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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{
Eric W. Biederman8b6312f2007-02-10 01:44:34 -080091 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
Eric W. Biederman8b6312f2007-02-10 01:44:34 -080092 schedule_work(SAK_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -070093}
94static struct sysrq_key_op sysrq_SAK_op = {
95 .handler = sysrq_handle_SAK,
96 .help_msg = "saK",
97 .action_msg = "SAK",
98 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
99};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800100#else
101#define sysrq_SAK_op (*(struct sysrq_key_op *)0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102#endif
103
104#ifdef CONFIG_VT
David Howells7d12e782006-10-05 14:55:46 +0100105static void sysrq_handle_unraw(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106{
107 struct kbd_struct *kbd = &kbd_table[fg_console];
108
109 if (kbd)
110 kbd->kbdmode = VC_XLATE;
111}
112static struct sysrq_key_op sysrq_unraw_op = {
113 .handler = sysrq_handle_unraw,
114 .help_msg = "unRaw",
115 .action_msg = "Keyboard mode set to XLATE",
116 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
117};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800118#else
119#define sysrq_unraw_op (*(struct sysrq_key_op *)0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120#endif /* CONFIG_VT */
121
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700122#ifdef CONFIG_KEXEC
David Howells7d12e782006-10-05 14:55:46 +0100123static void sysrq_handle_crashdump(int key, struct tty_struct *tty)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700124{
David Howells7d12e782006-10-05 14:55:46 +0100125 crash_kexec(get_irq_regs());
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700126}
127static struct sysrq_key_op sysrq_crashdump_op = {
128 .handler = sysrq_handle_crashdump,
129 .help_msg = "Crashdump",
130 .action_msg = "Trigger a crashdump",
131 .enable_mask = SYSRQ_ENABLE_DUMP,
132};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800133#else
134#define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700135#endif
136
David Howells7d12e782006-10-05 14:55:46 +0100137static void sysrq_handle_reboot(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138{
Peter Zijlstrab2e9c7d2006-09-30 23:28:02 -0700139 lockdep_off();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 local_irq_enable();
Eric W. Biederman4de8b9b2005-07-26 11:51:06 -0600141 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143static struct sysrq_key_op sysrq_reboot_op = {
144 .handler = sysrq_handle_reboot,
145 .help_msg = "reBoot",
146 .action_msg = "Resetting",
147 .enable_mask = SYSRQ_ENABLE_BOOT,
148};
149
David Howells7d12e782006-10-05 14:55:46 +0100150static void sysrq_handle_sync(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151{
152 emergency_sync();
153}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154static struct sysrq_key_op sysrq_sync_op = {
155 .handler = sysrq_handle_sync,
156 .help_msg = "Sync",
157 .action_msg = "Emergency Sync",
158 .enable_mask = SYSRQ_ENABLE_SYNC,
159};
160
David Howells7d12e782006-10-05 14:55:46 +0100161static void sysrq_handle_mountro(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162{
163 emergency_remount();
164}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165static struct sysrq_key_op sysrq_mountro_op = {
166 .handler = sysrq_handle_mountro,
167 .help_msg = "Unmount",
168 .action_msg = "Emergency Remount R/O",
169 .enable_mask = SYSRQ_ENABLE_REMOUNT,
170};
171
Ingo Molnar8c645802006-07-03 00:24:56 -0700172#ifdef CONFIG_LOCKDEP
David Howells7d12e782006-10-05 14:55:46 +0100173static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800174{
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700175 debug_show_all_locks();
Ingo Molnarde5097c2006-01-09 15:59:21 -0800176}
Ingo Molnar8c645802006-07-03 00:24:56 -0700177
Ingo Molnarde5097c2006-01-09 15:59:21 -0800178static struct sysrq_key_op sysrq_showlocks_op = {
179 .handler = sysrq_handle_showlocks,
180 .help_msg = "show-all-locks(D)",
181 .action_msg = "Show Locks Held",
182};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800183#else
184#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800185#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186
David Howells7d12e782006-10-05 14:55:46 +0100187static void sysrq_handle_showregs(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188{
David Howells7d12e782006-10-05 14:55:46 +0100189 struct pt_regs *regs = get_irq_regs();
190 if (regs)
191 show_regs(regs);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192}
193static struct sysrq_key_op sysrq_showregs_op = {
194 .handler = sysrq_handle_showregs,
195 .help_msg = "showPc",
196 .action_msg = "Show Regs",
197 .enable_mask = SYSRQ_ENABLE_DUMP,
198};
199
David Howells7d12e782006-10-05 14:55:46 +0100200static void sysrq_handle_showstate(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201{
202 show_state();
203}
204static struct sysrq_key_op sysrq_showstate_op = {
205 .handler = sysrq_handle_showstate,
206 .help_msg = "showTasks",
207 .action_msg = "Show State",
208 .enable_mask = SYSRQ_ENABLE_DUMP,
209};
210
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800211static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
212{
213 show_state_filter(TASK_UNINTERRUPTIBLE);
214}
215static struct sysrq_key_op sysrq_showstate_blocked_op = {
216 .handler = sysrq_handle_showstate_blocked,
Randy Dunlapd346cce2007-01-31 23:48:17 -0800217 .help_msg = "shoW-blocked-tasks",
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800218 .action_msg = "Show Blocked State",
219 .enable_mask = SYSRQ_ENABLE_DUMP,
220};
221
222
David Howells7d12e782006-10-05 14:55:46 +0100223static void sysrq_handle_showmem(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224{
225 show_mem();
226}
227static struct sysrq_key_op sysrq_showmem_op = {
228 .handler = sysrq_handle_showmem,
229 .help_msg = "showMem",
230 .action_msg = "Show Memory",
231 .enable_mask = SYSRQ_ENABLE_DUMP,
232};
233
Andrew Mortonbf36b902006-03-25 03:07:08 -0800234/*
235 * Signal sysrq helper function. Sends a signal to all user processes.
236 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237static void send_sig_all(int sig)
238{
239 struct task_struct *p;
240
241 for_each_process(p) {
Sukadev Bhattiproluf400e192006-09-29 02:00:07 -0700242 if (p->mm && !is_init(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 /* Not swapper, init nor kernel thread */
244 force_sig(sig, p);
245 }
246}
247
David Howells7d12e782006-10-05 14:55:46 +0100248static void sysrq_handle_term(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249{
250 send_sig_all(SIGTERM);
251 console_loglevel = 8;
252}
253static struct sysrq_key_op sysrq_term_op = {
254 .handler = sysrq_handle_term,
255 .help_msg = "tErm",
256 .action_msg = "Terminate All Tasks",
257 .enable_mask = SYSRQ_ENABLE_SIGNAL,
258};
259
David Howells65f27f32006-11-22 14:55:48 +0000260static void moom_callback(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261{
Andrew Mortonbf36b902006-03-25 03:07:08 -0800262 out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
263 GFP_KERNEL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264}
265
David Howells65f27f32006-11-22 14:55:48 +0000266static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267
David Howells7d12e782006-10-05 14:55:46 +0100268static void sysrq_handle_moom(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269{
270 schedule_work(&moom_work);
271}
272static struct sysrq_key_op sysrq_moom_op = {
273 .handler = sysrq_handle_moom,
274 .help_msg = "Full",
275 .action_msg = "Manual OOM execution",
276};
277
David Howells7d12e782006-10-05 14:55:46 +0100278static void sysrq_handle_kill(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279{
280 send_sig_all(SIGKILL);
281 console_loglevel = 8;
282}
283static struct sysrq_key_op sysrq_kill_op = {
284 .handler = sysrq_handle_kill,
285 .help_msg = "kIll",
286 .action_msg = "Kill All Tasks",
287 .enable_mask = SYSRQ_ENABLE_SIGNAL,
288};
289
David Howells7d12e782006-10-05 14:55:46 +0100290static void sysrq_handle_unrt(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291{
292 normalize_rt_tasks();
293}
294static struct sysrq_key_op sysrq_unrt_op = {
295 .handler = sysrq_handle_unrt,
296 .help_msg = "Nice",
297 .action_msg = "Nice All RT Tasks",
298 .enable_mask = SYSRQ_ENABLE_RTNICE,
299};
300
301/* Key Operations table and lock */
302static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800303
304static struct sysrq_key_op *sysrq_key_table[36] = {
305 &sysrq_loglevel_op, /* 0 */
306 &sysrq_loglevel_op, /* 1 */
307 &sysrq_loglevel_op, /* 2 */
308 &sysrq_loglevel_op, /* 3 */
309 &sysrq_loglevel_op, /* 4 */
310 &sysrq_loglevel_op, /* 5 */
311 &sysrq_loglevel_op, /* 6 */
312 &sysrq_loglevel_op, /* 7 */
313 &sysrq_loglevel_op, /* 8 */
314 &sysrq_loglevel_op, /* 9 */
315
316 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800317 * a: Don't use for system provided sysrqs, it is handled specially on
318 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800319 */
320 NULL, /* a */
321 &sysrq_reboot_op, /* b */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800322 &sysrq_crashdump_op, /* c & ibm_emac driver debug */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800323 &sysrq_showlocks_op, /* d */
324 &sysrq_term_op, /* e */
325 &sysrq_moom_op, /* f */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800326 /* g: May be registered by ppc for kgdb */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800327 NULL, /* g */
328 NULL, /* h */
329 &sysrq_kill_op, /* i */
330 NULL, /* j */
331 &sysrq_SAK_op, /* k */
332 NULL, /* l */
333 &sysrq_showmem_op, /* m */
334 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800335 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800336 NULL, /* o */
337 &sysrq_showregs_op, /* p */
338 NULL, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800339 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800340 &sysrq_sync_op, /* s */
341 &sysrq_showstate_op, /* t */
342 &sysrq_mountro_op, /* u */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800343 /* v: May be registered at init time by SMP VOYAGER */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800344 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800345 &sysrq_showstate_blocked_op, /* w */
346 /* x: May be registered on ppc/powerpc for xmon */
347 NULL, /* x */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800348 NULL, /* y */
349 NULL /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350};
351
352/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800353static int sysrq_key_table_key2index(int key)
354{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800356
357 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800359 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800361 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 return retval;
364}
365
366/*
367 * get and put functions for the table, exposed to modules.
368 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800369struct sysrq_key_op *__sysrq_get_key_op(int key)
370{
371 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800373
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800375 if (i != -1)
376 op_p = sysrq_key_table[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377 return op_p;
378}
379
Andrew Mortonbf36b902006-03-25 03:07:08 -0800380static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
381{
382 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 if (i != -1)
385 sysrq_key_table[i] = op_p;
386}
387
388/*
Andrew Mortonbf36b902006-03-25 03:07:08 -0800389 * This is the non-locking version of handle_sysrq. It must/can only be called
390 * by sysrq key handlers, as they are inside of the lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 */
David Howells7d12e782006-10-05 14:55:46 +0100392void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393{
394 struct sysrq_key_op *op_p;
395 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800396 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 unsigned long flags;
398
399 spin_lock_irqsave(&sysrq_key_table_lock, flags);
400 orig_log_level = console_loglevel;
401 console_loglevel = 7;
402 printk(KERN_INFO "SysRq : ");
403
404 op_p = __sysrq_get_key_op(key);
405 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800406 /*
407 * Should we check for enabled operations (/proc/sysrq-trigger
408 * should not) and is the invoked operation enabled?
409 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800410 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800411 printk("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 console_loglevel = orig_log_level;
David Howells7d12e782006-10-05 14:55:46 +0100413 op_p->handler(key, tty);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800414 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 printk("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800416 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 } else {
418 printk("HELP : ");
419 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800420 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
421 if (sysrq_key_table[i]) {
422 int j;
423
424 for (j = 0; sysrq_key_table[i] !=
425 sysrq_key_table[j]; j++)
426 ;
427 if (j != i)
428 continue;
429 printk("%s ", sysrq_key_table[i]->help_msg);
430 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 }
Andrew Mortonbf36b902006-03-25 03:07:08 -0800432 printk("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433 console_loglevel = orig_log_level;
434 }
435 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
436}
437
438/*
439 * This function is called by the keyboard handler when SysRq is pressed
440 * and any other keycode arrives.
441 */
David Howells7d12e782006-10-05 14:55:46 +0100442void handle_sysrq(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800444 if (sysrq_on())
445 __handle_sysrq(key, tty, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800447EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800449static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800450 struct sysrq_key_op *remove_op_p)
451{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452
453 int retval;
454 unsigned long flags;
455
456 spin_lock_irqsave(&sysrq_key_table_lock, flags);
457 if (__sysrq_get_key_op(key) == remove_op_p) {
458 __sysrq_put_key_op(key, insert_op_p);
459 retval = 0;
460 } else {
461 retval = -1;
462 }
463 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 return retval;
465}
466
467int register_sysrq_key(int key, struct sysrq_key_op *op_p)
468{
469 return __sysrq_swap_key_ops(key, op_p, NULL);
470}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800471EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472
473int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
474{
475 return __sysrq_swap_key_ops(key, NULL, op_p);
476}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477EXPORT_SYMBOL(unregister_sysrq_key);