Commit | Line | Data |
---|---|---|
1da177e4 LT |
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. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 LT |
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> | |
1da177e4 LT |
23 | #include <linux/console.h> |
24 | #include <linux/init.h> | |
bfe8df3d RD |
25 | #include <linux/jiffies.h> |
26 | #include <linux/nmi.h> | |
1da177e4 | 27 | #include <linux/module.h> |
3b9c0410 | 28 | #include <linux/moduleparam.h> |
1da177e4 | 29 | #include <linux/interrupt.h> /* For in_interrupt() */ |
1da177e4 LT |
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 | ||
076f9776 IM |
38 | /* |
39 | * Architectures can override it: | |
40 | */ | |
41 | void __attribute__((weak)) early_printk(const char *fmt, ...) | |
42 | { | |
43 | } | |
44 | ||
1da177e4 LT |
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 | ||
1da177e4 | 63 | /* |
0bbfb7c2 | 64 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
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); | |
557240b4 | 76 | static DECLARE_MUTEX(secondary_console_sem); |
1da177e4 | 77 | struct console *console_drivers; |
87c8a644 IM |
78 | EXPORT_SYMBOL_GPL(console_drivers); |
79 | ||
1da177e4 LT |
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 | */ | |
557240b4 | 88 | static int console_locked, console_suspended; |
1da177e4 LT |
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 | ||
eed4a2ab | 97 | #define LOG_BUF_MASK (log_buf_len-1) |
1da177e4 LT |
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 | */ | |
eed4a2ab DV |
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 */ | |
1da177e4 LT |
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 */ | |
f7511d5f ST |
116 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
117 | char *brl_options; /* Options for braille driver */ | |
118 | #endif | |
1da177e4 LT |
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 | ||
127 | /* Flag: console code may call schedule() */ | |
128 | static int console_may_schedule; | |
129 | ||
d59745ce MM |
130 | #ifdef CONFIG_PRINTK |
131 | ||
132 | static char __log_buf[__LOG_BUF_LEN]; | |
133 | static char *log_buf = __log_buf; | |
134 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 135 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
d59745ce | 136 | |
1da177e4 LT |
137 | static int __init log_buf_len_setup(char *str) |
138 | { | |
eed4a2ab | 139 | unsigned size = memparse(str, &str); |
1da177e4 LT |
140 | unsigned long flags; |
141 | ||
142 | if (size) | |
143 | size = roundup_pow_of_two(size); | |
144 | if (size > log_buf_len) { | |
eed4a2ab | 145 | unsigned start, dest_idx, offset; |
40dc5651 | 146 | char *new_log_buf; |
1da177e4 LT |
147 | |
148 | new_log_buf = alloc_bootmem(size); | |
149 | if (!new_log_buf) { | |
40dc5651 | 150 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
151 | goto out; |
152 | } | |
153 | ||
154 | spin_lock_irqsave(&logbuf_lock, flags); | |
155 | log_buf_len = size; | |
156 | log_buf = new_log_buf; | |
157 | ||
158 | offset = start = min(con_start, log_start); | |
159 | dest_idx = 0; | |
160 | while (start != log_end) { | |
161 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
162 | start++; | |
163 | dest_idx++; | |
164 | } | |
165 | log_start -= offset; | |
166 | con_start -= offset; | |
167 | log_end -= offset; | |
168 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
169 | ||
40dc5651 | 170 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
171 | } |
172 | out: | |
1da177e4 LT |
173 | return 1; |
174 | } | |
175 | ||
176 | __setup("log_buf_len=", log_buf_len_setup); | |
177 | ||
bfe8df3d RD |
178 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
179 | ||
180 | static unsigned int boot_delay; /* msecs delay after each printk during bootup */ | |
181 | static unsigned long long printk_delay_msec; /* per msec, based on boot_delay */ | |
182 | ||
183 | static int __init boot_delay_setup(char *str) | |
184 | { | |
185 | unsigned long lpj; | |
186 | unsigned long long loops_per_msec; | |
187 | ||
188 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
189 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
190 | ||
191 | get_option(&str, &boot_delay); | |
192 | if (boot_delay > 10 * 1000) | |
193 | boot_delay = 0; | |
194 | ||
195 | printk_delay_msec = loops_per_msec; | |
196 | printk(KERN_DEBUG "boot_delay: %u, preset_lpj: %ld, lpj: %lu, " | |
197 | "HZ: %d, printk_delay_msec: %llu\n", | |
198 | boot_delay, preset_lpj, lpj, HZ, printk_delay_msec); | |
199 | return 1; | |
200 | } | |
201 | __setup("boot_delay=", boot_delay_setup); | |
202 | ||
203 | static void boot_delay_msec(void) | |
204 | { | |
205 | unsigned long long k; | |
206 | unsigned long timeout; | |
207 | ||
208 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
209 | return; | |
210 | ||
211 | k = (unsigned long long)printk_delay_msec * boot_delay; | |
212 | ||
213 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
214 | while (k) { | |
215 | k--; | |
216 | cpu_relax(); | |
217 | /* | |
218 | * use (volatile) jiffies to prevent | |
219 | * compiler reduction; loop termination via jiffies | |
220 | * is secondary and may or may not happen. | |
221 | */ | |
222 | if (time_after(jiffies, timeout)) | |
223 | break; | |
224 | touch_nmi_watchdog(); | |
225 | } | |
226 | } | |
227 | #else | |
228 | static inline void boot_delay_msec(void) | |
229 | { | |
230 | } | |
231 | #endif | |
232 | ||
0b15d04a MF |
233 | /* |
234 | * Return the number of unread characters in the log buffer. | |
235 | */ | |
7f6f3a39 | 236 | static int log_buf_get_len(void) |
0b15d04a MF |
237 | { |
238 | return logged_chars; | |
239 | } | |
240 | ||
241 | /* | |
242 | * Copy a range of characters from the log buffer. | |
243 | */ | |
244 | int log_buf_copy(char *dest, int idx, int len) | |
245 | { | |
246 | int ret, max; | |
247 | bool took_lock = false; | |
248 | ||
249 | if (!oops_in_progress) { | |
250 | spin_lock_irq(&logbuf_lock); | |
251 | took_lock = true; | |
252 | } | |
253 | ||
254 | max = log_buf_get_len(); | |
255 | if (idx < 0 || idx >= max) { | |
256 | ret = -1; | |
257 | } else { | |
258 | if (len > max) | |
259 | len = max; | |
260 | ret = len; | |
261 | idx += (log_end - max); | |
262 | while (len-- > 0) | |
263 | dest[len] = LOG_BUF(idx + len); | |
264 | } | |
265 | ||
266 | if (took_lock) | |
267 | spin_unlock_irq(&logbuf_lock); | |
268 | ||
269 | return ret; | |
270 | } | |
271 | ||
1da177e4 LT |
272 | /* |
273 | * Commands to do_syslog: | |
274 | * | |
275 | * 0 -- Close the log. Currently a NOP. | |
276 | * 1 -- Open the log. Currently a NOP. | |
277 | * 2 -- Read from the log. | |
278 | * 3 -- Read all messages remaining in the ring buffer. | |
279 | * 4 -- Read and clear all messages remaining in the ring buffer | |
280 | * 5 -- Clear ring buffer. | |
281 | * 6 -- Disable printk's to console | |
282 | * 7 -- Enable printk's to console | |
283 | * 8 -- Set level of messages printed to console | |
284 | * 9 -- Return number of unread characters in the log buffer | |
285 | * 10 -- Return size of the log buffer | |
286 | */ | |
40dc5651 | 287 | int do_syslog(int type, char __user *buf, int len) |
1da177e4 | 288 | { |
eed4a2ab | 289 | unsigned i, j, limit, count; |
1da177e4 LT |
290 | int do_clear = 0; |
291 | char c; | |
292 | int error = 0; | |
293 | ||
294 | error = security_syslog(type); | |
295 | if (error) | |
296 | return error; | |
297 | ||
298 | switch (type) { | |
299 | case 0: /* Close log */ | |
300 | break; | |
301 | case 1: /* Open log */ | |
302 | break; | |
303 | case 2: /* Read from log */ | |
304 | error = -EINVAL; | |
305 | if (!buf || len < 0) | |
306 | goto out; | |
307 | error = 0; | |
308 | if (!len) | |
309 | goto out; | |
310 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
311 | error = -EFAULT; | |
312 | goto out; | |
313 | } | |
40dc5651 JJ |
314 | error = wait_event_interruptible(log_wait, |
315 | (log_start - log_end)); | |
1da177e4 LT |
316 | if (error) |
317 | goto out; | |
318 | i = 0; | |
319 | spin_lock_irq(&logbuf_lock); | |
320 | while (!error && (log_start != log_end) && i < len) { | |
321 | c = LOG_BUF(log_start); | |
322 | log_start++; | |
323 | spin_unlock_irq(&logbuf_lock); | |
324 | error = __put_user(c,buf); | |
325 | buf++; | |
326 | i++; | |
327 | cond_resched(); | |
328 | spin_lock_irq(&logbuf_lock); | |
329 | } | |
330 | spin_unlock_irq(&logbuf_lock); | |
331 | if (!error) | |
332 | error = i; | |
333 | break; | |
334 | case 4: /* Read/clear last kernel messages */ | |
40dc5651 | 335 | do_clear = 1; |
1da177e4 LT |
336 | /* FALL THRU */ |
337 | case 3: /* Read last kernel messages */ | |
338 | error = -EINVAL; | |
339 | if (!buf || len < 0) | |
340 | goto out; | |
341 | error = 0; | |
342 | if (!len) | |
343 | goto out; | |
344 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
345 | error = -EFAULT; | |
346 | goto out; | |
347 | } | |
348 | count = len; | |
349 | if (count > log_buf_len) | |
350 | count = log_buf_len; | |
351 | spin_lock_irq(&logbuf_lock); | |
352 | if (count > logged_chars) | |
353 | count = logged_chars; | |
354 | if (do_clear) | |
355 | logged_chars = 0; | |
356 | limit = log_end; | |
357 | /* | |
358 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 359 | * printk() could overwrite the messages |
1da177e4 LT |
360 | * we try to copy to user space. Therefore |
361 | * the messages are copied in reverse. <manfreds> | |
362 | */ | |
40dc5651 | 363 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
364 | j = limit-1-i; |
365 | if (j + log_buf_len < log_end) | |
366 | break; | |
367 | c = LOG_BUF(j); | |
368 | spin_unlock_irq(&logbuf_lock); | |
369 | error = __put_user(c,&buf[count-1-i]); | |
370 | cond_resched(); | |
371 | spin_lock_irq(&logbuf_lock); | |
372 | } | |
373 | spin_unlock_irq(&logbuf_lock); | |
374 | if (error) | |
375 | break; | |
376 | error = i; | |
40dc5651 | 377 | if (i != count) { |
1da177e4 LT |
378 | int offset = count-error; |
379 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 380 | for (i = 0; i < error; i++) { |
1da177e4 LT |
381 | if (__get_user(c,&buf[i+offset]) || |
382 | __put_user(c,&buf[i])) { | |
383 | error = -EFAULT; | |
384 | break; | |
385 | } | |
386 | cond_resched(); | |
387 | } | |
388 | } | |
389 | break; | |
390 | case 5: /* Clear ring buffer */ | |
391 | logged_chars = 0; | |
392 | break; | |
393 | case 6: /* Disable logging to console */ | |
394 | console_loglevel = minimum_console_loglevel; | |
395 | break; | |
396 | case 7: /* Enable logging to console */ | |
397 | console_loglevel = default_console_loglevel; | |
398 | break; | |
399 | case 8: /* Set level of messages printed to console */ | |
400 | error = -EINVAL; | |
401 | if (len < 1 || len > 8) | |
402 | goto out; | |
403 | if (len < minimum_console_loglevel) | |
404 | len = minimum_console_loglevel; | |
405 | console_loglevel = len; | |
406 | error = 0; | |
407 | break; | |
408 | case 9: /* Number of chars in the log buffer */ | |
409 | error = log_end - log_start; | |
410 | break; | |
411 | case 10: /* Size of the log buffer */ | |
412 | error = log_buf_len; | |
413 | break; | |
414 | default: | |
415 | error = -EINVAL; | |
416 | break; | |
417 | } | |
418 | out: | |
419 | return error; | |
420 | } | |
421 | ||
40dc5651 | 422 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
1da177e4 LT |
423 | { |
424 | return do_syslog(type, buf, len); | |
425 | } | |
426 | ||
427 | /* | |
428 | * Call the console drivers on a range of log_buf | |
429 | */ | |
eed4a2ab | 430 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
431 | { |
432 | struct console *con; | |
433 | ||
434 | for (con = console_drivers; con; con = con->next) { | |
76a8ad29 ME |
435 | if ((con->flags & CON_ENABLED) && con->write && |
436 | (cpu_online(smp_processor_id()) || | |
437 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
438 | con->write(con, &LOG_BUF(start), end - start); |
439 | } | |
440 | } | |
441 | ||
79290822 IM |
442 | static int __read_mostly ignore_loglevel; |
443 | ||
99eea6a1 | 444 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
445 | { |
446 | ignore_loglevel = 1; | |
447 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
448 | ||
c4772d99 | 449 | return 0; |
79290822 IM |
450 | } |
451 | ||
c4772d99 | 452 | early_param("ignore_loglevel", ignore_loglevel_setup); |
79290822 | 453 | |
1da177e4 LT |
454 | /* |
455 | * Write out chars from start to end - 1 inclusive | |
456 | */ | |
eed4a2ab DV |
457 | static void _call_console_drivers(unsigned start, |
458 | unsigned end, int msg_log_level) | |
1da177e4 | 459 | { |
79290822 | 460 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
461 | console_drivers && start != end) { |
462 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
463 | /* wrapped write */ | |
464 | __call_console_drivers(start & LOG_BUF_MASK, | |
465 | log_buf_len); | |
466 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
467 | } else { | |
468 | __call_console_drivers(start, end); | |
469 | } | |
470 | } | |
471 | } | |
472 | ||
473 | /* | |
474 | * Call the console drivers, asking them to write out | |
475 | * log_buf[start] to log_buf[end - 1]. | |
476 | * The console_sem must be held. | |
477 | */ | |
eed4a2ab | 478 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 479 | { |
eed4a2ab | 480 | unsigned cur_index, start_print; |
1da177e4 LT |
481 | static int msg_level = -1; |
482 | ||
eed4a2ab | 483 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
484 | |
485 | cur_index = start; | |
486 | start_print = start; | |
487 | while (cur_index != end) { | |
40dc5651 JJ |
488 | if (msg_level < 0 && ((end - cur_index) > 2) && |
489 | LOG_BUF(cur_index + 0) == '<' && | |
490 | LOG_BUF(cur_index + 1) >= '0' && | |
491 | LOG_BUF(cur_index + 1) <= '7' && | |
492 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
493 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
494 | cur_index += 3; | |
495 | start_print = cur_index; | |
496 | } | |
497 | while (cur_index != end) { | |
498 | char c = LOG_BUF(cur_index); | |
1da177e4 | 499 | |
40dc5651 | 500 | cur_index++; |
1da177e4 LT |
501 | if (c == '\n') { |
502 | if (msg_level < 0) { | |
503 | /* | |
504 | * printk() has already given us loglevel tags in | |
505 | * the buffer. This code is here in case the | |
506 | * log buffer has wrapped right round and scribbled | |
507 | * on those tags | |
508 | */ | |
509 | msg_level = default_message_loglevel; | |
510 | } | |
511 | _call_console_drivers(start_print, cur_index, msg_level); | |
512 | msg_level = -1; | |
513 | start_print = cur_index; | |
514 | break; | |
515 | } | |
516 | } | |
517 | } | |
518 | _call_console_drivers(start_print, end, msg_level); | |
519 | } | |
520 | ||
521 | static void emit_log_char(char c) | |
522 | { | |
523 | LOG_BUF(log_end) = c; | |
524 | log_end++; | |
525 | if (log_end - log_start > log_buf_len) | |
526 | log_start = log_end - log_buf_len; | |
527 | if (log_end - con_start > log_buf_len) | |
528 | con_start = log_end - log_buf_len; | |
529 | if (logged_chars < log_buf_len) | |
530 | logged_chars++; | |
531 | } | |
532 | ||
533 | /* | |
534 | * Zap console related locks when oopsing. Only zap at most once | |
535 | * every 10 seconds, to leave time for slow consoles to print a | |
536 | * full oops. | |
537 | */ | |
538 | static void zap_locks(void) | |
539 | { | |
540 | static unsigned long oops_timestamp; | |
541 | ||
542 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 543 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
544 | return; |
545 | ||
546 | oops_timestamp = jiffies; | |
547 | ||
548 | /* If a crash is occurring, make sure we can't deadlock */ | |
549 | spin_lock_init(&logbuf_lock); | |
550 | /* And make sure that we print immediately */ | |
551 | init_MUTEX(&console_sem); | |
552 | } | |
553 | ||
554 | #if defined(CONFIG_PRINTK_TIME) | |
555 | static int printk_time = 1; | |
556 | #else | |
557 | static int printk_time = 0; | |
558 | #endif | |
e84845c4 | 559 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 560 | |
76a8ad29 ME |
561 | /* Check if we have any console registered that can be called early in boot. */ |
562 | static int have_callable_console(void) | |
563 | { | |
564 | struct console *con; | |
565 | ||
566 | for (con = console_drivers; con; con = con->next) | |
567 | if (con->flags & CON_ANYTIME) | |
568 | return 1; | |
569 | ||
570 | return 0; | |
571 | } | |
572 | ||
ddad86c2 MW |
573 | /** |
574 | * printk - print a kernel message | |
575 | * @fmt: format string | |
576 | * | |
72fd4a35 | 577 | * This is printk(). It can be called from any context. We want it to work. |
1492192b JK |
578 | * Be aware of the fact that if oops_in_progress is not set, we might try to |
579 | * wake klogd up which could deadlock on runqueue lock if printk() is called | |
580 | * from scheduler code. | |
40dc5651 | 581 | * |
1da177e4 LT |
582 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
583 | * call the console drivers. If we fail to get the semaphore we place the output | |
584 | * into the log buffer and return. The current holder of the console_sem will | |
585 | * notice the new output in release_console_sem() and will send it to the | |
586 | * consoles before releasing the semaphore. | |
587 | * | |
588 | * One effect of this deferred printing is that code which calls printk() and | |
589 | * then changes console_loglevel may break. This is because console_loglevel | |
590 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
591 | * |
592 | * See also: | |
593 | * printf(3) | |
1da177e4 | 594 | */ |
d59745ce | 595 | |
1da177e4 LT |
596 | asmlinkage int printk(const char *fmt, ...) |
597 | { | |
598 | va_list args; | |
599 | int r; | |
600 | ||
601 | va_start(args, fmt); | |
602 | r = vprintk(fmt, args); | |
603 | va_end(args); | |
604 | ||
605 | return r; | |
606 | } | |
607 | ||
fe21773d DH |
608 | /* cpu currently holding logbuf_lock */ |
609 | static volatile unsigned int printk_cpu = UINT_MAX; | |
610 | ||
266c2e0a LT |
611 | /* |
612 | * Can we actually use the console at this time on this cpu? | |
613 | * | |
614 | * Console drivers may assume that per-cpu resources have | |
615 | * been allocated. So unless they're explicitly marked as | |
616 | * being able to cope (CON_ANYTIME) don't call them until | |
617 | * this CPU is officially up. | |
618 | */ | |
619 | static inline int can_use_console(unsigned int cpu) | |
620 | { | |
621 | return cpu_online(cpu) || have_callable_console(); | |
622 | } | |
623 | ||
624 | /* | |
625 | * Try to get console ownership to actually show the kernel | |
626 | * messages from a 'printk'. Return true (and with the | |
627 | * console_semaphore held, and 'console_locked' set) if it | |
628 | * is successful, false otherwise. | |
629 | * | |
630 | * This gets called with the 'logbuf_lock' spinlock held and | |
631 | * interrupts disabled. It should return with 'lockbuf_lock' | |
632 | * released but interrupts still disabled. | |
633 | */ | |
634 | static int acquire_console_semaphore_for_printk(unsigned int cpu) | |
635 | { | |
636 | int retval = 0; | |
637 | ||
093a07e2 LT |
638 | if (!try_acquire_console_sem()) { |
639 | retval = 1; | |
640 | ||
641 | /* | |
642 | * If we can't use the console, we need to release | |
643 | * the console semaphore by hand to avoid flushing | |
644 | * the buffer. We need to hold the console semaphore | |
645 | * in order to do this test safely. | |
646 | */ | |
647 | if (!can_use_console(cpu)) { | |
648 | console_locked = 0; | |
649 | up(&console_sem); | |
650 | retval = 0; | |
651 | } | |
652 | } | |
266c2e0a LT |
653 | printk_cpu = UINT_MAX; |
654 | spin_unlock(&logbuf_lock); | |
655 | return retval; | |
656 | } | |
3b8945e8 TH |
657 | static const char recursion_bug_msg [] = |
658 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
659 | static int recursion_bug; | |
ac60ad74 | 660 | static int new_text_line = 1; |
3b8945e8 | 661 | static char printk_buf[1024]; |
32a76006 | 662 | |
1da177e4 LT |
663 | asmlinkage int vprintk(const char *fmt, va_list args) |
664 | { | |
32a76006 | 665 | int printed_len = 0; |
09159308 | 666 | int current_log_level = default_message_loglevel; |
ac60ad74 | 667 | unsigned long flags; |
32a76006 | 668 | int this_cpu; |
1da177e4 | 669 | char *p; |
1da177e4 | 670 | |
bfe8df3d RD |
671 | boot_delay_msec(); |
672 | ||
fe21773d | 673 | preempt_disable(); |
1da177e4 | 674 | /* This stops the holder of console_sem just where we want him */ |
1efc5da3 | 675 | raw_local_irq_save(flags); |
32a76006 IM |
676 | this_cpu = smp_processor_id(); |
677 | ||
678 | /* | |
679 | * Ouch, printk recursed into itself! | |
680 | */ | |
681 | if (unlikely(printk_cpu == this_cpu)) { | |
682 | /* | |
683 | * If a crash is occurring during printk() on this CPU, | |
684 | * then try to get the crash message out but make sure | |
685 | * we can't deadlock. Otherwise just return to avoid the | |
686 | * recursion and return - but flag the recursion so that | |
687 | * it can be printed at the next appropriate moment: | |
688 | */ | |
689 | if (!oops_in_progress) { | |
3b8945e8 | 690 | recursion_bug = 1; |
32a76006 IM |
691 | goto out_restore_irqs; |
692 | } | |
693 | zap_locks(); | |
694 | } | |
695 | ||
a0f1ccfd IM |
696 | lockdep_off(); |
697 | spin_lock(&logbuf_lock); | |
32a76006 | 698 | printk_cpu = this_cpu; |
1da177e4 | 699 | |
3b8945e8 TH |
700 | if (recursion_bug) { |
701 | recursion_bug = 0; | |
702 | strcpy(printk_buf, recursion_bug_msg); | |
703 | printed_len = sizeof(recursion_bug_msg); | |
32a76006 | 704 | } |
1da177e4 | 705 | /* Emit the output into the temporary buffer */ |
32a76006 | 706 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 707 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 708 | |
ac60ad74 | 709 | |
1da177e4 LT |
710 | /* |
711 | * Copy the output into log_buf. If the caller didn't provide | |
712 | * appropriate log level tags, we insert them here | |
713 | */ | |
714 | for (p = printk_buf; *p; p++) { | |
ac60ad74 | 715 | if (new_text_line) { |
ac60ad74 NA |
716 | /* If a token, set current_log_level and skip over */ |
717 | if (p[0] == '<' && p[1] >= '0' && p[1] <= '7' && | |
718 | p[2] == '>') { | |
719 | current_log_level = p[1] - '0'; | |
720 | p += 3; | |
721 | printed_len -= 3; | |
722 | } | |
723 | ||
724 | /* Always output the token */ | |
725 | emit_log_char('<'); | |
726 | emit_log_char(current_log_level + '0'); | |
727 | emit_log_char('>'); | |
728 | printed_len += 3; | |
729 | new_text_line = 0; | |
730 | ||
1da177e4 | 731 | if (printk_time) { |
ac60ad74 | 732 | /* Follow the token with the time */ |
1da177e4 LT |
733 | char tbuf[50], *tp; |
734 | unsigned tlen; | |
735 | unsigned long long t; | |
736 | unsigned long nanosec_rem; | |
737 | ||
326e96b9 | 738 | t = cpu_clock(printk_cpu); |
1da177e4 | 739 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
740 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
741 | (unsigned long) t, | |
742 | nanosec_rem / 1000); | |
1da177e4 LT |
743 | |
744 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
745 | emit_log_char(*tp); | |
025510cd | 746 | printed_len += tlen; |
1da177e4 | 747 | } |
ac60ad74 | 748 | |
1da177e4 LT |
749 | if (!*p) |
750 | break; | |
751 | } | |
ac60ad74 | 752 | |
1da177e4 LT |
753 | emit_log_char(*p); |
754 | if (*p == '\n') | |
ac60ad74 | 755 | new_text_line = 1; |
1da177e4 LT |
756 | } |
757 | ||
266c2e0a LT |
758 | /* |
759 | * Try to acquire and then immediately release the | |
760 | * console semaphore. The release will do all the | |
761 | * actual magic (print out buffers, wake up klogd, | |
762 | * etc). | |
763 | * | |
764 | * The acquire_console_semaphore_for_printk() function | |
765 | * will release 'logbuf_lock' regardless of whether it | |
766 | * actually gets the semaphore or not. | |
767 | */ | |
768 | if (acquire_console_semaphore_for_printk(this_cpu)) | |
769 | release_console_sem(); | |
76a8ad29 | 770 | |
266c2e0a | 771 | lockdep_on(); |
32a76006 | 772 | out_restore_irqs: |
266c2e0a | 773 | raw_local_irq_restore(flags); |
76a8ad29 | 774 | |
fe21773d | 775 | preempt_enable(); |
1da177e4 LT |
776 | return printed_len; |
777 | } | |
778 | EXPORT_SYMBOL(printk); | |
779 | EXPORT_SYMBOL(vprintk); | |
780 | ||
d59745ce MM |
781 | #else |
782 | ||
40dc5651 | 783 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
d59745ce | 784 | { |
c36264df | 785 | return -ENOSYS; |
40dc5651 JJ |
786 | } |
787 | ||
eed4a2ab | 788 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
789 | { |
790 | } | |
d59745ce MM |
791 | |
792 | #endif | |
793 | ||
f7511d5f ST |
794 | static int __add_preferred_console(char *name, int idx, char *options, |
795 | char *brl_options) | |
796 | { | |
797 | struct console_cmdline *c; | |
798 | int i; | |
799 | ||
800 | /* | |
801 | * See if this tty is not yet registered, and | |
802 | * if we have a slot free. | |
803 | */ | |
804 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
805 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
806 | console_cmdline[i].index == idx) { | |
807 | if (!brl_options) | |
808 | selected_console = i; | |
809 | return 0; | |
810 | } | |
811 | if (i == MAX_CMDLINECONSOLES) | |
812 | return -E2BIG; | |
813 | if (!brl_options) | |
814 | selected_console = i; | |
815 | c = &console_cmdline[i]; | |
816 | strlcpy(c->name, name, sizeof(c->name)); | |
817 | c->options = options; | |
818 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
819 | c->brl_options = brl_options; | |
820 | #endif | |
821 | c->index = idx; | |
822 | return 0; | |
823 | } | |
2ea1c539 JB |
824 | /* |
825 | * Set up a list of consoles. Called from init/main.c | |
826 | */ | |
827 | static int __init console_setup(char *str) | |
828 | { | |
eaa944af | 829 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 830 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
831 | int idx; |
832 | ||
f7511d5f ST |
833 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
834 | if (!memcmp(str, "brl,", 4)) { | |
835 | brl_options = ""; | |
836 | str += 4; | |
837 | } else if (!memcmp(str, "brl=", 4)) { | |
838 | brl_options = str + 4; | |
839 | str = strchr(brl_options, ','); | |
840 | if (!str) { | |
841 | printk(KERN_ERR "need port name after brl=\n"); | |
842 | return 1; | |
843 | } | |
844 | *(str++) = 0; | |
845 | } | |
846 | #endif | |
847 | ||
2ea1c539 JB |
848 | /* |
849 | * Decode str into name, index, options. | |
850 | */ | |
851 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
852 | strcpy(buf, "ttyS"); |
853 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 854 | } else { |
eaa944af | 855 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 856 | } |
eaa944af | 857 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
858 | if ((options = strchr(str, ',')) != NULL) |
859 | *(options++) = 0; | |
860 | #ifdef __sparc__ | |
861 | if (!strcmp(str, "ttya")) | |
eaa944af | 862 | strcpy(buf, "ttyS0"); |
2ea1c539 | 863 | if (!strcmp(str, "ttyb")) |
eaa944af | 864 | strcpy(buf, "ttyS1"); |
2ea1c539 | 865 | #endif |
eaa944af | 866 | for (s = buf; *s; s++) |
2ea1c539 JB |
867 | if ((*s >= '0' && *s <= '9') || *s == ',') |
868 | break; | |
869 | idx = simple_strtoul(s, NULL, 10); | |
870 | *s = 0; | |
871 | ||
f7511d5f | 872 | __add_preferred_console(buf, idx, options, brl_options); |
2ea1c539 JB |
873 | return 1; |
874 | } | |
875 | __setup("console=", console_setup); | |
876 | ||
3c0547ba MM |
877 | /** |
878 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
879 | * @name: device name |
880 | * @idx: device index | |
881 | * @options: options for this console | |
3c0547ba MM |
882 | * |
883 | * The last preferred console added will be used for kernel messages | |
884 | * and stdin/out/err for init. Normally this is used by console_setup | |
885 | * above to handle user-supplied console arguments; however it can also | |
886 | * be used by arch-specific code either to override the user or more | |
887 | * commonly to provide a default console (ie from PROM variables) when | |
888 | * the user has not supplied one. | |
889 | */ | |
fb445ee5 | 890 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 891 | { |
f7511d5f | 892 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
893 | } |
894 | ||
b6b1d877 | 895 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
896 | { |
897 | struct console_cmdline *c; | |
898 | int i; | |
899 | ||
900 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
901 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
902 | console_cmdline[i].index == idx) { | |
903 | c = &console_cmdline[i]; | |
f735295b | 904 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
905 | c->name[sizeof(c->name) - 1] = 0; |
906 | c->options = options; | |
907 | c->index = idx_new; | |
908 | return i; | |
909 | } | |
910 | /* not found */ | |
911 | return -1; | |
912 | } | |
913 | ||
8f4ce8c3 AS |
914 | int console_suspend_enabled = 1; |
915 | EXPORT_SYMBOL(console_suspend_enabled); | |
916 | ||
917 | static int __init console_suspend_disable(char *str) | |
918 | { | |
919 | console_suspend_enabled = 0; | |
920 | return 1; | |
921 | } | |
922 | __setup("no_console_suspend", console_suspend_disable); | |
923 | ||
557240b4 LT |
924 | /** |
925 | * suspend_console - suspend the console subsystem | |
926 | * | |
927 | * This disables printk() while we go into suspend states | |
928 | */ | |
929 | void suspend_console(void) | |
930 | { | |
8f4ce8c3 AS |
931 | if (!console_suspend_enabled) |
932 | return; | |
c8eb8b40 | 933 | printk("Suspending console(s)\n"); |
557240b4 LT |
934 | acquire_console_sem(); |
935 | console_suspended = 1; | |
936 | } | |
937 | ||
938 | void resume_console(void) | |
939 | { | |
8f4ce8c3 AS |
940 | if (!console_suspend_enabled) |
941 | return; | |
557240b4 LT |
942 | console_suspended = 0; |
943 | release_console_sem(); | |
944 | } | |
945 | ||
1da177e4 LT |
946 | /** |
947 | * acquire_console_sem - lock the console system for exclusive use. | |
948 | * | |
949 | * Acquires a semaphore which guarantees that the caller has | |
950 | * exclusive access to the console system and the console_drivers list. | |
951 | * | |
952 | * Can sleep, returns nothing. | |
953 | */ | |
954 | void acquire_console_sem(void) | |
955 | { | |
8abd8e29 | 956 | BUG_ON(in_interrupt()); |
557240b4 LT |
957 | if (console_suspended) { |
958 | down(&secondary_console_sem); | |
959 | return; | |
960 | } | |
1da177e4 LT |
961 | down(&console_sem); |
962 | console_locked = 1; | |
963 | console_may_schedule = 1; | |
964 | } | |
965 | EXPORT_SYMBOL(acquire_console_sem); | |
966 | ||
967 | int try_acquire_console_sem(void) | |
968 | { | |
969 | if (down_trylock(&console_sem)) | |
970 | return -1; | |
971 | console_locked = 1; | |
972 | console_may_schedule = 0; | |
973 | return 0; | |
974 | } | |
975 | EXPORT_SYMBOL(try_acquire_console_sem); | |
976 | ||
977 | int is_console_locked(void) | |
978 | { | |
979 | return console_locked; | |
980 | } | |
1da177e4 | 981 | |
e3e8a75d KK |
982 | void wake_up_klogd(void) |
983 | { | |
984 | if (!oops_in_progress && waitqueue_active(&log_wait)) | |
985 | wake_up_interruptible(&log_wait); | |
986 | } | |
987 | ||
1da177e4 LT |
988 | /** |
989 | * release_console_sem - unlock the console system | |
990 | * | |
991 | * Releases the semaphore which the caller holds on the console system | |
992 | * and the console driver list. | |
993 | * | |
994 | * While the semaphore was held, console output may have been buffered | |
995 | * by printk(). If this is the case, release_console_sem() emits | |
996 | * the output prior to releasing the semaphore. | |
997 | * | |
998 | * If there is output waiting for klogd, we wake it up. | |
999 | * | |
1000 | * release_console_sem() may be called from any context. | |
1001 | */ | |
1002 | void release_console_sem(void) | |
1003 | { | |
1004 | unsigned long flags; | |
eed4a2ab DV |
1005 | unsigned _con_start, _log_end; |
1006 | unsigned wake_klogd = 0; | |
1da177e4 | 1007 | |
557240b4 LT |
1008 | if (console_suspended) { |
1009 | up(&secondary_console_sem); | |
1010 | return; | |
1011 | } | |
78944e54 AD |
1012 | |
1013 | console_may_schedule = 0; | |
1014 | ||
1da177e4 LT |
1015 | for ( ; ; ) { |
1016 | spin_lock_irqsave(&logbuf_lock, flags); | |
1017 | wake_klogd |= log_start - log_end; | |
1018 | if (con_start == log_end) | |
1019 | break; /* Nothing to print */ | |
1020 | _con_start = con_start; | |
1021 | _log_end = log_end; | |
1022 | con_start = log_end; /* Flush */ | |
1023 | spin_unlock(&logbuf_lock); | |
1024 | call_console_drivers(_con_start, _log_end); | |
1025 | local_irq_restore(flags); | |
1026 | } | |
1027 | console_locked = 0; | |
1da177e4 LT |
1028 | up(&console_sem); |
1029 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
1030 | if (wake_klogd) |
1031 | wake_up_klogd(); | |
1da177e4 LT |
1032 | } |
1033 | EXPORT_SYMBOL(release_console_sem); | |
1034 | ||
ddad86c2 MW |
1035 | /** |
1036 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1037 | * |
1038 | * If the console code is currently allowed to sleep, and | |
1039 | * if this CPU should yield the CPU to another task, do | |
1040 | * so here. | |
1041 | * | |
1042 | * Must be called within acquire_console_sem(). | |
1043 | */ | |
1044 | void __sched console_conditional_schedule(void) | |
1045 | { | |
1046 | if (console_may_schedule) | |
1047 | cond_resched(); | |
1048 | } | |
1049 | EXPORT_SYMBOL(console_conditional_schedule); | |
1050 | ||
1051 | void console_print(const char *s) | |
1052 | { | |
1053 | printk(KERN_EMERG "%s", s); | |
1054 | } | |
1055 | EXPORT_SYMBOL(console_print); | |
1056 | ||
1057 | void console_unblank(void) | |
1058 | { | |
1059 | struct console *c; | |
1060 | ||
1061 | /* | |
1062 | * console_unblank can no longer be called in interrupt context unless | |
1063 | * oops_in_progress is set to 1.. | |
1064 | */ | |
1065 | if (oops_in_progress) { | |
1066 | if (down_trylock(&console_sem) != 0) | |
1067 | return; | |
1068 | } else | |
1069 | acquire_console_sem(); | |
1070 | ||
1071 | console_locked = 1; | |
1072 | console_may_schedule = 0; | |
1073 | for (c = console_drivers; c != NULL; c = c->next) | |
1074 | if ((c->flags & CON_ENABLED) && c->unblank) | |
1075 | c->unblank(); | |
1076 | release_console_sem(); | |
1077 | } | |
1da177e4 LT |
1078 | |
1079 | /* | |
1080 | * Return the console tty driver structure and its associated index | |
1081 | */ | |
1082 | struct tty_driver *console_device(int *index) | |
1083 | { | |
1084 | struct console *c; | |
1085 | struct tty_driver *driver = NULL; | |
1086 | ||
1087 | acquire_console_sem(); | |
1088 | for (c = console_drivers; c != NULL; c = c->next) { | |
1089 | if (!c->device) | |
1090 | continue; | |
1091 | driver = c->device(c, index); | |
1092 | if (driver) | |
1093 | break; | |
1094 | } | |
1095 | release_console_sem(); | |
1096 | return driver; | |
1097 | } | |
1098 | ||
1099 | /* | |
1100 | * Prevent further output on the passed console device so that (for example) | |
1101 | * serial drivers can disable console output before suspending a port, and can | |
1102 | * re-enable output afterwards. | |
1103 | */ | |
1104 | void console_stop(struct console *console) | |
1105 | { | |
1106 | acquire_console_sem(); | |
1107 | console->flags &= ~CON_ENABLED; | |
1108 | release_console_sem(); | |
1109 | } | |
1110 | EXPORT_SYMBOL(console_stop); | |
1111 | ||
1112 | void console_start(struct console *console) | |
1113 | { | |
1114 | acquire_console_sem(); | |
1115 | console->flags |= CON_ENABLED; | |
1116 | release_console_sem(); | |
1117 | } | |
1118 | EXPORT_SYMBOL(console_start); | |
1119 | ||
1120 | /* | |
1121 | * The console driver calls this routine during kernel initialization | |
1122 | * to register the console printing procedure with printk() and to | |
1123 | * print any messages that were printed by the kernel before the | |
1124 | * console driver was initialized. | |
1125 | */ | |
40dc5651 | 1126 | void register_console(struct console *console) |
1da177e4 | 1127 | { |
40dc5651 | 1128 | int i; |
1da177e4 | 1129 | unsigned long flags; |
69331af7 | 1130 | struct console *bootconsole = NULL; |
1da177e4 | 1131 | |
69331af7 GH |
1132 | if (console_drivers) { |
1133 | if (console->flags & CON_BOOT) | |
1134 | return; | |
1135 | if (console_drivers->flags & CON_BOOT) | |
1136 | bootconsole = console_drivers; | |
1137 | } | |
1138 | ||
1139 | if (preferred_console < 0 || bootconsole || !console_drivers) | |
1da177e4 LT |
1140 | preferred_console = selected_console; |
1141 | ||
18a8bd94 YL |
1142 | if (console->early_setup) |
1143 | console->early_setup(); | |
1144 | ||
1da177e4 LT |
1145 | /* |
1146 | * See if we want to use this console driver. If we | |
1147 | * didn't select a console we take the first one | |
1148 | * that registers here. | |
1149 | */ | |
1150 | if (preferred_console < 0) { | |
1151 | if (console->index < 0) | |
1152 | console->index = 0; | |
1153 | if (console->setup == NULL || | |
1154 | console->setup(console, NULL) == 0) { | |
cd3a1b85 JK |
1155 | console->flags |= CON_ENABLED; |
1156 | if (console->device) { | |
1157 | console->flags |= CON_CONSDEV; | |
1158 | preferred_console = 0; | |
1159 | } | |
1da177e4 LT |
1160 | } |
1161 | } | |
1162 | ||
1163 | /* | |
1164 | * See if this console matches one we selected on | |
1165 | * the command line. | |
1166 | */ | |
40dc5651 JJ |
1167 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1168 | i++) { | |
1da177e4 LT |
1169 | if (strcmp(console_cmdline[i].name, console->name) != 0) |
1170 | continue; | |
1171 | if (console->index >= 0 && | |
1172 | console->index != console_cmdline[i].index) | |
1173 | continue; | |
1174 | if (console->index < 0) | |
1175 | console->index = console_cmdline[i].index; | |
f7511d5f ST |
1176 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1177 | if (console_cmdline[i].brl_options) { | |
1178 | console->flags |= CON_BRL; | |
1179 | braille_register_console(console, | |
1180 | console_cmdline[i].index, | |
1181 | console_cmdline[i].options, | |
1182 | console_cmdline[i].brl_options); | |
1183 | return; | |
1184 | } | |
1185 | #endif | |
1da177e4 LT |
1186 | if (console->setup && |
1187 | console->setup(console, console_cmdline[i].options) != 0) | |
1188 | break; | |
1189 | console->flags |= CON_ENABLED; | |
1190 | console->index = console_cmdline[i].index; | |
ab4af03a | 1191 | if (i == selected_console) { |
1da177e4 | 1192 | console->flags |= CON_CONSDEV; |
ab4af03a GE |
1193 | preferred_console = selected_console; |
1194 | } | |
1da177e4 LT |
1195 | break; |
1196 | } | |
1197 | ||
1198 | if (!(console->flags & CON_ENABLED)) | |
1199 | return; | |
1200 | ||
d37bf60d | 1201 | if (bootconsole && (console->flags & CON_CONSDEV)) { |
69331af7 GH |
1202 | printk(KERN_INFO "console handover: boot [%s%d] -> real [%s%d]\n", |
1203 | bootconsole->name, bootconsole->index, | |
1204 | console->name, console->index); | |
1205 | unregister_console(bootconsole); | |
1da177e4 | 1206 | console->flags &= ~CON_PRINTBUFFER; |
d37bf60d YL |
1207 | } else { |
1208 | printk(KERN_INFO "console [%s%d] enabled\n", | |
1209 | console->name, console->index); | |
1da177e4 LT |
1210 | } |
1211 | ||
1212 | /* | |
1213 | * Put this console in the list - keep the | |
1214 | * preferred driver at the head of the list. | |
1215 | */ | |
1216 | acquire_console_sem(); | |
1217 | if ((console->flags & CON_CONSDEV) || console_drivers == NULL) { | |
1218 | console->next = console_drivers; | |
1219 | console_drivers = console; | |
ab4af03a GE |
1220 | if (console->next) |
1221 | console->next->flags &= ~CON_CONSDEV; | |
1da177e4 LT |
1222 | } else { |
1223 | console->next = console_drivers->next; | |
1224 | console_drivers->next = console; | |
1225 | } | |
1226 | if (console->flags & CON_PRINTBUFFER) { | |
1227 | /* | |
1228 | * release_console_sem() will print out the buffered messages | |
1229 | * for us. | |
1230 | */ | |
1231 | spin_lock_irqsave(&logbuf_lock, flags); | |
1232 | con_start = log_start; | |
1233 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1234 | } | |
1235 | release_console_sem(); | |
1236 | } | |
1237 | EXPORT_SYMBOL(register_console); | |
1238 | ||
40dc5651 | 1239 | int unregister_console(struct console *console) |
1da177e4 | 1240 | { |
40dc5651 | 1241 | struct console *a, *b; |
1da177e4 LT |
1242 | int res = 1; |
1243 | ||
f7511d5f ST |
1244 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1245 | if (console->flags & CON_BRL) | |
1246 | return braille_unregister_console(console); | |
1247 | #endif | |
1248 | ||
1da177e4 LT |
1249 | acquire_console_sem(); |
1250 | if (console_drivers == console) { | |
1251 | console_drivers=console->next; | |
1252 | res = 0; | |
e9b15b54 | 1253 | } else if (console_drivers) { |
1da177e4 LT |
1254 | for (a=console_drivers->next, b=console_drivers ; |
1255 | a; b=a, a=b->next) { | |
1256 | if (a == console) { | |
1257 | b->next = a->next; | |
1258 | res = 0; | |
1259 | break; | |
40dc5651 | 1260 | } |
1da177e4 LT |
1261 | } |
1262 | } | |
40dc5651 | 1263 | |
69331af7 | 1264 | /* |
ab4af03a GE |
1265 | * If this isn't the last console and it has CON_CONSDEV set, we |
1266 | * need to set it on the next preferred console. | |
1da177e4 | 1267 | */ |
69331af7 | 1268 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1269 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 LT |
1270 | |
1271 | release_console_sem(); | |
1272 | return res; | |
1273 | } | |
1274 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1275 | |
0c5564bd RG |
1276 | static int __init disable_boot_consoles(void) |
1277 | { | |
cb00e99c RG |
1278 | if (console_drivers != NULL) { |
1279 | if (console_drivers->flags & CON_BOOT) { | |
1280 | printk(KERN_INFO "turn off boot console %s%d\n", | |
1281 | console_drivers->name, console_drivers->index); | |
1282 | return unregister_console(console_drivers); | |
1283 | } | |
0c5564bd RG |
1284 | } |
1285 | return 0; | |
1286 | } | |
1287 | late_initcall(disable_boot_consoles); | |
1288 | ||
1da177e4 LT |
1289 | /** |
1290 | * tty_write_message - write a message to a certain tty, not just the console. | |
ddad86c2 MW |
1291 | * @tty: the destination tty_struct |
1292 | * @msg: the message to write | |
1da177e4 LT |
1293 | * |
1294 | * This is used for messages that need to be redirected to a specific tty. | |
1295 | * We don't put it into the syslog queue right now maybe in the future if | |
1296 | * really needed. | |
1297 | */ | |
1298 | void tty_write_message(struct tty_struct *tty, char *msg) | |
1299 | { | |
f34d7a5b AC |
1300 | if (tty && tty->ops->write) |
1301 | tty->ops->write(tty, msg, strlen(msg)); | |
1da177e4 LT |
1302 | return; |
1303 | } | |
1304 | ||
7ef3d2fd | 1305 | #if defined CONFIG_PRINTK |
1da177e4 LT |
1306 | /* |
1307 | * printk rate limiting, lifted from the networking subsystem. | |
1308 | * | |
1309 | * This enforces a rate limit: not more than one kernel message | |
1310 | * every printk_ratelimit_jiffies to make a denial-of-service | |
1311 | * attack impossible. | |
1312 | */ | |
1313 | int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst) | |
1314 | { | |
5f97a5a8 | 1315 | return __ratelimit(ratelimit_jiffies, ratelimit_burst); |
1da177e4 LT |
1316 | } |
1317 | EXPORT_SYMBOL(__printk_ratelimit); | |
1318 | ||
1319 | /* minimum time in jiffies between messages */ | |
40dc5651 | 1320 | int printk_ratelimit_jiffies = 5 * HZ; |
1da177e4 LT |
1321 | |
1322 | /* number of messages we send before ratelimiting */ | |
1323 | int printk_ratelimit_burst = 10; | |
1324 | ||
1325 | int printk_ratelimit(void) | |
1326 | { | |
1327 | return __printk_ratelimit(printk_ratelimit_jiffies, | |
1328 | printk_ratelimit_burst); | |
1329 | } | |
1330 | EXPORT_SYMBOL(printk_ratelimit); | |
f46c4833 AM |
1331 | |
1332 | /** | |
1333 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1334 | * @caller_jiffies: pointer to caller's state | |
1335 | * @interval_msecs: minimum interval between prints | |
1336 | * | |
1337 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1338 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1339 | * returned true. | |
1340 | */ | |
1341 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1342 | unsigned int interval_msecs) | |
1343 | { | |
1344 | if (*caller_jiffies == 0 || time_after(jiffies, *caller_jiffies)) { | |
1345 | *caller_jiffies = jiffies + msecs_to_jiffies(interval_msecs); | |
1346 | return true; | |
1347 | } | |
1348 | return false; | |
1349 | } | |
1350 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
7ef3d2fd | 1351 | #endif |