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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 | |
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 | #include <linux/kexec.h> | |
36 | ||
37 | #include <asm/uaccess.h> | |
38 | ||
39 | /* | |
40 | * Architectures can override it: | |
41 | */ | |
42 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) | |
43 | { | |
44 | } | |
45 | ||
46 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) | |
47 | ||
48 | /* printk's without a loglevel use this.. */ | |
49 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ | |
50 | ||
51 | /* We show everything that is MORE important than this.. */ | |
52 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
53 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
54 | ||
55 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
56 | ||
57 | int console_printk[4] = { | |
58 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
59 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
60 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
61 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
62 | }; | |
63 | ||
64 | /* | |
65 | * Low level drivers may need that to know if they can schedule in | |
66 | * their unblank() callback or not. So let's export it. | |
67 | */ | |
68 | int oops_in_progress; | |
69 | EXPORT_SYMBOL(oops_in_progress); | |
70 | ||
71 | /* | |
72 | * console_sem protects the console_drivers list, and also | |
73 | * provides serialisation for access to the entire console | |
74 | * driver system. | |
75 | */ | |
76 | static DECLARE_MUTEX(console_sem); | |
77 | struct console *console_drivers; | |
78 | EXPORT_SYMBOL_GPL(console_drivers); | |
79 | ||
80 | /* | |
81 | * This is used for debugging the mess that is the VT code by | |
82 | * keeping track if we have the console semaphore held. It's | |
83 | * definitely not the perfect debug tool (we don't know if _WE_ | |
84 | * hold it are racing, but it helps tracking those weird code | |
85 | * path in the console code where we end up in places I want | |
86 | * locked without the console sempahore held | |
87 | */ | |
88 | static int console_locked, console_suspended; | |
89 | ||
90 | /* | |
91 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
92 | * It is also used in interesting ways to provide interlocking in | |
93 | * release_console_sem(). | |
94 | */ | |
95 | static DEFINE_SPINLOCK(logbuf_lock); | |
96 | ||
97 | #define LOG_BUF_MASK (log_buf_len-1) | |
98 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) | |
99 | ||
100 | /* | |
101 | * The indices into log_buf are not constrained to log_buf_len - they | |
102 | * must be masked before subscripting | |
103 | */ | |
104 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ | |
105 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ | |
106 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
107 | ||
108 | /* | |
109 | * Array of consoles built from command line options (console=) | |
110 | */ | |
111 | struct console_cmdline | |
112 | { | |
113 | char name[8]; /* Name of the driver */ | |
114 | int index; /* Minor dev. to use */ | |
115 | char *options; /* Options for the driver */ | |
116 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
117 | char *brl_options; /* Options for braille driver */ | |
118 | #endif | |
119 | }; | |
120 | ||
121 | #define MAX_CMDLINECONSOLES 8 | |
122 | ||
123 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
124 | static int selected_console = -1; | |
125 | static int preferred_console = -1; | |
126 | int console_set_on_cmdline; | |
127 | EXPORT_SYMBOL(console_set_on_cmdline); | |
128 | ||
129 | /* Flag: console code may call schedule() */ | |
130 | static int console_may_schedule; | |
131 | ||
132 | #ifdef CONFIG_PRINTK | |
133 | ||
134 | static char __log_buf[__LOG_BUF_LEN]; | |
135 | static char *log_buf = __log_buf; | |
136 | static int log_buf_len = __LOG_BUF_LEN; | |
137 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ | |
138 | ||
139 | #ifdef CONFIG_KEXEC | |
140 | /* | |
141 | * This appends the listed symbols to /proc/vmcoreinfo | |
142 | * | |
143 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
144 | * obtain access to symbols that are otherwise very difficult to locate. These | |
145 | * symbols are specifically used so that utilities can access and extract the | |
146 | * dmesg log from a vmcore file after a crash. | |
147 | */ | |
148 | void log_buf_kexec_setup(void) | |
149 | { | |
150 | VMCOREINFO_SYMBOL(log_buf); | |
151 | VMCOREINFO_SYMBOL(log_end); | |
152 | VMCOREINFO_SYMBOL(log_buf_len); | |
153 | VMCOREINFO_SYMBOL(logged_chars); | |
154 | } | |
155 | #endif | |
156 | ||
157 | static int __init log_buf_len_setup(char *str) | |
158 | { | |
159 | unsigned size = memparse(str, &str); | |
160 | unsigned long flags; | |
161 | ||
162 | if (size) | |
163 | size = roundup_pow_of_two(size); | |
164 | if (size > log_buf_len) { | |
165 | unsigned start, dest_idx, offset; | |
166 | char *new_log_buf; | |
167 | ||
168 | new_log_buf = alloc_bootmem(size); | |
169 | if (!new_log_buf) { | |
170 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); | |
171 | goto out; | |
172 | } | |
173 | ||
174 | spin_lock_irqsave(&logbuf_lock, flags); | |
175 | log_buf_len = size; | |
176 | log_buf = new_log_buf; | |
177 | ||
178 | offset = start = min(con_start, log_start); | |
179 | dest_idx = 0; | |
180 | while (start != log_end) { | |
181 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
182 | start++; | |
183 | dest_idx++; | |
184 | } | |
185 | log_start -= offset; | |
186 | con_start -= offset; | |
187 | log_end -= offset; | |
188 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
189 | ||
190 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); | |
191 | } | |
192 | out: | |
193 | return 1; | |
194 | } | |
195 | ||
196 | __setup("log_buf_len=", log_buf_len_setup); | |
197 | ||
198 | #ifdef CONFIG_BOOT_PRINTK_DELAY | |
199 | ||
200 | static unsigned int boot_delay; /* msecs delay after each printk during bootup */ | |
201 | static unsigned long long printk_delay_msec; /* per msec, based on boot_delay */ | |
202 | ||
203 | static int __init boot_delay_setup(char *str) | |
204 | { | |
205 | unsigned long lpj; | |
206 | unsigned long long loops_per_msec; | |
207 | ||
208 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
209 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
210 | ||
211 | get_option(&str, &boot_delay); | |
212 | if (boot_delay > 10 * 1000) | |
213 | boot_delay = 0; | |
214 | ||
215 | printk_delay_msec = loops_per_msec; | |
216 | printk(KERN_DEBUG "boot_delay: %u, preset_lpj: %ld, lpj: %lu, " | |
217 | "HZ: %d, printk_delay_msec: %llu\n", | |
218 | boot_delay, preset_lpj, lpj, HZ, printk_delay_msec); | |
219 | return 1; | |
220 | } | |
221 | __setup("boot_delay=", boot_delay_setup); | |
222 | ||
223 | static void boot_delay_msec(void) | |
224 | { | |
225 | unsigned long long k; | |
226 | unsigned long timeout; | |
227 | ||
228 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
229 | return; | |
230 | ||
231 | k = (unsigned long long)printk_delay_msec * boot_delay; | |
232 | ||
233 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
234 | while (k) { | |
235 | k--; | |
236 | cpu_relax(); | |
237 | /* | |
238 | * use (volatile) jiffies to prevent | |
239 | * compiler reduction; loop termination via jiffies | |
240 | * is secondary and may or may not happen. | |
241 | */ | |
242 | if (time_after(jiffies, timeout)) | |
243 | break; | |
244 | touch_nmi_watchdog(); | |
245 | } | |
246 | } | |
247 | #else | |
248 | static inline void boot_delay_msec(void) | |
249 | { | |
250 | } | |
251 | #endif | |
252 | ||
253 | /* | |
254 | * Commands to do_syslog: | |
255 | * | |
256 | * 0 -- Close the log. Currently a NOP. | |
257 | * 1 -- Open the log. Currently a NOP. | |
258 | * 2 -- Read from the log. | |
259 | * 3 -- Read all messages remaining in the ring buffer. | |
260 | * 4 -- Read and clear all messages remaining in the ring buffer | |
261 | * 5 -- Clear ring buffer. | |
262 | * 6 -- Disable printk's to console | |
263 | * 7 -- Enable printk's to console | |
264 | * 8 -- Set level of messages printed to console | |
265 | * 9 -- Return number of unread characters in the log buffer | |
266 | * 10 -- Return size of the log buffer | |
267 | */ | |
268 | int do_syslog(int type, char __user *buf, int len) | |
269 | { | |
270 | unsigned i, j, limit, count; | |
271 | int do_clear = 0; | |
272 | char c; | |
273 | int error = 0; | |
274 | ||
275 | error = security_syslog(type); | |
276 | if (error) | |
277 | return error; | |
278 | ||
279 | switch (type) { | |
280 | case 0: /* Close log */ | |
281 | break; | |
282 | case 1: /* Open log */ | |
283 | break; | |
284 | case 2: /* Read from log */ | |
285 | error = -EINVAL; | |
286 | if (!buf || len < 0) | |
287 | goto out; | |
288 | error = 0; | |
289 | if (!len) | |
290 | goto out; | |
291 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
292 | error = -EFAULT; | |
293 | goto out; | |
294 | } | |
295 | error = wait_event_interruptible(log_wait, | |
296 | (log_start - log_end)); | |
297 | if (error) | |
298 | goto out; | |
299 | i = 0; | |
300 | spin_lock_irq(&logbuf_lock); | |
301 | while (!error && (log_start != log_end) && i < len) { | |
302 | c = LOG_BUF(log_start); | |
303 | log_start++; | |
304 | spin_unlock_irq(&logbuf_lock); | |
305 | error = __put_user(c,buf); | |
306 | buf++; | |
307 | i++; | |
308 | cond_resched(); | |
309 | spin_lock_irq(&logbuf_lock); | |
310 | } | |
311 | spin_unlock_irq(&logbuf_lock); | |
312 | if (!error) | |
313 | error = i; | |
314 | break; | |
315 | case 4: /* Read/clear last kernel messages */ | |
316 | do_clear = 1; | |
317 | /* FALL THRU */ | |
318 | case 3: /* Read last kernel messages */ | |
319 | error = -EINVAL; | |
320 | if (!buf || len < 0) | |
321 | goto out; | |
322 | error = 0; | |
323 | if (!len) | |
324 | goto out; | |
325 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
326 | error = -EFAULT; | |
327 | goto out; | |
328 | } | |
329 | count = len; | |
330 | if (count > log_buf_len) | |
331 | count = log_buf_len; | |
332 | spin_lock_irq(&logbuf_lock); | |
333 | if (count > logged_chars) | |
334 | count = logged_chars; | |
335 | if (do_clear) | |
336 | logged_chars = 0; | |
337 | limit = log_end; | |
338 | /* | |
339 | * __put_user() could sleep, and while we sleep | |
340 | * printk() could overwrite the messages | |
341 | * we try to copy to user space. Therefore | |
342 | * the messages are copied in reverse. <manfreds> | |
343 | */ | |
344 | for (i = 0; i < count && !error; i++) { | |
345 | j = limit-1-i; | |
346 | if (j + log_buf_len < log_end) | |
347 | break; | |
348 | c = LOG_BUF(j); | |
349 | spin_unlock_irq(&logbuf_lock); | |
350 | error = __put_user(c,&buf[count-1-i]); | |
351 | cond_resched(); | |
352 | spin_lock_irq(&logbuf_lock); | |
353 | } | |
354 | spin_unlock_irq(&logbuf_lock); | |
355 | if (error) | |
356 | break; | |
357 | error = i; | |
358 | if (i != count) { | |
359 | int offset = count-error; | |
360 | /* buffer overflow during copy, correct user buffer. */ | |
361 | for (i = 0; i < error; i++) { | |
362 | if (__get_user(c,&buf[i+offset]) || | |
363 | __put_user(c,&buf[i])) { | |
364 | error = -EFAULT; | |
365 | break; | |
366 | } | |
367 | cond_resched(); | |
368 | } | |
369 | } | |
370 | break; | |
371 | case 5: /* Clear ring buffer */ | |
372 | logged_chars = 0; | |
373 | break; | |
374 | case 6: /* Disable logging to console */ | |
375 | console_loglevel = minimum_console_loglevel; | |
376 | break; | |
377 | case 7: /* Enable logging to console */ | |
378 | console_loglevel = default_console_loglevel; | |
379 | break; | |
380 | case 8: /* Set level of messages printed to console */ | |
381 | error = -EINVAL; | |
382 | if (len < 1 || len > 8) | |
383 | goto out; | |
384 | if (len < minimum_console_loglevel) | |
385 | len = minimum_console_loglevel; | |
386 | console_loglevel = len; | |
387 | error = 0; | |
388 | break; | |
389 | case 9: /* Number of chars in the log buffer */ | |
390 | error = log_end - log_start; | |
391 | break; | |
392 | case 10: /* Size of the log buffer */ | |
393 | error = log_buf_len; | |
394 | break; | |
395 | default: | |
396 | error = -EINVAL; | |
397 | break; | |
398 | } | |
399 | out: | |
400 | return error; | |
401 | } | |
402 | ||
403 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) | |
404 | { | |
405 | return do_syslog(type, buf, len); | |
406 | } | |
407 | ||
408 | /* | |
409 | * Call the console drivers on a range of log_buf | |
410 | */ | |
411 | static void __call_console_drivers(unsigned start, unsigned end) | |
412 | { | |
413 | struct console *con; | |
414 | ||
415 | for (con = console_drivers; con; con = con->next) { | |
416 | if ((con->flags & CON_ENABLED) && con->write && | |
417 | (cpu_online(smp_processor_id()) || | |
418 | (con->flags & CON_ANYTIME))) | |
419 | con->write(con, &LOG_BUF(start), end - start); | |
420 | } | |
421 | } | |
422 | ||
423 | static int __read_mostly ignore_loglevel; | |
424 | ||
425 | static int __init ignore_loglevel_setup(char *str) | |
426 | { | |
427 | ignore_loglevel = 1; | |
428 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
429 | ||
430 | return 0; | |
431 | } | |
432 | ||
433 | early_param("ignore_loglevel", ignore_loglevel_setup); | |
434 | ||
435 | /* | |
436 | * Write out chars from start to end - 1 inclusive | |
437 | */ | |
438 | static void _call_console_drivers(unsigned start, | |
439 | unsigned end, int msg_log_level) | |
440 | { | |
441 | if ((msg_log_level < console_loglevel || ignore_loglevel) && | |
442 | console_drivers && start != end) { | |
443 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
444 | /* wrapped write */ | |
445 | __call_console_drivers(start & LOG_BUF_MASK, | |
446 | log_buf_len); | |
447 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
448 | } else { | |
449 | __call_console_drivers(start, end); | |
450 | } | |
451 | } | |
452 | } | |
453 | ||
454 | /* | |
455 | * Call the console drivers, asking them to write out | |
456 | * log_buf[start] to log_buf[end - 1]. | |
457 | * The console_sem must be held. | |
458 | */ | |
459 | static void call_console_drivers(unsigned start, unsigned end) | |
460 | { | |
461 | unsigned cur_index, start_print; | |
462 | static int msg_level = -1; | |
463 | ||
464 | BUG_ON(((int)(start - end)) > 0); | |
465 | ||
466 | cur_index = start; | |
467 | start_print = start; | |
468 | while (cur_index != end) { | |
469 | if (msg_level < 0 && ((end - cur_index) > 2) && | |
470 | LOG_BUF(cur_index + 0) == '<' && | |
471 | LOG_BUF(cur_index + 1) >= '0' && | |
472 | LOG_BUF(cur_index + 1) <= '7' && | |
473 | LOG_BUF(cur_index + 2) == '>') { | |
474 | msg_level = LOG_BUF(cur_index + 1) - '0'; | |
475 | cur_index += 3; | |
476 | start_print = cur_index; | |
477 | } | |
478 | while (cur_index != end) { | |
479 | char c = LOG_BUF(cur_index); | |
480 | ||
481 | cur_index++; | |
482 | if (c == '\n') { | |
483 | if (msg_level < 0) { | |
484 | /* | |
485 | * printk() has already given us loglevel tags in | |
486 | * the buffer. This code is here in case the | |
487 | * log buffer has wrapped right round and scribbled | |
488 | * on those tags | |
489 | */ | |
490 | msg_level = default_message_loglevel; | |
491 | } | |
492 | _call_console_drivers(start_print, cur_index, msg_level); | |
493 | msg_level = -1; | |
494 | start_print = cur_index; | |
495 | break; | |
496 | } | |
497 | } | |
498 | } | |
499 | _call_console_drivers(start_print, end, msg_level); | |
500 | } | |
501 | ||
502 | static void emit_log_char(char c) | |
503 | { | |
504 | LOG_BUF(log_end) = c; | |
505 | log_end++; | |
506 | if (log_end - log_start > log_buf_len) | |
507 | log_start = log_end - log_buf_len; | |
508 | if (log_end - con_start > log_buf_len) | |
509 | con_start = log_end - log_buf_len; | |
510 | if (logged_chars < log_buf_len) | |
511 | logged_chars++; | |
512 | } | |
513 | ||
514 | /* | |
515 | * Zap console related locks when oopsing. Only zap at most once | |
516 | * every 10 seconds, to leave time for slow consoles to print a | |
517 | * full oops. | |
518 | */ | |
519 | static void zap_locks(void) | |
520 | { | |
521 | static unsigned long oops_timestamp; | |
522 | ||
523 | if (time_after_eq(jiffies, oops_timestamp) && | |
524 | !time_after(jiffies, oops_timestamp + 30 * HZ)) | |
525 | return; | |
526 | ||
527 | oops_timestamp = jiffies; | |
528 | ||
529 | /* If a crash is occurring, make sure we can't deadlock */ | |
530 | spin_lock_init(&logbuf_lock); | |
531 | /* And make sure that we print immediately */ | |
532 | init_MUTEX(&console_sem); | |
533 | } | |
534 | ||
535 | #if defined(CONFIG_PRINTK_TIME) | |
536 | static int printk_time = 1; | |
537 | #else | |
538 | static int printk_time = 0; | |
539 | #endif | |
540 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); | |
541 | ||
542 | /* Check if we have any console registered that can be called early in boot. */ | |
543 | static int have_callable_console(void) | |
544 | { | |
545 | struct console *con; | |
546 | ||
547 | for (con = console_drivers; con; con = con->next) | |
548 | if (con->flags & CON_ANYTIME) | |
549 | return 1; | |
550 | ||
551 | return 0; | |
552 | } | |
553 | ||
554 | /** | |
555 | * printk - print a kernel message | |
556 | * @fmt: format string | |
557 | * | |
558 | * This is printk(). It can be called from any context. We want it to work. | |
559 | * | |
560 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and | |
561 | * call the console drivers. If we fail to get the semaphore we place the output | |
562 | * into the log buffer and return. The current holder of the console_sem will | |
563 | * notice the new output in release_console_sem() and will send it to the | |
564 | * consoles before releasing the semaphore. | |
565 | * | |
566 | * One effect of this deferred printing is that code which calls printk() and | |
567 | * then changes console_loglevel may break. This is because console_loglevel | |
568 | * is inspected when the actual printing occurs. | |
569 | * | |
570 | * See also: | |
571 | * printf(3) | |
572 | * | |
573 | * See the vsnprintf() documentation for format string extensions over C99. | |
574 | */ | |
575 | ||
576 | asmlinkage int printk(const char *fmt, ...) | |
577 | { | |
578 | va_list args; | |
579 | int r; | |
580 | ||
581 | va_start(args, fmt); | |
582 | r = vprintk(fmt, args); | |
583 | va_end(args); | |
584 | ||
585 | return r; | |
586 | } | |
587 | ||
588 | /* cpu currently holding logbuf_lock */ | |
589 | static volatile unsigned int printk_cpu = UINT_MAX; | |
590 | ||
591 | /* | |
592 | * Can we actually use the console at this time on this cpu? | |
593 | * | |
594 | * Console drivers may assume that per-cpu resources have | |
595 | * been allocated. So unless they're explicitly marked as | |
596 | * being able to cope (CON_ANYTIME) don't call them until | |
597 | * this CPU is officially up. | |
598 | */ | |
599 | static inline int can_use_console(unsigned int cpu) | |
600 | { | |
601 | return cpu_online(cpu) || have_callable_console(); | |
602 | } | |
603 | ||
604 | /* | |
605 | * Try to get console ownership to actually show the kernel | |
606 | * messages from a 'printk'. Return true (and with the | |
607 | * console_semaphore held, and 'console_locked' set) if it | |
608 | * is successful, false otherwise. | |
609 | * | |
610 | * This gets called with the 'logbuf_lock' spinlock held and | |
611 | * interrupts disabled. It should return with 'lockbuf_lock' | |
612 | * released but interrupts still disabled. | |
613 | */ | |
614 | static int acquire_console_semaphore_for_printk(unsigned int cpu) | |
615 | { | |
616 | int retval = 0; | |
617 | ||
618 | if (!try_acquire_console_sem()) { | |
619 | retval = 1; | |
620 | ||
621 | /* | |
622 | * If we can't use the console, we need to release | |
623 | * the console semaphore by hand to avoid flushing | |
624 | * the buffer. We need to hold the console semaphore | |
625 | * in order to do this test safely. | |
626 | */ | |
627 | if (!can_use_console(cpu)) { | |
628 | console_locked = 0; | |
629 | up(&console_sem); | |
630 | retval = 0; | |
631 | } | |
632 | } | |
633 | printk_cpu = UINT_MAX; | |
634 | spin_unlock(&logbuf_lock); | |
635 | return retval; | |
636 | } | |
637 | static const char recursion_bug_msg [] = | |
638 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
639 | static int recursion_bug; | |
640 | static int new_text_line = 1; | |
641 | static char printk_buf[1024]; | |
642 | ||
643 | asmlinkage int vprintk(const char *fmt, va_list args) | |
644 | { | |
645 | int printed_len = 0; | |
646 | int current_log_level = default_message_loglevel; | |
647 | unsigned long flags; | |
648 | int this_cpu; | |
649 | char *p; | |
650 | ||
651 | boot_delay_msec(); | |
652 | ||
653 | preempt_disable(); | |
654 | /* This stops the holder of console_sem just where we want him */ | |
655 | raw_local_irq_save(flags); | |
656 | this_cpu = smp_processor_id(); | |
657 | ||
658 | /* | |
659 | * Ouch, printk recursed into itself! | |
660 | */ | |
661 | if (unlikely(printk_cpu == this_cpu)) { | |
662 | /* | |
663 | * If a crash is occurring during printk() on this CPU, | |
664 | * then try to get the crash message out but make sure | |
665 | * we can't deadlock. Otherwise just return to avoid the | |
666 | * recursion and return - but flag the recursion so that | |
667 | * it can be printed at the next appropriate moment: | |
668 | */ | |
669 | if (!oops_in_progress) { | |
670 | recursion_bug = 1; | |
671 | goto out_restore_irqs; | |
672 | } | |
673 | zap_locks(); | |
674 | } | |
675 | ||
676 | lockdep_off(); | |
677 | spin_lock(&logbuf_lock); | |
678 | printk_cpu = this_cpu; | |
679 | ||
680 | if (recursion_bug) { | |
681 | recursion_bug = 0; | |
682 | strcpy(printk_buf, recursion_bug_msg); | |
683 | printed_len = strlen(recursion_bug_msg); | |
684 | } | |
685 | /* Emit the output into the temporary buffer */ | |
686 | printed_len += vscnprintf(printk_buf + printed_len, | |
687 | sizeof(printk_buf) - printed_len, fmt, args); | |
688 | ||
689 | ||
690 | /* | |
691 | * Copy the output into log_buf. If the caller didn't provide | |
692 | * appropriate log level tags, we insert them here | |
693 | */ | |
694 | for (p = printk_buf; *p; p++) { | |
695 | if (new_text_line) { | |
696 | /* If a token, set current_log_level and skip over */ | |
697 | if (p[0] == '<' && p[1] >= '0' && p[1] <= '7' && | |
698 | p[2] == '>') { | |
699 | current_log_level = p[1] - '0'; | |
700 | p += 3; | |
701 | printed_len -= 3; | |
702 | } | |
703 | ||
704 | /* Always output the token */ | |
705 | emit_log_char('<'); | |
706 | emit_log_char(current_log_level + '0'); | |
707 | emit_log_char('>'); | |
708 | printed_len += 3; | |
709 | new_text_line = 0; | |
710 | ||
711 | if (printk_time) { | |
712 | /* Follow the token with the time */ | |
713 | char tbuf[50], *tp; | |
714 | unsigned tlen; | |
715 | unsigned long long t; | |
716 | unsigned long nanosec_rem; | |
717 | ||
718 | t = cpu_clock(printk_cpu); | |
719 | nanosec_rem = do_div(t, 1000000000); | |
720 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", | |
721 | (unsigned long) t, | |
722 | nanosec_rem / 1000); | |
723 | ||
724 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
725 | emit_log_char(*tp); | |
726 | printed_len += tlen; | |
727 | } | |
728 | ||
729 | if (!*p) | |
730 | break; | |
731 | } | |
732 | ||
733 | emit_log_char(*p); | |
734 | if (*p == '\n') | |
735 | new_text_line = 1; | |
736 | } | |
737 | ||
738 | /* | |
739 | * Try to acquire and then immediately release the | |
740 | * console semaphore. The release will do all the | |
741 | * actual magic (print out buffers, wake up klogd, | |
742 | * etc). | |
743 | * | |
744 | * The acquire_console_semaphore_for_printk() function | |
745 | * will release 'logbuf_lock' regardless of whether it | |
746 | * actually gets the semaphore or not. | |
747 | */ | |
748 | if (acquire_console_semaphore_for_printk(this_cpu)) | |
749 | release_console_sem(); | |
750 | ||
751 | lockdep_on(); | |
752 | out_restore_irqs: | |
753 | raw_local_irq_restore(flags); | |
754 | ||
755 | preempt_enable(); | |
756 | return printed_len; | |
757 | } | |
758 | EXPORT_SYMBOL(printk); | |
759 | EXPORT_SYMBOL(vprintk); | |
760 | ||
761 | #else | |
762 | ||
763 | static void call_console_drivers(unsigned start, unsigned end) | |
764 | { | |
765 | } | |
766 | ||
767 | #endif | |
768 | ||
769 | static int __add_preferred_console(char *name, int idx, char *options, | |
770 | char *brl_options) | |
771 | { | |
772 | struct console_cmdline *c; | |
773 | int i; | |
774 | ||
775 | /* | |
776 | * See if this tty is not yet registered, and | |
777 | * if we have a slot free. | |
778 | */ | |
779 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
780 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
781 | console_cmdline[i].index == idx) { | |
782 | if (!brl_options) | |
783 | selected_console = i; | |
784 | return 0; | |
785 | } | |
786 | if (i == MAX_CMDLINECONSOLES) | |
787 | return -E2BIG; | |
788 | if (!brl_options) | |
789 | selected_console = i; | |
790 | c = &console_cmdline[i]; | |
791 | strlcpy(c->name, name, sizeof(c->name)); | |
792 | c->options = options; | |
793 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
794 | c->brl_options = brl_options; | |
795 | #endif | |
796 | c->index = idx; | |
797 | return 0; | |
798 | } | |
799 | /* | |
800 | * Set up a list of consoles. Called from init/main.c | |
801 | */ | |
802 | static int __init console_setup(char *str) | |
803 | { | |
804 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ | |
805 | char *s, *options, *brl_options = NULL; | |
806 | int idx; | |
807 | ||
808 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
809 | if (!memcmp(str, "brl,", 4)) { | |
810 | brl_options = ""; | |
811 | str += 4; | |
812 | } else if (!memcmp(str, "brl=", 4)) { | |
813 | brl_options = str + 4; | |
814 | str = strchr(brl_options, ','); | |
815 | if (!str) { | |
816 | printk(KERN_ERR "need port name after brl=\n"); | |
817 | return 1; | |
818 | } | |
819 | *(str++) = 0; | |
820 | } | |
821 | #endif | |
822 | ||
823 | /* | |
824 | * Decode str into name, index, options. | |
825 | */ | |
826 | if (str[0] >= '0' && str[0] <= '9') { | |
827 | strcpy(buf, "ttyS"); | |
828 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
829 | } else { | |
830 | strncpy(buf, str, sizeof(buf) - 1); | |
831 | } | |
832 | buf[sizeof(buf) - 1] = 0; | |
833 | if ((options = strchr(str, ',')) != NULL) | |
834 | *(options++) = 0; | |
835 | #ifdef __sparc__ | |
836 | if (!strcmp(str, "ttya")) | |
837 | strcpy(buf, "ttyS0"); | |
838 | if (!strcmp(str, "ttyb")) | |
839 | strcpy(buf, "ttyS1"); | |
840 | #endif | |
841 | for (s = buf; *s; s++) | |
842 | if ((*s >= '0' && *s <= '9') || *s == ',') | |
843 | break; | |
844 | idx = simple_strtoul(s, NULL, 10); | |
845 | *s = 0; | |
846 | ||
847 | __add_preferred_console(buf, idx, options, brl_options); | |
848 | console_set_on_cmdline = 1; | |
849 | return 1; | |
850 | } | |
851 | __setup("console=", console_setup); | |
852 | ||
853 | /** | |
854 | * add_preferred_console - add a device to the list of preferred consoles. | |
855 | * @name: device name | |
856 | * @idx: device index | |
857 | * @options: options for this console | |
858 | * | |
859 | * The last preferred console added will be used for kernel messages | |
860 | * and stdin/out/err for init. Normally this is used by console_setup | |
861 | * above to handle user-supplied console arguments; however it can also | |
862 | * be used by arch-specific code either to override the user or more | |
863 | * commonly to provide a default console (ie from PROM variables) when | |
864 | * the user has not supplied one. | |
865 | */ | |
866 | int add_preferred_console(char *name, int idx, char *options) | |
867 | { | |
868 | return __add_preferred_console(name, idx, options, NULL); | |
869 | } | |
870 | ||
871 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) | |
872 | { | |
873 | struct console_cmdline *c; | |
874 | int i; | |
875 | ||
876 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
877 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
878 | console_cmdline[i].index == idx) { | |
879 | c = &console_cmdline[i]; | |
880 | strlcpy(c->name, name_new, sizeof(c->name)); | |
881 | c->name[sizeof(c->name) - 1] = 0; | |
882 | c->options = options; | |
883 | c->index = idx_new; | |
884 | return i; | |
885 | } | |
886 | /* not found */ | |
887 | return -1; | |
888 | } | |
889 | ||
890 | int console_suspend_enabled = 1; | |
891 | EXPORT_SYMBOL(console_suspend_enabled); | |
892 | ||
893 | static int __init console_suspend_disable(char *str) | |
894 | { | |
895 | console_suspend_enabled = 0; | |
896 | return 1; | |
897 | } | |
898 | __setup("no_console_suspend", console_suspend_disable); | |
899 | ||
900 | /** | |
901 | * suspend_console - suspend the console subsystem | |
902 | * | |
903 | * This disables printk() while we go into suspend states | |
904 | */ | |
905 | void suspend_console(void) | |
906 | { | |
907 | if (!console_suspend_enabled) | |
908 | return; | |
909 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); | |
910 | acquire_console_sem(); | |
911 | console_suspended = 1; | |
912 | up(&console_sem); | |
913 | } | |
914 | ||
915 | void resume_console(void) | |
916 | { | |
917 | if (!console_suspend_enabled) | |
918 | return; | |
919 | down(&console_sem); | |
920 | console_suspended = 0; | |
921 | release_console_sem(); | |
922 | } | |
923 | ||
924 | /** | |
925 | * acquire_console_sem - lock the console system for exclusive use. | |
926 | * | |
927 | * Acquires a semaphore which guarantees that the caller has | |
928 | * exclusive access to the console system and the console_drivers list. | |
929 | * | |
930 | * Can sleep, returns nothing. | |
931 | */ | |
932 | void acquire_console_sem(void) | |
933 | { | |
934 | BUG_ON(in_interrupt()); | |
935 | down(&console_sem); | |
936 | if (console_suspended) | |
937 | return; | |
938 | console_locked = 1; | |
939 | console_may_schedule = 1; | |
940 | } | |
941 | EXPORT_SYMBOL(acquire_console_sem); | |
942 | ||
943 | int try_acquire_console_sem(void) | |
944 | { | |
945 | if (down_trylock(&console_sem)) | |
946 | return -1; | |
947 | if (console_suspended) { | |
948 | up(&console_sem); | |
949 | return -1; | |
950 | } | |
951 | console_locked = 1; | |
952 | console_may_schedule = 0; | |
953 | return 0; | |
954 | } | |
955 | EXPORT_SYMBOL(try_acquire_console_sem); | |
956 | ||
957 | int is_console_locked(void) | |
958 | { | |
959 | return console_locked; | |
960 | } | |
961 | ||
962 | static DEFINE_PER_CPU(int, printk_pending); | |
963 | ||
964 | void printk_tick(void) | |
965 | { | |
966 | if (__get_cpu_var(printk_pending)) { | |
967 | __get_cpu_var(printk_pending) = 0; | |
968 | wake_up_interruptible(&log_wait); | |
969 | } | |
970 | } | |
971 | ||
972 | int printk_needs_cpu(int cpu) | |
973 | { | |
974 | return per_cpu(printk_pending, cpu); | |
975 | } | |
976 | ||
977 | void wake_up_klogd(void) | |
978 | { | |
979 | if (waitqueue_active(&log_wait)) | |
980 | __raw_get_cpu_var(printk_pending) = 1; | |
981 | } | |
982 | ||
983 | /** | |
984 | * release_console_sem - unlock the console system | |
985 | * | |
986 | * Releases the semaphore which the caller holds on the console system | |
987 | * and the console driver list. | |
988 | * | |
989 | * While the semaphore was held, console output may have been buffered | |
990 | * by printk(). If this is the case, release_console_sem() emits | |
991 | * the output prior to releasing the semaphore. | |
992 | * | |
993 | * If there is output waiting for klogd, we wake it up. | |
994 | * | |
995 | * release_console_sem() may be called from any context. | |
996 | */ | |
997 | void release_console_sem(void) | |
998 | { | |
999 | unsigned long flags; | |
1000 | unsigned _con_start, _log_end; | |
1001 | unsigned wake_klogd = 0; | |
1002 | ||
1003 | if (console_suspended) { | |
1004 | up(&console_sem); | |
1005 | return; | |
1006 | } | |
1007 | ||
1008 | console_may_schedule = 0; | |
1009 | ||
1010 | for ( ; ; ) { | |
1011 | spin_lock_irqsave(&logbuf_lock, flags); | |
1012 | wake_klogd |= log_start - log_end; | |
1013 | if (con_start == log_end) | |
1014 | break; /* Nothing to print */ | |
1015 | _con_start = con_start; | |
1016 | _log_end = log_end; | |
1017 | con_start = log_end; /* Flush */ | |
1018 | spin_unlock(&logbuf_lock); | |
1019 | stop_critical_timings(); /* don't trace print latency */ | |
1020 | call_console_drivers(_con_start, _log_end); | |
1021 | start_critical_timings(); | |
1022 | local_irq_restore(flags); | |
1023 | } | |
1024 | console_locked = 0; | |
1025 | up(&console_sem); | |
1026 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1027 | if (wake_klogd) | |
1028 | wake_up_klogd(); | |
1029 | } | |
1030 | EXPORT_SYMBOL(release_console_sem); | |
1031 | ||
1032 | /** | |
1033 | * console_conditional_schedule - yield the CPU if required | |
1034 | * | |
1035 | * If the console code is currently allowed to sleep, and | |
1036 | * if this CPU should yield the CPU to another task, do | |
1037 | * so here. | |
1038 | * | |
1039 | * Must be called within acquire_console_sem(). | |
1040 | */ | |
1041 | void __sched console_conditional_schedule(void) | |
1042 | { | |
1043 | if (console_may_schedule) | |
1044 | cond_resched(); | |
1045 | } | |
1046 | EXPORT_SYMBOL(console_conditional_schedule); | |
1047 | ||
1048 | void console_print(const char *s) | |
1049 | { | |
1050 | printk(KERN_EMERG "%s", s); | |
1051 | } | |
1052 | EXPORT_SYMBOL(console_print); | |
1053 | ||
1054 | void console_unblank(void) | |
1055 | { | |
1056 | struct console *c; | |
1057 | ||
1058 | /* | |
1059 | * console_unblank can no longer be called in interrupt context unless | |
1060 | * oops_in_progress is set to 1.. | |
1061 | */ | |
1062 | if (oops_in_progress) { | |
1063 | if (down_trylock(&console_sem) != 0) | |
1064 | return; | |
1065 | } else | |
1066 | acquire_console_sem(); | |
1067 | ||
1068 | console_locked = 1; | |
1069 | console_may_schedule = 0; | |
1070 | for (c = console_drivers; c != NULL; c = c->next) | |
1071 | if ((c->flags & CON_ENABLED) && c->unblank) | |
1072 | c->unblank(); | |
1073 | release_console_sem(); | |
1074 | } | |
1075 | ||
1076 | /* | |
1077 | * Return the console tty driver structure and its associated index | |
1078 | */ | |
1079 | struct tty_driver *console_device(int *index) | |
1080 | { | |
1081 | struct console *c; | |
1082 | struct tty_driver *driver = NULL; | |
1083 | ||
1084 | acquire_console_sem(); | |
1085 | for (c = console_drivers; c != NULL; c = c->next) { | |
1086 | if (!c->device) | |
1087 | continue; | |
1088 | driver = c->device(c, index); | |
1089 | if (driver) | |
1090 | break; | |
1091 | } | |
1092 | release_console_sem(); | |
1093 | return driver; | |
1094 | } | |
1095 | ||
1096 | /* | |
1097 | * Prevent further output on the passed console device so that (for example) | |
1098 | * serial drivers can disable console output before suspending a port, and can | |
1099 | * re-enable output afterwards. | |
1100 | */ | |
1101 | void console_stop(struct console *console) | |
1102 | { | |
1103 | acquire_console_sem(); | |
1104 | console->flags &= ~CON_ENABLED; | |
1105 | release_console_sem(); | |
1106 | } | |
1107 | EXPORT_SYMBOL(console_stop); | |
1108 | ||
1109 | void console_start(struct console *console) | |
1110 | { | |
1111 | acquire_console_sem(); | |
1112 | console->flags |= CON_ENABLED; | |
1113 | release_console_sem(); | |
1114 | } | |
1115 | EXPORT_SYMBOL(console_start); | |
1116 | ||
1117 | /* | |
1118 | * The console driver calls this routine during kernel initialization | |
1119 | * to register the console printing procedure with printk() and to | |
1120 | * print any messages that were printed by the kernel before the | |
1121 | * console driver was initialized. | |
1122 | */ | |
1123 | void register_console(struct console *console) | |
1124 | { | |
1125 | int i; | |
1126 | unsigned long flags; | |
1127 | struct console *bootconsole = NULL; | |
1128 | ||
1129 | if (console_drivers) { | |
1130 | if (console->flags & CON_BOOT) | |
1131 | return; | |
1132 | if (console_drivers->flags & CON_BOOT) | |
1133 | bootconsole = console_drivers; | |
1134 | } | |
1135 | ||
1136 | if (preferred_console < 0 || bootconsole || !console_drivers) | |
1137 | preferred_console = selected_console; | |
1138 | ||
1139 | if (console->early_setup) | |
1140 | console->early_setup(); | |
1141 | ||
1142 | /* | |
1143 | * See if we want to use this console driver. If we | |
1144 | * didn't select a console we take the first one | |
1145 | * that registers here. | |
1146 | */ | |
1147 | if (preferred_console < 0) { | |
1148 | if (console->index < 0) | |
1149 | console->index = 0; | |
1150 | if (console->setup == NULL || | |
1151 | console->setup(console, NULL) == 0) { | |
1152 | console->flags |= CON_ENABLED; | |
1153 | if (console->device) { | |
1154 | console->flags |= CON_CONSDEV; | |
1155 | preferred_console = 0; | |
1156 | } | |
1157 | } | |
1158 | } | |
1159 | ||
1160 | /* | |
1161 | * See if this console matches one we selected on | |
1162 | * the command line. | |
1163 | */ | |
1164 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; | |
1165 | i++) { | |
1166 | if (strcmp(console_cmdline[i].name, console->name) != 0) | |
1167 | continue; | |
1168 | if (console->index >= 0 && | |
1169 | console->index != console_cmdline[i].index) | |
1170 | continue; | |
1171 | if (console->index < 0) | |
1172 | console->index = console_cmdline[i].index; | |
1173 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
1174 | if (console_cmdline[i].brl_options) { | |
1175 | console->flags |= CON_BRL; | |
1176 | braille_register_console(console, | |
1177 | console_cmdline[i].index, | |
1178 | console_cmdline[i].options, | |
1179 | console_cmdline[i].brl_options); | |
1180 | return; | |
1181 | } | |
1182 | #endif | |
1183 | if (console->setup && | |
1184 | console->setup(console, console_cmdline[i].options) != 0) | |
1185 | break; | |
1186 | console->flags |= CON_ENABLED; | |
1187 | console->index = console_cmdline[i].index; | |
1188 | if (i == selected_console) { | |
1189 | console->flags |= CON_CONSDEV; | |
1190 | preferred_console = selected_console; | |
1191 | } | |
1192 | break; | |
1193 | } | |
1194 | ||
1195 | if (!(console->flags & CON_ENABLED)) | |
1196 | return; | |
1197 | ||
1198 | if (bootconsole && (console->flags & CON_CONSDEV)) { | |
1199 | printk(KERN_INFO "console handover: boot [%s%d] -> real [%s%d]\n", | |
1200 | bootconsole->name, bootconsole->index, | |
1201 | console->name, console->index); | |
1202 | unregister_console(bootconsole); | |
1203 | console->flags &= ~CON_PRINTBUFFER; | |
1204 | } else { | |
1205 | printk(KERN_INFO "console [%s%d] enabled\n", | |
1206 | console->name, console->index); | |
1207 | } | |
1208 | ||
1209 | /* | |
1210 | * Put this console in the list - keep the | |
1211 | * preferred driver at the head of the list. | |
1212 | */ | |
1213 | acquire_console_sem(); | |
1214 | if ((console->flags & CON_CONSDEV) || console_drivers == NULL) { | |
1215 | console->next = console_drivers; | |
1216 | console_drivers = console; | |
1217 | if (console->next) | |
1218 | console->next->flags &= ~CON_CONSDEV; | |
1219 | } else { | |
1220 | console->next = console_drivers->next; | |
1221 | console_drivers->next = console; | |
1222 | } | |
1223 | if (console->flags & CON_PRINTBUFFER) { | |
1224 | /* | |
1225 | * release_console_sem() will print out the buffered messages | |
1226 | * for us. | |
1227 | */ | |
1228 | spin_lock_irqsave(&logbuf_lock, flags); | |
1229 | con_start = log_start; | |
1230 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1231 | } | |
1232 | release_console_sem(); | |
1233 | } | |
1234 | EXPORT_SYMBOL(register_console); | |
1235 | ||
1236 | int unregister_console(struct console *console) | |
1237 | { | |
1238 | struct console *a, *b; | |
1239 | int res = 1; | |
1240 | ||
1241 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
1242 | if (console->flags & CON_BRL) | |
1243 | return braille_unregister_console(console); | |
1244 | #endif | |
1245 | ||
1246 | acquire_console_sem(); | |
1247 | if (console_drivers == console) { | |
1248 | console_drivers=console->next; | |
1249 | res = 0; | |
1250 | } else if (console_drivers) { | |
1251 | for (a=console_drivers->next, b=console_drivers ; | |
1252 | a; b=a, a=b->next) { | |
1253 | if (a == console) { | |
1254 | b->next = a->next; | |
1255 | res = 0; | |
1256 | break; | |
1257 | } | |
1258 | } | |
1259 | } | |
1260 | ||
1261 | /* | |
1262 | * If this isn't the last console and it has CON_CONSDEV set, we | |
1263 | * need to set it on the next preferred console. | |
1264 | */ | |
1265 | if (console_drivers != NULL && console->flags & CON_CONSDEV) | |
1266 | console_drivers->flags |= CON_CONSDEV; | |
1267 | ||
1268 | release_console_sem(); | |
1269 | return res; | |
1270 | } | |
1271 | EXPORT_SYMBOL(unregister_console); | |
1272 | ||
1273 | static int __init disable_boot_consoles(void) | |
1274 | { | |
1275 | if (console_drivers != NULL) { | |
1276 | if (console_drivers->flags & CON_BOOT) { | |
1277 | printk(KERN_INFO "turn off boot console %s%d\n", | |
1278 | console_drivers->name, console_drivers->index); | |
1279 | return unregister_console(console_drivers); | |
1280 | } | |
1281 | } | |
1282 | return 0; | |
1283 | } | |
1284 | late_initcall(disable_boot_consoles); | |
1285 | ||
1286 | #if defined CONFIG_PRINTK | |
1287 | ||
1288 | /* | |
1289 | * printk rate limiting, lifted from the networking subsystem. | |
1290 | * | |
1291 | * This enforces a rate limit: not more than 10 kernel messages | |
1292 | * every 5s to make a denial-of-service attack impossible. | |
1293 | */ | |
1294 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); | |
1295 | ||
1296 | int printk_ratelimit(void) | |
1297 | { | |
1298 | return __ratelimit(&printk_ratelimit_state); | |
1299 | } | |
1300 | EXPORT_SYMBOL(printk_ratelimit); | |
1301 | ||
1302 | /** | |
1303 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1304 | * @caller_jiffies: pointer to caller's state | |
1305 | * @interval_msecs: minimum interval between prints | |
1306 | * | |
1307 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1308 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1309 | * returned true. | |
1310 | */ | |
1311 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1312 | unsigned int interval_msecs) | |
1313 | { | |
1314 | if (*caller_jiffies == 0 || time_after(jiffies, *caller_jiffies)) { | |
1315 | *caller_jiffies = jiffies + msecs_to_jiffies(interval_msecs); | |
1316 | return true; | |
1317 | } | |
1318 | return false; | |
1319 | } | |
1320 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
1321 | #endif |