2 * linux/kernel/printk.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * Modified to make sys_syslog() more flexible: added commands to
7 * return the last 4k of kernel messages, regardless of whether
8 * they've been read or not. Added option to suppress kernel printk's
9 * to the console. Added hook for sending the console messages
10 * elsewhere, in preparation for a serial line console (someday).
12 * Modified for sysctl support, 1/8/97, Chris Horn.
13 * Fixed SMP synchronization, 08/08/99, Manfred Spraul
14 * manfreds@colorfullife.com
15 * Rewrote bits to get rid of console_lock
16 * 01Mar01 Andrew Morton <andrewm@uow.edu.au>
19 #include <linux/kernel.h>
21 #include <linux/tty.h>
22 #include <linux/tty_driver.h>
23 #include <linux/smp_lock.h>
24 #include <linux/console.h>
25 #include <linux/init.h>
26 #include <linux/module.h>
27 #include <linux/interrupt.h> /* For in_interrupt() */
28 #include <linux/config.h>
29 #include <linux/delay.h>
30 #include <linux/smp.h>
31 #include <linux/security.h>
32 #include <linux/bootmem.h>
33 #include <linux/syscalls.h>
35 #include <asm/uaccess.h>
37 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
39 #ifdef CONFIG_DEBUG_LL
40 extern void printascii(char *);
43 /* printk's without a loglevel use this.. */
44 #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */
46 /* We show everything that is MORE important than this.. */
47 #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
48 #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
50 DECLARE_WAIT_QUEUE_HEAD(log_wait);
52 int console_printk[4] = {
53 DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
54 DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
55 MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */
56 DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
59 EXPORT_SYMBOL(console_printk);
62 * Low lever drivers may need that to know if they can schedule in
63 * their unblank() callback or not. So let's export it.
66 EXPORT_SYMBOL(oops_in_progress);
69 * console_sem protects the console_drivers list, and also
70 * provides serialisation for access to the entire console
73 static DECLARE_MUTEX(console_sem);
74 struct console *console_drivers;
76 * This is used for debugging the mess that is the VT code by
77 * keeping track if we have the console semaphore held. It's
78 * definitely not the perfect debug tool (we don't know if _WE_
79 * hold it are racing, but it helps tracking those weird code
80 * path in the console code where we end up in places I want
81 * locked without the console sempahore held
83 static int console_locked;
86 * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars
87 * It is also used in interesting ways to provide interlocking in
88 * release_console_sem().
90 static DEFINE_SPINLOCK(logbuf_lock);
92 #define LOG_BUF_MASK (log_buf_len-1)
93 #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK])
96 * The indices into log_buf are not constrained to log_buf_len - they
97 * must be masked before subscripting
99 static unsigned long log_start; /* Index into log_buf: next char to be read by syslog() */
100 static unsigned long con_start; /* Index into log_buf: next char to be sent to consoles */
101 static unsigned long log_end; /* Index into log_buf: most-recently-written-char + 1 */
104 * Array of consoles built from command line options (console=)
106 struct console_cmdline
108 char name[8]; /* Name of the driver */
109 int index; /* Minor dev. to use */
110 char *options; /* Options for the driver */
113 #define MAX_CMDLINECONSOLES 8
115 static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
116 static int selected_console = -1;
117 static int preferred_console = -1;
119 /* Flag: console code may call schedule() */
120 static int console_may_schedule;
124 static char __log_buf[__LOG_BUF_LEN];
125 static char *log_buf = __log_buf;
126 static int log_buf_len = __LOG_BUF_LEN;
127 static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */
130 * Setup a list of consoles. Called from init/main.c
132 static int __init console_setup(char *str)
134 char name[sizeof(console_cmdline[0].name)];
139 * Decode str into name, index, options.
141 if (str[0] >= '0' && str[0] <= '9') {
142 strcpy(name, "ttyS");
143 strncpy(name + 4, str, sizeof(name) - 5);
145 strncpy(name, str, sizeof(name) - 1);
146 name[sizeof(name) - 1] = 0;
147 if ((options = strchr(str, ',')) != NULL)
150 if (!strcmp(str, "ttya"))
151 strcpy(name, "ttyS0");
152 if (!strcmp(str, "ttyb"))
153 strcpy(name, "ttyS1");
155 for (s = name; *s; s++)
156 if ((*s >= '0' && *s <= '9') || *s == ',')
158 idx = simple_strtoul(s, NULL, 10);
161 add_preferred_console(name, idx, options);
165 __setup("console=", console_setup);
167 static int __init log_buf_len_setup(char *str)
169 unsigned long size = memparse(str, &str);
173 size = roundup_pow_of_two(size);
174 if (size > log_buf_len) {
175 unsigned long start, dest_idx, offset;
178 new_log_buf = alloc_bootmem(size);
180 printk(KERN_WARNING "log_buf_len: allocation failed\n");
184 spin_lock_irqsave(&logbuf_lock, flags);
186 log_buf = new_log_buf;
188 offset = start = min(con_start, log_start);
190 while (start != log_end) {
191 log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)];
198 spin_unlock_irqrestore(&logbuf_lock, flags);
200 printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len);
206 __setup("log_buf_len=", log_buf_len_setup);
209 * Commands to do_syslog:
211 * 0 -- Close the log. Currently a NOP.
212 * 1 -- Open the log. Currently a NOP.
213 * 2 -- Read from the log.
214 * 3 -- Read all messages remaining in the ring buffer.
215 * 4 -- Read and clear all messages remaining in the ring buffer
216 * 5 -- Clear ring buffer.
217 * 6 -- Disable printk's to console
218 * 7 -- Enable printk's to console
219 * 8 -- Set level of messages printed to console
220 * 9 -- Return number of unread characters in the log buffer
221 * 10 -- Return size of the log buffer
223 int do_syslog(int type, char __user *buf, int len)
225 unsigned long i, j, limit, count;
230 error = security_syslog(type);
235 case 0: /* Close log */
237 case 1: /* Open log */
239 case 2: /* Read from log */
246 if (!access_ok(VERIFY_WRITE, buf, len)) {
250 error = wait_event_interruptible(log_wait,
251 (log_start - log_end));
255 spin_lock_irq(&logbuf_lock);
256 while (!error && (log_start != log_end) && i < len) {
257 c = LOG_BUF(log_start);
259 spin_unlock_irq(&logbuf_lock);
260 error = __put_user(c,buf);
264 spin_lock_irq(&logbuf_lock);
266 spin_unlock_irq(&logbuf_lock);
270 case 4: /* Read/clear last kernel messages */
273 case 3: /* Read last kernel messages */
280 if (!access_ok(VERIFY_WRITE, buf, len)) {
285 if (count > log_buf_len)
287 spin_lock_irq(&logbuf_lock);
288 if (count > logged_chars)
289 count = logged_chars;
294 * __put_user() could sleep, and while we sleep
295 * printk() could overwrite the messages
296 * we try to copy to user space. Therefore
297 * the messages are copied in reverse. <manfreds>
299 for (i = 0; i < count && !error; i++) {
301 if (j + log_buf_len < log_end)
304 spin_unlock_irq(&logbuf_lock);
305 error = __put_user(c,&buf[count-1-i]);
307 spin_lock_irq(&logbuf_lock);
309 spin_unlock_irq(&logbuf_lock);
314 int offset = count-error;
315 /* buffer overflow during copy, correct user buffer. */
316 for (i = 0; i < error; i++) {
317 if (__get_user(c,&buf[i+offset]) ||
318 __put_user(c,&buf[i])) {
326 case 5: /* Clear ring buffer */
329 case 6: /* Disable logging to console */
330 console_loglevel = minimum_console_loglevel;
332 case 7: /* Enable logging to console */
333 console_loglevel = default_console_loglevel;
335 case 8: /* Set level of messages printed to console */
337 if (len < 1 || len > 8)
339 if (len < minimum_console_loglevel)
340 len = minimum_console_loglevel;
341 console_loglevel = len;
344 case 9: /* Number of chars in the log buffer */
345 error = log_end - log_start;
347 case 10: /* Size of the log buffer */
358 asmlinkage long sys_syslog(int type, char __user *buf, int len)
360 return do_syslog(type, buf, len);
364 * Call the console drivers on a range of log_buf
366 static void __call_console_drivers(unsigned long start, unsigned long end)
370 for (con = console_drivers; con; con = con->next) {
371 if ((con->flags & CON_ENABLED) && con->write)
372 con->write(con, &LOG_BUF(start), end - start);
377 * Write out chars from start to end - 1 inclusive
379 static void _call_console_drivers(unsigned long start,
380 unsigned long end, int msg_log_level)
382 if (msg_log_level < console_loglevel &&
383 console_drivers && start != end) {
384 if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) {
386 __call_console_drivers(start & LOG_BUF_MASK,
388 __call_console_drivers(0, end & LOG_BUF_MASK);
390 __call_console_drivers(start, end);
396 * Call the console drivers, asking them to write out
397 * log_buf[start] to log_buf[end - 1].
398 * The console_sem must be held.
400 static void call_console_drivers(unsigned long start, unsigned long end)
402 unsigned long cur_index, start_print;
403 static int msg_level = -1;
405 if (((long)(start - end)) > 0)
410 while (cur_index != end) {
411 if (msg_level < 0 && ((end - cur_index) > 2) &&
412 LOG_BUF(cur_index + 0) == '<' &&
413 LOG_BUF(cur_index + 1) >= '0' &&
414 LOG_BUF(cur_index + 1) <= '7' &&
415 LOG_BUF(cur_index + 2) == '>') {
416 msg_level = LOG_BUF(cur_index + 1) - '0';
418 start_print = cur_index;
420 while (cur_index != end) {
421 char c = LOG_BUF(cur_index);
427 * printk() has already given us loglevel tags in
428 * the buffer. This code is here in case the
429 * log buffer has wrapped right round and scribbled
432 msg_level = default_message_loglevel;
434 _call_console_drivers(start_print, cur_index, msg_level);
436 start_print = cur_index;
441 _call_console_drivers(start_print, end, msg_level);
444 static void emit_log_char(char c)
446 LOG_BUF(log_end) = c;
448 if (log_end - log_start > log_buf_len)
449 log_start = log_end - log_buf_len;
450 if (log_end - con_start > log_buf_len)
451 con_start = log_end - log_buf_len;
452 if (logged_chars < log_buf_len)
457 * Zap console related locks when oopsing. Only zap at most once
458 * every 10 seconds, to leave time for slow consoles to print a
461 static void zap_locks(void)
463 static unsigned long oops_timestamp;
465 if (time_after_eq(jiffies, oops_timestamp) &&
466 !time_after(jiffies, oops_timestamp + 30 * HZ))
469 oops_timestamp = jiffies;
471 /* If a crash is occurring, make sure we can't deadlock */
472 spin_lock_init(&logbuf_lock);
473 /* And make sure that we print immediately */
474 init_MUTEX(&console_sem);
477 #if defined(CONFIG_PRINTK_TIME)
478 static int printk_time = 1;
480 static int printk_time = 0;
483 static int __init printk_time_setup(char *str)
491 __setup("time", printk_time_setup);
493 __attribute__((weak)) unsigned long long printk_clock(void)
495 return sched_clock();
499 * This is printk. It can be called from any context. We want it to work.
501 * We try to grab the console_sem. If we succeed, it's easy - we log the output and
502 * call the console drivers. If we fail to get the semaphore we place the output
503 * into the log buffer and return. The current holder of the console_sem will
504 * notice the new output in release_console_sem() and will send it to the
505 * consoles before releasing the semaphore.
507 * One effect of this deferred printing is that code which calls printk() and
508 * then changes console_loglevel may break. This is because console_loglevel
509 * is inspected when the actual printing occurs.
512 asmlinkage int printk(const char *fmt, ...)
518 r = vprintk(fmt, args);
524 /* cpu currently holding logbuf_lock */
525 static volatile unsigned int printk_cpu = UINT_MAX;
527 asmlinkage int vprintk(const char *fmt, va_list args)
532 static char printk_buf[1024];
533 static int log_level_unknown = 1;
536 if (unlikely(oops_in_progress) && printk_cpu == smp_processor_id())
537 /* If a crash is occurring during printk() on this CPU,
538 * make sure we can't deadlock */
541 /* This stops the holder of console_sem just where we want him */
542 spin_lock_irqsave(&logbuf_lock, flags);
543 printk_cpu = smp_processor_id();
545 /* Emit the output into the temporary buffer */
546 printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args);
548 #ifdef CONFIG_DEBUG_LL
549 printascii(printk_buf);
553 * Copy the output into log_buf. If the caller didn't provide
554 * appropriate log level tags, we insert them here
556 for (p = printk_buf; *p; p++) {
557 if (log_level_unknown) {
558 /* log_level_unknown signals the start of a new line */
563 unsigned long long t;
564 unsigned long nanosec_rem;
567 * force the log level token to be
568 * before the time output.
570 if (p[0] == '<' && p[1] >='0' &&
571 p[1] <= '7' && p[2] == '>') {
576 loglev_char = default_message_loglevel
580 nanosec_rem = do_div(t, 1000000000);
587 for (tp = tbuf; tp < tbuf + tlen; tp++)
589 printed_len += tlen - 3;
591 if (p[0] != '<' || p[1] < '0' ||
592 p[1] > '7' || p[2] != '>') {
594 emit_log_char(default_message_loglevel
600 log_level_unknown = 0;
606 log_level_unknown = 1;
609 if (!cpu_online(smp_processor_id())) {
611 * Some console drivers may assume that per-cpu resources have
612 * been allocated. So don't allow them to be called by this
613 * CPU until it is officially up. We shouldn't be calling into
614 * random console drivers on a CPU which doesn't exist yet..
616 printk_cpu = UINT_MAX;
617 spin_unlock_irqrestore(&logbuf_lock, flags);
620 if (!down_trylock(&console_sem)) {
623 * We own the drivers. We can drop the spinlock and let
624 * release_console_sem() print the text
626 printk_cpu = UINT_MAX;
627 spin_unlock_irqrestore(&logbuf_lock, flags);
628 console_may_schedule = 0;
629 release_console_sem();
632 * Someone else owns the drivers. We drop the spinlock, which
633 * allows the semaphore holder to proceed and to call the
634 * console drivers with the output which we just produced.
636 printk_cpu = UINT_MAX;
637 spin_unlock_irqrestore(&logbuf_lock, flags);
643 EXPORT_SYMBOL(printk);
644 EXPORT_SYMBOL(vprintk);
648 asmlinkage long sys_syslog(int type, char __user *buf, int len)
653 int do_syslog(int type, char __user *buf, int len)
658 static void call_console_drivers(unsigned long start, unsigned long end)
665 * add_preferred_console - add a device to the list of preferred consoles.
667 * The last preferred console added will be used for kernel messages
668 * and stdin/out/err for init. Normally this is used by console_setup
669 * above to handle user-supplied console arguments; however it can also
670 * be used by arch-specific code either to override the user or more
671 * commonly to provide a default console (ie from PROM variables) when
672 * the user has not supplied one.
674 int __init add_preferred_console(char *name, int idx, char *options)
676 struct console_cmdline *c;
680 * See if this tty is not yet registered, and
681 * if we have a slot free.
683 for(i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
684 if (strcmp(console_cmdline[i].name, name) == 0 &&
685 console_cmdline[i].index == idx) {
686 selected_console = i;
689 if (i == MAX_CMDLINECONSOLES)
691 selected_console = i;
692 c = &console_cmdline[i];
693 memcpy(c->name, name, sizeof(c->name));
694 c->name[sizeof(c->name) - 1] = 0;
695 c->options = options;
701 * acquire_console_sem - lock the console system for exclusive use.
703 * Acquires a semaphore which guarantees that the caller has
704 * exclusive access to the console system and the console_drivers list.
706 * Can sleep, returns nothing.
708 void acquire_console_sem(void)
714 console_may_schedule = 1;
716 EXPORT_SYMBOL(acquire_console_sem);
718 int try_acquire_console_sem(void)
720 if (down_trylock(&console_sem))
723 console_may_schedule = 0;
726 EXPORT_SYMBOL(try_acquire_console_sem);
728 int is_console_locked(void)
730 return console_locked;
732 EXPORT_SYMBOL(is_console_locked);
735 * release_console_sem - unlock the console system
737 * Releases the semaphore which the caller holds on the console system
738 * and the console driver list.
740 * While the semaphore was held, console output may have been buffered
741 * by printk(). If this is the case, release_console_sem() emits
742 * the output prior to releasing the semaphore.
744 * If there is output waiting for klogd, we wake it up.
746 * release_console_sem() may be called from any context.
748 void release_console_sem(void)
751 unsigned long _con_start, _log_end;
752 unsigned long wake_klogd = 0;
755 spin_lock_irqsave(&logbuf_lock, flags);
756 wake_klogd |= log_start - log_end;
757 if (con_start == log_end)
758 break; /* Nothing to print */
759 _con_start = con_start;
761 con_start = log_end; /* Flush */
762 spin_unlock(&logbuf_lock);
763 call_console_drivers(_con_start, _log_end);
764 local_irq_restore(flags);
767 console_may_schedule = 0;
769 spin_unlock_irqrestore(&logbuf_lock, flags);
770 if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait))
771 wake_up_interruptible(&log_wait);
773 EXPORT_SYMBOL(release_console_sem);
775 /** console_conditional_schedule - yield the CPU if required
777 * If the console code is currently allowed to sleep, and
778 * if this CPU should yield the CPU to another task, do
781 * Must be called within acquire_console_sem().
783 void __sched console_conditional_schedule(void)
785 if (console_may_schedule)
788 EXPORT_SYMBOL(console_conditional_schedule);
790 void console_print(const char *s)
792 printk(KERN_EMERG "%s", s);
794 EXPORT_SYMBOL(console_print);
796 void console_unblank(void)
801 * console_unblank can no longer be called in interrupt context unless
802 * oops_in_progress is set to 1..
804 if (oops_in_progress) {
805 if (down_trylock(&console_sem) != 0)
808 acquire_console_sem();
811 console_may_schedule = 0;
812 for (c = console_drivers; c != NULL; c = c->next)
813 if ((c->flags & CON_ENABLED) && c->unblank)
815 release_console_sem();
819 * Return the console tty driver structure and its associated index
821 struct tty_driver *console_device(int *index)
824 struct tty_driver *driver = NULL;
826 acquire_console_sem();
827 for (c = console_drivers; c != NULL; c = c->next) {
830 driver = c->device(c, index);
834 release_console_sem();
839 * Prevent further output on the passed console device so that (for example)
840 * serial drivers can disable console output before suspending a port, and can
841 * re-enable output afterwards.
843 void console_stop(struct console *console)
845 acquire_console_sem();
846 console->flags &= ~CON_ENABLED;
847 release_console_sem();
849 EXPORT_SYMBOL(console_stop);
851 void console_start(struct console *console)
853 acquire_console_sem();
854 console->flags |= CON_ENABLED;
855 release_console_sem();
857 EXPORT_SYMBOL(console_start);
860 * The console driver calls this routine during kernel initialization
861 * to register the console printing procedure with printk() and to
862 * print any messages that were printed by the kernel before the
863 * console driver was initialized.
865 void register_console(struct console *console)
870 if (preferred_console < 0)
871 preferred_console = selected_console;
874 * See if we want to use this console driver. If we
875 * didn't select a console we take the first one
876 * that registers here.
878 if (preferred_console < 0) {
879 if (console->index < 0)
881 if (console->setup == NULL ||
882 console->setup(console, NULL) == 0) {
883 console->flags |= CON_ENABLED | CON_CONSDEV;
884 preferred_console = 0;
889 * See if this console matches one we selected on
892 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
894 if (strcmp(console_cmdline[i].name, console->name) != 0)
896 if (console->index >= 0 &&
897 console->index != console_cmdline[i].index)
899 if (console->index < 0)
900 console->index = console_cmdline[i].index;
901 if (console->setup &&
902 console->setup(console, console_cmdline[i].options) != 0)
904 console->flags |= CON_ENABLED;
905 console->index = console_cmdline[i].index;
906 if (i == selected_console) {
907 console->flags |= CON_CONSDEV;
908 preferred_console = selected_console;
913 if (!(console->flags & CON_ENABLED))
916 if (console_drivers && (console_drivers->flags & CON_BOOT)) {
917 unregister_console(console_drivers);
918 console->flags &= ~CON_PRINTBUFFER;
922 * Put this console in the list - keep the
923 * preferred driver at the head of the list.
925 acquire_console_sem();
926 if ((console->flags & CON_CONSDEV) || console_drivers == NULL) {
927 console->next = console_drivers;
928 console_drivers = console;
930 console->next->flags &= ~CON_CONSDEV;
932 console->next = console_drivers->next;
933 console_drivers->next = console;
935 if (console->flags & CON_PRINTBUFFER) {
937 * release_console_sem() will print out the buffered messages
940 spin_lock_irqsave(&logbuf_lock, flags);
941 con_start = log_start;
942 spin_unlock_irqrestore(&logbuf_lock, flags);
944 release_console_sem();
946 EXPORT_SYMBOL(register_console);
948 int unregister_console(struct console *console)
950 struct console *a, *b;
953 acquire_console_sem();
954 if (console_drivers == console) {
955 console_drivers=console->next;
958 for (a=console_drivers->next, b=console_drivers ;
968 /* If last console is removed, we re-enable picking the first
969 * one that gets registered. Without that, pmac early boot console
970 * would prevent fbcon from taking over.
972 * If this isn't the last console and it has CON_CONSDEV set, we
973 * need to set it on the next preferred console.
975 if (console_drivers == NULL)
976 preferred_console = selected_console;
977 else if (console->flags & CON_CONSDEV)
978 console_drivers->flags |= CON_CONSDEV;
980 release_console_sem();
983 EXPORT_SYMBOL(unregister_console);
986 * tty_write_message - write a message to a certain tty, not just the console.
988 * This is used for messages that need to be redirected to a specific tty.
989 * We don't put it into the syslog queue right now maybe in the future if
992 void tty_write_message(struct tty_struct *tty, char *msg)
994 if (tty && tty->driver->write)
995 tty->driver->write(tty, msg, strlen(msg));
1000 * printk rate limiting, lifted from the networking subsystem.
1002 * This enforces a rate limit: not more than one kernel message
1003 * every printk_ratelimit_jiffies to make a denial-of-service
1004 * attack impossible.
1006 int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst)
1008 static DEFINE_SPINLOCK(ratelimit_lock);
1009 static unsigned long toks = 10 * 5 * HZ;
1010 static unsigned long last_msg;
1012 unsigned long flags;
1013 unsigned long now = jiffies;
1015 spin_lock_irqsave(&ratelimit_lock, flags);
1016 toks += now - last_msg;
1018 if (toks > (ratelimit_burst * ratelimit_jiffies))
1019 toks = ratelimit_burst * ratelimit_jiffies;
1020 if (toks >= ratelimit_jiffies) {
1024 toks -= ratelimit_jiffies;
1025 spin_unlock_irqrestore(&ratelimit_lock, flags);
1027 printk(KERN_WARNING "printk: %d messages suppressed.\n", lost);
1031 spin_unlock_irqrestore(&ratelimit_lock, flags);
1034 EXPORT_SYMBOL(__printk_ratelimit);
1036 /* minimum time in jiffies between messages */
1037 int printk_ratelimit_jiffies = 5 * HZ;
1039 /* number of messages we send before ratelimiting */
1040 int printk_ratelimit_burst = 10;
1042 int printk_ratelimit(void)
1044 return __printk_ratelimit(printk_ratelimit_jiffies,
1045 printk_ratelimit_burst);
1047 EXPORT_SYMBOL(printk_ratelimit);