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1da177e4 LT |
1 | /* -*- linux-c -*- |
2 | * | |
3 | * $Id: sysrq.c,v 1.15 1998/08/23 14:56:41 mj Exp $ | |
4 | * | |
5 | * Linux Magic System Request Key Hacks | |
6 | * | |
7 | * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz> | |
8 | * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz> | |
9 | * | |
10 | * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com> | |
11 | * overhauled to use key registration | |
12 | * based upon discusions in irc://irc.openprojects.net/#kernelnewbies | |
13 | */ | |
14 | ||
1da177e4 LT |
15 | #include <linux/sched.h> |
16 | #include <linux/interrupt.h> | |
17 | #include <linux/mm.h> | |
18 | #include <linux/fs.h> | |
19 | #include <linux/tty.h> | |
20 | #include <linux/mount.h> | |
21 | #include <linux/kdev_t.h> | |
22 | #include <linux/major.h> | |
23 | #include <linux/reboot.h> | |
24 | #include <linux/sysrq.h> | |
25 | #include <linux/kbd_kern.h> | |
26 | #include <linux/quotaops.h> | |
1da177e4 LT |
27 | #include <linux/kernel.h> |
28 | #include <linux/module.h> | |
29 | #include <linux/suspend.h> | |
30 | #include <linux/writeback.h> | |
31 | #include <linux/buffer_head.h> /* for fsync_bdev() */ | |
32 | #include <linux/swap.h> | |
33 | #include <linux/spinlock.h> | |
34 | #include <linux/vt_kern.h> | |
35 | #include <linux/workqueue.h> | |
86b1ae38 | 36 | #include <linux/kexec.h> |
7d12e780 | 37 | #include <linux/irq.h> |
88ad0bf6 | 38 | #include <linux/hrtimer.h> |
5a3135c2 | 39 | #include <linux/oom.h> |
1da177e4 LT |
40 | |
41 | #include <asm/ptrace.h> | |
2033b0c3 | 42 | #include <asm/irq_regs.h> |
1da177e4 LT |
43 | |
44 | /* Whether we react on sysrq keys or just ignore them */ | |
5d6f647f IM |
45 | int __read_mostly __sysrq_enabled = 1; |
46 | ||
47 | static int __read_mostly sysrq_always_enabled; | |
48 | ||
49 | int sysrq_on(void) | |
50 | { | |
51 | return __sysrq_enabled || sysrq_always_enabled; | |
52 | } | |
53 | ||
54 | /* | |
55 | * A value of 1 means 'all', other nonzero values are an op mask: | |
56 | */ | |
57 | static inline int sysrq_on_mask(int mask) | |
58 | { | |
59 | return sysrq_always_enabled || __sysrq_enabled == 1 || | |
60 | (__sysrq_enabled & mask); | |
61 | } | |
62 | ||
63 | static int __init sysrq_always_enabled_setup(char *str) | |
64 | { | |
65 | sysrq_always_enabled = 1; | |
66 | printk(KERN_INFO "debug: sysrq always enabled.\n"); | |
67 | ||
68 | return 1; | |
69 | } | |
70 | ||
71 | __setup("sysrq_always_enabled", sysrq_always_enabled_setup); | |
72 | ||
1da177e4 | 73 | |
7d12e780 | 74 | static void sysrq_handle_loglevel(int key, struct tty_struct *tty) |
1da177e4 LT |
75 | { |
76 | int i; | |
77 | i = key - '0'; | |
78 | console_loglevel = 7; | |
79 | printk("Loglevel set to %d\n", i); | |
80 | console_loglevel = i; | |
bf36b901 | 81 | } |
1da177e4 LT |
82 | static struct sysrq_key_op sysrq_loglevel_op = { |
83 | .handler = sysrq_handle_loglevel, | |
84 | .help_msg = "loglevel0-8", | |
85 | .action_msg = "Changing Loglevel", | |
86 | .enable_mask = SYSRQ_ENABLE_LOG, | |
87 | }; | |
88 | ||
1da177e4 | 89 | #ifdef CONFIG_VT |
7d12e780 | 90 | static void sysrq_handle_SAK(int key, struct tty_struct *tty) |
1da177e4 | 91 | { |
8b6312f4 | 92 | struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work; |
8b6312f4 | 93 | schedule_work(SAK_work); |
1da177e4 LT |
94 | } |
95 | static struct sysrq_key_op sysrq_SAK_op = { | |
96 | .handler = sysrq_handle_SAK, | |
97 | .help_msg = "saK", | |
98 | .action_msg = "SAK", | |
99 | .enable_mask = SYSRQ_ENABLE_KEYBOARD, | |
100 | }; | |
bf36b901 AM |
101 | #else |
102 | #define sysrq_SAK_op (*(struct sysrq_key_op *)0) | |
1da177e4 LT |
103 | #endif |
104 | ||
105 | #ifdef CONFIG_VT | |
7d12e780 | 106 | static void sysrq_handle_unraw(int key, struct tty_struct *tty) |
1da177e4 LT |
107 | { |
108 | struct kbd_struct *kbd = &kbd_table[fg_console]; | |
109 | ||
110 | if (kbd) | |
2e8ecb9d | 111 | kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE; |
1da177e4 LT |
112 | } |
113 | static struct sysrq_key_op sysrq_unraw_op = { | |
114 | .handler = sysrq_handle_unraw, | |
115 | .help_msg = "unRaw", | |
2e8ecb9d | 116 | .action_msg = "Keyboard mode set to system default", |
1da177e4 LT |
117 | .enable_mask = SYSRQ_ENABLE_KEYBOARD, |
118 | }; | |
bf36b901 AM |
119 | #else |
120 | #define sysrq_unraw_op (*(struct sysrq_key_op *)0) | |
1da177e4 LT |
121 | #endif /* CONFIG_VT */ |
122 | ||
86b1ae38 | 123 | #ifdef CONFIG_KEXEC |
7d12e780 | 124 | static void sysrq_handle_crashdump(int key, struct tty_struct *tty) |
86b1ae38 | 125 | { |
7d12e780 | 126 | crash_kexec(get_irq_regs()); |
86b1ae38 HN |
127 | } |
128 | static struct sysrq_key_op sysrq_crashdump_op = { | |
129 | .handler = sysrq_handle_crashdump, | |
130 | .help_msg = "Crashdump", | |
131 | .action_msg = "Trigger a crashdump", | |
132 | .enable_mask = SYSRQ_ENABLE_DUMP, | |
133 | }; | |
bf36b901 AM |
134 | #else |
135 | #define sysrq_crashdump_op (*(struct sysrq_key_op *)0) | |
86b1ae38 HN |
136 | #endif |
137 | ||
7d12e780 | 138 | static void sysrq_handle_reboot(int key, struct tty_struct *tty) |
1da177e4 | 139 | { |
b2e9c7d0 | 140 | lockdep_off(); |
1da177e4 | 141 | local_irq_enable(); |
4de8b9b7 | 142 | emergency_restart(); |
1da177e4 | 143 | } |
1da177e4 LT |
144 | static struct sysrq_key_op sysrq_reboot_op = { |
145 | .handler = sysrq_handle_reboot, | |
146 | .help_msg = "reBoot", | |
147 | .action_msg = "Resetting", | |
148 | .enable_mask = SYSRQ_ENABLE_BOOT, | |
149 | }; | |
150 | ||
7d12e780 | 151 | static void sysrq_handle_sync(int key, struct tty_struct *tty) |
1da177e4 LT |
152 | { |
153 | emergency_sync(); | |
154 | } | |
1da177e4 LT |
155 | static struct sysrq_key_op sysrq_sync_op = { |
156 | .handler = sysrq_handle_sync, | |
157 | .help_msg = "Sync", | |
158 | .action_msg = "Emergency Sync", | |
159 | .enable_mask = SYSRQ_ENABLE_SYNC, | |
160 | }; | |
161 | ||
88ad0bf6 IM |
162 | static void sysrq_handle_show_timers(int key, struct tty_struct *tty) |
163 | { | |
164 | sysrq_timer_list_show(); | |
165 | } | |
166 | ||
167 | static struct sysrq_key_op sysrq_show_timers_op = { | |
168 | .handler = sysrq_handle_show_timers, | |
169 | .help_msg = "show-all-timers(Q)", | |
170 | .action_msg = "Show Pending Timers", | |
171 | }; | |
172 | ||
7d12e780 | 173 | static void sysrq_handle_mountro(int key, struct tty_struct *tty) |
1da177e4 LT |
174 | { |
175 | emergency_remount(); | |
176 | } | |
1da177e4 LT |
177 | static struct sysrq_key_op sysrq_mountro_op = { |
178 | .handler = sysrq_handle_mountro, | |
179 | .help_msg = "Unmount", | |
180 | .action_msg = "Emergency Remount R/O", | |
181 | .enable_mask = SYSRQ_ENABLE_REMOUNT, | |
182 | }; | |
183 | ||
8c64580d | 184 | #ifdef CONFIG_LOCKDEP |
7d12e780 | 185 | static void sysrq_handle_showlocks(int key, struct tty_struct *tty) |
de5097c2 | 186 | { |
9a11b49a | 187 | debug_show_all_locks(); |
de5097c2 | 188 | } |
8c64580d | 189 | |
de5097c2 IM |
190 | static struct sysrq_key_op sysrq_showlocks_op = { |
191 | .handler = sysrq_handle_showlocks, | |
192 | .help_msg = "show-all-locks(D)", | |
193 | .action_msg = "Show Locks Held", | |
194 | }; | |
bf36b901 AM |
195 | #else |
196 | #define sysrq_showlocks_op (*(struct sysrq_key_op *)0) | |
de5097c2 | 197 | #endif |
1da177e4 | 198 | |
5045bcae RR |
199 | #ifdef CONFIG_SMP |
200 | static DEFINE_SPINLOCK(show_lock); | |
201 | ||
202 | static void showacpu(void *dummy) | |
203 | { | |
204 | unsigned long flags; | |
205 | ||
206 | /* Idle CPUs have no interesting backtrace. */ | |
207 | if (idle_cpu(smp_processor_id())) | |
208 | return; | |
209 | ||
210 | spin_lock_irqsave(&show_lock, flags); | |
211 | printk(KERN_INFO "CPU%d:\n", smp_processor_id()); | |
212 | show_stack(NULL, NULL); | |
213 | spin_unlock_irqrestore(&show_lock, flags); | |
214 | } | |
215 | ||
216 | static void sysrq_showregs_othercpus(struct work_struct *dummy) | |
217 | { | |
218 | smp_call_function(showacpu, NULL, 0, 0); | |
219 | } | |
220 | ||
221 | static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus); | |
222 | ||
223 | static void sysrq_handle_showallcpus(int key, struct tty_struct *tty) | |
224 | { | |
225 | struct pt_regs *regs = get_irq_regs(); | |
226 | if (regs) { | |
227 | printk(KERN_INFO "CPU%d:\n", smp_processor_id()); | |
228 | show_regs(regs); | |
229 | } | |
230 | schedule_work(&sysrq_showallcpus); | |
231 | } | |
232 | ||
233 | static struct sysrq_key_op sysrq_showallcpus_op = { | |
234 | .handler = sysrq_handle_showallcpus, | |
235 | .help_msg = "aLlcpus", | |
236 | .action_msg = "Show backtrace of all active CPUs", | |
237 | .enable_mask = SYSRQ_ENABLE_DUMP, | |
238 | }; | |
239 | #endif | |
240 | ||
7d12e780 | 241 | static void sysrq_handle_showregs(int key, struct tty_struct *tty) |
1da177e4 | 242 | { |
7d12e780 DH |
243 | struct pt_regs *regs = get_irq_regs(); |
244 | if (regs) | |
245 | show_regs(regs); | |
1da177e4 LT |
246 | } |
247 | static struct sysrq_key_op sysrq_showregs_op = { | |
248 | .handler = sysrq_handle_showregs, | |
249 | .help_msg = "showPc", | |
250 | .action_msg = "Show Regs", | |
251 | .enable_mask = SYSRQ_ENABLE_DUMP, | |
252 | }; | |
253 | ||
7d12e780 | 254 | static void sysrq_handle_showstate(int key, struct tty_struct *tty) |
1da177e4 LT |
255 | { |
256 | show_state(); | |
257 | } | |
258 | static struct sysrq_key_op sysrq_showstate_op = { | |
259 | .handler = sysrq_handle_showstate, | |
260 | .help_msg = "showTasks", | |
261 | .action_msg = "Show State", | |
262 | .enable_mask = SYSRQ_ENABLE_DUMP, | |
263 | }; | |
264 | ||
e59e2ae2 IM |
265 | static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty) |
266 | { | |
267 | show_state_filter(TASK_UNINTERRUPTIBLE); | |
268 | } | |
269 | static struct sysrq_key_op sysrq_showstate_blocked_op = { | |
270 | .handler = sysrq_handle_showstate_blocked, | |
d346cce3 | 271 | .help_msg = "shoW-blocked-tasks", |
e59e2ae2 IM |
272 | .action_msg = "Show Blocked State", |
273 | .enable_mask = SYSRQ_ENABLE_DUMP, | |
274 | }; | |
275 | ||
276 | ||
7d12e780 | 277 | static void sysrq_handle_showmem(int key, struct tty_struct *tty) |
1da177e4 LT |
278 | { |
279 | show_mem(); | |
280 | } | |
281 | static struct sysrq_key_op sysrq_showmem_op = { | |
282 | .handler = sysrq_handle_showmem, | |
283 | .help_msg = "showMem", | |
284 | .action_msg = "Show Memory", | |
285 | .enable_mask = SYSRQ_ENABLE_DUMP, | |
286 | }; | |
287 | ||
bf36b901 AM |
288 | /* |
289 | * Signal sysrq helper function. Sends a signal to all user processes. | |
290 | */ | |
1da177e4 LT |
291 | static void send_sig_all(int sig) |
292 | { | |
293 | struct task_struct *p; | |
294 | ||
295 | for_each_process(p) { | |
b460cbc5 | 296 | if (p->mm && !is_global_init(p)) |
1da177e4 LT |
297 | /* Not swapper, init nor kernel thread */ |
298 | force_sig(sig, p); | |
299 | } | |
300 | } | |
301 | ||
7d12e780 | 302 | static void sysrq_handle_term(int key, struct tty_struct *tty) |
1da177e4 LT |
303 | { |
304 | send_sig_all(SIGTERM); | |
305 | console_loglevel = 8; | |
306 | } | |
307 | static struct sysrq_key_op sysrq_term_op = { | |
308 | .handler = sysrq_handle_term, | |
309 | .help_msg = "tErm", | |
310 | .action_msg = "Terminate All Tasks", | |
311 | .enable_mask = SYSRQ_ENABLE_SIGNAL, | |
312 | }; | |
313 | ||
65f27f38 | 314 | static void moom_callback(struct work_struct *ignored) |
1da177e4 | 315 | { |
0e88460d | 316 | out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0); |
1da177e4 LT |
317 | } |
318 | ||
65f27f38 | 319 | static DECLARE_WORK(moom_work, moom_callback); |
1da177e4 | 320 | |
7d12e780 | 321 | static void sysrq_handle_moom(int key, struct tty_struct *tty) |
1da177e4 LT |
322 | { |
323 | schedule_work(&moom_work); | |
324 | } | |
325 | static struct sysrq_key_op sysrq_moom_op = { | |
326 | .handler = sysrq_handle_moom, | |
327 | .help_msg = "Full", | |
328 | .action_msg = "Manual OOM execution", | |
329 | }; | |
330 | ||
7d12e780 | 331 | static void sysrq_handle_kill(int key, struct tty_struct *tty) |
1da177e4 LT |
332 | { |
333 | send_sig_all(SIGKILL); | |
334 | console_loglevel = 8; | |
335 | } | |
336 | static struct sysrq_key_op sysrq_kill_op = { | |
337 | .handler = sysrq_handle_kill, | |
338 | .help_msg = "kIll", | |
339 | .action_msg = "Kill All Tasks", | |
340 | .enable_mask = SYSRQ_ENABLE_SIGNAL, | |
341 | }; | |
342 | ||
7d12e780 | 343 | static void sysrq_handle_unrt(int key, struct tty_struct *tty) |
1da177e4 LT |
344 | { |
345 | normalize_rt_tasks(); | |
346 | } | |
347 | static struct sysrq_key_op sysrq_unrt_op = { | |
348 | .handler = sysrq_handle_unrt, | |
349 | .help_msg = "Nice", | |
350 | .action_msg = "Nice All RT Tasks", | |
351 | .enable_mask = SYSRQ_ENABLE_RTNICE, | |
352 | }; | |
353 | ||
354 | /* Key Operations table and lock */ | |
355 | static DEFINE_SPINLOCK(sysrq_key_table_lock); | |
bf36b901 AM |
356 | |
357 | static struct sysrq_key_op *sysrq_key_table[36] = { | |
358 | &sysrq_loglevel_op, /* 0 */ | |
359 | &sysrq_loglevel_op, /* 1 */ | |
360 | &sysrq_loglevel_op, /* 2 */ | |
361 | &sysrq_loglevel_op, /* 3 */ | |
362 | &sysrq_loglevel_op, /* 4 */ | |
363 | &sysrq_loglevel_op, /* 5 */ | |
364 | &sysrq_loglevel_op, /* 6 */ | |
365 | &sysrq_loglevel_op, /* 7 */ | |
366 | &sysrq_loglevel_op, /* 8 */ | |
367 | &sysrq_loglevel_op, /* 9 */ | |
368 | ||
369 | /* | |
d346cce3 RD |
370 | * a: Don't use for system provided sysrqs, it is handled specially on |
371 | * sparc and will never arrive. | |
bf36b901 AM |
372 | */ |
373 | NULL, /* a */ | |
374 | &sysrq_reboot_op, /* b */ | |
d346cce3 | 375 | &sysrq_crashdump_op, /* c & ibm_emac driver debug */ |
bf36b901 AM |
376 | &sysrq_showlocks_op, /* d */ |
377 | &sysrq_term_op, /* e */ | |
378 | &sysrq_moom_op, /* f */ | |
d346cce3 | 379 | /* g: May be registered by ppc for kgdb */ |
bf36b901 AM |
380 | NULL, /* g */ |
381 | NULL, /* h */ | |
382 | &sysrq_kill_op, /* i */ | |
383 | NULL, /* j */ | |
384 | &sysrq_SAK_op, /* k */ | |
5045bcae RR |
385 | #ifdef CONFIG_SMP |
386 | &sysrq_showallcpus_op, /* l */ | |
387 | #else | |
bf36b901 | 388 | NULL, /* l */ |
5045bcae | 389 | #endif |
bf36b901 AM |
390 | &sysrq_showmem_op, /* m */ |
391 | &sysrq_unrt_op, /* n */ | |
d346cce3 | 392 | /* o: This will often be registered as 'Off' at init time */ |
bf36b901 AM |
393 | NULL, /* o */ |
394 | &sysrq_showregs_op, /* p */ | |
88ad0bf6 | 395 | &sysrq_show_timers_op, /* q */ |
d346cce3 | 396 | &sysrq_unraw_op, /* r */ |
bf36b901 AM |
397 | &sysrq_sync_op, /* s */ |
398 | &sysrq_showstate_op, /* t */ | |
399 | &sysrq_mountro_op, /* u */ | |
d346cce3 | 400 | /* v: May be registered at init time by SMP VOYAGER */ |
bf36b901 | 401 | NULL, /* v */ |
d346cce3 RD |
402 | &sysrq_showstate_blocked_op, /* w */ |
403 | /* x: May be registered on ppc/powerpc for xmon */ | |
404 | NULL, /* x */ | |
bf36b901 AM |
405 | NULL, /* y */ |
406 | NULL /* z */ | |
1da177e4 LT |
407 | }; |
408 | ||
409 | /* key2index calculation, -1 on invalid index */ | |
bf36b901 AM |
410 | static int sysrq_key_table_key2index(int key) |
411 | { | |
1da177e4 | 412 | int retval; |
bf36b901 AM |
413 | |
414 | if ((key >= '0') && (key <= '9')) | |
1da177e4 | 415 | retval = key - '0'; |
bf36b901 | 416 | else if ((key >= 'a') && (key <= 'z')) |
1da177e4 | 417 | retval = key + 10 - 'a'; |
bf36b901 | 418 | else |
1da177e4 | 419 | retval = -1; |
1da177e4 LT |
420 | return retval; |
421 | } | |
422 | ||
423 | /* | |
424 | * get and put functions for the table, exposed to modules. | |
425 | */ | |
bf36b901 AM |
426 | struct sysrq_key_op *__sysrq_get_key_op(int key) |
427 | { | |
428 | struct sysrq_key_op *op_p = NULL; | |
1da177e4 | 429 | int i; |
bf36b901 | 430 | |
1da177e4 | 431 | i = sysrq_key_table_key2index(key); |
bf36b901 AM |
432 | if (i != -1) |
433 | op_p = sysrq_key_table[i]; | |
1da177e4 LT |
434 | return op_p; |
435 | } | |
436 | ||
bf36b901 AM |
437 | static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) |
438 | { | |
439 | int i = sysrq_key_table_key2index(key); | |
1da177e4 | 440 | |
1da177e4 LT |
441 | if (i != -1) |
442 | sysrq_key_table[i] = op_p; | |
443 | } | |
444 | ||
445 | /* | |
bf36b901 AM |
446 | * This is the non-locking version of handle_sysrq. It must/can only be called |
447 | * by sysrq key handlers, as they are inside of the lock | |
1da177e4 | 448 | */ |
7d12e780 | 449 | void __handle_sysrq(int key, struct tty_struct *tty, int check_mask) |
1da177e4 LT |
450 | { |
451 | struct sysrq_key_op *op_p; | |
452 | int orig_log_level; | |
bf36b901 | 453 | int i; |
1da177e4 LT |
454 | unsigned long flags; |
455 | ||
456 | spin_lock_irqsave(&sysrq_key_table_lock, flags); | |
457 | orig_log_level = console_loglevel; | |
458 | console_loglevel = 7; | |
459 | printk(KERN_INFO "SysRq : "); | |
460 | ||
461 | op_p = __sysrq_get_key_op(key); | |
462 | if (op_p) { | |
bf36b901 AM |
463 | /* |
464 | * Should we check for enabled operations (/proc/sysrq-trigger | |
465 | * should not) and is the invoked operation enabled? | |
466 | */ | |
5d6f647f | 467 | if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { |
bf36b901 | 468 | printk("%s\n", op_p->action_msg); |
1da177e4 | 469 | console_loglevel = orig_log_level; |
7d12e780 | 470 | op_p->handler(key, tty); |
bf36b901 | 471 | } else { |
1da177e4 | 472 | printk("This sysrq operation is disabled.\n"); |
bf36b901 | 473 | } |
1da177e4 LT |
474 | } else { |
475 | printk("HELP : "); | |
476 | /* Only print the help msg once per handler */ | |
bf36b901 AM |
477 | for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { |
478 | if (sysrq_key_table[i]) { | |
479 | int j; | |
480 | ||
481 | for (j = 0; sysrq_key_table[i] != | |
482 | sysrq_key_table[j]; j++) | |
483 | ; | |
484 | if (j != i) | |
485 | continue; | |
486 | printk("%s ", sysrq_key_table[i]->help_msg); | |
487 | } | |
1da177e4 | 488 | } |
bf36b901 | 489 | printk("\n"); |
1da177e4 LT |
490 | console_loglevel = orig_log_level; |
491 | } | |
492 | spin_unlock_irqrestore(&sysrq_key_table_lock, flags); | |
493 | } | |
494 | ||
495 | /* | |
496 | * This function is called by the keyboard handler when SysRq is pressed | |
497 | * and any other keycode arrives. | |
498 | */ | |
7d12e780 | 499 | void handle_sysrq(int key, struct tty_struct *tty) |
1da177e4 | 500 | { |
5d6f647f IM |
501 | if (sysrq_on()) |
502 | __handle_sysrq(key, tty, 1); | |
1da177e4 | 503 | } |
bf36b901 | 504 | EXPORT_SYMBOL(handle_sysrq); |
1da177e4 | 505 | |
cf62ddce | 506 | static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, |
bf36b901 AM |
507 | struct sysrq_key_op *remove_op_p) |
508 | { | |
1da177e4 LT |
509 | |
510 | int retval; | |
511 | unsigned long flags; | |
512 | ||
513 | spin_lock_irqsave(&sysrq_key_table_lock, flags); | |
514 | if (__sysrq_get_key_op(key) == remove_op_p) { | |
515 | __sysrq_put_key_op(key, insert_op_p); | |
516 | retval = 0; | |
517 | } else { | |
518 | retval = -1; | |
519 | } | |
520 | spin_unlock_irqrestore(&sysrq_key_table_lock, flags); | |
1da177e4 LT |
521 | return retval; |
522 | } | |
523 | ||
524 | int register_sysrq_key(int key, struct sysrq_key_op *op_p) | |
525 | { | |
526 | return __sysrq_swap_key_ops(key, op_p, NULL); | |
527 | } | |
bf36b901 | 528 | EXPORT_SYMBOL(register_sysrq_key); |
1da177e4 LT |
529 | |
530 | int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) | |
531 | { | |
532 | return __sysrq_swap_key_ops(key, NULL, op_p); | |
533 | } | |
1da177e4 | 534 | EXPORT_SYMBOL(unregister_sysrq_key); |