netfilter: complete the deprecation of CONFIG_NF_CT_ACCT
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / printk.c
blob444b770c95959261a491b8a673ff42e29a181592
1 /*
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).
11 * Ted Ts'o, 2/11/93.
12 * Modified for sysctl support, 1/8/97, Chris Horn.
13 * Fixed SMP synchronization, 08/08/99, Manfred Spraul
14 * manfred@colorfullife.com
15 * Rewrote bits to get rid of console_lock
16 * 01Mar01 Andrew Morton
19 #include <linux/kernel.h>
20 #include <linux/mm.h>
21 #include <linux/tty.h>
22 #include <linux/tty_driver.h>
23 #include <linux/console.h>
24 #include <linux/init.h>
25 #include <linux/jiffies.h>
26 #include <linux/nmi.h>
27 #include <linux/module.h>
28 #include <linux/moduleparam.h>
29 #include <linux/interrupt.h> /* For in_interrupt() */
30 #include <linux/delay.h>
31 #include <linux/smp.h>
32 #include <linux/security.h>
33 #include <linux/bootmem.h>
34 #include <linux/syscalls.h>
35 #include <linux/kexec.h>
36 #include <linux/kdb.h>
37 #include <linux/ratelimit.h>
38 #include <linux/kmsg_dump.h>
39 #include <linux/syslog.h>
41 #include <asm/uaccess.h>
44 * for_each_console() allows you to iterate on each console
46 #define for_each_console(con) \
47 for (con = console_drivers; con != NULL; con = con->next)
50 * Architectures can override it:
52 void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...)
56 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
58 /* printk's without a loglevel use this.. */
59 #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */
61 /* We show everything that is MORE important than this.. */
62 #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
63 #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
65 DECLARE_WAIT_QUEUE_HEAD(log_wait);
67 int console_printk[4] = {
68 DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
69 DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
70 MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */
71 DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
75 * Low level drivers may need that to know if they can schedule in
76 * their unblank() callback or not. So let's export it.
78 int oops_in_progress;
79 EXPORT_SYMBOL(oops_in_progress);
82 * console_sem protects the console_drivers list, and also
83 * provides serialisation for access to the entire console
84 * driver system.
86 static DECLARE_MUTEX(console_sem);
87 struct console *console_drivers;
88 EXPORT_SYMBOL_GPL(console_drivers);
91 * This is used for debugging the mess that is the VT code by
92 * keeping track if we have the console semaphore held. It's
93 * definitely not the perfect debug tool (we don't know if _WE_
94 * hold it are racing, but it helps tracking those weird code
95 * path in the console code where we end up in places I want
96 * locked without the console sempahore held
98 static int console_locked, console_suspended;
101 * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars
102 * It is also used in interesting ways to provide interlocking in
103 * release_console_sem().
105 static DEFINE_SPINLOCK(logbuf_lock);
107 #define LOG_BUF_MASK (log_buf_len-1)
108 #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK])
111 * The indices into log_buf are not constrained to log_buf_len - they
112 * must be masked before subscripting
114 static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */
115 static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */
116 static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */
119 * Array of consoles built from command line options (console=)
121 struct console_cmdline
123 char name[8]; /* Name of the driver */
124 int index; /* Minor dev. to use */
125 char *options; /* Options for the driver */
126 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
127 char *brl_options; /* Options for braille driver */
128 #endif
131 #define MAX_CMDLINECONSOLES 8
133 static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
134 static int selected_console = -1;
135 static int preferred_console = -1;
136 int console_set_on_cmdline;
137 EXPORT_SYMBOL(console_set_on_cmdline);
139 /* Flag: console code may call schedule() */
140 static int console_may_schedule;
142 #ifdef CONFIG_PRINTK
144 static char __log_buf[__LOG_BUF_LEN];
145 static char *log_buf = __log_buf;
146 static int log_buf_len = __LOG_BUF_LEN;
147 static unsigned logged_chars; /* Number of chars produced since last read+clear operation */
148 static int saved_console_loglevel = -1;
150 #ifdef CONFIG_KEXEC
152 * This appends the listed symbols to /proc/vmcoreinfo
154 * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
155 * obtain access to symbols that are otherwise very difficult to locate. These
156 * symbols are specifically used so that utilities can access and extract the
157 * dmesg log from a vmcore file after a crash.
159 void log_buf_kexec_setup(void)
161 VMCOREINFO_SYMBOL(log_buf);
162 VMCOREINFO_SYMBOL(log_end);
163 VMCOREINFO_SYMBOL(log_buf_len);
164 VMCOREINFO_SYMBOL(logged_chars);
166 #endif
168 static int __init log_buf_len_setup(char *str)
170 unsigned size = memparse(str, &str);
171 unsigned long flags;
173 if (size)
174 size = roundup_pow_of_two(size);
175 if (size > log_buf_len) {
176 unsigned start, dest_idx, offset;
177 char *new_log_buf;
179 new_log_buf = alloc_bootmem(size);
180 if (!new_log_buf) {
181 printk(KERN_WARNING "log_buf_len: allocation failed\n");
182 goto out;
185 spin_lock_irqsave(&logbuf_lock, flags);
186 log_buf_len = size;
187 log_buf = new_log_buf;
189 offset = start = min(con_start, log_start);
190 dest_idx = 0;
191 while (start != log_end) {
192 log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)];
193 start++;
194 dest_idx++;
196 log_start -= offset;
197 con_start -= offset;
198 log_end -= offset;
199 spin_unlock_irqrestore(&logbuf_lock, flags);
201 printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len);
203 out:
204 return 1;
207 __setup("log_buf_len=", log_buf_len_setup);
209 #ifdef CONFIG_BOOT_PRINTK_DELAY
211 static unsigned int boot_delay; /* msecs delay after each printk during bootup */
212 static unsigned long long loops_per_msec; /* based on boot_delay */
214 static int __init boot_delay_setup(char *str)
216 unsigned long lpj;
218 lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */
219 loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
221 get_option(&str, &boot_delay);
222 if (boot_delay > 10 * 1000)
223 boot_delay = 0;
225 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
226 "HZ: %d, loops_per_msec: %llu\n",
227 boot_delay, preset_lpj, lpj, HZ, loops_per_msec);
228 return 1;
230 __setup("boot_delay=", boot_delay_setup);
232 static void boot_delay_msec(void)
234 unsigned long long k;
235 unsigned long timeout;
237 if (boot_delay == 0 || system_state != SYSTEM_BOOTING)
238 return;
240 k = (unsigned long long)loops_per_msec * boot_delay;
242 timeout = jiffies + msecs_to_jiffies(boot_delay);
243 while (k) {
244 k--;
245 cpu_relax();
247 * use (volatile) jiffies to prevent
248 * compiler reduction; loop termination via jiffies
249 * is secondary and may or may not happen.
251 if (time_after(jiffies, timeout))
252 break;
253 touch_nmi_watchdog();
256 #else
257 static inline void boot_delay_msec(void)
260 #endif
262 int do_syslog(int type, char __user *buf, int len, bool from_file)
264 unsigned i, j, limit, count;
265 int do_clear = 0;
266 char c;
267 int error = 0;
269 error = security_syslog(type, from_file);
270 if (error)
271 return error;
273 switch (type) {
274 case SYSLOG_ACTION_CLOSE: /* Close log */
275 break;
276 case SYSLOG_ACTION_OPEN: /* Open log */
277 break;
278 case SYSLOG_ACTION_READ: /* Read from log */
279 error = -EINVAL;
280 if (!buf || len < 0)
281 goto out;
282 error = 0;
283 if (!len)
284 goto out;
285 if (!access_ok(VERIFY_WRITE, buf, len)) {
286 error = -EFAULT;
287 goto out;
289 error = wait_event_interruptible(log_wait,
290 (log_start - log_end));
291 if (error)
292 goto out;
293 i = 0;
294 spin_lock_irq(&logbuf_lock);
295 while (!error && (log_start != log_end) && i < len) {
296 c = LOG_BUF(log_start);
297 log_start++;
298 spin_unlock_irq(&logbuf_lock);
299 error = __put_user(c,buf);
300 buf++;
301 i++;
302 cond_resched();
303 spin_lock_irq(&logbuf_lock);
305 spin_unlock_irq(&logbuf_lock);
306 if (!error)
307 error = i;
308 break;
309 /* Read/clear last kernel messages */
310 case SYSLOG_ACTION_READ_CLEAR:
311 do_clear = 1;
312 /* FALL THRU */
313 /* Read last kernel messages */
314 case SYSLOG_ACTION_READ_ALL:
315 error = -EINVAL;
316 if (!buf || len < 0)
317 goto out;
318 error = 0;
319 if (!len)
320 goto out;
321 if (!access_ok(VERIFY_WRITE, buf, len)) {
322 error = -EFAULT;
323 goto out;
325 count = len;
326 if (count > log_buf_len)
327 count = log_buf_len;
328 spin_lock_irq(&logbuf_lock);
329 if (count > logged_chars)
330 count = logged_chars;
331 if (do_clear)
332 logged_chars = 0;
333 limit = log_end;
335 * __put_user() could sleep, and while we sleep
336 * printk() could overwrite the messages
337 * we try to copy to user space. Therefore
338 * the messages are copied in reverse. <manfreds>
340 for (i = 0; i < count && !error; i++) {
341 j = limit-1-i;
342 if (j + log_buf_len < log_end)
343 break;
344 c = LOG_BUF(j);
345 spin_unlock_irq(&logbuf_lock);
346 error = __put_user(c,&buf[count-1-i]);
347 cond_resched();
348 spin_lock_irq(&logbuf_lock);
350 spin_unlock_irq(&logbuf_lock);
351 if (error)
352 break;
353 error = i;
354 if (i != count) {
355 int offset = count-error;
356 /* buffer overflow during copy, correct user buffer. */
357 for (i = 0; i < error; i++) {
358 if (__get_user(c,&buf[i+offset]) ||
359 __put_user(c,&buf[i])) {
360 error = -EFAULT;
361 break;
363 cond_resched();
366 break;
367 /* Clear ring buffer */
368 case SYSLOG_ACTION_CLEAR:
369 logged_chars = 0;
370 break;
371 /* Disable logging to console */
372 case SYSLOG_ACTION_CONSOLE_OFF:
373 if (saved_console_loglevel == -1)
374 saved_console_loglevel = console_loglevel;
375 console_loglevel = minimum_console_loglevel;
376 break;
377 /* Enable logging to console */
378 case SYSLOG_ACTION_CONSOLE_ON:
379 if (saved_console_loglevel != -1) {
380 console_loglevel = saved_console_loglevel;
381 saved_console_loglevel = -1;
383 break;
384 /* Set level of messages printed to console */
385 case SYSLOG_ACTION_CONSOLE_LEVEL:
386 error = -EINVAL;
387 if (len < 1 || len > 8)
388 goto out;
389 if (len < minimum_console_loglevel)
390 len = minimum_console_loglevel;
391 console_loglevel = len;
392 /* Implicitly re-enable logging to console */
393 saved_console_loglevel = -1;
394 error = 0;
395 break;
396 /* Number of chars in the log buffer */
397 case SYSLOG_ACTION_SIZE_UNREAD:
398 error = log_end - log_start;
399 break;
400 /* Size of the log buffer */
401 case SYSLOG_ACTION_SIZE_BUFFER:
402 error = log_buf_len;
403 break;
404 default:
405 error = -EINVAL;
406 break;
408 out:
409 return error;
412 SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
414 return do_syslog(type, buf, len, SYSLOG_FROM_CALL);
417 #ifdef CONFIG_KGDB_KDB
418 /* kdb dmesg command needs access to the syslog buffer. do_syslog()
419 * uses locks so it cannot be used during debugging. Just tell kdb
420 * where the start and end of the physical and logical logs are. This
421 * is equivalent to do_syslog(3).
423 void kdb_syslog_data(char *syslog_data[4])
425 syslog_data[0] = log_buf;
426 syslog_data[1] = log_buf + log_buf_len;
427 syslog_data[2] = log_buf + log_end -
428 (logged_chars < log_buf_len ? logged_chars : log_buf_len);
429 syslog_data[3] = log_buf + log_end;
431 #endif /* CONFIG_KGDB_KDB */
434 * Call the console drivers on a range of log_buf
436 static void __call_console_drivers(unsigned start, unsigned end)
438 struct console *con;
440 for_each_console(con) {
441 if ((con->flags & CON_ENABLED) && con->write &&
442 (cpu_online(smp_processor_id()) ||
443 (con->flags & CON_ANYTIME)))
444 con->write(con, &LOG_BUF(start), end - start);
448 static int __read_mostly ignore_loglevel;
450 static int __init ignore_loglevel_setup(char *str)
452 ignore_loglevel = 1;
453 printk(KERN_INFO "debug: ignoring loglevel setting.\n");
455 return 0;
458 early_param("ignore_loglevel", ignore_loglevel_setup);
461 * Write out chars from start to end - 1 inclusive
463 static void _call_console_drivers(unsigned start,
464 unsigned end, int msg_log_level)
466 if ((msg_log_level < console_loglevel || ignore_loglevel) &&
467 console_drivers && start != end) {
468 if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) {
469 /* wrapped write */
470 __call_console_drivers(start & LOG_BUF_MASK,
471 log_buf_len);
472 __call_console_drivers(0, end & LOG_BUF_MASK);
473 } else {
474 __call_console_drivers(start, end);
480 * Call the console drivers, asking them to write out
481 * log_buf[start] to log_buf[end - 1].
482 * The console_sem must be held.
484 static void call_console_drivers(unsigned start, unsigned end)
486 unsigned cur_index, start_print;
487 static int msg_level = -1;
489 BUG_ON(((int)(start - end)) > 0);
491 cur_index = start;
492 start_print = start;
493 while (cur_index != end) {
494 if (msg_level < 0 && ((end - cur_index) > 2) &&
495 LOG_BUF(cur_index + 0) == '<' &&
496 LOG_BUF(cur_index + 1) >= '0' &&
497 LOG_BUF(cur_index + 1) <= '7' &&
498 LOG_BUF(cur_index + 2) == '>') {
499 msg_level = LOG_BUF(cur_index + 1) - '0';
500 cur_index += 3;
501 start_print = cur_index;
503 while (cur_index != end) {
504 char c = LOG_BUF(cur_index);
506 cur_index++;
507 if (c == '\n') {
508 if (msg_level < 0) {
510 * printk() has already given us loglevel tags in
511 * the buffer. This code is here in case the
512 * log buffer has wrapped right round and scribbled
513 * on those tags
515 msg_level = default_message_loglevel;
517 _call_console_drivers(start_print, cur_index, msg_level);
518 msg_level = -1;
519 start_print = cur_index;
520 break;
524 _call_console_drivers(start_print, end, msg_level);
527 static void emit_log_char(char c)
529 LOG_BUF(log_end) = c;
530 log_end++;
531 if (log_end - log_start > log_buf_len)
532 log_start = log_end - log_buf_len;
533 if (log_end - con_start > log_buf_len)
534 con_start = log_end - log_buf_len;
535 if (logged_chars < log_buf_len)
536 logged_chars++;
540 * Zap console related locks when oopsing. Only zap at most once
541 * every 10 seconds, to leave time for slow consoles to print a
542 * full oops.
544 static void zap_locks(void)
546 static unsigned long oops_timestamp;
548 if (time_after_eq(jiffies, oops_timestamp) &&
549 !time_after(jiffies, oops_timestamp + 30 * HZ))
550 return;
552 oops_timestamp = jiffies;
554 /* If a crash is occurring, make sure we can't deadlock */
555 spin_lock_init(&logbuf_lock);
556 /* And make sure that we print immediately */
557 init_MUTEX(&console_sem);
560 #if defined(CONFIG_PRINTK_TIME)
561 static int printk_time = 1;
562 #else
563 static int printk_time = 0;
564 #endif
565 module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
567 /* Check if we have any console registered that can be called early in boot. */
568 static int have_callable_console(void)
570 struct console *con;
572 for_each_console(con)
573 if (con->flags & CON_ANYTIME)
574 return 1;
576 return 0;
580 * printk - print a kernel message
581 * @fmt: format string
583 * This is printk(). It can be called from any context. We want it to work.
585 * We try to grab the console_sem. If we succeed, it's easy - we log the output and
586 * call the console drivers. If we fail to get the semaphore we place the output
587 * into the log buffer and return. The current holder of the console_sem will
588 * notice the new output in release_console_sem() and will send it to the
589 * consoles before releasing the semaphore.
591 * One effect of this deferred printing is that code which calls printk() and
592 * then changes console_loglevel may break. This is because console_loglevel
593 * is inspected when the actual printing occurs.
595 * See also:
596 * printf(3)
598 * See the vsnprintf() documentation for format string extensions over C99.
601 asmlinkage int printk(const char *fmt, ...)
603 va_list args;
604 int r;
606 #ifdef CONFIG_KGDB_KDB
607 if (unlikely(kdb_trap_printk)) {
608 va_start(args, fmt);
609 r = vkdb_printf(fmt, args);
610 va_end(args);
611 return r;
613 #endif
614 va_start(args, fmt);
615 r = vprintk(fmt, args);
616 va_end(args);
618 return r;
621 /* cpu currently holding logbuf_lock */
622 static volatile unsigned int printk_cpu = UINT_MAX;
625 * Can we actually use the console at this time on this cpu?
627 * Console drivers may assume that per-cpu resources have
628 * been allocated. So unless they're explicitly marked as
629 * being able to cope (CON_ANYTIME) don't call them until
630 * this CPU is officially up.
632 static inline int can_use_console(unsigned int cpu)
634 return cpu_online(cpu) || have_callable_console();
638 * Try to get console ownership to actually show the kernel
639 * messages from a 'printk'. Return true (and with the
640 * console_semaphore held, and 'console_locked' set) if it
641 * is successful, false otherwise.
643 * This gets called with the 'logbuf_lock' spinlock held and
644 * interrupts disabled. It should return with 'lockbuf_lock'
645 * released but interrupts still disabled.
647 static int acquire_console_semaphore_for_printk(unsigned int cpu)
649 int retval = 0;
651 if (!try_acquire_console_sem()) {
652 retval = 1;
655 * If we can't use the console, we need to release
656 * the console semaphore by hand to avoid flushing
657 * the buffer. We need to hold the console semaphore
658 * in order to do this test safely.
660 if (!can_use_console(cpu)) {
661 console_locked = 0;
662 up(&console_sem);
663 retval = 0;
666 printk_cpu = UINT_MAX;
667 spin_unlock(&logbuf_lock);
668 return retval;
670 static const char recursion_bug_msg [] =
671 KERN_CRIT "BUG: recent printk recursion!\n";
672 static int recursion_bug;
673 static int new_text_line = 1;
674 static char printk_buf[1024];
676 int printk_delay_msec __read_mostly;
678 static inline void printk_delay(void)
680 if (unlikely(printk_delay_msec)) {
681 int m = printk_delay_msec;
683 while (m--) {
684 mdelay(1);
685 touch_nmi_watchdog();
690 asmlinkage int vprintk(const char *fmt, va_list args)
692 int printed_len = 0;
693 int current_log_level = default_message_loglevel;
694 unsigned long flags;
695 int this_cpu;
696 char *p;
698 boot_delay_msec();
699 printk_delay();
701 preempt_disable();
702 /* This stops the holder of console_sem just where we want him */
703 raw_local_irq_save(flags);
704 this_cpu = smp_processor_id();
707 * Ouch, printk recursed into itself!
709 if (unlikely(printk_cpu == this_cpu)) {
711 * If a crash is occurring during printk() on this CPU,
712 * then try to get the crash message out but make sure
713 * we can't deadlock. Otherwise just return to avoid the
714 * recursion and return - but flag the recursion so that
715 * it can be printed at the next appropriate moment:
717 if (!oops_in_progress) {
718 recursion_bug = 1;
719 goto out_restore_irqs;
721 zap_locks();
724 lockdep_off();
725 spin_lock(&logbuf_lock);
726 printk_cpu = this_cpu;
728 if (recursion_bug) {
729 recursion_bug = 0;
730 strcpy(printk_buf, recursion_bug_msg);
731 printed_len = strlen(recursion_bug_msg);
733 /* Emit the output into the temporary buffer */
734 printed_len += vscnprintf(printk_buf + printed_len,
735 sizeof(printk_buf) - printed_len, fmt, args);
738 p = printk_buf;
740 /* Do we have a loglevel in the string? */
741 if (p[0] == '<') {
742 unsigned char c = p[1];
743 if (c && p[2] == '>') {
744 switch (c) {
745 case '0' ... '7': /* loglevel */
746 current_log_level = c - '0';
747 /* Fallthrough - make sure we're on a new line */
748 case 'd': /* KERN_DEFAULT */
749 if (!new_text_line) {
750 emit_log_char('\n');
751 new_text_line = 1;
753 /* Fallthrough - skip the loglevel */
754 case 'c': /* KERN_CONT */
755 p += 3;
756 break;
762 * Copy the output into log_buf. If the caller didn't provide
763 * appropriate log level tags, we insert them here
765 for ( ; *p; p++) {
766 if (new_text_line) {
767 /* Always output the token */
768 emit_log_char('<');
769 emit_log_char(current_log_level + '0');
770 emit_log_char('>');
771 printed_len += 3;
772 new_text_line = 0;
774 if (printk_time) {
775 /* Follow the token with the time */
776 char tbuf[50], *tp;
777 unsigned tlen;
778 unsigned long long t;
779 unsigned long nanosec_rem;
781 t = cpu_clock(printk_cpu);
782 nanosec_rem = do_div(t, 1000000000);
783 tlen = sprintf(tbuf, "[%5lu.%06lu] ",
784 (unsigned long) t,
785 nanosec_rem / 1000);
787 for (tp = tbuf; tp < tbuf + tlen; tp++)
788 emit_log_char(*tp);
789 printed_len += tlen;
792 if (!*p)
793 break;
796 emit_log_char(*p);
797 if (*p == '\n')
798 new_text_line = 1;
802 * Try to acquire and then immediately release the
803 * console semaphore. The release will do all the
804 * actual magic (print out buffers, wake up klogd,
805 * etc).
807 * The acquire_console_semaphore_for_printk() function
808 * will release 'logbuf_lock' regardless of whether it
809 * actually gets the semaphore or not.
811 if (acquire_console_semaphore_for_printk(this_cpu))
812 release_console_sem();
814 lockdep_on();
815 out_restore_irqs:
816 raw_local_irq_restore(flags);
818 preempt_enable();
819 return printed_len;
821 EXPORT_SYMBOL(printk);
822 EXPORT_SYMBOL(vprintk);
824 #else
826 static void call_console_drivers(unsigned start, unsigned end)
830 #endif
832 static int __add_preferred_console(char *name, int idx, char *options,
833 char *brl_options)
835 struct console_cmdline *c;
836 int i;
839 * See if this tty is not yet registered, and
840 * if we have a slot free.
842 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
843 if (strcmp(console_cmdline[i].name, name) == 0 &&
844 console_cmdline[i].index == idx) {
845 if (!brl_options)
846 selected_console = i;
847 return 0;
849 if (i == MAX_CMDLINECONSOLES)
850 return -E2BIG;
851 if (!brl_options)
852 selected_console = i;
853 c = &console_cmdline[i];
854 strlcpy(c->name, name, sizeof(c->name));
855 c->options = options;
856 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
857 c->brl_options = brl_options;
858 #endif
859 c->index = idx;
860 return 0;
863 * Set up a list of consoles. Called from init/main.c
865 static int __init console_setup(char *str)
867 char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
868 char *s, *options, *brl_options = NULL;
869 int idx;
871 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
872 if (!memcmp(str, "brl,", 4)) {
873 brl_options = "";
874 str += 4;
875 } else if (!memcmp(str, "brl=", 4)) {
876 brl_options = str + 4;
877 str = strchr(brl_options, ',');
878 if (!str) {
879 printk(KERN_ERR "need port name after brl=\n");
880 return 1;
882 *(str++) = 0;
884 #endif
887 * Decode str into name, index, options.
889 if (str[0] >= '0' && str[0] <= '9') {
890 strcpy(buf, "ttyS");
891 strncpy(buf + 4, str, sizeof(buf) - 5);
892 } else {
893 strncpy(buf, str, sizeof(buf) - 1);
895 buf[sizeof(buf) - 1] = 0;
896 if ((options = strchr(str, ',')) != NULL)
897 *(options++) = 0;
898 #ifdef __sparc__
899 if (!strcmp(str, "ttya"))
900 strcpy(buf, "ttyS0");
901 if (!strcmp(str, "ttyb"))
902 strcpy(buf, "ttyS1");
903 #endif
904 for (s = buf; *s; s++)
905 if ((*s >= '0' && *s <= '9') || *s == ',')
906 break;
907 idx = simple_strtoul(s, NULL, 10);
908 *s = 0;
910 __add_preferred_console(buf, idx, options, brl_options);
911 console_set_on_cmdline = 1;
912 return 1;
914 __setup("console=", console_setup);
917 * add_preferred_console - add a device to the list of preferred consoles.
918 * @name: device name
919 * @idx: device index
920 * @options: options for this console
922 * The last preferred console added will be used for kernel messages
923 * and stdin/out/err for init. Normally this is used by console_setup
924 * above to handle user-supplied console arguments; however it can also
925 * be used by arch-specific code either to override the user or more
926 * commonly to provide a default console (ie from PROM variables) when
927 * the user has not supplied one.
929 int add_preferred_console(char *name, int idx, char *options)
931 return __add_preferred_console(name, idx, options, NULL);
934 int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
936 struct console_cmdline *c;
937 int i;
939 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
940 if (strcmp(console_cmdline[i].name, name) == 0 &&
941 console_cmdline[i].index == idx) {
942 c = &console_cmdline[i];
943 strlcpy(c->name, name_new, sizeof(c->name));
944 c->name[sizeof(c->name) - 1] = 0;
945 c->options = options;
946 c->index = idx_new;
947 return i;
949 /* not found */
950 return -1;
953 int console_suspend_enabled = 1;
954 EXPORT_SYMBOL(console_suspend_enabled);
956 static int __init console_suspend_disable(char *str)
958 console_suspend_enabled = 0;
959 return 1;
961 __setup("no_console_suspend", console_suspend_disable);
964 * suspend_console - suspend the console subsystem
966 * This disables printk() while we go into suspend states
968 void suspend_console(void)
970 if (!console_suspend_enabled)
971 return;
972 printk("Suspending console(s) (use no_console_suspend to debug)\n");
973 acquire_console_sem();
974 console_suspended = 1;
975 up(&console_sem);
978 void resume_console(void)
980 if (!console_suspend_enabled)
981 return;
982 down(&console_sem);
983 console_suspended = 0;
984 release_console_sem();
988 * acquire_console_sem - lock the console system for exclusive use.
990 * Acquires a semaphore which guarantees that the caller has
991 * exclusive access to the console system and the console_drivers list.
993 * Can sleep, returns nothing.
995 void acquire_console_sem(void)
997 BUG_ON(in_interrupt());
998 down(&console_sem);
999 if (console_suspended)
1000 return;
1001 console_locked = 1;
1002 console_may_schedule = 1;
1004 EXPORT_SYMBOL(acquire_console_sem);
1006 int try_acquire_console_sem(void)
1008 if (down_trylock(&console_sem))
1009 return -1;
1010 if (console_suspended) {
1011 up(&console_sem);
1012 return -1;
1014 console_locked = 1;
1015 console_may_schedule = 0;
1016 return 0;
1018 EXPORT_SYMBOL(try_acquire_console_sem);
1020 int is_console_locked(void)
1022 return console_locked;
1025 static DEFINE_PER_CPU(int, printk_pending);
1027 void printk_tick(void)
1029 if (__get_cpu_var(printk_pending)) {
1030 __get_cpu_var(printk_pending) = 0;
1031 wake_up_interruptible(&log_wait);
1035 int printk_needs_cpu(int cpu)
1037 return per_cpu(printk_pending, cpu);
1040 void wake_up_klogd(void)
1042 if (waitqueue_active(&log_wait))
1043 __raw_get_cpu_var(printk_pending) = 1;
1047 * release_console_sem - unlock the console system
1049 * Releases the semaphore which the caller holds on the console system
1050 * and the console driver list.
1052 * While the semaphore was held, console output may have been buffered
1053 * by printk(). If this is the case, release_console_sem() emits
1054 * the output prior to releasing the semaphore.
1056 * If there is output waiting for klogd, we wake it up.
1058 * release_console_sem() may be called from any context.
1060 void release_console_sem(void)
1062 unsigned long flags;
1063 unsigned _con_start, _log_end;
1064 unsigned wake_klogd = 0;
1066 if (console_suspended) {
1067 up(&console_sem);
1068 return;
1071 console_may_schedule = 0;
1073 for ( ; ; ) {
1074 spin_lock_irqsave(&logbuf_lock, flags);
1075 wake_klogd |= log_start - log_end;
1076 if (con_start == log_end)
1077 break; /* Nothing to print */
1078 _con_start = con_start;
1079 _log_end = log_end;
1080 con_start = log_end; /* Flush */
1081 spin_unlock(&logbuf_lock);
1082 stop_critical_timings(); /* don't trace print latency */
1083 call_console_drivers(_con_start, _log_end);
1084 start_critical_timings();
1085 local_irq_restore(flags);
1087 console_locked = 0;
1088 up(&console_sem);
1089 spin_unlock_irqrestore(&logbuf_lock, flags);
1090 if (wake_klogd)
1091 wake_up_klogd();
1093 EXPORT_SYMBOL(release_console_sem);
1096 * console_conditional_schedule - yield the CPU if required
1098 * If the console code is currently allowed to sleep, and
1099 * if this CPU should yield the CPU to another task, do
1100 * so here.
1102 * Must be called within acquire_console_sem().
1104 void __sched console_conditional_schedule(void)
1106 if (console_may_schedule)
1107 cond_resched();
1109 EXPORT_SYMBOL(console_conditional_schedule);
1111 void console_unblank(void)
1113 struct console *c;
1116 * console_unblank can no longer be called in interrupt context unless
1117 * oops_in_progress is set to 1..
1119 if (oops_in_progress) {
1120 if (down_trylock(&console_sem) != 0)
1121 return;
1122 } else
1123 acquire_console_sem();
1125 console_locked = 1;
1126 console_may_schedule = 0;
1127 for_each_console(c)
1128 if ((c->flags & CON_ENABLED) && c->unblank)
1129 c->unblank();
1130 release_console_sem();
1134 * Return the console tty driver structure and its associated index
1136 struct tty_driver *console_device(int *index)
1138 struct console *c;
1139 struct tty_driver *driver = NULL;
1141 acquire_console_sem();
1142 for_each_console(c) {
1143 if (!c->device)
1144 continue;
1145 driver = c->device(c, index);
1146 if (driver)
1147 break;
1149 release_console_sem();
1150 return driver;
1154 * Prevent further output on the passed console device so that (for example)
1155 * serial drivers can disable console output before suspending a port, and can
1156 * re-enable output afterwards.
1158 void console_stop(struct console *console)
1160 acquire_console_sem();
1161 console->flags &= ~CON_ENABLED;
1162 release_console_sem();
1164 EXPORT_SYMBOL(console_stop);
1166 void console_start(struct console *console)
1168 acquire_console_sem();
1169 console->flags |= CON_ENABLED;
1170 release_console_sem();
1172 EXPORT_SYMBOL(console_start);
1175 * The console driver calls this routine during kernel initialization
1176 * to register the console printing procedure with printk() and to
1177 * print any messages that were printed by the kernel before the
1178 * console driver was initialized.
1180 * This can happen pretty early during the boot process (because of
1181 * early_printk) - sometimes before setup_arch() completes - be careful
1182 * of what kernel features are used - they may not be initialised yet.
1184 * There are two types of consoles - bootconsoles (early_printk) and
1185 * "real" consoles (everything which is not a bootconsole) which are
1186 * handled differently.
1187 * - Any number of bootconsoles can be registered at any time.
1188 * - As soon as a "real" console is registered, all bootconsoles
1189 * will be unregistered automatically.
1190 * - Once a "real" console is registered, any attempt to register a
1191 * bootconsoles will be rejected
1193 void register_console(struct console *newcon)
1195 int i;
1196 unsigned long flags;
1197 struct console *bcon = NULL;
1200 * before we register a new CON_BOOT console, make sure we don't
1201 * already have a valid console
1203 if (console_drivers && newcon->flags & CON_BOOT) {
1204 /* find the last or real console */
1205 for_each_console(bcon) {
1206 if (!(bcon->flags & CON_BOOT)) {
1207 printk(KERN_INFO "Too late to register bootconsole %s%d\n",
1208 newcon->name, newcon->index);
1209 return;
1214 if (console_drivers && console_drivers->flags & CON_BOOT)
1215 bcon = console_drivers;
1217 if (preferred_console < 0 || bcon || !console_drivers)
1218 preferred_console = selected_console;
1220 if (newcon->early_setup)
1221 newcon->early_setup();
1224 * See if we want to use this console driver. If we
1225 * didn't select a console we take the first one
1226 * that registers here.
1228 if (preferred_console < 0) {
1229 if (newcon->index < 0)
1230 newcon->index = 0;
1231 if (newcon->setup == NULL ||
1232 newcon->setup(newcon, NULL) == 0) {
1233 newcon->flags |= CON_ENABLED;
1234 if (newcon->device) {
1235 newcon->flags |= CON_CONSDEV;
1236 preferred_console = 0;
1242 * See if this console matches one we selected on
1243 * the command line.
1245 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
1246 i++) {
1247 if (strcmp(console_cmdline[i].name, newcon->name) != 0)
1248 continue;
1249 if (newcon->index >= 0 &&
1250 newcon->index != console_cmdline[i].index)
1251 continue;
1252 if (newcon->index < 0)
1253 newcon->index = console_cmdline[i].index;
1254 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1255 if (console_cmdline[i].brl_options) {
1256 newcon->flags |= CON_BRL;
1257 braille_register_console(newcon,
1258 console_cmdline[i].index,
1259 console_cmdline[i].options,
1260 console_cmdline[i].brl_options);
1261 return;
1263 #endif
1264 if (newcon->setup &&
1265 newcon->setup(newcon, console_cmdline[i].options) != 0)
1266 break;
1267 newcon->flags |= CON_ENABLED;
1268 newcon->index = console_cmdline[i].index;
1269 if (i == selected_console) {
1270 newcon->flags |= CON_CONSDEV;
1271 preferred_console = selected_console;
1273 break;
1276 if (!(newcon->flags & CON_ENABLED))
1277 return;
1280 * If we have a bootconsole, and are switching to a real console,
1281 * don't print everything out again, since when the boot console, and
1282 * the real console are the same physical device, it's annoying to
1283 * see the beginning boot messages twice
1285 if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
1286 newcon->flags &= ~CON_PRINTBUFFER;
1289 * Put this console in the list - keep the
1290 * preferred driver at the head of the list.
1292 acquire_console_sem();
1293 if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
1294 newcon->next = console_drivers;
1295 console_drivers = newcon;
1296 if (newcon->next)
1297 newcon->next->flags &= ~CON_CONSDEV;
1298 } else {
1299 newcon->next = console_drivers->next;
1300 console_drivers->next = newcon;
1302 if (newcon->flags & CON_PRINTBUFFER) {
1304 * release_console_sem() will print out the buffered messages
1305 * for us.
1307 spin_lock_irqsave(&logbuf_lock, flags);
1308 con_start = log_start;
1309 spin_unlock_irqrestore(&logbuf_lock, flags);
1311 release_console_sem();
1314 * By unregistering the bootconsoles after we enable the real console
1315 * we get the "console xxx enabled" message on all the consoles -
1316 * boot consoles, real consoles, etc - this is to ensure that end
1317 * users know there might be something in the kernel's log buffer that
1318 * went to the bootconsole (that they do not see on the real console)
1320 if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) {
1321 /* we need to iterate through twice, to make sure we print
1322 * everything out, before we unregister the console(s)
1324 printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n",
1325 newcon->name, newcon->index);
1326 for_each_console(bcon)
1327 if (bcon->flags & CON_BOOT)
1328 unregister_console(bcon);
1329 } else {
1330 printk(KERN_INFO "%sconsole [%s%d] enabled\n",
1331 (newcon->flags & CON_BOOT) ? "boot" : "" ,
1332 newcon->name, newcon->index);
1335 EXPORT_SYMBOL(register_console);
1337 int unregister_console(struct console *console)
1339 struct console *a, *b;
1340 int res = 1;
1342 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1343 if (console->flags & CON_BRL)
1344 return braille_unregister_console(console);
1345 #endif
1347 acquire_console_sem();
1348 if (console_drivers == console) {
1349 console_drivers=console->next;
1350 res = 0;
1351 } else if (console_drivers) {
1352 for (a=console_drivers->next, b=console_drivers ;
1353 a; b=a, a=b->next) {
1354 if (a == console) {
1355 b->next = a->next;
1356 res = 0;
1357 break;
1363 * If this isn't the last console and it has CON_CONSDEV set, we
1364 * need to set it on the next preferred console.
1366 if (console_drivers != NULL && console->flags & CON_CONSDEV)
1367 console_drivers->flags |= CON_CONSDEV;
1369 release_console_sem();
1370 return res;
1372 EXPORT_SYMBOL(unregister_console);
1374 static int __init disable_boot_consoles(void)
1376 struct console *con;
1378 for_each_console(con) {
1379 if (con->flags & CON_BOOT) {
1380 printk(KERN_INFO "turn off boot console %s%d\n",
1381 con->name, con->index);
1382 unregister_console(con);
1385 return 0;
1387 late_initcall(disable_boot_consoles);
1389 #if defined CONFIG_PRINTK
1392 * printk rate limiting, lifted from the networking subsystem.
1394 * This enforces a rate limit: not more than 10 kernel messages
1395 * every 5s to make a denial-of-service attack impossible.
1397 DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
1399 int __printk_ratelimit(const char *func)
1401 return ___ratelimit(&printk_ratelimit_state, func);
1403 EXPORT_SYMBOL(__printk_ratelimit);
1406 * printk_timed_ratelimit - caller-controlled printk ratelimiting
1407 * @caller_jiffies: pointer to caller's state
1408 * @interval_msecs: minimum interval between prints
1410 * printk_timed_ratelimit() returns true if more than @interval_msecs
1411 * milliseconds have elapsed since the last time printk_timed_ratelimit()
1412 * returned true.
1414 bool printk_timed_ratelimit(unsigned long *caller_jiffies,
1415 unsigned int interval_msecs)
1417 if (*caller_jiffies == 0
1418 || !time_in_range(jiffies, *caller_jiffies,
1419 *caller_jiffies
1420 + msecs_to_jiffies(interval_msecs))) {
1421 *caller_jiffies = jiffies;
1422 return true;
1424 return false;
1426 EXPORT_SYMBOL(printk_timed_ratelimit);
1428 static DEFINE_SPINLOCK(dump_list_lock);
1429 static LIST_HEAD(dump_list);
1432 * kmsg_dump_register - register a kernel log dumper.
1433 * @dumper: pointer to the kmsg_dumper structure
1435 * Adds a kernel log dumper to the system. The dump callback in the
1436 * structure will be called when the kernel oopses or panics and must be
1437 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
1439 int kmsg_dump_register(struct kmsg_dumper *dumper)
1441 unsigned long flags;
1442 int err = -EBUSY;
1444 /* The dump callback needs to be set */
1445 if (!dumper->dump)
1446 return -EINVAL;
1448 spin_lock_irqsave(&dump_list_lock, flags);
1449 /* Don't allow registering multiple times */
1450 if (!dumper->registered) {
1451 dumper->registered = 1;
1452 list_add_tail(&dumper->list, &dump_list);
1453 err = 0;
1455 spin_unlock_irqrestore(&dump_list_lock, flags);
1457 return err;
1459 EXPORT_SYMBOL_GPL(kmsg_dump_register);
1462 * kmsg_dump_unregister - unregister a kmsg dumper.
1463 * @dumper: pointer to the kmsg_dumper structure
1465 * Removes a dump device from the system. Returns zero on success and
1466 * %-EINVAL otherwise.
1468 int kmsg_dump_unregister(struct kmsg_dumper *dumper)
1470 unsigned long flags;
1471 int err = -EINVAL;
1473 spin_lock_irqsave(&dump_list_lock, flags);
1474 if (dumper->registered) {
1475 dumper->registered = 0;
1476 list_del(&dumper->list);
1477 err = 0;
1479 spin_unlock_irqrestore(&dump_list_lock, flags);
1481 return err;
1483 EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
1485 static const char const *kmsg_reasons[] = {
1486 [KMSG_DUMP_OOPS] = "oops",
1487 [KMSG_DUMP_PANIC] = "panic",
1488 [KMSG_DUMP_KEXEC] = "kexec",
1491 static const char *kmsg_to_str(enum kmsg_dump_reason reason)
1493 if (reason >= ARRAY_SIZE(kmsg_reasons) || reason < 0)
1494 return "unknown";
1496 return kmsg_reasons[reason];
1500 * kmsg_dump - dump kernel log to kernel message dumpers.
1501 * @reason: the reason (oops, panic etc) for dumping
1503 * Iterate through each of the dump devices and call the oops/panic
1504 * callbacks with the log buffer.
1506 void kmsg_dump(enum kmsg_dump_reason reason)
1508 unsigned long end;
1509 unsigned chars;
1510 struct kmsg_dumper *dumper;
1511 const char *s1, *s2;
1512 unsigned long l1, l2;
1513 unsigned long flags;
1515 /* Theoretically, the log could move on after we do this, but
1516 there's not a lot we can do about that. The new messages
1517 will overwrite the start of what we dump. */
1518 spin_lock_irqsave(&logbuf_lock, flags);
1519 end = log_end & LOG_BUF_MASK;
1520 chars = logged_chars;
1521 spin_unlock_irqrestore(&logbuf_lock, flags);
1523 if (logged_chars > end) {
1524 s1 = log_buf + log_buf_len - logged_chars + end;
1525 l1 = logged_chars - end;
1527 s2 = log_buf;
1528 l2 = end;
1529 } else {
1530 s1 = "";
1531 l1 = 0;
1533 s2 = log_buf + end - logged_chars;
1534 l2 = logged_chars;
1537 if (!spin_trylock_irqsave(&dump_list_lock, flags)) {
1538 printk(KERN_ERR "dump_kmsg: dump list lock is held during %s, skipping dump\n",
1539 kmsg_to_str(reason));
1540 return;
1542 list_for_each_entry(dumper, &dump_list, list)
1543 dumper->dump(dumper, reason, s1, l1, s2, l2);
1544 spin_unlock_irqrestore(&dump_list_lock, flags);
1546 #endif