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9f77da9f PM |
1 | /* |
2 | * Read-Copy Update mechanism for mutual exclusion (tree-based version) | |
3 | * Internal non-public definitions. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation; either version 2 of the License, or | |
8 | * (at your option) any later version. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
87de1cfd PM |
16 | * along with this program; if not, you can access it online at |
17 | * http://www.gnu.org/licenses/gpl-2.0.html. | |
9f77da9f PM |
18 | * |
19 | * Copyright IBM Corporation, 2008 | |
20 | * | |
21 | * Author: Ingo Molnar <mingo@elte.hu> | |
22 | * Paul E. McKenney <paulmck@linux.vnet.ibm.com> | |
23 | */ | |
24 | ||
25 | #include <linux/cache.h> | |
26 | #include <linux/spinlock.h> | |
27 | #include <linux/threads.h> | |
28 | #include <linux/cpumask.h> | |
29 | #include <linux/seqlock.h> | |
30 | ||
31 | /* | |
8932a63d PM |
32 | * Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and |
33 | * CONFIG_RCU_FANOUT_LEAF. | |
9f77da9f | 34 | * In theory, it should be possible to add more levels straightforwardly. |
0209f649 PM |
35 | * In practice, this did work well going from three levels to four. |
36 | * Of course, your mileage may vary. | |
9f77da9f | 37 | */ |
cf244dc0 | 38 | #define MAX_RCU_LVLS 4 |
8932a63d | 39 | #define RCU_FANOUT_1 (CONFIG_RCU_FANOUT_LEAF) |
0209f649 PM |
40 | #define RCU_FANOUT_2 (RCU_FANOUT_1 * CONFIG_RCU_FANOUT) |
41 | #define RCU_FANOUT_3 (RCU_FANOUT_2 * CONFIG_RCU_FANOUT) | |
42 | #define RCU_FANOUT_4 (RCU_FANOUT_3 * CONFIG_RCU_FANOUT) | |
9f77da9f | 43 | |
0209f649 | 44 | #if NR_CPUS <= RCU_FANOUT_1 |
f885b7f2 | 45 | # define RCU_NUM_LVLS 1 |
9f77da9f PM |
46 | # define NUM_RCU_LVL_0 1 |
47 | # define NUM_RCU_LVL_1 (NR_CPUS) | |
48 | # define NUM_RCU_LVL_2 0 | |
49 | # define NUM_RCU_LVL_3 0 | |
cf244dc0 | 50 | # define NUM_RCU_LVL_4 0 |
0209f649 | 51 | #elif NR_CPUS <= RCU_FANOUT_2 |
f885b7f2 | 52 | # define RCU_NUM_LVLS 2 |
9f77da9f | 53 | # define NUM_RCU_LVL_0 1 |
0209f649 | 54 | # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) |
9f77da9f PM |
55 | # define NUM_RCU_LVL_2 (NR_CPUS) |
56 | # define NUM_RCU_LVL_3 0 | |
cf244dc0 | 57 | # define NUM_RCU_LVL_4 0 |
0209f649 | 58 | #elif NR_CPUS <= RCU_FANOUT_3 |
f885b7f2 | 59 | # define RCU_NUM_LVLS 3 |
9f77da9f | 60 | # define NUM_RCU_LVL_0 1 |
0209f649 PM |
61 | # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2) |
62 | # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) | |
63 | # define NUM_RCU_LVL_3 (NR_CPUS) | |
cf244dc0 | 64 | # define NUM_RCU_LVL_4 0 |
0209f649 | 65 | #elif NR_CPUS <= RCU_FANOUT_4 |
f885b7f2 | 66 | # define RCU_NUM_LVLS 4 |
cf244dc0 | 67 | # define NUM_RCU_LVL_0 1 |
0209f649 PM |
68 | # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3) |
69 | # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2) | |
70 | # define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) | |
71 | # define NUM_RCU_LVL_4 (NR_CPUS) | |
9f77da9f PM |
72 | #else |
73 | # error "CONFIG_RCU_FANOUT insufficient for NR_CPUS" | |
0209f649 | 74 | #endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */ |
9f77da9f | 75 | |
cf244dc0 | 76 | #define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4) |
9f77da9f PM |
77 | #define NUM_RCU_NODES (RCU_SUM - NR_CPUS) |
78 | ||
f885b7f2 PM |
79 | extern int rcu_num_lvls; |
80 | extern int rcu_num_nodes; | |
81 | ||
9f77da9f PM |
82 | /* |
83 | * Dynticks per-CPU state. | |
84 | */ | |
85 | struct rcu_dynticks { | |
9b2e4f18 PM |
86 | long long dynticks_nesting; /* Track irq/process nesting level. */ |
87 | /* Process level is worth LLONG_MAX/2. */ | |
88 | int dynticks_nmi_nesting; /* Track NMI nesting level. */ | |
89 | atomic_t dynticks; /* Even value for idle, else odd. */ | |
2333210b PM |
90 | #ifdef CONFIG_NO_HZ_FULL_SYSIDLE |
91 | long long dynticks_idle_nesting; | |
92 | /* irq/process nesting level from idle. */ | |
93 | atomic_t dynticks_idle; /* Even value for idle, else odd. */ | |
94 | /* "Idle" excludes userspace execution. */ | |
95 | unsigned long dynticks_idle_jiffies; | |
96 | /* End of last non-NMI non-idle period. */ | |
97 | #endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */ | |
5955f7ee | 98 | #ifdef CONFIG_RCU_FAST_NO_HZ |
c0f4dfd4 | 99 | bool all_lazy; /* Are all CPU's CBs lazy? */ |
5955f7ee PM |
100 | unsigned long nonlazy_posted; |
101 | /* # times non-lazy CBs posted to CPU. */ | |
102 | unsigned long nonlazy_posted_snap; | |
103 | /* idle-period nonlazy_posted snapshot. */ | |
c0f4dfd4 PM |
104 | unsigned long last_accelerate; |
105 | /* Last jiffy CBs were accelerated. */ | |
c229828c PM |
106 | unsigned long last_advance_all; |
107 | /* Last jiffy CBs were all advanced. */ | |
9d2ad243 | 108 | int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */ |
5955f7ee | 109 | #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ |
9f77da9f PM |
110 | }; |
111 | ||
d71df90e PM |
112 | /* RCU's kthread states for tracing. */ |
113 | #define RCU_KTHREAD_STOPPED 0 | |
114 | #define RCU_KTHREAD_RUNNING 1 | |
115 | #define RCU_KTHREAD_WAITING 2 | |
15ba0ba8 PM |
116 | #define RCU_KTHREAD_OFFCPU 3 |
117 | #define RCU_KTHREAD_YIELDING 4 | |
118 | #define RCU_KTHREAD_MAX 4 | |
d71df90e | 119 | |
9f77da9f PM |
120 | /* |
121 | * Definition for node within the RCU grace-period-detection hierarchy. | |
122 | */ | |
123 | struct rcu_node { | |
1304afb2 | 124 | raw_spinlock_t lock; /* Root rcu_node's lock protects some */ |
1eba8f84 | 125 | /* rcu_state fields as well as following. */ |
20133cfc | 126 | unsigned long gpnum; /* Current grace period for this node. */ |
86848966 PM |
127 | /* This will either be equal to or one */ |
128 | /* behind the root rcu_node's gpnum. */ | |
20133cfc | 129 | unsigned long completed; /* Last GP completed for this node. */ |
d09b62df PM |
130 | /* This will either be equal to or one */ |
131 | /* behind the root rcu_node's gpnum. */ | |
9f77da9f PM |
132 | unsigned long qsmask; /* CPUs or groups that need to switch in */ |
133 | /* order for current grace period to proceed.*/ | |
1eba8f84 PM |
134 | /* In leaf rcu_node, each bit corresponds to */ |
135 | /* an rcu_data structure, otherwise, each */ | |
136 | /* bit corresponds to a child rcu_node */ | |
137 | /* structure. */ | |
12f5f524 | 138 | unsigned long expmask; /* Groups that have ->blkd_tasks */ |
d9a3da06 PM |
139 | /* elements that need to drain to allow the */ |
140 | /* current expedited grace period to */ | |
28f6569a | 141 | /* complete (only for PREEMPT_RCU). */ |
9f77da9f | 142 | unsigned long qsmaskinit; |
d9a3da06 | 143 | /* Per-GP initial value for qsmask & expmask. */ |
9f77da9f | 144 | unsigned long grpmask; /* Mask to apply to parent qsmask. */ |
1eba8f84 | 145 | /* Only one bit will be set in this mask. */ |
9f77da9f PM |
146 | int grplo; /* lowest-numbered CPU or group here. */ |
147 | int grphi; /* highest-numbered CPU or group here. */ | |
148 | u8 grpnum; /* CPU/group number for next level up. */ | |
149 | u8 level; /* root is at level 0. */ | |
150 | struct rcu_node *parent; | |
12f5f524 PM |
151 | struct list_head blkd_tasks; |
152 | /* Tasks blocked in RCU read-side critical */ | |
153 | /* section. Tasks are placed at the head */ | |
154 | /* of this list and age towards the tail. */ | |
155 | struct list_head *gp_tasks; | |
156 | /* Pointer to the first task blocking the */ | |
157 | /* current grace period, or NULL if there */ | |
158 | /* is no such task. */ | |
159 | struct list_head *exp_tasks; | |
160 | /* Pointer to the first task blocking the */ | |
161 | /* current expedited grace period, or NULL */ | |
162 | /* if there is no such task. If there */ | |
163 | /* is no current expedited grace period, */ | |
164 | /* then there can cannot be any such task. */ | |
27f4d280 PM |
165 | #ifdef CONFIG_RCU_BOOST |
166 | struct list_head *boost_tasks; | |
167 | /* Pointer to first task that needs to be */ | |
168 | /* priority boosted, or NULL if no priority */ | |
169 | /* boosting is needed for this rcu_node */ | |
170 | /* structure. If there are no tasks */ | |
171 | /* queued on this rcu_node structure that */ | |
172 | /* are blocking the current grace period, */ | |
173 | /* there can be no such task. */ | |
abaa93d9 PM |
174 | struct rt_mutex boost_mtx; |
175 | /* Used only for the priority-boosting */ | |
176 | /* side effect, not as a lock. */ | |
27f4d280 PM |
177 | unsigned long boost_time; |
178 | /* When to start boosting (jiffies). */ | |
179 | struct task_struct *boost_kthread_task; | |
180 | /* kthread that takes care of priority */ | |
181 | /* boosting for this rcu_node structure. */ | |
d71df90e PM |
182 | unsigned int boost_kthread_status; |
183 | /* State of boost_kthread_task for tracing. */ | |
0ea1f2eb PM |
184 | unsigned long n_tasks_boosted; |
185 | /* Total number of tasks boosted. */ | |
186 | unsigned long n_exp_boosts; | |
187 | /* Number of tasks boosted for expedited GP. */ | |
188 | unsigned long n_normal_boosts; | |
189 | /* Number of tasks boosted for normal GP. */ | |
190 | unsigned long n_balk_blkd_tasks; | |
191 | /* Refused to boost: no blocked tasks. */ | |
192 | unsigned long n_balk_exp_gp_tasks; | |
193 | /* Refused to boost: nothing blocking GP. */ | |
194 | unsigned long n_balk_boost_tasks; | |
195 | /* Refused to boost: already boosting. */ | |
196 | unsigned long n_balk_notblocked; | |
197 | /* Refused to boost: RCU RS CS still running. */ | |
198 | unsigned long n_balk_notyet; | |
199 | /* Refused to boost: not yet time. */ | |
200 | unsigned long n_balk_nos; | |
201 | /* Refused to boost: not sure why, though. */ | |
202 | /* This can happen due to race conditions. */ | |
27f4d280 | 203 | #endif /* #ifdef CONFIG_RCU_BOOST */ |
dae6e64d PM |
204 | #ifdef CONFIG_RCU_NOCB_CPU |
205 | wait_queue_head_t nocb_gp_wq[2]; | |
206 | /* Place for rcu_nocb_kthread() to wait GP. */ | |
dae6e64d | 207 | #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ |
8b425aa8 PM |
208 | int need_future_gp[2]; |
209 | /* Counts of upcoming no-CB GP requests. */ | |
394f2769 | 210 | raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp; |
9f77da9f PM |
211 | } ____cacheline_internodealigned_in_smp; |
212 | ||
a0b6c9a7 PM |
213 | /* |
214 | * Do a full breadth-first scan of the rcu_node structures for the | |
215 | * specified rcu_state structure. | |
216 | */ | |
217 | #define rcu_for_each_node_breadth_first(rsp, rnp) \ | |
218 | for ((rnp) = &(rsp)->node[0]; \ | |
f885b7f2 | 219 | (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) |
a0b6c9a7 | 220 | |
d9a3da06 PM |
221 | /* |
222 | * Do a breadth-first scan of the non-leaf rcu_node structures for the | |
223 | * specified rcu_state structure. Note that if there is a singleton | |
224 | * rcu_node tree with but one rcu_node structure, this loop is a no-op. | |
225 | */ | |
226 | #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \ | |
227 | for ((rnp) = &(rsp)->node[0]; \ | |
f885b7f2 | 228 | (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++) |
d9a3da06 PM |
229 | |
230 | /* | |
231 | * Scan the leaves of the rcu_node hierarchy for the specified rcu_state | |
232 | * structure. Note that if there is a singleton rcu_node tree with but | |
233 | * one rcu_node structure, this loop -will- visit the rcu_node structure. | |
234 | * It is still a leaf node, even if it is also the root node. | |
235 | */ | |
a0b6c9a7 | 236 | #define rcu_for_each_leaf_node(rsp, rnp) \ |
f885b7f2 PM |
237 | for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \ |
238 | (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) | |
a0b6c9a7 | 239 | |
9f77da9f PM |
240 | /* Index values for nxttail array in struct rcu_data. */ |
241 | #define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */ | |
242 | #define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */ | |
243 | #define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */ | |
244 | #define RCU_NEXT_TAIL 3 | |
245 | #define RCU_NEXT_SIZE 4 | |
246 | ||
247 | /* Per-CPU data for read-copy update. */ | |
248 | struct rcu_data { | |
249 | /* 1) quiescent-state and grace-period handling : */ | |
20133cfc | 250 | unsigned long completed; /* Track rsp->completed gp number */ |
9f77da9f | 251 | /* in order to detect GP end. */ |
20133cfc | 252 | unsigned long gpnum; /* Highest gp number that this CPU */ |
9f77da9f | 253 | /* is aware of having started. */ |
5cd37193 PM |
254 | unsigned long rcu_qs_ctr_snap;/* Snapshot of rcu_qs_ctr to check */ |
255 | /* for rcu_all_qs() invocations. */ | |
e4cc1f22 | 256 | bool passed_quiesce; /* User-mode/idle loop etc. */ |
9f77da9f PM |
257 | bool qs_pending; /* Core waits for quiesc state. */ |
258 | bool beenonline; /* CPU online at least once. */ | |
e3663b10 | 259 | bool gpwrap; /* Possible gpnum/completed wrap. */ |
9f77da9f PM |
260 | struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ |
261 | unsigned long grpmask; /* Mask to apply to leaf qsmask. */ | |
a858af28 PM |
262 | #ifdef CONFIG_RCU_CPU_STALL_INFO |
263 | unsigned long ticks_this_gp; /* The number of scheduling-clock */ | |
264 | /* ticks this CPU has handled */ | |
265 | /* during and after the last grace */ | |
266 | /* period it is aware of. */ | |
267 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ | |
9f77da9f PM |
268 | |
269 | /* 2) batch handling */ | |
270 | /* | |
271 | * If nxtlist is not NULL, it is partitioned as follows. | |
272 | * Any of the partitions might be empty, in which case the | |
273 | * pointer to that partition will be equal to the pointer for | |
274 | * the following partition. When the list is empty, all of | |
1eba8f84 PM |
275 | * the nxttail elements point to the ->nxtlist pointer itself, |
276 | * which in that case is NULL. | |
9f77da9f | 277 | * |
9f77da9f PM |
278 | * [nxtlist, *nxttail[RCU_DONE_TAIL]): |
279 | * Entries that batch # <= ->completed | |
280 | * The grace period for these entries has completed, and | |
281 | * the other grace-period-completed entries may be moved | |
282 | * here temporarily in rcu_process_callbacks(). | |
1eba8f84 PM |
283 | * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]): |
284 | * Entries that batch # <= ->completed - 1: waiting for current GP | |
285 | * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]): | |
286 | * Entries known to have arrived before current GP ended | |
287 | * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]): | |
288 | * Entries that might have arrived after current GP ended | |
289 | * Note that the value of *nxttail[RCU_NEXT_TAIL] will | |
290 | * always be NULL, as this is the end of the list. | |
9f77da9f PM |
291 | */ |
292 | struct rcu_head *nxtlist; | |
293 | struct rcu_head **nxttail[RCU_NEXT_SIZE]; | |
dc35c893 PM |
294 | unsigned long nxtcompleted[RCU_NEXT_SIZE]; |
295 | /* grace periods for sublists. */ | |
486e2593 PM |
296 | long qlen_lazy; /* # of lazy queued callbacks */ |
297 | long qlen; /* # of queued callbacks, incl lazy */ | |
37c72e56 PM |
298 | long qlen_last_fqs_check; |
299 | /* qlen at last check for QS forcing */ | |
269dcc1c | 300 | unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */ |
c635a4e1 | 301 | unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */ |
29494be7 LJ |
302 | unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */ |
303 | unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */ | |
37c72e56 PM |
304 | unsigned long n_force_qs_snap; |
305 | /* did other CPU force QS recently? */ | |
9f77da9f PM |
306 | long blimit; /* Upper limit on a processed batch */ |
307 | ||
9f77da9f PM |
308 | /* 3) dynticks interface. */ |
309 | struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ | |
310 | int dynticks_snap; /* Per-GP tracking for dynticks. */ | |
9f77da9f PM |
311 | |
312 | /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ | |
9f77da9f | 313 | unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ |
9f77da9f | 314 | unsigned long offline_fqs; /* Kicked due to being offline. */ |
4a81e832 PM |
315 | unsigned long cond_resched_completed; |
316 | /* Grace period that needs help */ | |
317 | /* from cond_resched(). */ | |
9f77da9f PM |
318 | |
319 | /* 5) __rcu_pending() statistics. */ | |
20133cfc PM |
320 | unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */ |
321 | unsigned long n_rp_qs_pending; | |
d21670ac | 322 | unsigned long n_rp_report_qs; |
20133cfc PM |
323 | unsigned long n_rp_cb_ready; |
324 | unsigned long n_rp_cpu_needs_gp; | |
325 | unsigned long n_rp_gp_completed; | |
326 | unsigned long n_rp_gp_started; | |
96d3fd0d | 327 | unsigned long n_rp_nocb_defer_wakeup; |
20133cfc | 328 | unsigned long n_rp_need_nothing; |
9f77da9f | 329 | |
b626c1b6 | 330 | /* 6) _rcu_barrier() and OOM callbacks. */ |
06668efa | 331 | struct rcu_head barrier_head; |
b626c1b6 PM |
332 | #ifdef CONFIG_RCU_FAST_NO_HZ |
333 | struct rcu_head oom_head; | |
334 | #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ | |
06668efa | 335 | |
3fbfbf7a PM |
336 | /* 7) Callback offloading. */ |
337 | #ifdef CONFIG_RCU_NOCB_CPU | |
338 | struct rcu_head *nocb_head; /* CBs waiting for kthread. */ | |
339 | struct rcu_head **nocb_tail; | |
41050a00 PM |
340 | atomic_long_t nocb_q_count; /* # CBs waiting for nocb */ |
341 | atomic_long_t nocb_q_count_lazy; /* invocation (all stages). */ | |
fbce7497 PM |
342 | struct rcu_head *nocb_follower_head; /* CBs ready to invoke. */ |
343 | struct rcu_head **nocb_follower_tail; | |
3fbfbf7a PM |
344 | wait_queue_head_t nocb_wq; /* For nocb kthreads to sleep on. */ |
345 | struct task_struct *nocb_kthread; | |
9fdd3bc9 | 346 | int nocb_defer_wakeup; /* Defer wakeup of nocb_kthread. */ |
fbce7497 PM |
347 | |
348 | /* The following fields are used by the leader, hence own cacheline. */ | |
349 | struct rcu_head *nocb_gp_head ____cacheline_internodealigned_in_smp; | |
350 | /* CBs waiting for GP. */ | |
351 | struct rcu_head **nocb_gp_tail; | |
11ed7f93 | 352 | bool nocb_leader_sleep; /* Is the nocb leader thread asleep? */ |
fbce7497 PM |
353 | struct rcu_data *nocb_next_follower; |
354 | /* Next follower in wakeup chain. */ | |
355 | ||
356 | /* The following fields are used by the follower, hence new cachline. */ | |
357 | struct rcu_data *nocb_leader ____cacheline_internodealigned_in_smp; | |
358 | /* Leader CPU takes GP-end wakeups. */ | |
3fbfbf7a PM |
359 | #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ |
360 | ||
6231069b PM |
361 | /* 8) RCU CPU stall data. */ |
362 | #ifdef CONFIG_RCU_CPU_STALL_INFO | |
363 | unsigned int softirq_snap; /* Snapshot of softirq activity. */ | |
364 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ | |
365 | ||
9f77da9f | 366 | int cpu; |
d4c08f2a | 367 | struct rcu_state *rsp; |
9f77da9f PM |
368 | }; |
369 | ||
af446b70 | 370 | /* Values for fqs_state field in struct rcu_state. */ |
83f5b01f PM |
371 | #define RCU_GP_IDLE 0 /* No grace period in progress. */ |
372 | #define RCU_GP_INIT 1 /* Grace period being initialized. */ | |
373 | #define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */ | |
ee47eb9f | 374 | #define RCU_FORCE_QS 3 /* Need to force quiescent state. */ |
9f77da9f | 375 | #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK |
9f77da9f | 376 | |
9fdd3bc9 PM |
377 | /* Values for nocb_defer_wakeup field in struct rcu_data. */ |
378 | #define RCU_NOGP_WAKE_NOT 0 | |
379 | #define RCU_NOGP_WAKE 1 | |
380 | #define RCU_NOGP_WAKE_FORCE 2 | |
381 | ||
026ad283 PM |
382 | #define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500)) |
383 | /* For jiffies_till_first_fqs and */ | |
384 | /* and jiffies_till_next_fqs. */ | |
007b0924 | 385 | |
026ad283 PM |
386 | #define RCU_JIFFIES_FQS_DIV 256 /* Very large systems need more */ |
387 | /* delay between bouts of */ | |
388 | /* quiescent-state forcing. */ | |
389 | ||
390 | #define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time to take */ | |
391 | /* at least one scheduling clock */ | |
392 | /* irq before ratting on them. */ | |
9f77da9f | 393 | |
08bca60a PZ |
394 | #define rcu_wait(cond) \ |
395 | do { \ | |
396 | for (;;) { \ | |
397 | set_current_state(TASK_INTERRUPTIBLE); \ | |
398 | if (cond) \ | |
399 | break; \ | |
400 | schedule(); \ | |
401 | } \ | |
402 | __set_current_state(TASK_RUNNING); \ | |
403 | } while (0) | |
9f77da9f PM |
404 | |
405 | /* | |
406 | * RCU global state, including node hierarchy. This hierarchy is | |
407 | * represented in "heap" form in a dense array. The root (first level) | |
408 | * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second | |
409 | * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]), | |
410 | * and the third level in ->node[m+1] and following (->node[m+1] referenced | |
411 | * by ->level[2]). The number of levels is determined by the number of | |
412 | * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy" | |
413 | * consisting of a single rcu_node. | |
414 | */ | |
415 | struct rcu_state { | |
416 | struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */ | |
f885b7f2 | 417 | struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */ |
9f77da9f | 418 | u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */ |
f885b7f2 | 419 | u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */ |
4a81e832 | 420 | u8 flavor_mask; /* bit in flavor mask. */ |
394f99a9 | 421 | struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */ |
037b64ed PM |
422 | void (*call)(struct rcu_head *head, /* call_rcu() flavor. */ |
423 | void (*func)(struct rcu_head *head)); | |
9f77da9f PM |
424 | |
425 | /* The following fields are guarded by the root rcu_node's lock. */ | |
426 | ||
af446b70 | 427 | u8 fqs_state ____cacheline_internodealigned_in_smp; |
9f77da9f | 428 | /* Force QS state. */ |
a46e0899 | 429 | u8 boost; /* Subject to priority boost. */ |
20133cfc PM |
430 | unsigned long gpnum; /* Current gp number. */ |
431 | unsigned long completed; /* # of last completed gp. */ | |
b3dbec76 PM |
432 | struct task_struct *gp_kthread; /* Task for grace periods. */ |
433 | wait_queue_head_t gp_wq; /* Where GP task waits. */ | |
afea227f PM |
434 | short gp_flags; /* Commands for GP task. */ |
435 | short gp_state; /* GP kthread sleep state. */ | |
1eba8f84 | 436 | |
d9a3da06 | 437 | /* End of fields guarded by root rcu_node's lock. */ |
1eba8f84 | 438 | |
7b2e6011 PM |
439 | raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp; |
440 | /* Protect following fields. */ | |
b1420f1c PM |
441 | struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */ |
442 | /* need a grace period. */ | |
443 | struct rcu_head **orphan_nxttail; /* Tail of above. */ | |
444 | struct rcu_head *orphan_donelist; /* Orphaned callbacks that */ | |
445 | /* are ready to invoke. */ | |
446 | struct rcu_head **orphan_donetail; /* Tail of above. */ | |
447 | long qlen_lazy; /* Number of lazy callbacks. */ | |
448 | long qlen; /* Total number of callbacks. */ | |
7b2e6011 | 449 | /* End of fields guarded by orphan_lock. */ |
a4fbe35a PM |
450 | |
451 | struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */ | |
452 | ||
7be7f0be | 453 | struct mutex barrier_mutex; /* Guards barrier fields. */ |
24ebbca8 | 454 | atomic_t barrier_cpu_count; /* # CPUs waiting on. */ |
7db74df8 | 455 | struct completion barrier_completion; /* Wake at barrier end. */ |
cf3a9c48 PM |
456 | unsigned long n_barrier_done; /* ++ at start and end of */ |
457 | /* _rcu_barrier(). */ | |
a4fbe35a PM |
458 | /* End of fields guarded by barrier_mutex. */ |
459 | ||
40694d66 PM |
460 | atomic_long_t expedited_start; /* Starting ticket. */ |
461 | atomic_long_t expedited_done; /* Done ticket. */ | |
a30489c5 PM |
462 | atomic_long_t expedited_wrap; /* # near-wrap incidents. */ |
463 | atomic_long_t expedited_tryfail; /* # acquisition failures. */ | |
464 | atomic_long_t expedited_workdone1; /* # done by others #1. */ | |
465 | atomic_long_t expedited_workdone2; /* # done by others #2. */ | |
466 | atomic_long_t expedited_normal; /* # fallbacks to normal. */ | |
467 | atomic_long_t expedited_stoppedcpus; /* # successful stop_cpus. */ | |
468 | atomic_long_t expedited_done_tries; /* # tries to update _done. */ | |
469 | atomic_long_t expedited_done_lost; /* # times beaten to _done. */ | |
470 | atomic_long_t expedited_done_exit; /* # times exited _done loop. */ | |
40694d66 | 471 | |
9f77da9f PM |
472 | unsigned long jiffies_force_qs; /* Time at which to invoke */ |
473 | /* force_quiescent_state(). */ | |
474 | unsigned long n_force_qs; /* Number of calls to */ | |
475 | /* force_quiescent_state(). */ | |
476 | unsigned long n_force_qs_lh; /* ~Number of calls leaving */ | |
477 | /* due to lock unavailable. */ | |
478 | unsigned long n_force_qs_ngp; /* Number of calls leaving */ | |
479 | /* due to no GP active. */ | |
9f77da9f PM |
480 | unsigned long gp_start; /* Time at which GP started, */ |
481 | /* but in jiffies. */ | |
6ccd2ecd PM |
482 | unsigned long gp_activity; /* Time of last GP kthread */ |
483 | /* activity in jiffies. */ | |
9f77da9f PM |
484 | unsigned long jiffies_stall; /* Time at which to check */ |
485 | /* for CPU stalls. */ | |
6193c76a PM |
486 | unsigned long jiffies_resched; /* Time at which to resched */ |
487 | /* a reluctant CPU. */ | |
fc908ed3 PM |
488 | unsigned long n_force_qs_gpstart; /* Snapshot of n_force_qs at */ |
489 | /* GP start. */ | |
15ba0ba8 PM |
490 | unsigned long gp_max; /* Maximum GP duration in */ |
491 | /* jiffies. */ | |
e66c33d5 | 492 | const char *name; /* Name of structure. */ |
a4889858 | 493 | char abbr; /* Abbreviated name. */ |
6ce75a23 | 494 | struct list_head flavors; /* List of RCU flavors. */ |
9f77da9f PM |
495 | }; |
496 | ||
4cdfc175 PM |
497 | /* Values for rcu_state structure's gp_flags field. */ |
498 | #define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */ | |
499 | #define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */ | |
500 | ||
afea227f PM |
501 | /* Values for rcu_state structure's gp_flags field. */ |
502 | #define RCU_GP_WAIT_INIT 0 /* Initial state. */ | |
503 | #define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */ | |
504 | #define RCU_GP_WAIT_FQS 2 /* Wait for force-quiescent-state time. */ | |
505 | ||
6ce75a23 | 506 | extern struct list_head rcu_struct_flavors; |
3fbfbf7a PM |
507 | |
508 | /* Sequence through rcu_state structures for each RCU flavor. */ | |
6ce75a23 PM |
509 | #define for_each_rcu_flavor(rsp) \ |
510 | list_for_each_entry((rsp), &rcu_struct_flavors, flavors) | |
511 | ||
6258c4fb IM |
512 | /* |
513 | * RCU implementation internal declarations: | |
514 | */ | |
d6714c22 PM |
515 | extern struct rcu_state rcu_sched_state; |
516 | DECLARE_PER_CPU(struct rcu_data, rcu_sched_data); | |
6258c4fb IM |
517 | |
518 | extern struct rcu_state rcu_bh_state; | |
519 | DECLARE_PER_CPU(struct rcu_data, rcu_bh_data); | |
520 | ||
28f6569a | 521 | #ifdef CONFIG_PREEMPT_RCU |
f41d911f PM |
522 | extern struct rcu_state rcu_preempt_state; |
523 | DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data); | |
28f6569a | 524 | #endif /* #ifdef CONFIG_PREEMPT_RCU */ |
f41d911f | 525 | |
eab0993c PM |
526 | #ifdef CONFIG_RCU_BOOST |
527 | DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status); | |
528 | DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu); | |
529 | DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); | |
530 | DECLARE_PER_CPU(char, rcu_cpu_has_work); | |
531 | #endif /* #ifdef CONFIG_RCU_BOOST */ | |
532 | ||
017c4261 | 533 | #ifndef RCU_TREE_NONCORE |
9f77da9f | 534 | |
9b2619af | 535 | /* Forward declarations for rcutree_plugin.h */ |
dbe01350 | 536 | static void rcu_bootup_announce(void); |
38200cf2 | 537 | static void rcu_preempt_note_context_switch(void); |
27f4d280 | 538 | static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp); |
b668c9cf | 539 | #ifdef CONFIG_HOTPLUG_CPU |
8af3a5e7 | 540 | static bool rcu_preempt_has_tasks(struct rcu_node *rnp); |
b668c9cf | 541 | #endif /* #ifdef CONFIG_HOTPLUG_CPU */ |
1ed509a2 | 542 | static void rcu_print_detail_task_stall(struct rcu_state *rsp); |
9bc8b558 | 543 | static int rcu_print_task_stall(struct rcu_node *rnp); |
9b2619af | 544 | static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); |
86aea0e6 | 545 | static void rcu_preempt_check_callbacks(void); |
9b2619af | 546 | void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); |
9b2619af | 547 | static void __init __rcu_init_preempt(void); |
1217ed1b | 548 | static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags); |
a46e0899 PM |
549 | static void rcu_preempt_boost_start_gp(struct rcu_node *rnp); |
550 | static void invoke_rcu_callbacks_kthread(void); | |
dff1672d | 551 | static bool rcu_is_callbacks_kthread(void); |
a46e0899 PM |
552 | #ifdef CONFIG_RCU_BOOST |
553 | static void rcu_preempt_do_callbacks(void); | |
49fb4c62 | 554 | static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp, |
5d01bbd1 | 555 | struct rcu_node *rnp); |
a46e0899 | 556 | #endif /* #ifdef CONFIG_RCU_BOOST */ |
9386c0b7 | 557 | static void __init rcu_spawn_boost_kthreads(void); |
49fb4c62 | 558 | static void rcu_prepare_kthreads(int cpu); |
8fa7845d | 559 | static void rcu_cleanup_after_idle(void); |
198bbf81 | 560 | static void rcu_prepare_for_idle(void); |
c57afe80 | 561 | static void rcu_idle_count_callbacks_posted(void); |
a858af28 PM |
562 | static void print_cpu_stall_info_begin(void); |
563 | static void print_cpu_stall_info(struct rcu_state *rsp, int cpu); | |
564 | static void print_cpu_stall_info_end(void); | |
565 | static void zero_cpu_stall_ticks(struct rcu_data *rdp); | |
566 | static void increment_cpu_stall_ticks(void); | |
d7e29933 | 567 | static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu); |
dae6e64d | 568 | static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq); |
0446be48 | 569 | static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp); |
dae6e64d | 570 | static void rcu_init_one_nocb(struct rcu_node *rnp); |
3fbfbf7a | 571 | static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp, |
96d3fd0d | 572 | bool lazy, unsigned long flags); |
3fbfbf7a | 573 | static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp, |
96d3fd0d PM |
574 | struct rcu_data *rdp, |
575 | unsigned long flags); | |
9fdd3bc9 | 576 | static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp); |
96d3fd0d | 577 | static void do_nocb_deferred_wakeup(struct rcu_data *rdp); |
3fbfbf7a | 578 | static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp); |
35ce7f29 PM |
579 | static void rcu_spawn_all_nocb_kthreads(int cpu); |
580 | static void __init rcu_spawn_nocb_kthreads(void); | |
581 | #ifdef CONFIG_RCU_NOCB_CPU | |
582 | static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp); | |
583 | #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ | |
4a81e832 | 584 | static void __maybe_unused rcu_kick_nohz_cpu(int cpu); |
34ed6246 | 585 | static bool init_nocb_callback_list(struct rcu_data *rdp); |
28ced795 CL |
586 | static void rcu_sysidle_enter(int irq); |
587 | static void rcu_sysidle_exit(int irq); | |
0edd1b17 PM |
588 | static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle, |
589 | unsigned long *maxj); | |
590 | static bool is_sysidle_rcu_state(struct rcu_state *rsp); | |
591 | static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle, | |
592 | unsigned long maxj); | |
eb75767b | 593 | static void rcu_bind_gp_kthread(void); |
2333210b | 594 | static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp); |
a096932f | 595 | static bool rcu_nohz_full_cpu(struct rcu_state *rsp); |
176f8f7a PM |
596 | static void rcu_dynticks_task_enter(void); |
597 | static void rcu_dynticks_task_exit(void); | |
9b2619af | 598 | |
017c4261 | 599 | #endif /* #ifndef RCU_TREE_NONCORE */ |
3fbfbf7a PM |
600 | |
601 | #ifdef CONFIG_RCU_TRACE | |
41050a00 | 602 | /* Read out queue lengths for tracing. */ |
3fbfbf7a PM |
603 | static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll) |
604 | { | |
41050a00 PM |
605 | #ifdef CONFIG_RCU_NOCB_CPU |
606 | *ql = atomic_long_read(&rdp->nocb_q_count); | |
607 | *qll = atomic_long_read(&rdp->nocb_q_count_lazy); | |
3fbfbf7a | 608 | #else /* #ifdef CONFIG_RCU_NOCB_CPU */ |
3fbfbf7a PM |
609 | *ql = 0; |
610 | *qll = 0; | |
3fbfbf7a | 611 | #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */ |
41050a00 | 612 | } |
3fbfbf7a | 613 | #endif /* #ifdef CONFIG_RCU_TRACE */ |