hrtimer: remove duplicate helper function
[linux-2.6.git] / kernel / printk.c
1 /*
2  *  linux/kernel/printk.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  *
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 <andrewm@uow.edu.au>
17  */
18
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
36 #include <asm/uaccess.h>
37
38 /*
39  * Architectures can override it:
40  */
41 void __attribute__((weak)) early_printk(const char *fmt, ...)
42 {
43 }
44
45 #define __LOG_BUF_LEN   (1 << CONFIG_LOG_BUF_SHIFT)
46
47 /* printk's without a loglevel use this.. */
48 #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */
49
50 /* We show everything that is MORE important than this.. */
51 #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
52 #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
53
54 DECLARE_WAIT_QUEUE_HEAD(log_wait);
55
56 int console_printk[4] = {
57         DEFAULT_CONSOLE_LOGLEVEL,       /* console_loglevel */
58         DEFAULT_MESSAGE_LOGLEVEL,       /* default_message_loglevel */
59         MINIMUM_CONSOLE_LOGLEVEL,       /* minimum_console_loglevel */
60         DEFAULT_CONSOLE_LOGLEVEL,       /* default_console_loglevel */
61 };
62
63 /*
64  * Low level drivers may need that to know if they can schedule in
65  * their unblank() callback or not. So let's export it.
66  */
67 int oops_in_progress;
68 EXPORT_SYMBOL(oops_in_progress);
69
70 /*
71  * console_sem protects the console_drivers list, and also
72  * provides serialisation for access to the entire console
73  * driver system.
74  */
75 static DECLARE_MUTEX(console_sem);
76 static DECLARE_MUTEX(secondary_console_sem);
77 struct console *console_drivers;
78 /*
79  * This is used for debugging the mess that is the VT code by
80  * keeping track if we have the console semaphore held. It's
81  * definitely not the perfect debug tool (we don't know if _WE_
82  * hold it are racing, but it helps tracking those weird code
83  * path in the console code where we end up in places I want
84  * locked without the console sempahore held
85  */
86 static int console_locked, console_suspended;
87
88 /*
89  * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars
90  * It is also used in interesting ways to provide interlocking in
91  * release_console_sem().
92  */
93 static DEFINE_SPINLOCK(logbuf_lock);
94
95 #define LOG_BUF_MASK (log_buf_len-1)
96 #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK])
97
98 /*
99  * The indices into log_buf are not constrained to log_buf_len - they
100  * must be masked before subscripting
101  */
102 static unsigned log_start;      /* Index into log_buf: next char to be read by syslog() */
103 static unsigned con_start;      /* Index into log_buf: next char to be sent to consoles */
104 static unsigned log_end;        /* Index into log_buf: most-recently-written-char + 1 */
105
106 /*
107  *      Array of consoles built from command line options (console=)
108  */
109 struct console_cmdline
110 {
111         char    name[8];                        /* Name of the driver       */
112         int     index;                          /* Minor dev. to use        */
113         char    *options;                       /* Options for the driver   */
114 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
115         char    *brl_options;                   /* Options for braille driver */
116 #endif
117 };
118
119 #define MAX_CMDLINECONSOLES 8
120
121 static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
122 static int selected_console = -1;
123 static int preferred_console = -1;
124
125 /* Flag: console code may call schedule() */
126 static int console_may_schedule;
127
128 #ifdef CONFIG_PRINTK
129
130 static char __log_buf[__LOG_BUF_LEN];
131 static char *log_buf = __log_buf;
132 static int log_buf_len = __LOG_BUF_LEN;
133 static unsigned logged_chars; /* Number of chars produced since last read+clear operation */
134
135 static int __init log_buf_len_setup(char *str)
136 {
137         unsigned size = memparse(str, &str);
138         unsigned long flags;
139
140         if (size)
141                 size = roundup_pow_of_two(size);
142         if (size > log_buf_len) {
143                 unsigned start, dest_idx, offset;
144                 char *new_log_buf;
145
146                 new_log_buf = alloc_bootmem(size);
147                 if (!new_log_buf) {
148                         printk(KERN_WARNING "log_buf_len: allocation failed\n");
149                         goto out;
150                 }
151
152                 spin_lock_irqsave(&logbuf_lock, flags);
153                 log_buf_len = size;
154                 log_buf = new_log_buf;
155
156                 offset = start = min(con_start, log_start);
157                 dest_idx = 0;
158                 while (start != log_end) {
159                         log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)];
160                         start++;
161                         dest_idx++;
162                 }
163                 log_start -= offset;
164                 con_start -= offset;
165                 log_end -= offset;
166                 spin_unlock_irqrestore(&logbuf_lock, flags);
167
168                 printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len);
169         }
170 out:
171         return 1;
172 }
173
174 __setup("log_buf_len=", log_buf_len_setup);
175
176 #ifdef CONFIG_BOOT_PRINTK_DELAY
177
178 static unsigned int boot_delay; /* msecs delay after each printk during bootup */
179 static unsigned long long printk_delay_msec; /* per msec, based on boot_delay */
180
181 static int __init boot_delay_setup(char *str)
182 {
183         unsigned long lpj;
184         unsigned long long loops_per_msec;
185
186         lpj = preset_lpj ? preset_lpj : 1000000;        /* some guess */
187         loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
188
189         get_option(&str, &boot_delay);
190         if (boot_delay > 10 * 1000)
191                 boot_delay = 0;
192
193         printk_delay_msec = loops_per_msec;
194         printk(KERN_DEBUG "boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
195                 "HZ: %d, printk_delay_msec: %llu\n",
196                 boot_delay, preset_lpj, lpj, HZ, printk_delay_msec);
197         return 1;
198 }
199 __setup("boot_delay=", boot_delay_setup);
200
201 static void boot_delay_msec(void)
202 {
203         unsigned long long k;
204         unsigned long timeout;
205
206         if (boot_delay == 0 || system_state != SYSTEM_BOOTING)
207                 return;
208
209         k = (unsigned long long)printk_delay_msec * boot_delay;
210
211         timeout = jiffies + msecs_to_jiffies(boot_delay);
212         while (k) {
213                 k--;
214                 cpu_relax();
215                 /*
216                  * use (volatile) jiffies to prevent
217                  * compiler reduction; loop termination via jiffies
218                  * is secondary and may or may not happen.
219                  */
220                 if (time_after(jiffies, timeout))
221                         break;
222                 touch_nmi_watchdog();
223         }
224 }
225 #else
226 static inline void boot_delay_msec(void)
227 {
228 }
229 #endif
230
231 /*
232  * Return the number of unread characters in the log buffer.
233  */
234 int log_buf_get_len(void)
235 {
236         return logged_chars;
237 }
238
239 /*
240  * Copy a range of characters from the log buffer.
241  */
242 int log_buf_copy(char *dest, int idx, int len)
243 {
244         int ret, max;
245         bool took_lock = false;
246
247         if (!oops_in_progress) {
248                 spin_lock_irq(&logbuf_lock);
249                 took_lock = true;
250         }
251
252         max = log_buf_get_len();
253         if (idx < 0 || idx >= max) {
254                 ret = -1;
255         } else {
256                 if (len > max)
257                         len = max;
258                 ret = len;
259                 idx += (log_end - max);
260                 while (len-- > 0)
261                         dest[len] = LOG_BUF(idx + len);
262         }
263
264         if (took_lock)
265                 spin_unlock_irq(&logbuf_lock);
266
267         return ret;
268 }
269
270 /*
271  * Extract a single character from the log buffer.
272  */
273 int log_buf_read(int idx)
274 {
275         char ret;
276
277         if (log_buf_copy(&ret, idx, 1) == 1)
278                 return ret;
279         else
280                 return -1;
281 }
282
283 /*
284  * Commands to do_syslog:
285  *
286  *      0 -- Close the log.  Currently a NOP.
287  *      1 -- Open the log. Currently a NOP.
288  *      2 -- Read from the log.
289  *      3 -- Read all messages remaining in the ring buffer.
290  *      4 -- Read and clear all messages remaining in the ring buffer
291  *      5 -- Clear ring buffer.
292  *      6 -- Disable printk's to console
293  *      7 -- Enable printk's to console
294  *      8 -- Set level of messages printed to console
295  *      9 -- Return number of unread characters in the log buffer
296  *     10 -- Return size of the log buffer
297  */
298 int do_syslog(int type, char __user *buf, int len)
299 {
300         unsigned i, j, limit, count;
301         int do_clear = 0;
302         char c;
303         int error = 0;
304
305         error = security_syslog(type);
306         if (error)
307                 return error;
308
309         switch (type) {
310         case 0:         /* Close log */
311                 break;
312         case 1:         /* Open log */
313                 break;
314         case 2:         /* Read from log */
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;
324                 }
325                 error = wait_event_interruptible(log_wait,
326                                                         (log_start - log_end));
327                 if (error)
328                         goto out;
329                 i = 0;
330                 spin_lock_irq(&logbuf_lock);
331                 while (!error && (log_start != log_end) && i < len) {
332                         c = LOG_BUF(log_start);
333                         log_start++;
334                         spin_unlock_irq(&logbuf_lock);
335                         error = __put_user(c,buf);
336                         buf++;
337                         i++;
338                         cond_resched();
339                         spin_lock_irq(&logbuf_lock);
340                 }
341                 spin_unlock_irq(&logbuf_lock);
342                 if (!error)
343                         error = i;
344                 break;
345         case 4:         /* Read/clear last kernel messages */
346                 do_clear = 1;
347                 /* FALL THRU */
348         case 3:         /* Read last kernel messages */
349                 error = -EINVAL;
350                 if (!buf || len < 0)
351                         goto out;
352                 error = 0;
353                 if (!len)
354                         goto out;
355                 if (!access_ok(VERIFY_WRITE, buf, len)) {
356                         error = -EFAULT;
357                         goto out;
358                 }
359                 count = len;
360                 if (count > log_buf_len)
361                         count = log_buf_len;
362                 spin_lock_irq(&logbuf_lock);
363                 if (count > logged_chars)
364                         count = logged_chars;
365                 if (do_clear)
366                         logged_chars = 0;
367                 limit = log_end;
368                 /*
369                  * __put_user() could sleep, and while we sleep
370                  * printk() could overwrite the messages
371                  * we try to copy to user space. Therefore
372                  * the messages are copied in reverse. <manfreds>
373                  */
374                 for (i = 0; i < count && !error; i++) {
375                         j = limit-1-i;
376                         if (j + log_buf_len < log_end)
377                                 break;
378                         c = LOG_BUF(j);
379                         spin_unlock_irq(&logbuf_lock);
380                         error = __put_user(c,&buf[count-1-i]);
381                         cond_resched();
382                         spin_lock_irq(&logbuf_lock);
383                 }
384                 spin_unlock_irq(&logbuf_lock);
385                 if (error)
386                         break;
387                 error = i;
388                 if (i != count) {
389                         int offset = count-error;
390                         /* buffer overflow during copy, correct user buffer. */
391                         for (i = 0; i < error; i++) {
392                                 if (__get_user(c,&buf[i+offset]) ||
393                                     __put_user(c,&buf[i])) {
394                                         error = -EFAULT;
395                                         break;
396                                 }
397                                 cond_resched();
398                         }
399                 }
400                 break;
401         case 5:         /* Clear ring buffer */
402                 logged_chars = 0;
403                 break;
404         case 6:         /* Disable logging to console */
405                 console_loglevel = minimum_console_loglevel;
406                 break;
407         case 7:         /* Enable logging to console */
408                 console_loglevel = default_console_loglevel;
409                 break;
410         case 8:         /* Set level of messages printed to console */
411                 error = -EINVAL;
412                 if (len < 1 || len > 8)
413                         goto out;
414                 if (len < minimum_console_loglevel)
415                         len = minimum_console_loglevel;
416                 console_loglevel = len;
417                 error = 0;
418                 break;
419         case 9:         /* Number of chars in the log buffer */
420                 error = log_end - log_start;
421                 break;
422         case 10:        /* Size of the log buffer */
423                 error = log_buf_len;
424                 break;
425         default:
426                 error = -EINVAL;
427                 break;
428         }
429 out:
430         return error;
431 }
432
433 asmlinkage long sys_syslog(int type, char __user *buf, int len)
434 {
435         return do_syslog(type, buf, len);
436 }
437
438 /*
439  * Call the console drivers on a range of log_buf
440  */
441 static void __call_console_drivers(unsigned start, unsigned end)
442 {
443         struct console *con;
444
445         for (con = console_drivers; con; con = con->next) {
446                 if ((con->flags & CON_ENABLED) && con->write &&
447                                 (cpu_online(smp_processor_id()) ||
448                                 (con->flags & CON_ANYTIME)))
449                         con->write(con, &LOG_BUF(start), end - start);
450         }
451 }
452
453 static int __read_mostly ignore_loglevel;
454
455 static int __init ignore_loglevel_setup(char *str)
456 {
457         ignore_loglevel = 1;
458         printk(KERN_INFO "debug: ignoring loglevel setting.\n");
459
460         return 0;
461 }
462
463 early_param("ignore_loglevel", ignore_loglevel_setup);
464
465 /*
466  * Write out chars from start to end - 1 inclusive
467  */
468 static void _call_console_drivers(unsigned start,
469                                 unsigned end, int msg_log_level)
470 {
471         if ((msg_log_level < console_loglevel || ignore_loglevel) &&
472                         console_drivers && start != end) {
473                 if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) {
474                         /* wrapped write */
475                         __call_console_drivers(start & LOG_BUF_MASK,
476                                                 log_buf_len);
477                         __call_console_drivers(0, end & LOG_BUF_MASK);
478                 } else {
479                         __call_console_drivers(start, end);
480                 }
481         }
482 }
483
484 /*
485  * Call the console drivers, asking them to write out
486  * log_buf[start] to log_buf[end - 1].
487  * The console_sem must be held.
488  */
489 static void call_console_drivers(unsigned start, unsigned end)
490 {
491         unsigned cur_index, start_print;
492         static int msg_level = -1;
493
494         BUG_ON(((int)(start - end)) > 0);
495
496         cur_index = start;
497         start_print = start;
498         while (cur_index != end) {
499                 if (msg_level < 0 && ((end - cur_index) > 2) &&
500                                 LOG_BUF(cur_index + 0) == '<' &&
501                                 LOG_BUF(cur_index + 1) >= '0' &&
502                                 LOG_BUF(cur_index + 1) <= '7' &&
503                                 LOG_BUF(cur_index + 2) == '>') {
504                         msg_level = LOG_BUF(cur_index + 1) - '0';
505                         cur_index += 3;
506                         start_print = cur_index;
507                 }
508                 while (cur_index != end) {
509                         char c = LOG_BUF(cur_index);
510
511                         cur_index++;
512                         if (c == '\n') {
513                                 if (msg_level < 0) {
514                                         /*
515                                          * printk() has already given us loglevel tags in
516                                          * the buffer.  This code is here in case the
517                                          * log buffer has wrapped right round and scribbled
518                                          * on those tags
519                                          */
520                                         msg_level = default_message_loglevel;
521                                 }
522                                 _call_console_drivers(start_print, cur_index, msg_level);
523                                 msg_level = -1;
524                                 start_print = cur_index;
525                                 break;
526                         }
527                 }
528         }
529         _call_console_drivers(start_print, end, msg_level);
530 }
531
532 static void emit_log_char(char c)
533 {
534         LOG_BUF(log_end) = c;
535         log_end++;
536         if (log_end - log_start > log_buf_len)
537                 log_start = log_end - log_buf_len;
538         if (log_end - con_start > log_buf_len)
539                 con_start = log_end - log_buf_len;
540         if (logged_chars < log_buf_len)
541                 logged_chars++;
542 }
543
544 /*
545  * Zap console related locks when oopsing. Only zap at most once
546  * every 10 seconds, to leave time for slow consoles to print a
547  * full oops.
548  */
549 static void zap_locks(void)
550 {
551         static unsigned long oops_timestamp;
552
553         if (time_after_eq(jiffies, oops_timestamp) &&
554                         !time_after(jiffies, oops_timestamp + 30 * HZ))
555                 return;
556
557         oops_timestamp = jiffies;
558
559         /* If a crash is occurring, make sure we can't deadlock */
560         spin_lock_init(&logbuf_lock);
561         /* And make sure that we print immediately */
562         init_MUTEX(&console_sem);
563 }
564
565 #if defined(CONFIG_PRINTK_TIME)
566 static int printk_time = 1;
567 #else
568 static int printk_time = 0;
569 #endif
570 module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
571
572 /* Check if we have any console registered that can be called early in boot. */
573 static int have_callable_console(void)
574 {
575         struct console *con;
576
577         for (con = console_drivers; con; con = con->next)
578                 if (con->flags & CON_ANYTIME)
579                         return 1;
580
581         return 0;
582 }
583
584 /**
585  * printk - print a kernel message
586  * @fmt: format string
587  *
588  * This is printk().  It can be called from any context.  We want it to work.
589  * Be aware of the fact that if oops_in_progress is not set, we might try to
590  * wake klogd up which could deadlock on runqueue lock if printk() is called
591  * from scheduler code.
592  *
593  * We try to grab the console_sem.  If we succeed, it's easy - we log the output and
594  * call the console drivers.  If we fail to get the semaphore we place the output
595  * into the log buffer and return.  The current holder of the console_sem will
596  * notice the new output in release_console_sem() and will send it to the
597  * consoles before releasing the semaphore.
598  *
599  * One effect of this deferred printing is that code which calls printk() and
600  * then changes console_loglevel may break. This is because console_loglevel
601  * is inspected when the actual printing occurs.
602  *
603  * See also:
604  * printf(3)
605  */
606
607 asmlinkage int printk(const char *fmt, ...)
608 {
609         va_list args;
610         int r;
611
612         va_start(args, fmt);
613         r = vprintk(fmt, args);
614         va_end(args);
615
616         return r;
617 }
618
619 /* cpu currently holding logbuf_lock */
620 static volatile unsigned int printk_cpu = UINT_MAX;
621
622 /*
623  * Can we actually use the console at this time on this cpu?
624  *
625  * Console drivers may assume that per-cpu resources have
626  * been allocated. So unless they're explicitly marked as
627  * being able to cope (CON_ANYTIME) don't call them until
628  * this CPU is officially up.
629  */
630 static inline int can_use_console(unsigned int cpu)
631 {
632         return cpu_online(cpu) || have_callable_console();
633 }
634
635 /*
636  * Try to get console ownership to actually show the kernel
637  * messages from a 'printk'. Return true (and with the
638  * console_semaphore held, and 'console_locked' set) if it
639  * is successful, false otherwise.
640  *
641  * This gets called with the 'logbuf_lock' spinlock held and
642  * interrupts disabled. It should return with 'lockbuf_lock'
643  * released but interrupts still disabled.
644  */
645 static int acquire_console_semaphore_for_printk(unsigned int cpu)
646 {
647         int retval = 0;
648
649         if (!try_acquire_console_sem()) {
650                 retval = 1;
651
652                 /*
653                  * If we can't use the console, we need to release
654                  * the console semaphore by hand to avoid flushing
655                  * the buffer. We need to hold the console semaphore
656                  * in order to do this test safely.
657                  */
658                 if (!can_use_console(cpu)) {
659                         console_locked = 0;
660                         up(&console_sem);
661                         retval = 0;
662                 }
663         }
664         printk_cpu = UINT_MAX;
665         spin_unlock(&logbuf_lock);
666         return retval;
667 }
668
669 const char printk_recursion_bug_msg [] =
670                         KERN_CRIT "BUG: recent printk recursion!\n";
671 static int printk_recursion_bug;
672
673 asmlinkage int vprintk(const char *fmt, va_list args)
674 {
675         static int log_level_unknown = 1;
676         static char printk_buf[1024];
677
678         unsigned long flags;
679         int printed_len = 0;
680         int this_cpu;
681         char *p;
682
683         boot_delay_msec();
684
685         preempt_disable();
686         /* This stops the holder of console_sem just where we want him */
687         raw_local_irq_save(flags);
688         this_cpu = smp_processor_id();
689
690         /*
691          * Ouch, printk recursed into itself!
692          */
693         if (unlikely(printk_cpu == this_cpu)) {
694                 /*
695                  * If a crash is occurring during printk() on this CPU,
696                  * then try to get the crash message out but make sure
697                  * we can't deadlock. Otherwise just return to avoid the
698                  * recursion and return - but flag the recursion so that
699                  * it can be printed at the next appropriate moment:
700                  */
701                 if (!oops_in_progress) {
702                         printk_recursion_bug = 1;
703                         goto out_restore_irqs;
704                 }
705                 zap_locks();
706         }
707
708         lockdep_off();
709         spin_lock(&logbuf_lock);
710         printk_cpu = this_cpu;
711
712         if (printk_recursion_bug) {
713                 printk_recursion_bug = 0;
714                 strcpy(printk_buf, printk_recursion_bug_msg);
715                 printed_len = sizeof(printk_recursion_bug_msg);
716         }
717         /* Emit the output into the temporary buffer */
718         printed_len += vscnprintf(printk_buf + printed_len,
719                                   sizeof(printk_buf) - printed_len, fmt, args);
720
721         /*
722          * Copy the output into log_buf.  If the caller didn't provide
723          * appropriate log level tags, we insert them here
724          */
725         for (p = printk_buf; *p; p++) {
726                 if (log_level_unknown) {
727                         /* log_level_unknown signals the start of a new line */
728                         if (printk_time) {
729                                 int loglev_char;
730                                 char tbuf[50], *tp;
731                                 unsigned tlen;
732                                 unsigned long long t;
733                                 unsigned long nanosec_rem;
734
735                                 /*
736                                  * force the log level token to be
737                                  * before the time output.
738                                  */
739                                 if (p[0] == '<' && p[1] >='0' &&
740                                    p[1] <= '7' && p[2] == '>') {
741                                         loglev_char = p[1];
742                                         p += 3;
743                                         printed_len -= 3;
744                                 } else {
745                                         loglev_char = default_message_loglevel
746                                                 + '0';
747                                 }
748                                 t = cpu_clock(printk_cpu);
749                                 nanosec_rem = do_div(t, 1000000000);
750                                 tlen = sprintf(tbuf,
751                                                 "<%c>[%5lu.%06lu] ",
752                                                 loglev_char,
753                                                 (unsigned long)t,
754                                                 nanosec_rem/1000);
755
756                                 for (tp = tbuf; tp < tbuf + tlen; tp++)
757                                         emit_log_char(*tp);
758                                 printed_len += tlen;
759                         } else {
760                                 if (p[0] != '<' || p[1] < '0' ||
761                                    p[1] > '7' || p[2] != '>') {
762                                         emit_log_char('<');
763                                         emit_log_char(default_message_loglevel
764                                                 + '0');
765                                         emit_log_char('>');
766                                         printed_len += 3;
767                                 }
768                         }
769                         log_level_unknown = 0;
770                         if (!*p)
771                                 break;
772                 }
773                 emit_log_char(*p);
774                 if (*p == '\n')
775                         log_level_unknown = 1;
776         }
777
778         /*
779          * Try to acquire and then immediately release the
780          * console semaphore. The release will do all the
781          * actual magic (print out buffers, wake up klogd,
782          * etc). 
783          *
784          * The acquire_console_semaphore_for_printk() function
785          * will release 'logbuf_lock' regardless of whether it
786          * actually gets the semaphore or not.
787          */
788         if (acquire_console_semaphore_for_printk(this_cpu))
789                 release_console_sem();
790
791         lockdep_on();
792 out_restore_irqs:
793         raw_local_irq_restore(flags);
794
795         preempt_enable();
796         return printed_len;
797 }
798 EXPORT_SYMBOL(printk);
799 EXPORT_SYMBOL(vprintk);
800
801 #else
802
803 asmlinkage long sys_syslog(int type, char __user *buf, int len)
804 {
805         return -ENOSYS;
806 }
807
808 static void call_console_drivers(unsigned start, unsigned end)
809 {
810 }
811
812 #endif
813
814 static int __add_preferred_console(char *name, int idx, char *options,
815                                    char *brl_options)
816 {
817         struct console_cmdline *c;
818         int i;
819
820         /*
821          *      See if this tty is not yet registered, and
822          *      if we have a slot free.
823          */
824         for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
825                 if (strcmp(console_cmdline[i].name, name) == 0 &&
826                           console_cmdline[i].index == idx) {
827                                 if (!brl_options)
828                                         selected_console = i;
829                                 return 0;
830                 }
831         if (i == MAX_CMDLINECONSOLES)
832                 return -E2BIG;
833         if (!brl_options)
834                 selected_console = i;
835         c = &console_cmdline[i];
836         strlcpy(c->name, name, sizeof(c->name));
837         c->options = options;
838 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
839         c->brl_options = brl_options;
840 #endif
841         c->index = idx;
842         return 0;
843 }
844 /*
845  * Set up a list of consoles.  Called from init/main.c
846  */
847 static int __init console_setup(char *str)
848 {
849         char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
850         char *s, *options, *brl_options = NULL;
851         int idx;
852
853 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
854         if (!memcmp(str, "brl,", 4)) {
855                 brl_options = "";
856                 str += 4;
857         } else if (!memcmp(str, "brl=", 4)) {
858                 brl_options = str + 4;
859                 str = strchr(brl_options, ',');
860                 if (!str) {
861                         printk(KERN_ERR "need port name after brl=\n");
862                         return 1;
863                 }
864                 *(str++) = 0;
865         }
866 #endif
867
868         /*
869          * Decode str into name, index, options.
870          */
871         if (str[0] >= '0' && str[0] <= '9') {
872                 strcpy(buf, "ttyS");
873                 strncpy(buf + 4, str, sizeof(buf) - 5);
874         } else {
875                 strncpy(buf, str, sizeof(buf) - 1);
876         }
877         buf[sizeof(buf) - 1] = 0;
878         if ((options = strchr(str, ',')) != NULL)
879                 *(options++) = 0;
880 #ifdef __sparc__
881         if (!strcmp(str, "ttya"))
882                 strcpy(buf, "ttyS0");
883         if (!strcmp(str, "ttyb"))
884                 strcpy(buf, "ttyS1");
885 #endif
886         for (s = buf; *s; s++)
887                 if ((*s >= '0' && *s <= '9') || *s == ',')
888                         break;
889         idx = simple_strtoul(s, NULL, 10);
890         *s = 0;
891
892         __add_preferred_console(buf, idx, options, brl_options);
893         return 1;
894 }
895 __setup("console=", console_setup);
896
897 /**
898  * add_preferred_console - add a device to the list of preferred consoles.
899  * @name: device name
900  * @idx: device index
901  * @options: options for this console
902  *
903  * The last preferred console added will be used for kernel messages
904  * and stdin/out/err for init.  Normally this is used by console_setup
905  * above to handle user-supplied console arguments; however it can also
906  * be used by arch-specific code either to override the user or more
907  * commonly to provide a default console (ie from PROM variables) when
908  * the user has not supplied one.
909  */
910 int add_preferred_console(char *name, int idx, char *options)
911 {
912         return __add_preferred_console(name, idx, options, NULL);
913 }
914
915 int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
916 {
917         struct console_cmdline *c;
918         int i;
919
920         for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
921                 if (strcmp(console_cmdline[i].name, name) == 0 &&
922                           console_cmdline[i].index == idx) {
923                                 c = &console_cmdline[i];
924                                 strlcpy(c->name, name_new, sizeof(c->name));
925                                 c->name[sizeof(c->name) - 1] = 0;
926                                 c->options = options;
927                                 c->index = idx_new;
928                                 return i;
929                 }
930         /* not found */
931         return -1;
932 }
933
934 int console_suspend_enabled = 1;
935 EXPORT_SYMBOL(console_suspend_enabled);
936
937 static int __init console_suspend_disable(char *str)
938 {
939         console_suspend_enabled = 0;
940         return 1;
941 }
942 __setup("no_console_suspend", console_suspend_disable);
943
944 /**
945  * suspend_console - suspend the console subsystem
946  *
947  * This disables printk() while we go into suspend states
948  */
949 void suspend_console(void)
950 {
951         if (!console_suspend_enabled)
952                 return;
953         printk("Suspending console(s)\n");
954         acquire_console_sem();
955         console_suspended = 1;
956 }
957
958 void resume_console(void)
959 {
960         if (!console_suspend_enabled)
961                 return;
962         console_suspended = 0;
963         release_console_sem();
964 }
965
966 /**
967  * acquire_console_sem - lock the console system for exclusive use.
968  *
969  * Acquires a semaphore which guarantees that the caller has
970  * exclusive access to the console system and the console_drivers list.
971  *
972  * Can sleep, returns nothing.
973  */
974 void acquire_console_sem(void)
975 {
976         BUG_ON(in_interrupt());
977         if (console_suspended) {
978                 down(&secondary_console_sem);
979                 return;
980         }
981         down(&console_sem);
982         console_locked = 1;
983         console_may_schedule = 1;
984 }
985 EXPORT_SYMBOL(acquire_console_sem);
986
987 int try_acquire_console_sem(void)
988 {
989         if (down_trylock(&console_sem))
990                 return -1;
991         console_locked = 1;
992         console_may_schedule = 0;
993         return 0;
994 }
995 EXPORT_SYMBOL(try_acquire_console_sem);
996
997 int is_console_locked(void)
998 {
999         return console_locked;
1000 }
1001
1002 void wake_up_klogd(void)
1003 {
1004         if (!oops_in_progress && waitqueue_active(&log_wait))
1005                 wake_up_interruptible(&log_wait);
1006 }
1007
1008 /**
1009  * release_console_sem - unlock the console system
1010  *
1011  * Releases the semaphore which the caller holds on the console system
1012  * and the console driver list.
1013  *
1014  * While the semaphore was held, console output may have been buffered
1015  * by printk().  If this is the case, release_console_sem() emits
1016  * the output prior to releasing the semaphore.
1017  *
1018  * If there is output waiting for klogd, we wake it up.
1019  *
1020  * release_console_sem() may be called from any context.
1021  */
1022 void release_console_sem(void)
1023 {
1024         unsigned long flags;
1025         unsigned _con_start, _log_end;
1026         unsigned wake_klogd = 0;
1027
1028         if (console_suspended) {
1029                 up(&secondary_console_sem);
1030                 return;
1031         }
1032
1033         console_may_schedule = 0;
1034
1035         for ( ; ; ) {
1036                 spin_lock_irqsave(&logbuf_lock, flags);
1037                 wake_klogd |= log_start - log_end;
1038                 if (con_start == log_end)
1039                         break;                  /* Nothing to print */
1040                 _con_start = con_start;
1041                 _log_end = log_end;
1042                 con_start = log_end;            /* Flush */
1043                 spin_unlock(&logbuf_lock);
1044                 call_console_drivers(_con_start, _log_end);
1045                 local_irq_restore(flags);
1046         }
1047         console_locked = 0;
1048         up(&console_sem);
1049         spin_unlock_irqrestore(&logbuf_lock, flags);
1050         if (wake_klogd)
1051                 wake_up_klogd();
1052 }
1053 EXPORT_SYMBOL(release_console_sem);
1054
1055 /**
1056  * console_conditional_schedule - yield the CPU if required
1057  *
1058  * If the console code is currently allowed to sleep, and
1059  * if this CPU should yield the CPU to another task, do
1060  * so here.
1061  *
1062  * Must be called within acquire_console_sem().
1063  */
1064 void __sched console_conditional_schedule(void)
1065 {
1066         if (console_may_schedule)
1067                 cond_resched();
1068 }
1069 EXPORT_SYMBOL(console_conditional_schedule);
1070
1071 void console_print(const char *s)
1072 {
1073         printk(KERN_EMERG "%s", s);
1074 }
1075 EXPORT_SYMBOL(console_print);
1076
1077 void console_unblank(void)
1078 {
1079         struct console *c;
1080
1081         /*
1082          * console_unblank can no longer be called in interrupt context unless
1083          * oops_in_progress is set to 1..
1084          */
1085         if (oops_in_progress) {
1086                 if (down_trylock(&console_sem) != 0)
1087                         return;
1088         } else
1089                 acquire_console_sem();
1090
1091         console_locked = 1;
1092         console_may_schedule = 0;
1093         for (c = console_drivers; c != NULL; c = c->next)
1094                 if ((c->flags & CON_ENABLED) && c->unblank)
1095                         c->unblank();
1096         release_console_sem();
1097 }
1098
1099 /*
1100  * Return the console tty driver structure and its associated index
1101  */
1102 struct tty_driver *console_device(int *index)
1103 {
1104         struct console *c;
1105         struct tty_driver *driver = NULL;
1106
1107         acquire_console_sem();
1108         for (c = console_drivers; c != NULL; c = c->next) {
1109                 if (!c->device)
1110                         continue;
1111                 driver = c->device(c, index);
1112                 if (driver)
1113                         break;
1114         }
1115         release_console_sem();
1116         return driver;
1117 }
1118
1119 /*
1120  * Prevent further output on the passed console device so that (for example)
1121  * serial drivers can disable console output before suspending a port, and can
1122  * re-enable output afterwards.
1123  */
1124 void console_stop(struct console *console)
1125 {
1126         acquire_console_sem();
1127         console->flags &= ~CON_ENABLED;
1128         release_console_sem();
1129 }
1130 EXPORT_SYMBOL(console_stop);
1131
1132 void console_start(struct console *console)
1133 {
1134         acquire_console_sem();
1135         console->flags |= CON_ENABLED;
1136         release_console_sem();
1137 }
1138 EXPORT_SYMBOL(console_start);
1139
1140 /*
1141  * The console driver calls this routine during kernel initialization
1142  * to register the console printing procedure with printk() and to
1143  * print any messages that were printed by the kernel before the
1144  * console driver was initialized.
1145  */
1146 void register_console(struct console *console)
1147 {
1148         int i;
1149         unsigned long flags;
1150         struct console *bootconsole = NULL;
1151
1152         if (console_drivers) {
1153                 if (console->flags & CON_BOOT)
1154                         return;
1155                 if (console_drivers->flags & CON_BOOT)
1156                         bootconsole = console_drivers;
1157         }
1158
1159         if (preferred_console < 0 || bootconsole || !console_drivers)
1160                 preferred_console = selected_console;
1161
1162         if (console->early_setup)
1163                 console->early_setup();
1164
1165         /*
1166          *      See if we want to use this console driver. If we
1167          *      didn't select a console we take the first one
1168          *      that registers here.
1169          */
1170         if (preferred_console < 0) {
1171                 if (console->index < 0)
1172                         console->index = 0;
1173                 if (console->setup == NULL ||
1174                     console->setup(console, NULL) == 0) {
1175                         console->flags |= CON_ENABLED | CON_CONSDEV;
1176                         preferred_console = 0;
1177                 }
1178         }
1179
1180         /*
1181          *      See if this console matches one we selected on
1182          *      the command line.
1183          */
1184         for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
1185                         i++) {
1186                 if (strcmp(console_cmdline[i].name, console->name) != 0)
1187                         continue;
1188                 if (console->index >= 0 &&
1189                     console->index != console_cmdline[i].index)
1190                         continue;
1191                 if (console->index < 0)
1192                         console->index = console_cmdline[i].index;
1193 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1194                 if (console_cmdline[i].brl_options) {
1195                         console->flags |= CON_BRL;
1196                         braille_register_console(console,
1197                                         console_cmdline[i].index,
1198                                         console_cmdline[i].options,
1199                                         console_cmdline[i].brl_options);
1200                         return;
1201                 }
1202 #endif
1203                 if (console->setup &&
1204                     console->setup(console, console_cmdline[i].options) != 0)
1205                         break;
1206                 console->flags |= CON_ENABLED;
1207                 console->index = console_cmdline[i].index;
1208                 if (i == selected_console) {
1209                         console->flags |= CON_CONSDEV;
1210                         preferred_console = selected_console;
1211                 }
1212                 break;
1213         }
1214
1215         if (!(console->flags & CON_ENABLED))
1216                 return;
1217
1218         if (bootconsole && (console->flags & CON_CONSDEV)) {
1219                 printk(KERN_INFO "console handover: boot [%s%d] -> real [%s%d]\n",
1220                        bootconsole->name, bootconsole->index,
1221                        console->name, console->index);
1222                 unregister_console(bootconsole);
1223                 console->flags &= ~CON_PRINTBUFFER;
1224         } else {
1225                 printk(KERN_INFO "console [%s%d] enabled\n",
1226                        console->name, console->index);
1227         }
1228
1229         /*
1230          *      Put this console in the list - keep the
1231          *      preferred driver at the head of the list.
1232          */
1233         acquire_console_sem();
1234         if ((console->flags & CON_CONSDEV) || console_drivers == NULL) {
1235                 console->next = console_drivers;
1236                 console_drivers = console;
1237                 if (console->next)
1238                         console->next->flags &= ~CON_CONSDEV;
1239         } else {
1240                 console->next = console_drivers->next;
1241                 console_drivers->next = console;
1242         }
1243         if (console->flags & CON_PRINTBUFFER) {
1244                 /*
1245                  * release_console_sem() will print out the buffered messages
1246                  * for us.
1247                  */
1248                 spin_lock_irqsave(&logbuf_lock, flags);
1249                 con_start = log_start;
1250                 spin_unlock_irqrestore(&logbuf_lock, flags);
1251         }
1252         release_console_sem();
1253 }
1254 EXPORT_SYMBOL(register_console);
1255
1256 int unregister_console(struct console *console)
1257 {
1258         struct console *a, *b;
1259         int res = 1;
1260
1261 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1262         if (console->flags & CON_BRL)
1263                 return braille_unregister_console(console);
1264 #endif
1265
1266         acquire_console_sem();
1267         if (console_drivers == console) {
1268                 console_drivers=console->next;
1269                 res = 0;
1270         } else if (console_drivers) {
1271                 for (a=console_drivers->next, b=console_drivers ;
1272                      a; b=a, a=b->next) {
1273                         if (a == console) {
1274                                 b->next = a->next;
1275                                 res = 0;
1276                                 break;
1277                         }
1278                 }
1279         }
1280
1281         /*
1282          * If this isn't the last console and it has CON_CONSDEV set, we
1283          * need to set it on the next preferred console.
1284          */
1285         if (console_drivers != NULL && console->flags & CON_CONSDEV)
1286                 console_drivers->flags |= CON_CONSDEV;
1287
1288         release_console_sem();
1289         return res;
1290 }
1291 EXPORT_SYMBOL(unregister_console);
1292
1293 static int __init disable_boot_consoles(void)
1294 {
1295         if (console_drivers != NULL) {
1296                 if (console_drivers->flags & CON_BOOT) {
1297                         printk(KERN_INFO "turn off boot console %s%d\n",
1298                                 console_drivers->name, console_drivers->index);
1299                         return unregister_console(console_drivers);
1300                 }
1301         }
1302         return 0;
1303 }
1304 late_initcall(disable_boot_consoles);
1305
1306 /**
1307  * tty_write_message - write a message to a certain tty, not just the console.
1308  * @tty: the destination tty_struct
1309  * @msg: the message to write
1310  *
1311  * This is used for messages that need to be redirected to a specific tty.
1312  * We don't put it into the syslog queue right now maybe in the future if
1313  * really needed.
1314  */
1315 void tty_write_message(struct tty_struct *tty, char *msg)
1316 {
1317         if (tty && tty->ops->write)
1318                 tty->ops->write(tty, msg, strlen(msg));
1319         return;
1320 }
1321
1322 #if defined CONFIG_PRINTK
1323 /*
1324  * printk rate limiting, lifted from the networking subsystem.
1325  *
1326  * This enforces a rate limit: not more than one kernel message
1327  * every printk_ratelimit_jiffies to make a denial-of-service
1328  * attack impossible.
1329  */
1330 int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst)
1331 {
1332         return __ratelimit(ratelimit_jiffies, ratelimit_burst);
1333 }
1334 EXPORT_SYMBOL(__printk_ratelimit);
1335
1336 /* minimum time in jiffies between messages */
1337 int printk_ratelimit_jiffies = 5 * HZ;
1338
1339 /* number of messages we send before ratelimiting */
1340 int printk_ratelimit_burst = 10;
1341
1342 int printk_ratelimit(void)
1343 {
1344         return __printk_ratelimit(printk_ratelimit_jiffies,
1345                                 printk_ratelimit_burst);
1346 }
1347 EXPORT_SYMBOL(printk_ratelimit);
1348
1349 /**
1350  * printk_timed_ratelimit - caller-controlled printk ratelimiting
1351  * @caller_jiffies: pointer to caller's state
1352  * @interval_msecs: minimum interval between prints
1353  *
1354  * printk_timed_ratelimit() returns true if more than @interval_msecs
1355  * milliseconds have elapsed since the last time printk_timed_ratelimit()
1356  * returned true.
1357  */
1358 bool printk_timed_ratelimit(unsigned long *caller_jiffies,
1359                         unsigned int interval_msecs)
1360 {
1361         if (*caller_jiffies == 0 || time_after(jiffies, *caller_jiffies)) {
1362                 *caller_jiffies = jiffies + msecs_to_jiffies(interval_msecs);
1363                 return true;
1364         }
1365         return false;
1366 }
1367 EXPORT_SYMBOL(printk_timed_ratelimit);
1368 #endif