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