | * Does the current CPU require a yet-as-unscheduled grace period? | |
289 | */ | |
290 | static int | |
291 | cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) | |
292 | { | |
fc2219d4 | 293 | return *rdp->nxttail[RCU_DONE_TAIL] && !rcu_gp_in_progress(rsp); |
64db4cff PM |
294 | } |
295 | ||
296 | /* | |
297 | * Return the root node of the specified rcu_state structure. | |
298 | */ | |
299 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp) | |
300 | { | |
301 | return &rsp->node[0]; | |
302 | } | |
303 | ||
304 | #ifdef CONFIG_SMP | |
305 | ||
306 | /* | |
307 | * If the specified CPU is offline, tell the caller that it is in | |
308 | * a quiescent state. Otherwise, whack it with a reschedule IPI. | |
309 | * Grace periods can end up waiting on an offline CPU when that | |
310 | * CPU is in the process of coming online -- it will be added to the | |
311 | * rcu_node bitmasks before it actually makes it online. The same thing | |
312 | * can happen while a CPU is in the process of coming online. Because this | |
313 | * race is quite rare, we check for it after detecting that the grace | |
314 | * period has been delayed rather than checking each and every CPU | |
315 | * each and every time we start a new grace period. | |
316 | */ | |
317 | static int rcu_implicit_offline_qs(struct rcu_data *rdp) | |
318 | { | |
319 | /* | |
320 | * If the CPU is offline, it is in a quiescent state. We can | |
321 | * trust its state not to change because interrupts are disabled. | |
322 | */ | |
323 | if (cpu_is_offline(rdp->cpu)) { | |
d4c08f2a | 324 | trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, "ofl"); |
64db4cff PM |
325 | rdp->offline_fqs++; |
326 | return 1; | |
327 | } | |
328 | ||
9b2e4f18 PM |
329 | /* |
330 | * The CPU is online, so send it a reschedule IPI. This forces | |
331 | * it through the scheduler, and (inefficiently) also handles cases | |
332 | * where idle loops fail to inform RCU about the CPU being idle. | |
333 | */ | |
64db4cff PM |
334 | if (rdp->cpu != smp_processor_id()) |
335 | smp_send_reschedule(rdp->cpu); | |
336 | else | |
337 | set_need_resched(); | |
338 | rdp->resched_ipi++; | |
339 | return 0; | |
340 | } | |
341 | ||
342 | #endif /* #ifdef CONFIG_SMP */ | |
343 | ||
9b2e4f18 PM |
344 | /* |
345 | * rcu_idle_enter_common - inform RCU that current CPU is moving towards idle | |
346 | * | |
347 | * If the new value of the ->dynticks_nesting counter now is zero, | |
348 | * we really have entered idle, and must do the appropriate accounting. | |
349 | * The caller must have disabled interrupts. | |
350 | */ | |
4145fa7f | 351 | static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval) |
9b2e4f18 | 352 | { |
facc4e15 | 353 | trace_rcu_dyntick("Start", oldval, 0); |
99745b6a | 354 | if (!is_idle_task(current)) { |
0989cb46 PM |
355 | struct task_struct *idle = idle_task(smp_processor_id()); |
356 | ||
facc4e15 | 357 | trace_rcu_dyntick("Error on entry: not idle task", oldval, 0); |
9b2e4f18 | 358 | ftrace_dump(DUMP_ALL); |
0989cb46 PM |
359 | WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", |
360 | current->pid, current->comm, | |
361 | idle->pid, idle->comm); /* must be idle task! */ | |
9b2e4f18 | 362 | } |
aea1b35e | 363 | rcu_prepare_for_idle(smp_processor_id()); |
9b2e4f18 PM |
364 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
365 | smp_mb__before_atomic_inc(); /* See above. */ | |
366 | atomic_inc(&rdtp->dynticks); | |
367 | smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ | |
368 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); | |
369 | } | |
64db4cff PM |
370 | |
371 | /** | |
9b2e4f18 | 372 | * rcu_idle_enter - inform RCU that current CPU is entering idle |
64db4cff | 373 | * |
9b2e4f18 | 374 | * Enter idle mode, in other words, -leave- the mode in which RCU |
64db4cff | 375 | * read-side critical sections can occur. (Though RCU read-side |
9b2e4f18 PM |
376 | * critical sections can occur in irq handlers in idle, a possibility |
377 | * handled by irq_enter() and irq_exit().) | |
378 | * | |
379 | * We crowbar the ->dynticks_nesting field to zero to allow for | |
380 | * the possibility of usermode upcalls having messed up our count | |
381 | * of interrupt nesting level during the prior busy period. | |
64db4cff | 382 | */ |
9b2e4f18 | 383 | void rcu_idle_enter(void) |
64db4cff PM |
384 | { |
385 | unsigned long flags; | |
4145fa7f | 386 | long long oldval; |
64db4cff PM |
387 | struct rcu_dynticks *rdtp; |
388 | ||
64db4cff PM |
389 | local_irq_save(flags); |
390 | rdtp = &__get_cpu_var(rcu_dynticks); | |
4145fa7f | 391 | oldval = rdtp->dynticks_nesting; |
9b2e4f18 | 392 | rdtp->dynticks_nesting = 0; |
4145fa7f | 393 | rcu_idle_enter_common(rdtp, oldval); |
64db4cff PM |
394 | local_irq_restore(flags); |
395 | } | |
396 | ||
9b2e4f18 PM |
397 | /** |
398 | * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle | |
399 | * | |
400 | * Exit from an interrupt handler, which might possibly result in entering | |
401 | * idle mode, in other words, leaving the mode in which read-side critical | |
402 | * sections can occur. | |
64db4cff | 403 | * |
9b2e4f18 PM |
404 | * This code assumes that the idle loop never does anything that might |
405 | * result in unbalanced calls to irq_enter() and irq_exit(). If your | |
406 | * architecture violates this assumption, RCU will give you what you | |
407 | * deserve, good and hard. But very infrequently and irreproducibly. | |
408 | * | |
409 | * Use things like work queues to work around this limitation. | |
410 | * | |
411 | * You have been warned. | |
64db4cff | 412 | */ |
9b2e4f18 | 413 | void rcu_irq_exit(void) |
64db4cff PM |
414 | { |
415 | unsigned long flags; | |
4145fa7f | 416 | long long oldval; |
64db4cff PM |
417 | struct rcu_dynticks *rdtp; |
418 | ||
419 | local_irq_save(flags); | |
420 | rdtp = &__get_cpu_var(rcu_dynticks); | |
4145fa7f | 421 | oldval = rdtp->dynticks_nesting; |
9b2e4f18 PM |
422 | rdtp->dynticks_nesting--; |
423 | WARN_ON_ONCE(rdtp->dynticks_nesting < 0); | |
b6fc6020 FW |
424 | if (rdtp->dynticks_nesting) |
425 | trace_rcu_dyntick("--=", oldval, rdtp->dynticks_nesting); | |
426 | else | |
427 | rcu_idle_enter_common(rdtp, oldval); | |
9b2e4f18 PM |
428 | local_irq_restore(flags); |
429 | } | |
430 | ||
431 | /* | |
432 | * rcu_idle_exit_common - inform RCU that current CPU is moving away from idle | |
433 | * | |
434 | * If the new value of the ->dynticks_nesting counter was previously zero, | |
435 | * we really have exited idle, and must do the appropriate accounting. | |
436 | * The caller must have disabled interrupts. | |
437 | */ | |
438 | static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval) | |
439 | { | |
23b5c8fa PM |
440 | smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */ |
441 | atomic_inc(&rdtp->dynticks); | |
442 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ | |
443 | smp_mb__after_atomic_inc(); /* See above. */ | |
444 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); | |
7cb92499 | 445 | rcu_cleanup_after_idle(smp_processor_id()); |
4145fa7f | 446 | trace_rcu_dyntick("End", oldval, rdtp->dynticks_nesting); |
99745b6a | 447 | if (!is_idle_task(current)) { |
0989cb46 PM |
448 | struct task_struct *idle = idle_task(smp_processor_id()); |
449 | ||
4145fa7f PM |
450 | trace_rcu_dyntick("Error on exit: not idle task", |
451 | oldval, rdtp->dynticks_nesting); | |
9b2e4f18 | 452 | ftrace_dump(DUMP_ALL); |
0989cb46 PM |
453 | WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", |
454 | current->pid, current->comm, | |
455 | idle->pid, idle->comm); /* must be idle task! */ | |
9b2e4f18 PM |
456 | } |
457 | } | |
458 | ||
459 | /** | |
460 | * rcu_idle_exit - inform RCU that current CPU is leaving idle | |
461 | * | |
462 | * Exit idle mode, in other words, -enter- the mode in which RCU | |
463 | * read-side critical sections can occur. | |
464 | * | |
4145fa7f PM |
465 | * We crowbar the ->dynticks_nesting field to DYNTICK_TASK_NESTING to |
466 | * allow for the possibility of usermode upcalls messing up our count | |
9b2e4f18 PM |
467 | * of interrupt nesting level during the busy period that is just |
468 | * now starting. | |
469 | */ | |
470 | void rcu_idle_exit(void) | |
471 | { | |
472 | unsigned long flags; | |
473 | struct rcu_dynticks *rdtp; | |
474 | long long oldval; | |
475 | ||
476 | local_irq_save(flags); | |
477 | rdtp = &__get_cpu_var(rcu_dynticks); | |
478 | oldval = rdtp->dynticks_nesting; | |
479 | WARN_ON_ONCE(oldval != 0); | |
4145fa7f | 480 | rdtp->dynticks_nesting = DYNTICK_TASK_NESTING; |
9b2e4f18 PM |
481 | rcu_idle_exit_common(rdtp, oldval); |
482 | local_irq_restore(flags); | |
483 | } | |
484 | ||
485 | /** | |
486 | * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle | |
487 | * | |
488 | * Enter an interrupt handler, which might possibly result in exiting | |
489 | * idle mode, in other words, entering the mode in which read-side critical | |
490 | * sections can occur. | |
491 | * | |
492 | * Note that the Linux kernel is fully capable of entering an interrupt | |
493 | * handler that it never exits, for example when doing upcalls to | |
494 | * user mode! This code assumes that the idle loop never does upcalls to | |
495 | * user mode. If your architecture does do upcalls from the idle loop (or | |
496 | * does anything else that results in unbalanced calls to the irq_enter() | |
497 | * and irq_exit() functions), RCU will give you what you deserve, good | |
498 | * and hard. But very infrequently and irreproducibly. | |
499 | * | |
500 | * Use things like work queues to work around this limitation. | |
501 | * | |
502 | * You have been warned. | |
503 | */ | |
504 | void rcu_irq_enter(void) | |
505 | { | |
506 | unsigned long flags; | |
507 | struct rcu_dynticks *rdtp; | |
508 | long long oldval; | |
509 | ||
510 | local_irq_save(flags); | |
511 | rdtp = &__get_cpu_var(rcu_dynticks); | |
512 | oldval = rdtp->dynticks_nesting; | |
513 | rdtp->dynticks_nesting++; | |
514 | WARN_ON_ONCE(rdtp->dynticks_nesting == 0); | |
b6fc6020 FW |
515 | if (oldval) |
516 | trace_rcu_dyntick("++=", oldval, rdtp->dynticks_nesting); | |
517 | else | |
518 | rcu_idle_exit_common(rdtp, oldval); | |
64db4cff | 519 | local_irq_restore(flags); |
64db4cff PM |
520 | } |
521 | ||
522 | /** | |
523 | * rcu_nmi_enter - inform RCU of entry to NMI context | |
524 | * | |
525 | * If the CPU was idle with dynamic ticks active, and there is no | |
526 | * irq handler running, this updates rdtp->dynticks_nmi to let the | |
527 | * RCU grace-period handling know that the CPU is active. | |
528 | */ | |
529 | void rcu_nmi_enter(void) | |
530 | { | |
531 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
532 | ||
23b5c8fa PM |
533 | if (rdtp->dynticks_nmi_nesting == 0 && |
534 | (atomic_read(&rdtp->dynticks) & 0x1)) | |
64db4cff | 535 | return; |
23b5c8fa PM |
536 | rdtp->dynticks_nmi_nesting++; |
537 | smp_mb__before_atomic_inc(); /* Force delay from prior write. */ | |
538 | atomic_inc(&rdtp->dynticks); | |
539 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ | |
540 | smp_mb__after_atomic_inc(); /* See above. */ | |
541 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); | |
64db4cff PM |
542 | } |
543 | ||
544 | /** | |
545 | * rcu_nmi_exit - inform RCU of exit from NMI context | |
546 | * | |
547 | * If the CPU was idle with dynamic ticks active, and there is no | |
548 | * irq handler running, this updates rdtp->dynticks_nmi to let the | |
549 | * RCU grace-period handling know that the CPU is no longer active. | |
550 | */ | |
551 | void rcu_nmi_exit(void) | |
552 | { | |
553 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
554 | ||
23b5c8fa PM |
555 | if (rdtp->dynticks_nmi_nesting == 0 || |
556 | --rdtp->dynticks_nmi_nesting != 0) | |
64db4cff | 557 | return; |
23b5c8fa PM |
558 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
559 | smp_mb__before_atomic_inc(); /* See above. */ | |
560 | atomic_inc(&rdtp->dynticks); | |
561 | smp_mb__after_atomic_inc(); /* Force delay to next write. */ | |
562 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); | |
64db4cff PM |
563 | } |
564 | ||
9b2e4f18 PM |
565 | #ifdef CONFIG_PROVE_RCU |
566 | ||
64db4cff | 567 | /** |
9b2e4f18 | 568 | * rcu_is_cpu_idle - see if RCU thinks that the current CPU is idle |
64db4cff | 569 | * |
9b2e4f18 | 570 | * If the current CPU is in its idle loop and is neither in an interrupt |
34240697 | 571 | * or NMI handler, return true. |
64db4cff | 572 | */ |
9b2e4f18 | 573 | int rcu_is_cpu_idle(void) |
64db4cff | 574 | { |
34240697 PM |
575 | int ret; |
576 | ||
577 | preempt_disable(); | |
578 | ret = (atomic_read(&__get_cpu_var(rcu_dynticks).dynticks) & 0x1) == 0; | |
579 | preempt_enable(); | |
580 | return ret; | |
64db4cff | 581 | } |
e6b80a3b | 582 | EXPORT_SYMBOL(rcu_is_cpu_idle); |
64db4cff | 583 | |
9b2e4f18 PM |
584 | #endif /* #ifdef CONFIG_PROVE_RCU */ |
585 | ||
64db4cff | 586 | /** |
9b2e4f18 | 587 | * rcu_is_cpu_rrupt_from_idle - see if idle or immediately interrupted from idle |
64db4cff | 588 | * |
9b2e4f18 PM |
589 | * If the current CPU is idle or running at a first-level (not nested) |
590 | * interrupt from idle, return true. The caller must have at least | |
591 | * disabled preemption. | |
64db4cff | 592 | */ |
9b2e4f18 | 593 | int rcu_is_cpu_rrupt_from_idle(void) |
64db4cff | 594 | { |
9b2e4f18 | 595 | return __get_cpu_var(rcu_dynticks).dynticks_nesting <= 1; |
64db4cff PM |
596 | } |
597 | ||
64db4cff PM |
598 | #ifdef CONFIG_SMP |
599 | ||
64db4cff PM |
600 | /* |
601 | * Snapshot the specified CPU's dynticks counter so that we can later | |
602 | * credit them with an implicit quiescent state. Return 1 if this CPU | |
1eba8f84 | 603 | * is in dynticks idle mode, which is an extended quiescent state. |
64db4cff PM |
604 | */ |
605 | static int dyntick_save_progress_counter(struct rcu_data *rdp) | |
606 | { | |
23b5c8fa | 607 | rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks); |
f0e7c19d | 608 | return (rdp->dynticks_snap & 0x1) == 0; |
64db4cff PM |
609 | } |
610 | ||
611 | /* | |
612 | * Return true if the specified CPU has passed through a quiescent | |
613 | * state by virtue of being in or having passed through an dynticks | |
614 | * idle state since the last call to dyntick_save_progress_counter() | |
615 | * for this same CPU. | |
616 | */ | |
617 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) | |
618 | { | |
7eb4f455 PM |
619 | unsigned int curr; |
620 | unsigned int snap; | |
64db4cff | 621 | |
7eb4f455 PM |
622 | curr = (unsigned int)atomic_add_return(0, &rdp->dynticks->dynticks); |
623 | snap = (unsigned int)rdp->dynticks_snap; | |
64db4cff PM |
624 | |
625 | /* | |
626 | * If the CPU passed through or entered a dynticks idle phase with | |
627 | * no active irq/NMI handlers, then we can safely pretend that the CPU | |
628 | * already acknowledged the request to pass through a quiescent | |
629 | * state. Either way, that CPU cannot possibly be in an RCU | |
630 | * read-side critical section that started before the beginning | |
631 | * of the current RCU grace period. | |
632 | */ | |
7eb4f455 | 633 | if ((curr & 0x1) == 0 || UINT_CMP_GE(curr, snap + 2)) { |
d4c08f2a | 634 | trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, "dti"); |
64db4cff PM |
635 | rdp->dynticks_fqs++; |
636 | return 1; | |
637 | } | |
638 | ||
639 | /* Go check for the CPU being offline. */ | |
640 | return rcu_implicit_offline_qs(rdp); | |
641 | } | |
642 | ||
643 | #endif /* #ifdef CONFIG_SMP */ | |
644 | ||
64db4cff PM |
645 | static void record_gp_stall_check_time(struct rcu_state *rsp) |
646 | { | |
647 | rsp->gp_start = jiffies; | |
648 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK; | |
649 | } | |
650 | ||
651 | static void print_other_cpu_stall(struct rcu_state *rsp) | |
652 | { | |
653 | int cpu; | |
654 | long delta; | |
655 | unsigned long flags; | |
9bc8b558 | 656 | int ndetected; |
64db4cff | 657 | struct rcu_node *rnp = rcu_get_root(rsp); |
64db4cff PM |
658 | |
659 | /* Only let one CPU complain about others per time interval. */ | |
660 | ||
1304afb2 | 661 | raw_spin_lock_irqsave(&rnp->lock, flags); |
64db4cff | 662 | delta = jiffies - rsp->jiffies_stall; |
fc2219d4 | 663 | if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) { |
1304afb2 | 664 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
665 | return; |
666 | } | |
667 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK; | |
a0b6c9a7 PM |
668 | |
669 | /* | |
670 | * Now rat on any tasks that got kicked up to the root rcu_node | |
671 | * due to CPU offlining. | |
672 | */ | |
9bc8b558 | 673 | ndetected = rcu_print_task_stall(rnp); |
1304afb2 | 674 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff | 675 | |
8cdd32a9 PM |
676 | /* |
677 | * OK, time to rat on our buddy... | |
678 | * See Documentation/RCU/stallwarn.txt for info on how to debug | |
679 | * RCU CPU stall warnings. | |
680 | */ | |
4300aa64 PM |
681 | printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {", |
682 | rsp->name); | |
a0b6c9a7 | 683 | rcu_for_each_leaf_node(rsp, rnp) { |
3acd9eb3 | 684 | raw_spin_lock_irqsave(&rnp->lock, flags); |
9bc8b558 | 685 | ndetected += rcu_print_task_stall(rnp); |
3acd9eb3 | 686 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
a0b6c9a7 | 687 | if (rnp->qsmask == 0) |
64db4cff | 688 | continue; |
a0b6c9a7 | 689 | for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) |
9bc8b558 | 690 | if (rnp->qsmask & (1UL << cpu)) { |
a0b6c9a7 | 691 | printk(" %d", rnp->grplo + cpu); |
9bc8b558 PM |
692 | ndetected++; |
693 | } | |
64db4cff | 694 | } |
4300aa64 | 695 | printk("} (detected by %d, t=%ld jiffies)\n", |
64db4cff | 696 | smp_processor_id(), (long)(jiffies - rsp->gp_start)); |
9bc8b558 PM |
697 | if (ndetected == 0) |
698 | printk(KERN_ERR "INFO: Stall ended before state dump start\n"); | |
699 | else if (!trigger_all_cpu_backtrace()) | |
4627e240 | 700 | dump_stack(); |
c1dc0b9c | 701 | |
1ed509a2 PM |
702 | /* If so configured, complain about tasks blocking the grace period. */ |
703 | ||
704 | rcu_print_detail_task_stall(rsp); | |
705 | ||
64db4cff PM |
706 | force_quiescent_state(rsp, 0); /* Kick them all. */ |
707 | } | |
708 | ||
709 | static void print_cpu_stall(struct rcu_state *rsp) | |
710 | { | |
711 | unsigned long flags; | |
712 | struct rcu_node *rnp = rcu_get_root(rsp); | |
713 | ||
8cdd32a9 PM |
714 | /* |
715 | * OK, time to rat on ourselves... | |
716 | * See Documentation/RCU/stallwarn.txt for info on how to debug | |
717 | * RCU CPU stall warnings. | |
718 | */ | |
4300aa64 PM |
719 | printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n", |
720 | rsp->name, smp_processor_id(), jiffies - rsp->gp_start); | |
4627e240 PM |
721 | if (!trigger_all_cpu_backtrace()) |
722 | dump_stack(); | |
c1dc0b9c | 723 | |
1304afb2 | 724 | raw_spin_lock_irqsave(&rnp->lock, flags); |
20133cfc | 725 | if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) |
64db4cff PM |
726 | rsp->jiffies_stall = |
727 | jiffies + RCU_SECONDS_TILL_STALL_RECHECK; | |
1304afb2 | 728 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
c1dc0b9c | 729 | |
64db4cff PM |
730 | set_need_resched(); /* kick ourselves to get things going. */ |
731 | } | |
732 | ||
733 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) | |
734 | { | |
bad6e139 PM |
735 | unsigned long j; |
736 | unsigned long js; | |
64db4cff PM |
737 | struct rcu_node *rnp; |
738 | ||
742734ee | 739 | if (rcu_cpu_stall_suppress) |
c68de209 | 740 | return; |
bad6e139 PM |
741 | j = ACCESS_ONCE(jiffies); |
742 | js = ACCESS_ONCE(rsp->jiffies_stall); | |
64db4cff | 743 | rnp = rdp->mynode; |
bad6e139 | 744 | if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && ULONG_CMP_GE(j, js)) { |
64db4cff PM |
745 | |
746 | /* We haven't checked in, so go dump stack. */ | |
747 | print_cpu_stall(rsp); | |
748 | ||
bad6e139 PM |
749 | } else if (rcu_gp_in_progress(rsp) && |
750 | ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY)) { | |
64db4cff | 751 | |
bad6e139 | 752 | /* They had a few time units to dump stack, so complain. */ |
64db4cff PM |
753 | print_other_cpu_stall(rsp); |
754 | } | |
755 | } | |
756 | ||
c68de209 PM |
757 | static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) |
758 | { | |
742734ee | 759 | rcu_cpu_stall_suppress = 1; |
c68de209 PM |
760 | return NOTIFY_DONE; |
761 | } | |
762 | ||
53d84e00 PM |
763 | /** |
764 | * rcu_cpu_stall_reset - prevent further stall warnings in current grace period | |
765 | * | |
766 | * Set the stall-warning timeout way off into the future, thus preventing | |
767 | * any RCU CPU stall-warning messages from appearing in the current set of | |
768 | * RCU grace periods. | |
769 | * | |
770 | * The caller must disable hard irqs. | |
771 | */ | |
772 | void rcu_cpu_stall_reset(void) | |
773 | { | |
774 | rcu_sched_state.jiffies_stall = jiffies + ULONG_MAX / 2; | |
775 | rcu_bh_state.jiffies_stall = jiffies + ULONG_MAX / 2; | |
776 | rcu_preempt_stall_reset(); | |
777 | } | |
778 | ||
c68de209 PM |
779 | static struct notifier_block rcu_panic_block = { |
780 | .notifier_call = rcu_panic, | |
781 | }; | |
782 | ||
783 | static void __init check_cpu_stall_init(void) | |
784 | { | |
785 | atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); | |
786 | } | |
787 | ||
64db4cff PM |
788 | /* |
789 | * Update CPU-local rcu_data state to record the newly noticed grace period. | |
790 | * This is used both when we started the grace period and when we notice | |
9160306e PM |
791 | * that someone else started the grace period. The caller must hold the |
792 | * ->lock of the leaf rcu_node structure corresponding to the current CPU, | |
793 | * and must have irqs disabled. | |
64db4cff | 794 | */ |
9160306e PM |
795 | static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
796 | { | |
797 | if (rdp->gpnum != rnp->gpnum) { | |
121dfc4b PM |
798 | /* |
799 | * If the current grace period is waiting for this CPU, | |
800 | * set up to detect a quiescent state, otherwise don't | |
801 | * go looking for one. | |
802 | */ | |
9160306e | 803 | rdp->gpnum = rnp->gpnum; |
d4c08f2a | 804 | trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpustart"); |
121dfc4b PM |
805 | if (rnp->qsmask & rdp->grpmask) { |
806 | rdp->qs_pending = 1; | |
e4cc1f22 | 807 | rdp->passed_quiesce = 0; |
121dfc4b PM |
808 | } else |
809 | rdp->qs_pending = 0; | |
9160306e PM |
810 | } |
811 | } | |
812 | ||
64db4cff PM |
813 | static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp) |
814 | { | |
9160306e PM |
815 | unsigned long flags; |
816 | struct rcu_node *rnp; | |
817 | ||
818 | local_irq_save(flags); | |
819 | rnp = rdp->mynode; | |
820 | if (rdp->gpnum == ACCESS_ONCE(rnp->gpnum) || /* outside lock. */ | |
1304afb2 | 821 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
9160306e PM |
822 | local_irq_restore(flags); |
823 | return; | |
824 | } | |
825 | __note_new_gpnum(rsp, rnp, rdp); | |
1304afb2 | 826 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
827 | } |
828 | ||
829 | /* | |
830 | * Did someone else start a new RCU grace period start since we last | |
831 | * checked? Update local state appropriately if so. Must be called | |
832 | * on the CPU corresponding to rdp. | |
833 | */ | |
834 | static int | |
835 | check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp) | |
836 | { | |
837 | unsigned long flags; | |
838 | int ret = 0; | |
839 | ||
840 | local_irq_save(flags); | |
841 | if (rdp->gpnum != rsp->gpnum) { | |
842 | note_new_gpnum(rsp, rdp); | |
843 | ret = 1; | |
844 | } | |
845 | local_irq_restore(flags); | |
846 | return ret; | |
847 | } | |
848 | ||
d09b62df PM |
849 | /* |
850 | * Advance this CPU's callbacks, but only if the current grace period | |
851 | * has ended. This may be called only from the CPU to whom the rdp | |
852 | * belongs. In addition, the corresponding leaf rcu_node structure's | |
853 | * ->lock must be held by the caller, with irqs disabled. | |
854 | */ | |
855 | static void | |
856 | __rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) | |
857 | { | |
858 | /* Did another grace period end? */ | |
859 | if (rdp->completed != rnp->completed) { | |
860 | ||
861 | /* Advance callbacks. No harm if list empty. */ | |
862 | rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL]; | |
863 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL]; | |
864 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
865 | ||
866 | /* Remember that we saw this grace-period completion. */ | |
867 | rdp->completed = rnp->completed; | |
d4c08f2a | 868 | trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpuend"); |
20377f32 | 869 | |
5ff8e6f0 FW |
870 | /* |
871 | * If we were in an extended quiescent state, we may have | |
121dfc4b | 872 | * missed some grace periods that others CPUs handled on |
5ff8e6f0 | 873 | * our behalf. Catch up with this state to avoid noting |
121dfc4b PM |
874 | * spurious new grace periods. If another grace period |
875 | * has started, then rnp->gpnum will have advanced, so | |
876 | * we will detect this later on. | |
5ff8e6f0 | 877 | */ |
121dfc4b | 878 | if (ULONG_CMP_LT(rdp->gpnum, rdp->completed)) |
5ff8e6f0 FW |
879 | rdp->gpnum = rdp->completed; |
880 | ||
20377f32 | 881 | /* |
121dfc4b PM |
882 | * If RCU does not need a quiescent state from this CPU, |
883 | * then make sure that this CPU doesn't go looking for one. | |
20377f32 | 884 | */ |
121dfc4b | 885 | if ((rnp->qsmask & rdp->grpmask) == 0) |
20377f32 | 886 | rdp->qs_pending = 0; |
d09b62df PM |
887 | } |
888 | } | |
889 | ||
890 | /* | |
891 | * Advance this CPU's callbacks, but only if the current grace period | |
892 | * has ended. This may be called only from the CPU to whom the rdp | |
893 | * belongs. | |
894 | */ | |
895 | static void | |
896 | rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp) | |
897 | { | |
898 | unsigned long flags; | |
899 | struct rcu_node *rnp; | |
900 | ||
901 | local_irq_save(flags); | |
902 | rnp = rdp->mynode; | |
903 | if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */ | |
1304afb2 | 904 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
d09b62df PM |
905 | local_irq_restore(flags); |
906 | return; | |
907 | } | |
908 | __rcu_process_gp_end(rsp, rnp, rdp); | |
1304afb2 | 909 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
d09b62df PM |
910 | } |
911 | ||
912 | /* | |
913 | * Do per-CPU grace-period initialization for running CPU. The caller | |
914 | * must hold the lock of the leaf rcu_node structure corresponding to | |
915 | * this CPU. | |
916 | */ | |
917 | static void | |
918 | rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) | |
919 | { | |
920 | /* Prior grace period ended, so advance callbacks for current CPU. */ | |
921 | __rcu_process_gp_end(rsp, rnp, rdp); | |
922 | ||
923 | /* | |
924 | * Because this CPU just now started the new grace period, we know | |
925 | * that all of its callbacks will be covered by this upcoming grace | |
926 | * period, even the ones that were registered arbitrarily recently. | |
927 | * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL. | |
928 | * | |
929 | * Other CPUs cannot be sure exactly when the grace period started. | |
930 | * Therefore, their recently registered callbacks must pass through | |
931 | * an additional RCU_NEXT_READY stage, so that they will be handled | |
932 | * by the next RCU grace period. | |
933 | */ | |
934 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
935 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
9160306e PM |
936 | |
937 | /* Set state so that this CPU will detect the next quiescent state. */ | |
938 | __note_new_gpnum(rsp, rnp, rdp); | |
d09b62df PM |
939 | } |
940 | ||
64db4cff PM |
941 | /* |
942 | * Start a new RCU grace period if warranted, re-initializing the hierarchy | |
943 | * in preparation for detecting the next grace period. The caller must hold | |
944 | * the root node's ->lock, which is released before return. Hard irqs must | |
945 | * be disabled. | |
e5601400 PM |
946 | * |
947 | * Note that it is legal for a dying CPU (which is marked as offline) to | |
948 | * invoke this function. This can happen when the dying CPU reports its | |
949 | * quiescent state. | |
64db4cff PM |
950 | */ |
951 | static void | |
952 | rcu_start_gp(struct rcu_state *rsp, unsigned long flags) | |
953 | __releases(rcu_get_root(rsp)->lock) | |
954 | { | |
394f99a9 | 955 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
64db4cff | 956 | struct rcu_node *rnp = rcu_get_root(rsp); |
64db4cff | 957 | |
037067a1 | 958 | if (!rcu_scheduler_fully_active || |
afe24b12 PM |
959 | !cpu_needs_another_gp(rsp, rdp)) { |
960 | /* | |
961 | * Either the scheduler hasn't yet spawned the first | |
962 | * non-idle task or this CPU does not need another | |
963 | * grace period. Either way, don't start a new grace | |
964 | * period. | |
965 | */ | |
966 | raw_spin_unlock_irqrestore(&rnp->lock, flags); | |
967 | return; | |
968 | } | |
b32e9eb6 | 969 | |
afe24b12 | 970 | if (rsp->fqs_active) { |
b32e9eb6 | 971 | /* |
afe24b12 PM |
972 | * This CPU needs a grace period, but force_quiescent_state() |
973 | * is running. Tell it to start one on this CPU's behalf. | |
b32e9eb6 | 974 | */ |
afe24b12 PM |
975 | rsp->fqs_need_gp = 1; |
976 | raw_spin_unlock_irqrestore(&rnp->lock, flags); | |
64db4cff PM |
977 | return; |
978 | } | |
979 | ||
980 | /* Advance to a new grace period and initialize state. */ | |
981 | rsp->gpnum++; | |
d4c08f2a | 982 | trace_rcu_grace_period(rsp->name, rsp->gpnum, "start"); |
af446b70 PM |
983 | WARN_ON_ONCE(rsp->fqs_state == RCU_GP_INIT); |
984 | rsp->fqs_state = RCU_GP_INIT; /* Hold off force_quiescent_state. */ | |
64db4cff | 985 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
64db4cff | 986 | record_gp_stall_check_time(rsp); |
1304afb2 | 987 | raw_spin_unlock(&rnp->lock); /* leave irqs disabled. */ |
64db4cff | 988 | |
64db4cff | 989 | /* Exclude any concurrent CPU-hotplug operations. */ |
1304afb2 | 990 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
64db4cff PM |
991 | |
992 | /* | |
b835db1f PM |
993 | * Set the quiescent-state-needed bits in all the rcu_node |
994 | * structures for all currently online CPUs in breadth-first | |
995 | * order, starting from the root rcu_node structure. This | |
996 | * operation relies on the layout of the hierarchy within the | |
997 | * rsp->node[] array. Note that other CPUs will access only | |
998 | * the leaves of the hierarchy, which still indicate that no | |
999 | * grace period is in progress, at least until the corresponding | |
1000 | * leaf node has been initialized. In addition, we have excluded | |
1001 | * CPU-hotplug operations. | |
64db4cff PM |
1002 | * |
1003 | * Note that the grace period cannot complete until we finish | |
1004 | * the initialization process, as there will be at least one | |
1005 | * qsmask bit set in the root node until that time, namely the | |
b835db1f PM |
1006 | * one corresponding to this CPU, due to the fact that we have |
1007 | * irqs disabled. | |
64db4cff | 1008 | */ |
a0b6c9a7 | 1009 | rcu_for_each_node_breadth_first(rsp, rnp) { |
1304afb2 | 1010 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
b0e165c0 | 1011 | rcu_preempt_check_blocked_tasks(rnp); |
49e29126 | 1012 | rnp->qsmask = rnp->qsmaskinit; |
de078d87 | 1013 | rnp->gpnum = rsp->gpnum; |
d09b62df PM |
1014 | rnp->completed = rsp->completed; |
1015 | if (rnp == rdp->mynode) | |
1016 | rcu_start_gp_per_cpu(rsp, rnp, rdp); | |
27f4d280 | 1017 | rcu_preempt_boost_start_gp(rnp); |
d4c08f2a PM |
1018 | trace_rcu_grace_period_init(rsp->name, rnp->gpnum, |
1019 | rnp->level, rnp->grplo, | |
1020 | rnp->grphi, rnp->qsmask); | |
1304afb2 | 1021 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff PM |
1022 | } |
1023 | ||
83f5b01f | 1024 | rnp = rcu_get_root(rsp); |
1304afb2 | 1025 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
af446b70 | 1026 | rsp->fqs_state = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ |
1304afb2 PM |
1027 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
1028 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); | |
64db4cff PM |
1029 | } |
1030 | ||
f41d911f | 1031 | /* |
d3f6bad3 PM |
1032 | * Report a full set of quiescent states to the specified rcu_state |
1033 | * data structure. This involves cleaning up after the prior grace | |
1034 | * period and letting rcu_start_gp() start up the next grace period | |
1035 | * if one is needed. Note that the caller must hold rnp->lock, as | |
1036 | * required by rcu_start_gp(), which will release it. | |
f41d911f | 1037 | */ |
d3f6bad3 | 1038 | static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) |
fc2219d4 | 1039 | __releases(rcu_get_root(rsp)->lock) |
f41d911f | 1040 | { |
15ba0ba8 | 1041 | unsigned long gp_duration; |
afe24b12 PM |
1042 | struct rcu_node *rnp = rcu_get_root(rsp); |
1043 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); | |
15ba0ba8 | 1044 | |
fc2219d4 | 1045 | WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); |
0bbcc529 PM |
1046 | |
1047 | /* | |
1048 | * Ensure that all grace-period and pre-grace-period activity | |
1049 | * is seen before the assignment to rsp->completed. | |
1050 | */ | |
1051 | smp_mb(); /* See above block comment. */ | |
15ba0ba8 PM |
1052 | gp_duration = jiffies - rsp->gp_start; |
1053 | if (gp_duration > rsp->gp_max) | |
1054 | rsp->gp_max = gp_duration; | |
afe24b12 PM |
1055 | |
1056 | /* | |
1057 | * We know the grace period is complete, but to everyone else | |
1058 | * it appears to still be ongoing. But it is also the case | |
1059 | * that to everyone else it looks like there is nothing that | |
1060 | * they can do to advance the grace period. It is therefore | |
1061 | * safe for us to drop the lock in order to mark the grace | |
1062 | * period as completed in all of the rcu_node structures. | |
1063 | * | |
1064 | * But if this CPU needs another grace period, it will take | |
1065 | * care of this while initializing the next grace period. | |
1066 | * We use RCU_WAIT_TAIL instead of the usual RCU_DONE_TAIL | |
1067 | * because the callbacks have not yet been advanced: Those | |
1068 | * callbacks are waiting on the grace period that just now | |
1069 | * completed. | |
1070 | */ | |
1071 | if (*rdp->nxttail[RCU_WAIT_TAIL] == NULL) { | |
1072 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ | |
1073 | ||
1074 | /* | |
1075 | * Propagate new ->completed value to rcu_node structures | |
1076 | * so that other CPUs don't have to wait until the start | |
1077 | * of the next grace period to process their callbacks. | |
1078 | */ | |
1079 | rcu_for_each_node_breadth_first(rsp, rnp) { | |
1080 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ | |
1081 | rnp->completed = rsp->gpnum; | |
1082 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ | |
1083 | } | |
1084 | rnp = rcu_get_root(rsp); | |
1085 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ | |
1086 | } | |
1087 | ||
1088 | rsp->completed = rsp->gpnum; /* Declare the grace period complete. */ | |
d4c08f2a | 1089 | trace_rcu_grace_period(rsp->name, rsp->completed, "end"); |
af446b70 | 1090 | rsp->fqs_state = RCU_GP_IDLE; |
f41d911f PM |
1091 | rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ |
1092 | } | |
1093 | ||
64db4cff | 1094 | /* |
d3f6bad3 PM |
1095 | * Similar to rcu_report_qs_rdp(), for which it is a helper function. |
1096 | * Allows quiescent states for a group of CPUs to be reported at one go | |
1097 | * to the specified rcu_node structure, though all the CPUs in the group | |
1098 | * must be represented by the same rcu_node structure (which need not be | |
1099 | * a leaf rcu_node structure, though it often will be). That structure's | |
1100 | * lock must be held upon entry, and it is released before return. | |
64db4cff PM |
1101 | */ |
1102 | static void | |
d3f6bad3 PM |
1103 | rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, |
1104 | struct rcu_node *rnp, unsigned long flags) | |
64db4cff PM |
1105 | __releases(rnp->lock) |
1106 | { | |
28ecd580 PM |
1107 | struct rcu_node *rnp_c; |
1108 | ||
64db4cff PM |
1109 | /* Walk up the rcu_node hierarchy. */ |
1110 | for (;;) { | |
1111 | if (!(rnp->qsmask & mask)) { | |
1112 | ||
1113 | /* Our bit has already been cleared, so done. */ | |
1304afb2 | 1114 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
1115 | return; |
1116 | } | |
1117 | rnp->qsmask &= ~mask; | |
d4c08f2a PM |
1118 | trace_rcu_quiescent_state_report(rsp->name, rnp->gpnum, |
1119 | mask, rnp->qsmask, rnp->level, | |
1120 | rnp->grplo, rnp->grphi, | |
1121 | !!rnp->gp_tasks); | |
27f4d280 | 1122 | if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) { |
64db4cff PM |
1123 | |
1124 | /* Other bits still set at this level, so done. */ | |
1304afb2 | 1125 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
1126 | return; |
1127 | } | |
1128 | mask = rnp->grpmask; | |
1129 | if (rnp->parent == NULL) { | |
1130 | ||
1131 | /* No more levels. Exit loop holding root lock. */ | |
1132 | ||
1133 | break; | |
1134 | } | |
1304afb2 | 1135 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
28ecd580 | 1136 | rnp_c = rnp; |
64db4cff | 1137 | rnp = rnp->parent; |
1304afb2 | 1138 | raw_spin_lock_irqsave(&rnp->lock, flags); |
28ecd580 | 1139 | WARN_ON_ONCE(rnp_c->qsmask); |
64db4cff PM |
1140 | } |
1141 | ||
1142 | /* | |
1143 | * Get here if we are the last CPU to pass through a quiescent | |
d3f6bad3 | 1144 | * state for this grace period. Invoke rcu_report_qs_rsp() |
f41d911f | 1145 | * to clean up and start the next grace period if one is needed. |
64db4cff | 1146 | */ |
d3f6bad3 | 1147 | rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */ |
64db4cff PM |
1148 | } |
1149 | ||
1150 | /* | |
d3f6bad3 PM |
1151 | * Record a quiescent state for the specified CPU to that CPU's rcu_data |
1152 | * structure. This must be either called from the specified CPU, or | |
1153 | * called when the specified CPU is known to be offline (and when it is | |
1154 | * also known that no other CPU is concurrently trying to help the offline | |
1155 | * CPU). The lastcomp argument is used to make sure we are still in the | |
1156 | * grace period of interest. We don't want to end the current grace period | |
1157 | * based on quiescent states detected in an earlier grace period! | |
64db4cff PM |
1158 | */ |
1159 | static void | |
e4cc1f22 | 1160 | rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastgp) |
64db4cff PM |
1161 | { |
1162 | unsigned long flags; | |
1163 | unsigned long mask; | |
1164 | struct rcu_node *rnp; | |
1165 | ||
1166 | rnp = rdp->mynode; | |
1304afb2 | 1167 | raw_spin_lock_irqsave(&rnp->lock, flags); |
e4cc1f22 | 1168 | if (lastgp != rnp->gpnum || rnp->completed == rnp->gpnum) { |
64db4cff PM |
1169 | |
1170 | /* | |
e4cc1f22 PM |
1171 | * The grace period in which this quiescent state was |
1172 | * recorded has ended, so don't report it upwards. | |
1173 | * We will instead need a new quiescent state that lies | |
1174 | * within the current grace period. | |
64db4cff | 1175 | */ |
e4cc1f22 | 1176 | rdp->passed_quiesce = 0; /* need qs for new gp. */ |
1304afb2 | 1177 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
1178 | return; |
1179 | } | |
1180 | mask = rdp->grpmask; | |
1181 | if ((rnp->qsmask & mask) == 0) { | |
1304afb2 | 1182 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
1183 | } else { |
1184 | rdp->qs_pending = 0; | |
1185 | ||
1186 | /* | |
1187 | * This GP can't end until cpu checks in, so all of our | |
1188 | * callbacks can be processed during the next GP. | |
1189 | */ | |
64db4cff PM |
1190 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
1191 | ||
d3f6bad3 | 1192 | rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */ |
64db4cff PM |
1193 | } |
1194 | } | |
1195 | ||
1196 | /* | |
1197 | * Check to see if there is a new grace period of which this CPU | |
1198 | * is not yet aware, and if so, set up local rcu_data state for it. | |
1199 | * Otherwise, see if this CPU has just passed through its first | |
1200 | * quiescent state for this grace period, and record that fact if so. | |
1201 | */ | |
1202 | static void | |
1203 | rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) | |
1204 | { | |
1205 | /* If there is now a new grace period, record and return. */ | |
1206 | if (check_for_new_grace_period(rsp, rdp)) | |
1207 | return; | |
1208 | ||
1209 | /* | |
1210 | * Does this CPU still need to do its part for current grace period? | |
1211 | * If no, return and let the other CPUs do their part as well. | |
1212 | */ | |
1213 | if (!rdp->qs_pending) | |
1214 | return; | |
1215 | ||
1216 | /* | |
1217 | * Was there a quiescent state since the beginning of the grace | |
1218 | * period? If no, then exit and wait for the next call. | |
1219 | */ | |
e4cc1f22 | 1220 | if (!rdp->passed_quiesce) |
64db4cff PM |
1221 | return; |
1222 | ||
d3f6bad3 PM |
1223 | /* |
1224 | * Tell RCU we are done (but rcu_report_qs_rdp() will be the | |
1225 | * judge of that). | |
1226 | */ | |
e4cc1f22 | 1227 | rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesce_gpnum); |
64db4cff PM |
1228 | } |
1229 | ||
1230 | #ifdef CONFIG_HOTPLUG_CPU | |
1231 | ||
e74f4c45 | 1232 | /* |
29494be7 | 1233 | * Move a dying CPU's RCU callbacks to online CPU's callback list. |
e5601400 PM |
1234 | * Also record a quiescent state for this CPU for the current grace period. |
1235 | * Synchronization and interrupt disabling are not required because | |
1236 | * this function executes in stop_machine() context. Therefore, cleanup | |
1237 | * operations that might block must be done later from the CPU_DEAD | |
1238 | * notifier. | |
1239 | * | |
1240 | * Note that the outgoing CPU's bit has already been cleared in the | |
1241 | * cpu_online_mask. This allows us to randomly pick a callback | |
1242 | * destination from the bits set in that mask. | |
e74f4c45 | 1243 | */ |
e5601400 | 1244 | static void rcu_cleanup_dying_cpu(struct rcu_state *rsp) |
e74f4c45 | 1245 | { |
e5601400 | 1246 | unsigned long flags; |
e74f4c45 | 1247 | int i; |
e5601400 PM |
1248 | unsigned long mask; |
1249 | int need_report; | |
29494be7 | 1250 | int receive_cpu = cpumask_any(cpu_online_mask); |
394f99a9 | 1251 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
29494be7 | 1252 | struct rcu_data *receive_rdp = per_cpu_ptr(rsp->rda, receive_cpu); |
e5601400 PM |
1253 | struct rcu_node *rnp = rdp->mynode; /* For dying CPU. */ |
1254 | ||
a50c3af9 PM |
1255 | /* First, adjust the counts. */ |
1256 | if (rdp->nxtlist != NULL) { | |
1257 | receive_rdp->qlen_lazy += rdp->qlen_lazy; | |
1258 | receive_rdp->qlen += rdp->qlen; | |
1259 | rdp->qlen_lazy = 0; | |
1260 | rdp->qlen = 0; | |
1261 | } | |
1262 | ||
1263 | /* | |
1264 | * Next, move ready-to-invoke callbacks to be invoked on some | |
1265 | * other CPU. These will not be required to pass through another | |
1266 | * grace period: They are done, regardless of CPU. | |
1267 | */ | |
1268 | if (rdp->nxtlist != NULL && | |
1269 | rdp->nxttail[RCU_DONE_TAIL] != &rdp->nxtlist) { | |
1270 | struct rcu_head *oldhead; | |
1271 | struct rcu_head **oldtail; | |
1272 | struct rcu_head **newtail; | |
1273 | ||
1274 | oldhead = rdp->nxtlist; | |
1275 | oldtail = receive_rdp->nxttail[RCU_DONE_TAIL]; | |
1276 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; | |
1277 | *rdp->nxttail[RCU_DONE_TAIL] = *oldtail; | |
1278 | *receive_rdp->nxttail[RCU_DONE_TAIL] = oldhead; | |
1279 | newtail = rdp->nxttail[RCU_DONE_TAIL]; | |
1280 | for (i = RCU_DONE_TAIL; i < RCU_NEXT_SIZE; i++) { | |
1281 | if (receive_rdp->nxttail[i] == oldtail) | |
1282 | receive_rdp->nxttail[i] = newtail; | |
1283 | if (rdp->nxttail[i] == newtail) | |
1284 | rdp->nxttail[i] = &rdp->nxtlist; | |
1285 | } | |
1286 | } | |
1287 | ||
1288 | /* | |
1289 | * Finally, put the rest of the callbacks at the end of the list. | |
1290 | * The ones that made it partway through get to start over: We | |
1291 | * cannot assume that grace periods are synchronized across CPUs. | |
1292 | * (We could splice RCU_WAIT_TAIL into RCU_NEXT_READY_TAIL, but | |
1293 | * this does not seem compelling. Not yet, anyway.) | |
1294 | */ | |
e5601400 PM |
1295 | if (rdp->nxtlist != NULL) { |
1296 | *receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxtlist; | |
1297 | receive_rdp->nxttail[RCU_NEXT_TAIL] = | |
1298 | rdp->nxttail[RCU_NEXT_TAIL]; | |
e5601400 PM |
1299 | receive_rdp->n_cbs_adopted += rdp->qlen; |
1300 | rdp->n_cbs_orphaned += rdp->qlen; | |
1301 | ||
1302 | rdp->nxtlist = NULL; | |
1303 | for (i = 0; i < RCU_NEXT_SIZE; i++) | |
1304 | rdp->nxttail[i] = &rdp->nxtlist; | |
e5601400 | 1305 | } |
e74f4c45 | 1306 | |
a50c3af9 PM |
1307 | /* |
1308 | * Record a quiescent state for the dying CPU. This is safe | |
1309 | * only because we have already cleared out the callbacks. | |
1310 | * (Otherwise, the RCU core might try to schedule the invocation | |
1311 | * of callbacks on this now-offline CPU, which would be bad.) | |
1312 | */ | |
64db4cff | 1313 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
e5601400 PM |
1314 | trace_rcu_grace_period(rsp->name, |
1315 | rnp->gpnum + 1 - !!(rnp->qsmask & mask), | |
1316 | "cpuofl"); | |
1317 | rcu_report_qs_rdp(smp_processor_id(), rsp, rdp, rsp->gpnum); | |
1318 | /* Note that rcu_report_qs_rdp() might call trace_rcu_grace_period(). */ | |
1319 | ||
1320 | /* | |
1321 | * Remove the dying CPU from the bitmasks in the rcu_node | |
1322 | * hierarchy. Because we are in stop_machine() context, we | |
1323 | * automatically exclude ->onofflock critical sections. | |
1324 | */ | |
64db4cff | 1325 | do { |
e5601400 | 1326 | raw_spin_lock_irqsave(&rnp->lock, flags); |
64db4cff PM |
1327 | rnp->qsmaskinit &= ~mask; |
1328 | if (rnp->qsmaskinit != 0) { | |
e5601400 | 1329 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
1330 | break; |
1331 | } | |
d4c08f2a | 1332 | if (rnp == rdp->mynode) { |
d9a3da06 | 1333 | need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp); |
e5601400 PM |
1334 | if (need_report & RCU_OFL_TASKS_NORM_GP) |
1335 | rcu_report_unblock_qs_rnp(rnp, flags); | |
1336 | else | |
1337 | raw_spin_unlock_irqrestore(&rnp->lock, flags); | |
1338 | if (need_report & RCU_OFL_TASKS_EXP_GP) | |
1339 | rcu_report_exp_rnp(rsp, rnp, true); | |
d4c08f2a | 1340 | } else |
e5601400 | 1341 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff | 1342 | mask = rnp->grpmask; |
64db4cff PM |
1343 | rnp = rnp->parent; |
1344 | } while (rnp != NULL); | |
64db4cff PM |
1345 | } |
1346 | ||
1347 | /* | |
e5601400 PM |
1348 | * The CPU has been completely removed, and some other CPU is reporting |
1349 | * this fact from process context. Do the remainder of the cleanup. | |
1350 | * There can only be one CPU hotplug operation at a time, so no other | |
1351 | * CPU can be attempting to update rcu_cpu_kthread_task. | |
64db4cff | 1352 | */ |
e5601400 | 1353 | static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp) |
64db4cff | 1354 | { |
e5601400 PM |
1355 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
1356 | struct rcu_node *rnp = rdp->mynode; | |
1357 | ||
1358 | rcu_stop_cpu_kthread(cpu); | |
1359 | rcu_node_kthread_setaffinity(rnp, -1); | |
64db4cff PM |
1360 | } |
1361 | ||
1362 | #else /* #ifdef CONFIG_HOTPLUG_CPU */ | |
1363 | ||
e5601400 | 1364 | static void rcu_cleanup_dying_cpu(struct rcu_state *rsp) |
e74f4c45 PM |
1365 | { |
1366 | } | |
1367 | ||
e5601400 | 1368 | static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp) |
64db4cff PM |
1369 | { |
1370 | } | |
1371 | ||
1372 | #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ | |
1373 | ||
1374 | /* | |
1375 | * Invoke any RCU callbacks that have made it to the end of their grace | |
1376 | * period. Thottle as specified by rdp->blimit. | |
1377 | */ | |
37c72e56 | 1378 | static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) |
64db4cff PM |
1379 | { |
1380 | unsigned long flags; | |
1381 | struct rcu_head *next, *list, **tail; | |
486e2593 | 1382 | int bl, count, count_lazy; |
64db4cff PM |
1383 | |
1384 | /* If no callbacks are ready, just return.*/ | |
29c00b4a | 1385 | if (!cpu_has_callbacks_ready_to_invoke(rdp)) { |
486e2593 | 1386 | trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, 0); |
4968c300 PM |
1387 | trace_rcu_batch_end(rsp->name, 0, !!ACCESS_ONCE(rdp->nxtlist), |
1388 | need_resched(), is_idle_task(current), | |
1389 | rcu_is_callbacks_kthread()); | |
64db4cff | 1390 | return; |
29c00b4a | 1391 | } |
64db4cff PM |
1392 | |
1393 | /* | |
1394 | * Extract the list of ready callbacks, disabling to prevent | |
1395 | * races with call_rcu() from interrupt handlers. | |
1396 | */ | |
1397 | local_irq_save(flags); | |
8146c4e2 | 1398 | WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); |
29c00b4a | 1399 | bl = rdp->blimit; |
486e2593 | 1400 | trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, bl); |
64db4cff PM |
1401 | list = rdp->nxtlist; |
1402 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; | |
1403 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; | |
1404 | tail = rdp->nxttail[RCU_DONE_TAIL]; | |
1405 | for (count = RCU_NEXT_SIZE - 1; count >= 0; count--) | |
1406 | if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL]) | |
1407 | rdp->nxttail[count] = &rdp->nxtlist; | |
1408 | local_irq_restore(flags); | |
1409 | ||
1410 | /* Invoke callbacks. */ | |
486e2593 | 1411 | count = count_lazy = 0; |
64db4cff PM |
1412 | while (list) { |
1413 | next = list->next; | |
1414 | prefetch(next); | |
551d55a9 | 1415 | debug_rcu_head_unqueue(list); |
486e2593 PM |
1416 | if (__rcu_reclaim(rsp->name, list)) |
1417 | count_lazy++; | |
64db4cff | 1418 | list = next; |
dff1672d PM |
1419 | /* Stop only if limit reached and CPU has something to do. */ |
1420 | if (++count >= bl && | |
1421 | (need_resched() || | |
1422 | (!is_idle_task(current) && !rcu_is_callbacks_kthread()))) | |
64db4cff PM |
1423 | break; |
1424 | } | |
1425 | ||
1426 | local_irq_save(flags); | |
4968c300 PM |
1427 | trace_rcu_batch_end(rsp->name, count, !!list, need_resched(), |
1428 | is_idle_task(current), | |
1429 | rcu_is_callbacks_kthread()); | |
64db4cff PM |
1430 | |
1431 | /* Update count, and requeue any remaining callbacks. */ | |
486e2593 | 1432 | rdp->qlen_lazy -= count_lazy; |
64db4cff | 1433 | rdp->qlen -= count; |
269dcc1c | 1434 | rdp->n_cbs_invoked += count; |
64db4cff PM |
1435 | if (list != NULL) { |
1436 | *tail = rdp->nxtlist; | |
1437 | rdp->nxtlist = list; | |
1438 | for (count = 0; count < RCU_NEXT_SIZE; count++) | |
1439 | if (&rdp->nxtlist == rdp->nxttail[count]) | |
1440 | rdp->nxttail[count] = tail; | |
1441 | else | |
1442 | break; | |
1443 | } | |
1444 | ||
1445 | /* Reinstate batch limit if we have worked down the excess. */ | |
1446 | if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark) | |
1447 | rdp->blimit = blimit; | |
1448 | ||
37c72e56 PM |
1449 | /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ |
1450 | if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) { | |
1451 | rdp->qlen_last_fqs_check = 0; | |
1452 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
1453 | } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark) | |
1454 | rdp->qlen_last_fqs_check = rdp->qlen; | |
1455 | ||
64db4cff PM |
1456 | local_irq_restore(flags); |
1457 | ||
e0f23060 | 1458 | /* Re-invoke RCU core processing if there are callbacks remaining. */ |
64db4cff | 1459 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
a46e0899 | 1460 | invoke_rcu_core(); |
64db4cff PM |
1461 | } |
1462 | ||
1463 | /* | |
1464 | * Check to see if this CPU is in a non-context-switch quiescent state | |
1465 | * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). | |
e0f23060 | 1466 | * Also schedule RCU core processing. |
64db4cff | 1467 | * |
9b2e4f18 | 1468 | * This function must be called from hardirq context. It is normally |
64db4cff PM |
1469 | * invoked from the scheduling-clock interrupt. If rcu_pending returns |
1470 | * false, there is no point in invoking rcu_check_callbacks(). | |
1471 | */ | |
1472 | void rcu_check_callbacks(int cpu, int user) | |
1473 | { | |
300df91c | 1474 | trace_rcu_utilization("Start scheduler-tick"); |
9b2e4f18 | 1475 | if (user || rcu_is_cpu_rrupt_from_idle()) { |
64db4cff PM |
1476 | |
1477 | /* | |
1478 | * Get here if this CPU took its interrupt from user | |
1479 | * mode or from the idle loop, and if this is not a | |
1480 | * nested interrupt. In this case, the CPU is in | |
d6714c22 | 1481 | * a quiescent state, so note it. |
64db4cff PM |
1482 | * |
1483 | * No memory barrier is required here because both | |
d6714c22 PM |
1484 | * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local |
1485 | * variables that other CPUs neither access nor modify, | |
1486 | * at least not while the corresponding CPU is online. | |
64db4cff PM |
1487 | */ |
1488 | ||
d6714c22 PM |
1489 | rcu_sched_qs(cpu); |
1490 | rcu_bh_qs(cpu); | |
64db4cff PM |
1491 | |
1492 | } else if (!in_softirq()) { | |
1493 | ||
1494 | /* | |
1495 | * Get here if this CPU did not take its interrupt from | |
1496 | * softirq, in other words, if it is not interrupting | |
1497 | * a rcu_bh read-side critical section. This is an _bh | |
d6714c22 | 1498 | * critical section, so note it. |
64db4cff PM |
1499 | */ |
1500 | ||
d6714c22 | 1501 | rcu_bh_qs(cpu); |
64db4cff | 1502 | } |
f41d911f | 1503 | rcu_preempt_check_callbacks(cpu); |
d21670ac | 1504 | if (rcu_pending(cpu)) |
a46e0899 | 1505 | invoke_rcu_core(); |
300df91c | 1506 | trace_rcu_utilization("End scheduler-tick"); |
64db4cff PM |
1507 | } |
1508 | ||
1509 | #ifdef CONFIG_SMP | |
1510 | ||
1511 | /* | |
1512 | * Scan the leaf rcu_node structures, processing dyntick state for any that | |
1513 | * have not yet encountered a quiescent state, using the function specified. | |
27f4d280 PM |
1514 | * Also initiate boosting for any threads blocked on the root rcu_node. |
1515 | * | |
ee47eb9f | 1516 | * The caller must have suppressed start of new grace periods. |
64db4cff | 1517 | */ |
45f014c5 | 1518 | static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *)) |
64db4cff PM |
1519 | { |
1520 | unsigned long bit; | |
1521 | int cpu; | |
1522 | unsigned long flags; | |
1523 | unsigned long mask; | |
a0b6c9a7 | 1524 | struct rcu_node *rnp; |
64db4cff | 1525 | |
a0b6c9a7 | 1526 | rcu_for_each_leaf_node(rsp, rnp) { |
64db4cff | 1527 | mask = 0; |
1304afb2 | 1528 | raw_spin_lock_irqsave(&rnp->lock, flags); |
ee47eb9f | 1529 | if (!rcu_gp_in_progress(rsp)) { |
1304afb2 | 1530 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
0f10dc82 | 1531 | return; |
64db4cff | 1532 | } |
a0b6c9a7 | 1533 | if (rnp->qsmask == 0) { |
1217ed1b | 1534 | rcu_initiate_boost(rnp, flags); /* releases rnp->lock */ |
64db4cff PM |
1535 | continue; |
1536 | } | |
a0b6c9a7 | 1537 | cpu = rnp->grplo; |
64db4cff | 1538 | bit = 1; |
a0b6c9a7 | 1539 | for (; cpu <= rnp->grphi; cpu++, bit <<= 1) { |
394f99a9 LJ |
1540 | if ((rnp->qsmask & bit) != 0 && |
1541 | f(per_cpu_ptr(rsp->rda, cpu))) | |
64db4cff PM |
1542 | mask |= bit; |
1543 | } | |
45f014c5 | 1544 | if (mask != 0) { |
64db4cff | 1545 | |
d3f6bad3 PM |
1546 | /* rcu_report_qs_rnp() releases rnp->lock. */ |
1547 | rcu_report_qs_rnp(mask, rsp, rnp, flags); | |
64db4cff PM |
1548 | continue; |
1549 | } | |
1304afb2 | 1550 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff | 1551 | } |
27f4d280 | 1552 | rnp = rcu_get_root(rsp); |
1217ed1b PM |
1553 | if (rnp->qsmask == 0) { |
1554 | raw_spin_lock_irqsave(&rnp->lock, flags); | |
1555 | rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */ | |
1556 | } | |
64db4cff PM |
1557 | } |
1558 | ||
1559 | /* | |
1560 | * Force quiescent states on reluctant CPUs, and also detect which | |
1561 | * CPUs are in dyntick-idle mode. | |
1562 | */ | |
1563 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) | |
1564 | { | |
1565 | unsigned long flags; | |
64db4cff | 1566 | struct rcu_node *rnp = rcu_get_root(rsp); |
64db4cff | 1567 | |
300df91c PM |
1568 | trace_rcu_utilization("Start fqs"); |
1569 | if (!rcu_gp_in_progress(rsp)) { | |
1570 | trace_rcu_utilization("End fqs"); | |
64db4cff | 1571 | return; /* No grace period in progress, nothing to force. */ |
300df91c | 1572 | } |
1304afb2 | 1573 | if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) { |
64db4cff | 1574 | rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */ |
300df91c | 1575 | trace_rcu_utilization("End fqs"); |
64db4cff PM |
1576 | return; /* Someone else is already on the job. */ |
1577 | } | |
20133cfc | 1578 | if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies)) |
f96e9232 | 1579 | goto unlock_fqs_ret; /* no emergency and done recently. */ |
64db4cff | 1580 | rsp->n_force_qs++; |
1304afb2 | 1581 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
64db4cff | 1582 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
560d4bc0 | 1583 | if(!rcu_gp_in_progress(rsp)) { |
64db4cff | 1584 | rsp->n_force_qs_ngp++; |
1304afb2 | 1585 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
f96e9232 | 1586 | goto unlock_fqs_ret; /* no GP in progress, time updated. */ |
64db4cff | 1587 | } |
07079d53 | 1588 | rsp->fqs_active = 1; |
af446b70 | 1589 | switch (rsp->fqs_state) { |
83f5b01f | 1590 | case RCU_GP_IDLE: |
64db4cff PM |
1591 | case RCU_GP_INIT: |
1592 | ||
83f5b01f | 1593 | break; /* grace period idle or initializing, ignore. */ |
64db4cff PM |
1594 | |
1595 | case RCU_SAVE_DYNTICK: | |
64db4cff PM |
1596 | if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK) |
1597 | break; /* So gcc recognizes the dead code. */ | |
1598 | ||
f261414f LJ |
1599 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
1600 | ||
64db4cff | 1601 | /* Record dyntick-idle state. */ |
45f014c5 | 1602 | force_qs_rnp(rsp, dyntick_save_progress_counter); |
1304afb2 | 1603 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
ee47eb9f | 1604 | if (rcu_gp_in_progress(rsp)) |
af446b70 | 1605 | rsp->fqs_state = RCU_FORCE_QS; |
ee47eb9f | 1606 | break; |
64db4cff PM |
1607 | |
1608 | case RCU_FORCE_QS: | |
1609 | ||
1610 | /* Check dyntick-idle state, send IPI to laggarts. */ | |
1304afb2 | 1611 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
45f014c5 | 1612 | force_qs_rnp(rsp, rcu_implicit_dynticks_qs); |
64db4cff PM |
1613 | |
1614 | /* Leave state in case more forcing is required. */ | |
1615 | ||
1304afb2 | 1616 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
f96e9232 | 1617 | break; |
64db4cff | 1618 | } |
07079d53 | 1619 | rsp->fqs_active = 0; |
46a1e34e | 1620 | if (rsp->fqs_need_gp) { |
1304afb2 | 1621 | raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */ |
46a1e34e PM |
1622 | rsp->fqs_need_gp = 0; |
1623 | rcu_start_gp(rsp, flags); /* releases rnp->lock */ | |
300df91c | 1624 | trace_rcu_utilization("End fqs"); |
46a1e34e PM |
1625 | return; |
1626 | } | |
1304afb2 | 1627 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
f96e9232 | 1628 | unlock_fqs_ret: |
1304afb2 | 1629 | raw_spin_unlock_irqrestore(&rsp->fqslock, flags); |
300df91c | 1630 | trace_rcu_utilization("End fqs"); |
64db4cff PM |
1631 | } |
1632 | ||
1633 | #else /* #ifdef CONFIG_SMP */ | |
1634 | ||
1635 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) | |
1636 | { | |
1637 | set_need_resched(); | |
1638 | } | |
1639 | ||
1640 | #endif /* #else #ifdef CONFIG_SMP */ | |
1641 | ||
1642 | /* | |
e0f23060 PM |
1643 | * This does the RCU core processing work for the specified rcu_state |
1644 | * and rcu_data structures. This may be called only from the CPU to | |
1645 | * whom the rdp belongs. | |
64db4cff PM |
1646 | */ |
1647 | static void | |
1648 | __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) | |
1649 | { | |
1650 | unsigned long flags; | |
1651 | ||
2e597558 PM |
1652 | WARN_ON_ONCE(rdp->beenonline == 0); |
1653 | ||
64db4cff PM |
1654 | /* |
1655 | * If an RCU GP has gone long enough, go check for dyntick | |
1656 | * idle CPUs and, if needed, send resched IPIs. | |
1657 | */ | |
20133cfc | 1658 | if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
64db4cff PM |
1659 | force_quiescent_state(rsp, 1); |
1660 | ||
1661 | /* | |
1662 | * Advance callbacks in response to end of earlier grace | |
1663 | * period that some other CPU ended. | |
1664 | */ | |
1665 | rcu_process_gp_end(rsp, rdp); | |
1666 | ||
1667 | /* Update RCU state based on any recent quiescent states. */ | |
1668 | rcu_check_quiescent_state(rsp, rdp); | |
1669 | ||
1670 | /* Does this CPU require a not-yet-started grace period? */ | |
1671 | if (cpu_needs_another_gp(rsp, rdp)) { | |
1304afb2 | 1672 | raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags); |
64db4cff PM |
1673 | rcu_start_gp(rsp, flags); /* releases above lock */ |
1674 | } | |
1675 | ||
1676 | /* If there are callbacks ready, invoke them. */ | |
09223371 | 1677 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
a46e0899 | 1678 | invoke_rcu_callbacks(rsp, rdp); |
09223371 SL |
1679 | } |
1680 | ||
64db4cff | 1681 | /* |
e0f23060 | 1682 | * Do RCU core processing for the current CPU. |
64db4cff | 1683 | */ |
09223371 | 1684 | static void rcu_process_callbacks(struct softirq_action *unused) |
64db4cff | 1685 | { |
300df91c | 1686 | trace_rcu_utilization("Start RCU core"); |
d6714c22 PM |
1687 | __rcu_process_callbacks(&rcu_sched_state, |
1688 | &__get_cpu_var(rcu_sched_data)); | |
64db4cff | 1689 | __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data)); |
f41d911f | 1690 | rcu_preempt_process_callbacks(); |
300df91c | 1691 | trace_rcu_utilization("End RCU core"); |
64db4cff PM |
1692 | } |
1693 | ||
a26ac245 | 1694 | /* |
e0f23060 PM |
1695 | * Schedule RCU callback invocation. If the specified type of RCU |
1696 | * does not support RCU priority boosting, just do a direct call, | |
1697 | * otherwise wake up the per-CPU kernel kthread. Note that because we | |
1698 | * are running on the current CPU with interrupts disabled, the | |
1699 | * rcu_cpu_kthread_task cannot disappear out from under us. | |
a26ac245 | 1700 | */ |
a46e0899 | 1701 | static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) |
a26ac245 | 1702 | { |
b0d30417 PM |
1703 | if (unlikely(!ACCESS_ONCE(rcu_scheduler_fully_active))) |
1704 | return; | |
a46e0899 PM |
1705 | if (likely(!rsp->boost)) { |
1706 | rcu_do_batch(rsp, rdp); | |
a26ac245 PM |
1707 | return; |
1708 | } | |
a46e0899 | 1709 | invoke_rcu_callbacks_kthread(); |
a26ac245 PM |
1710 | } |
1711 | ||
a46e0899 | 1712 | static void invoke_rcu_core(void) |
09223371 SL |
1713 | { |
1714 | raise_softirq(RCU_SOFTIRQ); | |
1715 | } | |
1716 | ||
64db4cff PM |
1717 | static void |
1718 | __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), | |
486e2593 | 1719 | struct rcu_state *rsp, bool lazy) |
64db4cff PM |
1720 | { |
1721 | unsigned long flags; | |
1722 | struct rcu_data *rdp; | |
1723 | ||
0bb7b59d | 1724 | WARN_ON_ONCE((unsigned long)head & 0x3); /* Misaligned rcu_head! */ |
551d55a9 | 1725 | debug_rcu_head_queue(head); |
64db4cff PM |
1726 | head->func = func; |
1727 | head->next = NULL; | |
1728 | ||
1729 | smp_mb(); /* Ensure RCU update seen before callback registry. */ | |
1730 | ||
1731 | /* | |
1732 | * Opportunistically note grace-period endings and beginnings. | |
1733 | * Note that we might see a beginning right after we see an | |
1734 | * end, but never vice versa, since this CPU has to pass through | |
1735 | * a quiescent state betweentimes. | |
1736 | */ | |
1737 | local_irq_save(flags); | |
e5601400 | 1738 | WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); |
394f99a9 | 1739 | rdp = this_cpu_ptr(rsp->rda); |
64db4cff PM |
1740 | |
1741 | /* Add the callback to our list. */ | |
1742 | *rdp->nxttail[RCU_NEXT_TAIL] = head; | |
1743 | rdp->nxttail[RCU_NEXT_TAIL] = &head->next; | |
2655d57e | 1744 | rdp->qlen++; |
486e2593 PM |
1745 | if (lazy) |
1746 | rdp->qlen_lazy++; | |
2655d57e | 1747 | |
d4c08f2a PM |
1748 | if (__is_kfree_rcu_offset((unsigned long)func)) |
1749 | trace_rcu_kfree_callback(rsp->name, head, (unsigned long)func, | |
486e2593 | 1750 | rdp->qlen_lazy, rdp->qlen); |
d4c08f2a | 1751 | else |
486e2593 | 1752 | trace_rcu_callback(rsp->name, head, rdp->qlen_lazy, rdp->qlen); |
d4c08f2a | 1753 | |
2655d57e PM |
1754 | /* If interrupts were disabled, don't dive into RCU core. */ |
1755 | if (irqs_disabled_flags(flags)) { | |
1756 | local_irq_restore(flags); | |
1757 | return; | |
1758 | } | |
64db4cff | 1759 | |
37c72e56 PM |
1760 | /* |
1761 | * Force the grace period if too many callbacks or too long waiting. | |
1762 | * Enforce hysteresis, and don't invoke force_quiescent_state() | |
1763 | * if some other CPU has recently done so. Also, don't bother | |
1764 | * invoking force_quiescent_state() if the newly enqueued callback | |
1765 | * is the only one waiting for a grace period to complete. | |
1766 | */ | |
2655d57e | 1767 | if (unlikely(rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { |
b52573d2 PM |
1768 | |
1769 | /* Are we ignoring a completed grace period? */ | |
1770 | rcu_process_gp_end(rsp, rdp); | |
1771 | check_for_new_grace_period(rsp, rdp); | |
1772 | ||
1773 | /* Start a new grace period if one not already started. */ | |
1774 | if (!rcu_gp_in_progress(rsp)) { | |
1775 | unsigned long nestflag; | |
1776 | struct rcu_node *rnp_root = rcu_get_root(rsp); | |
1777 | ||
1778 | raw_spin_lock_irqsave(&rnp_root->lock, nestflag); | |
1779 | rcu_start_gp(rsp, nestflag); /* rlses rnp_root->lock */ | |
1780 | } else { | |
1781 | /* Give the grace period a kick. */ | |
1782 | rdp->blimit = LONG_MAX; | |
1783 | if (rsp->n_force_qs == rdp->n_force_qs_snap && | |
1784 | *rdp->nxttail[RCU_DONE_TAIL] != head) | |
1785 | force_quiescent_state(rsp, 0); | |
1786 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
1787 | rdp->qlen_last_fqs_check = rdp->qlen; | |
1788 | } | |
20133cfc | 1789 | } else if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
64db4cff PM |
1790 | force_quiescent_state(rsp, 1); |
1791 | local_irq_restore(flags); | |
1792 | } | |
1793 | ||
1794 | /* | |
d6714c22 | 1795 | * Queue an RCU-sched callback for invocation after a grace period. |
64db4cff | 1796 | */ |
d6714c22 | 1797 | void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
64db4cff | 1798 | { |
486e2593 | 1799 | __call_rcu(head, func, &rcu_sched_state, 0); |
64db4cff | 1800 | } |
d6714c22 | 1801 | EXPORT_SYMBOL_GPL(call_rcu_sched); |
64db4cff PM |
1802 | |
1803 | /* | |
486e2593 | 1804 | * Queue an RCU callback for invocation after a quicker grace period. |
64db4cff PM |
1805 | */ |
1806 | void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) | |
1807 | { | |
486e2593 | 1808 | __call_rcu(head, func, &rcu_bh_state, 0); |
64db4cff PM |
1809 | } |
1810 | EXPORT_SYMBOL_GPL(call_rcu_bh); | |
1811 | ||
6ebb237b PM |
1812 | /** |
1813 | * synchronize_sched - wait until an rcu-sched grace period has elapsed. | |
1814 | * | |
1815 | * Control will return to the caller some time after a full rcu-sched | |
1816 | * grace period has elapsed, in other words after all currently executing | |
1817 | * rcu-sched read-side critical sections have completed. These read-side | |
1818 | * critical sections are delimited by rcu_read_lock_sched() and | |
1819 | * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(), | |
1820 | * local_irq_disable(), and so on may be used in place of | |
1821 | * rcu_read_lock_sched(). | |
1822 | * | |
1823 | * This means that all preempt_disable code sequences, including NMI and | |
1824 | * hardware-interrupt handlers, in progress on entry will have completed | |
1825 | * before this primitive returns. However, this does not guarantee that | |
1826 | * softirq handlers will have completed, since in some kernels, these | |
1827 | * handlers can run in process context, and can block. | |
1828 | * | |
1829 | * This primitive provides the guarantees made by the (now removed) | |
1830 | * synchronize_kernel() API. In contrast, synchronize_rcu() only | |
1831 | * guarantees that rcu_read_lock() sections will have completed. | |
1832 | * In "classic RCU", these two guarantees happen to be one and | |
1833 | * the same, but can differ in realtime RCU implementations. | |
1834 | */ | |
1835 | void synchronize_sched(void) | |
1836 | { | |
fe15d706 PM |
1837 | rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) && |
1838 | !lock_is_held(&rcu_lock_map) && | |
1839 | !lock_is_held(&rcu_sched_lock_map), | |
1840 | "Illegal synchronize_sched() in RCU-sched read-side critical section"); | |
6ebb237b PM |
1841 | if (rcu_blocking_is_gp()) |
1842 | return; | |
2c42818e | 1843 | wait_rcu_gp(call_rcu_sched); |
6ebb237b PM |
1844 | } |
1845 | EXPORT_SYMBOL_GPL(synchronize_sched); | |
1846 | ||
1847 | /** | |
1848 | * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. | |
1849 | * | |
1850 | * Control will return to the caller some time after a full rcu_bh grace | |
1851 | * period has elapsed, in other words after all currently executing rcu_bh | |
1852 | * read-side critical sections have completed. RCU read-side critical | |
1853 | * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), | |
1854 | * and may be nested. | |
1855 | */ | |
1856 | void synchronize_rcu_bh(void) | |
1857 | { | |
fe15d706 PM |
1858 | rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) && |
1859 | !lock_is_held(&rcu_lock_map) && | |
1860 | !lock_is_held(&rcu_sched_lock_map), | |
1861 | "Illegal synchronize_rcu_bh() in RCU-bh read-side critical section"); | |
6ebb237b PM |
1862 | if (rcu_blocking_is_gp()) |
1863 | return; | |
2c42818e | 1864 | wait_rcu_gp(call_rcu_bh); |
6ebb237b PM |
1865 | } |
1866 | EXPORT_SYMBOL_GPL(synchronize_rcu_bh); | |
1867 | ||
64db4cff PM |
1868 | /* |
1869 | * Check to see if there is any immediate RCU-related work to be done | |
1870 | * by the current CPU, for the specified type of RCU, returning 1 if so. | |
1871 | * The checks are in order of increasing expense: checks that can be | |
1872 | * carried out against CPU-local state are performed first. However, | |
1873 | * we must check for CPU stalls first, else we might not get a chance. | |
1874 | */ | |
1875 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) | |
1876 | { | |
2f51f988 PM |
1877 | struct rcu_node *rnp = rdp->mynode; |
1878 | ||
64db4cff PM |
1879 | rdp->n_rcu_pending++; |
1880 | ||
1881 | /* Check for CPU stalls, if enabled. */ | |
1882 | check_cpu_stall(rsp, rdp); | |
1883 | ||
1884 | /* Is the RCU core waiting for a quiescent state from this CPU? */ | |
5c51dd73 PM |
1885 | if (rcu_scheduler_fully_active && |
1886 | rdp->qs_pending && !rdp->passed_quiesce) { | |
d25eb944 PM |
1887 | |
1888 | /* | |
1889 | * If force_quiescent_state() coming soon and this CPU | |
1890 | * needs a quiescent state, and this is either RCU-sched | |
1891 | * or RCU-bh, force a local reschedule. | |
1892 | */ | |
d21670ac | 1893 | rdp->n_rp_qs_pending++; |
6cc68793 | 1894 | if (!rdp->preemptible && |
d25eb944 PM |
1895 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1, |
1896 | jiffies)) | |
1897 | set_need_resched(); | |
e4cc1f22 | 1898 | } else if (rdp->qs_pending && rdp->passed_quiesce) { |
d21670ac | 1899 | rdp->n_rp_report_qs++; |
64db4cff | 1900 | return 1; |
7ba5c840 | 1901 | } |
64db4cff PM |
1902 | |
1903 | /* Does this CPU have callbacks ready to invoke? */ | |
7ba5c840 PM |
1904 | if (cpu_has_callbacks_ready_to_invoke(rdp)) { |
1905 | rdp->n_rp_cb_ready++; | |
64db4cff | 1906 | return 1; |
7ba5c840 | 1907 | } |
64db4cff PM |
1908 | |
1909 | /* Has RCU gone idle with this CPU needing another grace period? */ | |
7ba5c840 PM |
1910 | if (cpu_needs_another_gp(rsp, rdp)) { |
1911 | rdp->n_rp_cpu_needs_gp++; | |
64db4cff | 1912 | return 1; |
7ba5c840 | 1913 | } |
64db4cff PM |
1914 | |
1915 | /* Has another RCU grace period completed? */ | |
2f51f988 | 1916 | if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */ |
7ba5c840 | 1917 | rdp->n_rp_gp_completed++; |
64db4cff | 1918 | return 1; |
7ba5c840 | 1919 | } |
64db4cff PM |
1920 | |
1921 | /* Has a new RCU grace period started? */ | |
2f51f988 | 1922 | if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */ |
7ba5c840 | 1923 | rdp->n_rp_gp_started++; |
64db4cff | 1924 | return 1; |
7ba5c840 | 1925 | } |
64db4cff PM |
1926 | |
1927 | /* Has an RCU GP gone long enough to send resched IPIs &c? */ | |
fc2219d4 | 1928 | if (rcu_gp_in_progress(rsp) && |
20133cfc | 1929 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) { |
7ba5c840 | 1930 | rdp->n_rp_need_fqs++; |
64db4cff | 1931 | return 1; |
7ba5c840 | 1932 | } |
64db4cff PM |
1933 | |
1934 | /* nothing to do */ | |
7ba5c840 | 1935 | rdp->n_rp_need_nothing++; |
64db4cff PM |
1936 | return 0; |
1937 | } | |
1938 | ||
1939 | /* | |
1940 | * Check to see if there is any immediate RCU-related work to be done | |
1941 | * by the current CPU, returning 1 if so. This function is part of the | |
1942 | * RCU implementation; it is -not- an exported member of the RCU API. | |
1943 | */ | |
a157229c | 1944 | static int rcu_pending(int cpu) |
64db4cff | 1945 | { |
d6714c22 | 1946 | return __rcu_pending(&rcu_sched_state, &per_cpu(rcu_sched_data, cpu)) || |
f41d911f PM |
1947 | __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) || |
1948 | rcu_preempt_pending(cpu); | |
64db4cff PM |
1949 | } |
1950 | ||
1951 | /* | |
1952 | * Check to see if any future RCU-related work will need to be done | |
1953 | * by the current CPU, even if none need be done immediately, returning | |
8bd93a2c | 1954 | * 1 if so. |
64db4cff | 1955 | */ |
aea1b35e | 1956 | static int rcu_cpu_has_callbacks(int cpu) |
64db4cff PM |
1957 | { |
1958 | /* RCU callbacks either ready or pending? */ | |
d6714c22 | 1959 | return per_cpu(rcu_sched_data, cpu).nxtlist || |
f41d911f PM |
1960 | per_cpu(rcu_bh_data, cpu).nxtlist || |
1961 | rcu_preempt_needs_cpu(cpu); | |
64db4cff PM |
1962 | } |
1963 | ||
d0ec774c PM |
1964 | static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; |
1965 | static atomic_t rcu_barrier_cpu_count; | |
1966 | static DEFINE_MUTEX(rcu_barrier_mutex); | |
1967 | static struct completion rcu_barrier_completion; | |
d0ec774c PM |
1968 | |
1969 | static void rcu_barrier_callback(struct rcu_head *notused) | |
1970 | { | |
1971 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) | |
1972 | complete(&rcu_barrier_completion); | |
1973 | } | |
1974 | ||
1975 | /* | |
1976 | * Called with preemption disabled, and from cross-cpu IRQ context. | |
1977 | */ | |
1978 | static void rcu_barrier_func(void *type) | |
1979 | { | |
1980 | int cpu = smp_processor_id(); | |
1981 | struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); | |
1982 | void (*call_rcu_func)(struct rcu_head *head, | |
1983 | void (*func)(struct rcu_head *head)); | |
1984 | ||
1985 | atomic_inc(&rcu_barrier_cpu_count); | |
1986 | call_rcu_func = type; | |
1987 | call_rcu_func(head, rcu_barrier_callback); | |
1988 | } | |
1989 | ||
d0ec774c PM |
1990 | /* |
1991 | * Orchestrate the specified type of RCU barrier, waiting for all | |
1992 | * RCU callbacks of the specified type to complete. | |
1993 | */ | |
e74f4c45 PM |
1994 | static void _rcu_barrier(struct rcu_state *rsp, |
1995 | void (*call_rcu_func)(struct rcu_head *head, | |
d0ec774c PM |
1996 | void (*func)(struct rcu_head *head))) |
1997 | { | |
1998 | BUG_ON(in_interrupt()); | |
e74f4c45 | 1999 | /* Take mutex to serialize concurrent rcu_barrier() requests. */ |
d0ec774c PM |
2000 | mutex_lock(&rcu_barrier_mutex); |
2001 | init_completion(&rcu_barrier_completion); | |
2002 | /* | |
2003 | * Initialize rcu_barrier_cpu_count to 1, then invoke | |
2004 | * rcu_barrier_func() on each CPU, so that each CPU also has | |
2005 | * incremented rcu_barrier_cpu_count. Only then is it safe to | |
2006 | * decrement rcu_barrier_cpu_count -- otherwise the first CPU | |
2007 | * might complete its grace period before all of the other CPUs | |
2008 | * did their increment, causing this function to return too | |
2d999e03 PM |
2009 | * early. Note that on_each_cpu() disables irqs, which prevents |
2010 | * any CPUs from coming online or going offline until each online | |
2011 | * CPU has queued its RCU-barrier callback. | |
d0ec774c PM |
2012 | */ |
2013 | atomic_set(&rcu_barrier_cpu_count, 1); | |
2014 | on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); | |
2015 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) | |
2016 | complete(&rcu_barrier_completion); | |
2017 | wait_for_completion(&rcu_barrier_completion); | |
2018 | mutex_unlock(&rcu_barrier_mutex); | |
d0ec774c | 2019 | } |
d0ec774c PM |
2020 | |
2021 | /** | |
2022 | * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. | |
2023 | */ | |
2024 | void rcu_barrier_bh(void) | |
2025 | { | |
e74f4c45 | 2026 | _rcu_barrier(&rcu_bh_state, call_rcu_bh); |
d0ec774c PM |
2027 | } |
2028 | EXPORT_SYMBOL_GPL(rcu_barrier_bh); | |
2029 | ||
2030 | /** | |
2031 | * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. | |
2032 | */ | |
2033 | void rcu_barrier_sched(void) | |
2034 | { | |
e74f4c45 | 2035 | _rcu_barrier(&rcu_sched_state, call_rcu_sched); |
d0ec774c PM |
2036 | } |
2037 | EXPORT_SYMBOL_GPL(rcu_barrier_sched); | |
2038 | ||
64db4cff | 2039 | /* |
27569620 | 2040 | * Do boot-time initialization of a CPU's per-CPU RCU data. |
64db4cff | 2041 | */ |
27569620 PM |
2042 | static void __init |
2043 | rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) | |
64db4cff PM |
2044 | { |
2045 | unsigned long flags; | |
2046 | int i; | |
394f99a9 | 2047 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
27569620 PM |
2048 | struct rcu_node *rnp = rcu_get_root(rsp); |
2049 | ||
2050 | /* Set up local state, ensuring consistent view of global state. */ | |
1304afb2 | 2051 | raw_spin_lock_irqsave(&rnp->lock, flags); |
27569620 PM |
2052 | rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); |
2053 | rdp->nxtlist = NULL; | |
2054 | for (i = 0; i < RCU_NEXT_SIZE; i++) | |
2055 | rdp->nxttail[i] = &rdp->nxtlist; | |
486e2593 | 2056 | rdp->qlen_lazy = 0; |
27569620 | 2057 | rdp->qlen = 0; |
27569620 | 2058 | rdp->dynticks = &per_cpu(rcu_dynticks, cpu); |
4145fa7f | 2059 | WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_NESTING); |
9b2e4f18 | 2060 | WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1); |
27569620 | 2061 | rdp->cpu = cpu; |
d4c08f2a | 2062 | rdp->rsp = rsp; |
1304afb2 | 2063 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
27569620 PM |
2064 | } |
2065 | ||
2066 | /* | |
2067 | * Initialize a CPU's per-CPU RCU data. Note that only one online or | |
2068 | * offline event can be happening at a given time. Note also that we | |
2069 | * can accept some slop in the rsp->completed access due to the fact | |
2070 | * that this CPU cannot possibly have any RCU callbacks in flight yet. | |
64db4cff | 2071 | */ |
e4fa4c97 | 2072 | static void __cpuinit |
6cc68793 | 2073 | rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible) |
64db4cff PM |
2074 | { |
2075 | unsigned long flags; | |
64db4cff | 2076 | unsigned long mask; |
394f99a9 | 2077 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
64db4cff PM |
2078 | struct rcu_node *rnp = rcu_get_root(rsp); |
2079 | ||
2080 | /* Set up local state, ensuring consistent view of global state. */ | |
1304afb2 | 2081 | raw_spin_lock_irqsave(&rnp->lock, flags); |
64db4cff | 2082 | rdp->beenonline = 1; /* We have now been online. */ |
6cc68793 | 2083 | rdp->preemptible = preemptible; |
37c72e56 PM |
2084 | rdp->qlen_last_fqs_check = 0; |
2085 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
64db4cff | 2086 | rdp->blimit = blimit; |
c92b131b PM |
2087 | rdp->dynticks->dynticks_nesting = DYNTICK_TASK_NESTING; |
2088 | atomic_set(&rdp->dynticks->dynticks, | |
2089 | (atomic_read(&rdp->dynticks->dynticks) & ~0x1) + 1); | |
7cb92499 | 2090 | rcu_prepare_for_idle_init(cpu); |
1304afb2 | 2091 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff PM |
2092 | |
2093 | /* | |
2094 | * A new grace period might start here. If so, we won't be part | |
2095 | * of it, but that is OK, as we are currently in a quiescent state. | |
2096 | */ | |
2097 | ||
2098 | /* Exclude any attempts to start a new GP on large systems. */ | |
1304afb2 | 2099 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
64db4cff PM |
2100 | |
2101 | /* Add CPU to rcu_node bitmasks. */ | |
2102 | rnp = rdp->mynode; | |
2103 | mask = rdp->grpmask; | |
2104 | do { | |
2105 | /* Exclude any attempts to start a new GP on small systems. */ | |
1304afb2 | 2106 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
64db4cff PM |
2107 | rnp->qsmaskinit |= mask; |
2108 | mask = rnp->grpmask; | |
d09b62df | 2109 | if (rnp == rdp->mynode) { |
06ae115a PM |
2110 | /* |
2111 | * If there is a grace period in progress, we will | |
2112 | * set up to wait for it next time we run the | |
2113 | * RCU core code. | |
2114 | */ | |
2115 | rdp->gpnum = rnp->completed; | |
d09b62df | 2116 | rdp->completed = rnp->completed; |
06ae115a PM |
2117 | rdp->passed_quiesce = 0; |
2118 | rdp->qs_pending = 0; | |
e4cc1f22 | 2119 | rdp->passed_quiesce_gpnum = rnp->gpnum - 1; |
d4c08f2a | 2120 | trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpuonl"); |
d09b62df | 2121 | } |
1304afb2 | 2122 | raw_spin_unlock(&rnp->lock); /* irqs already disabled. */ |
64db4cff PM |
2123 | rnp = rnp->parent; |
2124 | } while (rnp != NULL && !(rnp->qsmaskinit & mask)); | |
2125 | ||
1304afb2 | 2126 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
64db4cff PM |
2127 | } |
2128 | ||
d72bce0e | 2129 | static void __cpuinit rcu_prepare_cpu(int cpu) |
64db4cff | 2130 | { |
f41d911f PM |
2131 | rcu_init_percpu_data(cpu, &rcu_sched_state, 0); |
2132 | rcu_init_percpu_data(cpu, &rcu_bh_state, 0); | |
2133 | rcu_preempt_init_percpu_data(cpu); | |
64db4cff PM |
2134 | } |
2135 | ||
2136 | /* | |
f41d911f | 2137 | * Handle CPU online/offline notification events. |
64db4cff | 2138 | */ |
9f680ab4 PM |
2139 | static int __cpuinit rcu_cpu_notify(struct notifier_block *self, |
2140 | unsigned long action, void *hcpu) | |
64db4cff PM |
2141 | { |
2142 | long cpu = (long)hcpu; | |
27f4d280 | 2143 | struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu); |
a26ac245 | 2144 | struct rcu_node *rnp = rdp->mynode; |
64db4cff | 2145 | |
300df91c | 2146 | trace_rcu_utilization("Start CPU hotplug"); |
64db4cff PM |
2147 | switch (action) { |
2148 | case CPU_UP_PREPARE: | |
2149 | case CPU_UP_PREPARE_FROZEN: | |
d72bce0e PZ |
2150 | rcu_prepare_cpu(cpu); |
2151 | rcu_prepare_kthreads(cpu); | |
a26ac245 PM |
2152 | break; |
2153 | case CPU_ONLINE: | |
0f962a5e PM |
2154 | case CPU_DOWN_FAILED: |
2155 | rcu_node_kthread_setaffinity(rnp, -1); | |
e3995a25 | 2156 | rcu_cpu_kthread_setrt(cpu, 1); |
0f962a5e PM |
2157 | break; |
2158 | case CPU_DOWN_PREPARE: | |
2159 | rcu_node_kthread_setaffinity(rnp, cpu); | |
e3995a25 | 2160 | rcu_cpu_kthread_setrt(cpu, 0); |
64db4cff | 2161 | break; |
d0ec774c PM |
2162 | case CPU_DYING: |
2163 | case CPU_DYING_FROZEN: | |
2164 | /* | |
2d999e03 PM |
2165 | * The whole machine is "stopped" except this CPU, so we can |
2166 | * touch any data without introducing corruption. We send the | |
2167 | * dying CPU's callbacks to an arbitrarily chosen online CPU. | |
d0ec774c | 2168 | */ |
e5601400 PM |
2169 | rcu_cleanup_dying_cpu(&rcu_bh_state); |
2170 | rcu_cleanup_dying_cpu(&rcu_sched_state); | |
2171 | rcu_preempt_cleanup_dying_cpu(); | |
7cb92499 | 2172 | rcu_cleanup_after_idle(cpu); |
d0ec774c | 2173 | break; |
64db4cff PM |
2174 | case CPU_DEAD: |
2175 | case CPU_DEAD_FROZEN: | |
2176 | case CPU_UP_CANCELED: | |
2177 | case CPU_UP_CANCELED_FROZEN: | |
e5601400 PM |
2178 | rcu_cleanup_dead_cpu(cpu, &rcu_bh_state); |
2179 | rcu_cleanup_dead_cpu(cpu, &rcu_sched_state); | |
2180 | rcu_preempt_cleanup_dead_cpu(cpu); | |
64db4cff PM |
2181 | break; |
2182 | default: | |
2183 | break; | |
2184 | } | |
300df91c | 2185 | trace_rcu_utilization("End CPU hotplug"); |
64db4cff PM |
2186 | return NOTIFY_OK; |
2187 | } | |
2188 | ||
bbad9379 PM |
2189 | /* |
2190 | * This function is invoked towards the end of the scheduler's initialization | |
2191 | * process. Before this is called, the idle task might contain | |
2192 | * RCU read-side critical sections (during which time, this idle | |
2193 | * task is booting the system). After this function is called, the | |
2194 | * idle tasks are prohibited from containing RCU read-side critical | |
2195 | * sections. This function also enables RCU lockdep checking. | |
2196 | */ | |
2197 | void rcu_scheduler_starting(void) | |
2198 | { | |
2199 | WARN_ON(num_online_cpus() != 1); | |
2200 | WARN_ON(nr_context_switches() > 0); | |
2201 | rcu_scheduler_active = 1; | |
2202 | } | |
2203 | ||
64db4cff PM |
2204 | /* |
2205 | * Compute the per-level fanout, either using the exact fanout specified | |
2206 | * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. | |
2207 | */ | |
2208 | #ifdef CONFIG_RCU_FANOUT_EXACT | |
2209 | static void __init rcu_init_levelspread(struct rcu_state *rsp) | |
2210 | { | |
2211 | int i; | |
2212 | ||
0209f649 | 2213 | for (i = NUM_RCU_LVLS - 1; i > 0; i--) |
64db4cff | 2214 | rsp->levelspread[i] = CONFIG_RCU_FANOUT; |
0209f649 | 2215 | rsp->levelspread[0] = RCU_FANOUT_LEAF; |
64db4cff PM |
2216 | } |
2217 | #else /* #ifdef CONFIG_RCU_FANOUT_EXACT */ | |
2218 | static void __init rcu_init_levelspread(struct rcu_state *rsp) | |
2219 | { | |
2220 | int ccur; | |
2221 | int cprv; | |
2222 | int i; | |
2223 | ||
2224 | cprv = NR_CPUS; | |
2225 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { | |
2226 | ccur = rsp->levelcnt[i]; | |
2227 | rsp->levelspread[i] = (cprv + ccur - 1) / ccur; | |
2228 | cprv = ccur; | |
2229 | } | |
2230 | } | |
2231 | #endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */ | |
2232 | ||
2233 | /* | |
2234 | * Helper function for rcu_init() that initializes one rcu_state structure. | |
2235 | */ | |
394f99a9 LJ |
2236 | static void __init rcu_init_one(struct rcu_state *rsp, |
2237 | struct rcu_data __percpu *rda) | |
64db4cff | 2238 | { |
b6407e86 PM |
2239 | static char *buf[] = { "rcu_node_level_0", |
2240 | "rcu_node_level_1", | |
2241 | "rcu_node_level_2", | |
2242 | "rcu_node_level_3" }; /* Match MAX_RCU_LVLS */ | |
64db4cff PM |
2243 | int cpustride = 1; |
2244 | int i; | |
2245 | int j; | |
2246 | struct rcu_node *rnp; | |
2247 | ||
b6407e86 PM |
2248 | BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */ |
2249 | ||
64db4cff PM |
2250 | /* Initialize the level-tracking arrays. */ |
2251 | ||
2252 | for (i = 1; i < NUM_RCU_LVLS; i++) | |
2253 | rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1]; | |
2254 | rcu_init_levelspread(rsp); | |
2255 | ||
2256 | /* Initialize the elements themselves, starting from the leaves. */ | |
2257 | ||
2258 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { | |
2259 | cpustride *= rsp->levelspread[i]; | |
2260 | rnp = rsp->level[i]; | |
2261 | for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { | |
1304afb2 | 2262 | raw_spin_lock_init(&rnp->lock); |
b6407e86 PM |
2263 | lockdep_set_class_and_name(&rnp->lock, |
2264 | &rcu_node_class[i], buf[i]); | |
f41d911f | 2265 | rnp->gpnum = 0; |
64db4cff PM |
2266 | rnp->qsmask = 0; |
2267 | rnp->qsmaskinit = 0; | |
2268 | rnp->grplo = j * cpustride; | |
2269 | rnp->grphi = (j + 1) * cpustride - 1; | |
2270 | if (rnp->grphi >= NR_CPUS) | |
2271 | rnp->grphi = NR_CPUS - 1; | |
2272 | if (i == 0) { | |
2273 | rnp->grpnum = 0; | |
2274 | rnp->grpmask = 0; | |
2275 | rnp->parent = NULL; | |
2276 | } else { | |
2277 | rnp->grpnum = j % rsp->levelspread[i - 1]; | |
2278 | rnp->grpmask = 1UL << rnp->grpnum; | |
2279 | rnp->parent = rsp->level[i - 1] + | |
2280 | j / rsp->levelspread[i - 1]; | |
2281 | } | |
2282 | rnp->level = i; | |
12f5f524 | 2283 | INIT_LIST_HEAD(&rnp->blkd_tasks); |
64db4cff PM |
2284 | } |
2285 | } | |
0c34029a | 2286 | |
394f99a9 | 2287 | rsp->rda = rda; |
0c34029a LJ |
2288 | rnp = rsp->level[NUM_RCU_LVLS - 1]; |
2289 | for_each_possible_cpu(i) { | |
4a90a068 | 2290 | while (i > rnp->grphi) |
0c34029a | 2291 | rnp++; |
394f99a9 | 2292 | per_cpu_ptr(rsp->rda, i)->mynode = rnp; |
0c34029a LJ |
2293 | rcu_boot_init_percpu_data(i, rsp); |
2294 | } | |
64db4cff PM |
2295 | } |
2296 | ||
9f680ab4 | 2297 | void __init rcu_init(void) |
64db4cff | 2298 | { |
017c4261 | 2299 | int cpu; |
9f680ab4 | 2300 | |
f41d911f | 2301 | rcu_bootup_announce(); |
394f99a9 LJ |
2302 | rcu_init_one(&rcu_sched_state, &rcu_sched_data); |
2303 | rcu_init_one(&rcu_bh_state, &rcu_bh_data); | |
f41d911f | 2304 | __rcu_init_preempt(); |
09223371 | 2305 | open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); |
9f680ab4 PM |
2306 | |
2307 | /* | |
2308 | * We don't need protection against CPU-hotplug here because | |
2309 | * this is called early in boot, before either interrupts | |
2310 | * or the scheduler are operational. | |
2311 | */ | |
2312 | cpu_notifier(rcu_cpu_notify, 0); | |
017c4261 PM |
2313 | for_each_online_cpu(cpu) |
2314 | rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu); | |
c68de209 | 2315 | check_cpu_stall_init(); |
64db4cff PM |
2316 | } |
2317 | ||
1eba8f84 | 2318 | #include "rcutree_plugin.h" |