blob: 7fd3cd5ddf2190269e206383ece44c481a889f78 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* -*- 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#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>
27#include <linux/smp_lock.h>
28#include <linux/kernel.h>
29#include <linux/module.h>
30#include <linux/suspend.h>
31#include <linux/writeback.h>
32#include <linux/buffer_head.h> /* for fsync_bdev() */
33#include <linux/swap.h>
34#include <linux/spinlock.h>
35#include <linux/vt_kern.h>
36#include <linux/workqueue.h>
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -070037#include <linux/kexec.h>
David Howells7d12e782006-10-05 14:55:46 +010038#include <linux/irq.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070039
40#include <asm/ptrace.h>
Heiko Carstens2033b0c2006-10-06 16:38:42 +020041#include <asm/irq_regs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
43/* Whether we react on sysrq keys or just ignore them */
Ingo Molnar5d6f6472006-12-13 00:34:36 -080044int __read_mostly __sysrq_enabled = 1;
45
46static int __read_mostly sysrq_always_enabled;
47
48int sysrq_on(void)
49{
50 return __sysrq_enabled || sysrq_always_enabled;
51}
52
53/*
54 * A value of 1 means 'all', other nonzero values are an op mask:
55 */
56static inline int sysrq_on_mask(int mask)
57{
58 return sysrq_always_enabled || __sysrq_enabled == 1 ||
59 (__sysrq_enabled & mask);
60}
61
62static int __init sysrq_always_enabled_setup(char *str)
63{
64 sysrq_always_enabled = 1;
65 printk(KERN_INFO "debug: sysrq always enabled.\n");
66
67 return 1;
68}
69
70__setup("sysrq_always_enabled", sysrq_always_enabled_setup);
71
Linus Torvalds1da177e2005-04-16 15:20:36 -070072
David Howells7d12e782006-10-05 14:55:46 +010073static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -070074{
75 int i;
76 i = key - '0';
77 console_loglevel = 7;
78 printk("Loglevel set to %d\n", i);
79 console_loglevel = i;
Andrew Mortonbf36b902006-03-25 03:07:08 -080080}
Linus Torvalds1da177e2005-04-16 15:20:36 -070081static struct sysrq_key_op sysrq_loglevel_op = {
82 .handler = sysrq_handle_loglevel,
83 .help_msg = "loglevel0-8",
84 .action_msg = "Changing Loglevel",
85 .enable_mask = SYSRQ_ENABLE_LOG,
86};
87
Linus Torvalds1da177e2005-04-16 15:20:36 -070088#ifdef CONFIG_VT
David Howells7d12e782006-10-05 14:55:46 +010089static void sysrq_handle_SAK(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -070090{
91 if (tty)
92 do_SAK(tty);
93 reset_vc(vc_cons[fg_console].d);
94}
95static 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};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800101#else
102#define sysrq_SAK_op (*(struct sysrq_key_op *)0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103#endif
104
105#ifdef CONFIG_VT
David Howells7d12e782006-10-05 14:55:46 +0100106static void sysrq_handle_unraw(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107{
108 struct kbd_struct *kbd = &kbd_table[fg_console];
109
110 if (kbd)
111 kbd->kbdmode = VC_XLATE;
112}
113static struct sysrq_key_op sysrq_unraw_op = {
114 .handler = sysrq_handle_unraw,
115 .help_msg = "unRaw",
116 .action_msg = "Keyboard mode set to XLATE",
117 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
118};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800119#else
120#define sysrq_unraw_op (*(struct sysrq_key_op *)0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121#endif /* CONFIG_VT */
122
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700123#ifdef CONFIG_KEXEC
David Howells7d12e782006-10-05 14:55:46 +0100124static void sysrq_handle_crashdump(int key, struct tty_struct *tty)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700125{
David Howells7d12e782006-10-05 14:55:46 +0100126 crash_kexec(get_irq_regs());
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700127}
128static 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};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800134#else
135#define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700136#endif
137
David Howells7d12e782006-10-05 14:55:46 +0100138static void sysrq_handle_reboot(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139{
Peter Zijlstrab2e9c7d2006-09-30 23:28:02 -0700140 lockdep_off();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 local_irq_enable();
Eric W. Biederman4de8b9b2005-07-26 11:51:06 -0600142 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144static 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
David Howells7d12e782006-10-05 14:55:46 +0100151static void sysrq_handle_sync(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152{
153 emergency_sync();
154}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155static 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
David Howells7d12e782006-10-05 14:55:46 +0100162static void sysrq_handle_mountro(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163{
164 emergency_remount();
165}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166static struct sysrq_key_op sysrq_mountro_op = {
167 .handler = sysrq_handle_mountro,
168 .help_msg = "Unmount",
169 .action_msg = "Emergency Remount R/O",
170 .enable_mask = SYSRQ_ENABLE_REMOUNT,
171};
172
Ingo Molnar8c645802006-07-03 00:24:56 -0700173#ifdef CONFIG_LOCKDEP
David Howells7d12e782006-10-05 14:55:46 +0100174static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800175{
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700176 debug_show_all_locks();
Ingo Molnarde5097c2006-01-09 15:59:21 -0800177}
Ingo Molnar8c645802006-07-03 00:24:56 -0700178
Ingo Molnarde5097c2006-01-09 15:59:21 -0800179static struct sysrq_key_op sysrq_showlocks_op = {
180 .handler = sysrq_handle_showlocks,
181 .help_msg = "show-all-locks(D)",
182 .action_msg = "Show Locks Held",
183};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800184#else
185#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800186#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
David Howells7d12e782006-10-05 14:55:46 +0100188static void sysrq_handle_showregs(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189{
David Howells7d12e782006-10-05 14:55:46 +0100190 struct pt_regs *regs = get_irq_regs();
191 if (regs)
192 show_regs(regs);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193}
194static struct sysrq_key_op sysrq_showregs_op = {
195 .handler = sysrq_handle_showregs,
196 .help_msg = "showPc",
197 .action_msg = "Show Regs",
198 .enable_mask = SYSRQ_ENABLE_DUMP,
199};
200
David Howells7d12e782006-10-05 14:55:46 +0100201static void sysrq_handle_showstate(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202{
203 show_state();
204}
205static struct sysrq_key_op sysrq_showstate_op = {
206 .handler = sysrq_handle_showstate,
207 .help_msg = "showTasks",
208 .action_msg = "Show State",
209 .enable_mask = SYSRQ_ENABLE_DUMP,
210};
211
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800212static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
213{
214 show_state_filter(TASK_UNINTERRUPTIBLE);
215}
216static struct sysrq_key_op sysrq_showstate_blocked_op = {
217 .handler = sysrq_handle_showstate_blocked,
Randy Dunlapd346cce2007-01-31 23:48:17 -0800218 .help_msg = "shoW-blocked-tasks",
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800219 .action_msg = "Show Blocked State",
220 .enable_mask = SYSRQ_ENABLE_DUMP,
221};
222
223
David Howells7d12e782006-10-05 14:55:46 +0100224static void sysrq_handle_showmem(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225{
226 show_mem();
227}
228static struct sysrq_key_op sysrq_showmem_op = {
229 .handler = sysrq_handle_showmem,
230 .help_msg = "showMem",
231 .action_msg = "Show Memory",
232 .enable_mask = SYSRQ_ENABLE_DUMP,
233};
234
Andrew Mortonbf36b902006-03-25 03:07:08 -0800235/*
236 * Signal sysrq helper function. Sends a signal to all user processes.
237 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238static void send_sig_all(int sig)
239{
240 struct task_struct *p;
241
242 for_each_process(p) {
Sukadev Bhattiproluf400e192006-09-29 02:00:07 -0700243 if (p->mm && !is_init(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 /* Not swapper, init nor kernel thread */
245 force_sig(sig, p);
246 }
247}
248
David Howells7d12e782006-10-05 14:55:46 +0100249static void sysrq_handle_term(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250{
251 send_sig_all(SIGTERM);
252 console_loglevel = 8;
253}
254static struct sysrq_key_op sysrq_term_op = {
255 .handler = sysrq_handle_term,
256 .help_msg = "tErm",
257 .action_msg = "Terminate All Tasks",
258 .enable_mask = SYSRQ_ENABLE_SIGNAL,
259};
260
David Howells65f27f32006-11-22 14:55:48 +0000261static void moom_callback(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262{
Andrew Mortonbf36b902006-03-25 03:07:08 -0800263 out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
264 GFP_KERNEL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265}
266
David Howells65f27f32006-11-22 14:55:48 +0000267static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268
David Howells7d12e782006-10-05 14:55:46 +0100269static void sysrq_handle_moom(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270{
271 schedule_work(&moom_work);
272}
273static struct sysrq_key_op sysrq_moom_op = {
274 .handler = sysrq_handle_moom,
275 .help_msg = "Full",
276 .action_msg = "Manual OOM execution",
277};
278
David Howells7d12e782006-10-05 14:55:46 +0100279static void sysrq_handle_kill(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280{
281 send_sig_all(SIGKILL);
282 console_loglevel = 8;
283}
284static struct sysrq_key_op sysrq_kill_op = {
285 .handler = sysrq_handle_kill,
286 .help_msg = "kIll",
287 .action_msg = "Kill All Tasks",
288 .enable_mask = SYSRQ_ENABLE_SIGNAL,
289};
290
David Howells7d12e782006-10-05 14:55:46 +0100291static void sysrq_handle_unrt(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292{
293 normalize_rt_tasks();
294}
295static struct sysrq_key_op sysrq_unrt_op = {
296 .handler = sysrq_handle_unrt,
297 .help_msg = "Nice",
298 .action_msg = "Nice All RT Tasks",
299 .enable_mask = SYSRQ_ENABLE_RTNICE,
300};
301
302/* Key Operations table and lock */
303static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800304
305static struct sysrq_key_op *sysrq_key_table[36] = {
306 &sysrq_loglevel_op, /* 0 */
307 &sysrq_loglevel_op, /* 1 */
308 &sysrq_loglevel_op, /* 2 */
309 &sysrq_loglevel_op, /* 3 */
310 &sysrq_loglevel_op, /* 4 */
311 &sysrq_loglevel_op, /* 5 */
312 &sysrq_loglevel_op, /* 6 */
313 &sysrq_loglevel_op, /* 7 */
314 &sysrq_loglevel_op, /* 8 */
315 &sysrq_loglevel_op, /* 9 */
316
317 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800318 * a: Don't use for system provided sysrqs, it is handled specially on
319 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800320 */
321 NULL, /* a */
322 &sysrq_reboot_op, /* b */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800323 &sysrq_crashdump_op, /* c & ibm_emac driver debug */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800324 &sysrq_showlocks_op, /* d */
325 &sysrq_term_op, /* e */
326 &sysrq_moom_op, /* f */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800327 /* g: May be registered by ppc for kgdb */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800328 NULL, /* g */
329 NULL, /* h */
330 &sysrq_kill_op, /* i */
331 NULL, /* j */
332 &sysrq_SAK_op, /* k */
333 NULL, /* l */
334 &sysrq_showmem_op, /* m */
335 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800336 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800337 NULL, /* o */
338 &sysrq_showregs_op, /* p */
339 NULL, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800340 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800341 &sysrq_sync_op, /* s */
342 &sysrq_showstate_op, /* t */
343 &sysrq_mountro_op, /* u */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800344 /* v: May be registered at init time by SMP VOYAGER */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800345 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800346 &sysrq_showstate_blocked_op, /* w */
347 /* x: May be registered on ppc/powerpc for xmon */
348 NULL, /* x */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800349 NULL, /* y */
350 NULL /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351};
352
353/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800354static int sysrq_key_table_key2index(int key)
355{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800357
358 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800360 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800362 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 return retval;
365}
366
367/*
368 * get and put functions for the table, exposed to modules.
369 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800370struct sysrq_key_op *__sysrq_get_key_op(int key)
371{
372 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800374
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800376 if (i != -1)
377 op_p = sysrq_key_table[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 return op_p;
379}
380
Andrew Mortonbf36b902006-03-25 03:07:08 -0800381static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
382{
383 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 if (i != -1)
386 sysrq_key_table[i] = op_p;
387}
388
389/*
Andrew Mortonbf36b902006-03-25 03:07:08 -0800390 * This is the non-locking version of handle_sysrq. It must/can only be called
391 * by sysrq key handlers, as they are inside of the lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 */
David Howells7d12e782006-10-05 14:55:46 +0100393void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394{
395 struct sysrq_key_op *op_p;
396 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800397 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 unsigned long flags;
399
400 spin_lock_irqsave(&sysrq_key_table_lock, flags);
401 orig_log_level = console_loglevel;
402 console_loglevel = 7;
403 printk(KERN_INFO "SysRq : ");
404
405 op_p = __sysrq_get_key_op(key);
406 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800407 /*
408 * Should we check for enabled operations (/proc/sysrq-trigger
409 * should not) and is the invoked operation enabled?
410 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800411 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800412 printk("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 console_loglevel = orig_log_level;
David Howells7d12e782006-10-05 14:55:46 +0100414 op_p->handler(key, tty);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800415 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 printk("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800417 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 } else {
419 printk("HELP : ");
420 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800421 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
422 if (sysrq_key_table[i]) {
423 int j;
424
425 for (j = 0; sysrq_key_table[i] !=
426 sysrq_key_table[j]; j++)
427 ;
428 if (j != i)
429 continue;
430 printk("%s ", sysrq_key_table[i]->help_msg);
431 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 }
Andrew Mortonbf36b902006-03-25 03:07:08 -0800433 printk("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 console_loglevel = orig_log_level;
435 }
436 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
437}
438
439/*
440 * This function is called by the keyboard handler when SysRq is pressed
441 * and any other keycode arrives.
442 */
David Howells7d12e782006-10-05 14:55:46 +0100443void handle_sysrq(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800445 if (sysrq_on())
446 __handle_sysrq(key, tty, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800448EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800450static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800451 struct sysrq_key_op *remove_op_p)
452{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453
454 int retval;
455 unsigned long flags;
456
457 spin_lock_irqsave(&sysrq_key_table_lock, flags);
458 if (__sysrq_get_key_op(key) == remove_op_p) {
459 __sysrq_put_key_op(key, insert_op_p);
460 retval = 0;
461 } else {
462 retval = -1;
463 }
464 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 return retval;
466}
467
468int register_sysrq_key(int key, struct sysrq_key_op *op_p)
469{
470 return __sysrq_swap_key_ops(key, op_p, NULL);
471}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800472EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473
474int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
475{
476 return __sysrq_swap_key_ops(key, NULL, op_p);
477}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478EXPORT_SYMBOL(unregister_sysrq_key);