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("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("log_buf_len: %d\n", log_buf_len);
207 __setup("log_buf_len=", log_buf_len_setup);
210 * Commands to do_syslog:
212 * 0 -- Close the log. Currently a NOP.
213 * 1 -- Open the log. Currently a NOP.
214 * 2 -- Read from the log.
215 * 3 -- Read all messages remaining in the ring buffer.
216 * 4 -- Read and clear all messages remaining in the ring buffer
217 * 5 -- Clear ring buffer.
218 * 6 -- Disable printk's to console
219 * 7 -- Enable printk's to console
220 * 8 -- Set level of messages printed to console
221 * 9 -- Return number of unread characters in the log buffer
222 * 10 -- Return size of the log buffer
224 int do_syslog(int type, char __user * buf, int len)
226 unsigned long i, j, limit, count;
231 error = security_syslog(type);
236 case 0: /* Close log */
238 case 1: /* Open log */
240 case 2: /* Read from log */
247 if (!access_ok(VERIFY_WRITE, buf, len)) {
251 error = wait_event_interruptible(log_wait, (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 &&
412 ((end - cur_index) > 2) &&
413 LOG_BUF(cur_index + 0) == '<' &&
414 LOG_BUF(cur_index + 1) >= '0' &&
415 LOG_BUF(cur_index + 1) <= '7' &&
416 LOG_BUF(cur_index + 2) == '>')
418 msg_level = LOG_BUF(cur_index + 1) - '0';
420 start_print = cur_index;
422 while (cur_index != end) {
423 char c = LOG_BUF(cur_index);
429 * printk() has already given us loglevel tags in
430 * the buffer. This code is here in case the
431 * log buffer has wrapped right round and scribbled
434 msg_level = default_message_loglevel;
436 _call_console_drivers(start_print, cur_index, msg_level);
438 start_print = cur_index;
443 _call_console_drivers(start_print, end, msg_level);
446 static void emit_log_char(char c)
448 LOG_BUF(log_end) = c;
450 if (log_end - log_start > log_buf_len)
451 log_start = log_end - log_buf_len;
452 if (log_end - con_start > log_buf_len)
453 con_start = log_end - log_buf_len;
454 if (logged_chars < log_buf_len)
459 * Zap console related locks when oopsing. Only zap at most once
460 * every 10 seconds, to leave time for slow consoles to print a
463 static void zap_locks(void)
465 static unsigned long oops_timestamp;
467 if (time_after_eq(jiffies, oops_timestamp) &&
468 !time_after(jiffies, oops_timestamp + 30*HZ))
471 oops_timestamp = jiffies;
473 /* If a crash is occurring, make sure we can't deadlock */
474 spin_lock_init(&logbuf_lock);
475 /* And make sure that we print immediately */
476 init_MUTEX(&console_sem);
479 #if defined(CONFIG_PRINTK_TIME)
480 static int printk_time = 1;
482 static int printk_time = 0;
485 static int __init printk_time_setup(char *str)
493 __setup("time", printk_time_setup);
496 * This is printk. It can be called from any context. We want it to work.
498 * We try to grab the console_sem. If we succeed, it's easy - we log the output and
499 * call the console drivers. If we fail to get the semaphore we place the output
500 * into the log buffer and return. The current holder of the console_sem will
501 * notice the new output in release_console_sem() and will send it to the
502 * consoles before releasing the semaphore.
504 * One effect of this deferred printing is that code which calls printk() and
505 * then changes console_loglevel may break. This is because console_loglevel
506 * is inspected when the actual printing occurs.
509 asmlinkage int printk(const char *fmt, ...)
515 r = vprintk(fmt, args);
521 /* cpu currently holding logbuf_lock */
522 static volatile unsigned int printk_cpu = UINT_MAX;
524 asmlinkage int vprintk(const char *fmt, va_list args)
529 static char printk_buf[1024];
530 static int log_level_unknown = 1;
533 if (unlikely(oops_in_progress) && printk_cpu == smp_processor_id())
534 /* If a crash is occurring during printk() on this CPU,
535 * make sure we can't deadlock */
538 /* This stops the holder of console_sem just where we want him */
539 spin_lock_irqsave(&logbuf_lock, flags);
540 printk_cpu = smp_processor_id();
542 /* Emit the output into the temporary buffer */
543 printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args);
545 #ifdef CONFIG_DEBUG_LL
546 printascii(printk_buf);
550 * Copy the output into log_buf. If the caller didn't provide
551 * appropriate log level tags, we insert them here
553 for (p = printk_buf; *p; p++) {
554 if (log_level_unknown) {
555 /* log_level_unknown signals the start of a new line */
560 unsigned long long t;
561 unsigned long nanosec_rem;
564 * force the log level token to be
565 * before the time output.
567 if (p[0] == '<' && p[1] >='0' &&
568 p[1] <= '7' && p[2] == '>') {
573 loglev_char = default_message_loglevel
577 nanosec_rem = do_div(t, 1000000000);
584 for (tp = tbuf; tp < tbuf + tlen; tp++)
586 printed_len += tlen - 3;
588 if (p[0] != '<' || p[1] < '0' ||
589 p[1] > '7' || p[2] != '>') {
591 emit_log_char(default_message_loglevel
597 log_level_unknown = 0;
603 log_level_unknown = 1;
606 if (!cpu_online(smp_processor_id())) {
608 * Some console drivers may assume that per-cpu resources have
609 * been allocated. So don't allow them to be called by this
610 * CPU until it is officially up. We shouldn't be calling into
611 * random console drivers on a CPU which doesn't exist yet..
613 printk_cpu = UINT_MAX;
614 spin_unlock_irqrestore(&logbuf_lock, flags);
617 if (!down_trylock(&console_sem)) {
620 * We own the drivers. We can drop the spinlock and let
621 * release_console_sem() print the text
623 printk_cpu = UINT_MAX;
624 spin_unlock_irqrestore(&logbuf_lock, flags);
625 console_may_schedule = 0;
626 release_console_sem();
629 * Someone else owns the drivers. We drop the spinlock, which
630 * allows the semaphore holder to proceed and to call the
631 * console drivers with the output which we just produced.
633 printk_cpu = UINT_MAX;
634 spin_unlock_irqrestore(&logbuf_lock, flags);
640 EXPORT_SYMBOL(printk);
641 EXPORT_SYMBOL(vprintk);
645 asmlinkage long sys_syslog(int type, char __user * buf, int len)
650 int do_syslog(int type, char __user * buf, int len) { return 0; }
651 static void call_console_drivers(unsigned long start, unsigned long end) {}
656 * add_preferred_console - add a device to the list of preferred consoles.
658 * The last preferred console added will be used for kernel messages
659 * and stdin/out/err for init. Normally this is used by console_setup
660 * above to handle user-supplied console arguments; however it can also
661 * be used by arch-specific code either to override the user or more
662 * commonly to provide a default console (ie from PROM variables) when
663 * the user has not supplied one.
665 int __init add_preferred_console(char *name, int idx, char *options)
667 struct console_cmdline *c;
671 * See if this tty is not yet registered, and
672 * if we have a slot free.
674 for(i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
675 if (strcmp(console_cmdline[i].name, name) == 0 &&
676 console_cmdline[i].index == idx) {
677 selected_console = i;
680 if (i == MAX_CMDLINECONSOLES)
682 selected_console = i;
683 c = &console_cmdline[i];
684 memcpy(c->name, name, sizeof(c->name));
685 c->name[sizeof(c->name) - 1] = 0;
686 c->options = options;
692 * acquire_console_sem - lock the console system for exclusive use.
694 * Acquires a semaphore which guarantees that the caller has
695 * exclusive access to the console system and the console_drivers list.
697 * Can sleep, returns nothing.
699 void acquire_console_sem(void)
705 console_may_schedule = 1;
707 EXPORT_SYMBOL(acquire_console_sem);
709 int try_acquire_console_sem(void)
711 if (down_trylock(&console_sem))
714 console_may_schedule = 0;
717 EXPORT_SYMBOL(try_acquire_console_sem);
719 int is_console_locked(void)
721 return console_locked;
723 EXPORT_SYMBOL(is_console_locked);
726 * release_console_sem - unlock the console system
728 * Releases the semaphore which the caller holds on the console system
729 * and the console driver list.
731 * While the semaphore was held, console output may have been buffered
732 * by printk(). If this is the case, release_console_sem() emits
733 * the output prior to releasing the semaphore.
735 * If there is output waiting for klogd, we wake it up.
737 * release_console_sem() may be called from any context.
739 void release_console_sem(void)
742 unsigned long _con_start, _log_end;
743 unsigned long wake_klogd = 0;
746 spin_lock_irqsave(&logbuf_lock, flags);
747 wake_klogd |= log_start - log_end;
748 if (con_start == log_end)
749 break; /* Nothing to print */
750 _con_start = con_start;
752 con_start = log_end; /* Flush */
753 spin_unlock(&logbuf_lock);
754 call_console_drivers(_con_start, _log_end);
755 local_irq_restore(flags);
758 console_may_schedule = 0;
760 spin_unlock_irqrestore(&logbuf_lock, flags);
761 if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait))
762 wake_up_interruptible(&log_wait);
764 EXPORT_SYMBOL(release_console_sem);
766 /** console_conditional_schedule - yield the CPU if required
768 * If the console code is currently allowed to sleep, and
769 * if this CPU should yield the CPU to another task, do
772 * Must be called within acquire_console_sem().
774 void __sched console_conditional_schedule(void)
776 if (console_may_schedule)
779 EXPORT_SYMBOL(console_conditional_schedule);
781 void console_print(const char *s)
783 printk(KERN_EMERG "%s", s);
785 EXPORT_SYMBOL(console_print);
787 void console_unblank(void)
792 * console_unblank can no longer be called in interrupt context unless
793 * oops_in_progress is set to 1..
795 if (oops_in_progress) {
796 if (down_trylock(&console_sem) != 0)
799 acquire_console_sem();
802 console_may_schedule = 0;
803 for (c = console_drivers; c != NULL; c = c->next)
804 if ((c->flags & CON_ENABLED) && c->unblank)
806 release_console_sem();
808 EXPORT_SYMBOL(console_unblank);
811 * Return the console tty driver structure and its associated index
813 struct tty_driver *console_device(int *index)
816 struct tty_driver *driver = NULL;
818 acquire_console_sem();
819 for (c = console_drivers; c != NULL; c = c->next) {
822 driver = c->device(c, index);
826 release_console_sem();
831 * Prevent further output on the passed console device so that (for example)
832 * serial drivers can disable console output before suspending a port, and can
833 * re-enable output afterwards.
835 void console_stop(struct console *console)
837 acquire_console_sem();
838 console->flags &= ~CON_ENABLED;
839 release_console_sem();
841 EXPORT_SYMBOL(console_stop);
843 void console_start(struct console *console)
845 acquire_console_sem();
846 console->flags |= CON_ENABLED;
847 release_console_sem();
849 EXPORT_SYMBOL(console_start);
852 * The console driver calls this routine during kernel initialization
853 * to register the console printing procedure with printk() and to
854 * print any messages that were printed by the kernel before the
855 * console driver was initialized.
857 void register_console(struct console * console)
862 if (preferred_console < 0)
863 preferred_console = selected_console;
866 * See if we want to use this console driver. If we
867 * didn't select a console we take the first one
868 * that registers here.
870 if (preferred_console < 0) {
871 if (console->index < 0)
873 if (console->setup == NULL ||
874 console->setup(console, NULL) == 0) {
875 console->flags |= CON_ENABLED | CON_CONSDEV;
876 preferred_console = 0;
881 * See if this console matches one we selected on
884 for(i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) {
885 if (strcmp(console_cmdline[i].name, console->name) != 0)
887 if (console->index >= 0 &&
888 console->index != console_cmdline[i].index)
890 if (console->index < 0)
891 console->index = console_cmdline[i].index;
892 if (console->setup &&
893 console->setup(console, console_cmdline[i].options) != 0)
895 console->flags |= CON_ENABLED;
896 console->index = console_cmdline[i].index;
897 if (i == selected_console) {
898 console->flags |= CON_CONSDEV;
899 preferred_console = selected_console;
904 if (!(console->flags & CON_ENABLED))
907 if (console_drivers && (console_drivers->flags & CON_BOOT)) {
908 unregister_console(console_drivers);
909 console->flags &= ~CON_PRINTBUFFER;
913 * Put this console in the list - keep the
914 * preferred driver at the head of the list.
916 acquire_console_sem();
917 if ((console->flags & CON_CONSDEV) || console_drivers == NULL) {
918 console->next = console_drivers;
919 console_drivers = console;
921 console->next->flags &= ~CON_CONSDEV;
923 console->next = console_drivers->next;
924 console_drivers->next = console;
926 if (console->flags & CON_PRINTBUFFER) {
928 * release_console_sem() will print out the buffered messages
931 spin_lock_irqsave(&logbuf_lock, flags);
932 con_start = log_start;
933 spin_unlock_irqrestore(&logbuf_lock, flags);
935 release_console_sem();
937 EXPORT_SYMBOL(register_console);
939 int unregister_console(struct console * console)
941 struct console *a,*b;
944 acquire_console_sem();
945 if (console_drivers == console) {
946 console_drivers=console->next;
949 for (a=console_drivers->next, b=console_drivers ;
959 /* If last console is removed, we re-enable picking the first
960 * one that gets registered. Without that, pmac early boot console
961 * would prevent fbcon from taking over.
963 * If this isn't the last console and it has CON_CONSDEV set, we
964 * need to set it on the next preferred console.
966 if (console_drivers == NULL)
967 preferred_console = selected_console;
968 else if (console->flags & CON_CONSDEV)
969 console_drivers->flags |= CON_CONSDEV;
971 release_console_sem();
974 EXPORT_SYMBOL(unregister_console);
977 * tty_write_message - write a message to a certain tty, not just the console.
979 * This is used for messages that need to be redirected to a specific tty.
980 * We don't put it into the syslog queue right now maybe in the future if
983 void tty_write_message(struct tty_struct *tty, char *msg)
985 if (tty && tty->driver->write)
986 tty->driver->write(tty, msg, strlen(msg));
991 * printk rate limiting, lifted from the networking subsystem.
993 * This enforces a rate limit: not more than one kernel message
994 * every printk_ratelimit_jiffies to make a denial-of-service
997 int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst)
999 static DEFINE_SPINLOCK(ratelimit_lock);
1000 static unsigned long toks = 10*5*HZ;
1001 static unsigned long last_msg;
1003 unsigned long flags;
1004 unsigned long now = jiffies;
1006 spin_lock_irqsave(&ratelimit_lock, flags);
1007 toks += now - last_msg;
1009 if (toks > (ratelimit_burst * ratelimit_jiffies))
1010 toks = ratelimit_burst * ratelimit_jiffies;
1011 if (toks >= ratelimit_jiffies) {
1014 toks -= ratelimit_jiffies;
1015 spin_unlock_irqrestore(&ratelimit_lock, flags);
1017 printk(KERN_WARNING "printk: %d messages suppressed.\n", lost);
1021 spin_unlock_irqrestore(&ratelimit_lock, flags);
1024 EXPORT_SYMBOL(__printk_ratelimit);
1026 /* minimum time in jiffies between messages */
1027 int printk_ratelimit_jiffies = 5*HZ;
1029 /* number of messages we send before ratelimiting */
1030 int printk_ratelimit_burst = 10;
1032 int printk_ratelimit(void)
1034 return __printk_ratelimit(printk_ratelimit_jiffies,
1035 printk_ratelimit_burst);
1037 EXPORT_SYMBOL(printk_ratelimit);