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 LT |
77 | struct console *console_drivers; |
78 | /* | |
79 | * This is used for debugging the mess that is the VT code by | |
80 | * keeping track if we have the console semaphore held. It's | |
81 | * definitely not the perfect debug tool (we don't know if _WE_ | |
82 | * hold it are racing, but it helps tracking those weird code | |
83 | * path in the console code where we end up in places I want | |
84 | * locked without the console sempahore held | |
85 | */ | |
557240b4 | 86 | static int console_locked, console_suspended; |
1da177e4 LT |
87 | |
88 | /* | |
89 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
90 | * It is also used in interesting ways to provide interlocking in | |
91 | * release_console_sem(). | |
92 | */ | |
93 | static DEFINE_SPINLOCK(logbuf_lock); | |
94 | ||
eed4a2ab | 95 | #define LOG_BUF_MASK (log_buf_len-1) |
1da177e4 LT |
96 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
97 | ||
98 | /* | |
99 | * The indices into log_buf are not constrained to log_buf_len - they | |
100 | * must be masked before subscripting | |
101 | */ | |
eed4a2ab DV |
102 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
103 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ | |
104 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
105 | |
106 | /* | |
107 | * Array of consoles built from command line options (console=) | |
108 | */ | |
109 | struct console_cmdline | |
110 | { | |
111 | char name[8]; /* Name of the driver */ | |
112 | int index; /* Minor dev. to use */ | |
113 | char *options; /* Options for the driver */ | |
f7511d5f ST |
114 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
115 | char *brl_options; /* Options for braille driver */ | |
116 | #endif | |
1da177e4 LT |
117 | }; |
118 | ||
119 | #define MAX_CMDLINECONSOLES 8 | |
120 | ||
121 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
122 | static int selected_console = -1; | |
123 | static int preferred_console = -1; | |
124 | ||
125 | /* Flag: console code may call schedule() */ | |
126 | static int console_may_schedule; | |
127 | ||
d59745ce MM |
128 | #ifdef CONFIG_PRINTK |
129 | ||
130 | static char __log_buf[__LOG_BUF_LEN]; | |
131 | static char *log_buf = __log_buf; | |
132 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 133 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
d59745ce | 134 | |
1da177e4 LT |
135 | static int __init log_buf_len_setup(char *str) |
136 | { | |
eed4a2ab | 137 | unsigned size = memparse(str, &str); |
1da177e4 LT |
138 | unsigned long flags; |
139 | ||
140 | if (size) | |
141 | size = roundup_pow_of_two(size); | |
142 | if (size > log_buf_len) { | |
eed4a2ab | 143 | unsigned start, dest_idx, offset; |
40dc5651 | 144 | char *new_log_buf; |
1da177e4 LT |
145 | |
146 | new_log_buf = alloc_bootmem(size); | |
147 | if (!new_log_buf) { | |
40dc5651 | 148 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
149 | goto out; |
150 | } | |
151 | ||
152 | spin_lock_irqsave(&logbuf_lock, flags); | |
153 | log_buf_len = size; | |
154 | log_buf = new_log_buf; | |
155 | ||
156 | offset = start = min(con_start, log_start); | |
157 | dest_idx = 0; | |
158 | while (start != log_end) { | |
159 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
160 | start++; | |
161 | dest_idx++; | |
162 | } | |
163 | log_start -= offset; | |
164 | con_start -= offset; | |
165 | log_end -= offset; | |
166 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
167 | ||
40dc5651 | 168 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
169 | } |
170 | out: | |
1da177e4 LT |
171 | return 1; |
172 | } | |
173 | ||
174 | __setup("log_buf_len=", log_buf_len_setup); | |
175 | ||
bfe8df3d RD |
176 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
177 | ||
178 | static unsigned int boot_delay; /* msecs delay after each printk during bootup */ | |
179 | static unsigned long long printk_delay_msec; /* per msec, based on boot_delay */ | |
180 | ||
181 | static int __init boot_delay_setup(char *str) | |
182 | { | |
183 | unsigned long lpj; | |
184 | unsigned long long loops_per_msec; | |
185 | ||
186 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
187 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
188 | ||
189 | get_option(&str, &boot_delay); | |
190 | if (boot_delay > 10 * 1000) | |
191 | boot_delay = 0; | |
192 | ||
193 | printk_delay_msec = loops_per_msec; | |
194 | printk(KERN_DEBUG "boot_delay: %u, preset_lpj: %ld, lpj: %lu, " | |
195 | "HZ: %d, printk_delay_msec: %llu\n", | |
196 | boot_delay, preset_lpj, lpj, HZ, printk_delay_msec); | |
197 | return 1; | |
198 | } | |
199 | __setup("boot_delay=", boot_delay_setup); | |
200 | ||
201 | static void boot_delay_msec(void) | |
202 | { | |
203 | unsigned long long k; | |
204 | unsigned long timeout; | |
205 | ||
206 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
207 | return; | |
208 | ||
209 | k = (unsigned long long)printk_delay_msec * boot_delay; | |
210 | ||
211 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
212 | while (k) { | |
213 | k--; | |
214 | cpu_relax(); | |
215 | /* | |
216 | * use (volatile) jiffies to prevent | |
217 | * compiler reduction; loop termination via jiffies | |
218 | * is secondary and may or may not happen. | |
219 | */ | |
220 | if (time_after(jiffies, timeout)) | |
221 | break; | |
222 | touch_nmi_watchdog(); | |
223 | } | |
224 | } | |
225 | #else | |
226 | static inline void boot_delay_msec(void) | |
227 | { | |
228 | } | |
229 | #endif | |
230 | ||
0b15d04a MF |
231 | /* |
232 | * Return the number of unread characters in the log buffer. | |
233 | */ | |
7f6f3a39 | 234 | static int log_buf_get_len(void) |
0b15d04a MF |
235 | { |
236 | return logged_chars; | |
237 | } | |
238 | ||
239 | /* | |
240 | * Copy a range of characters from the log buffer. | |
241 | */ | |
242 | int log_buf_copy(char *dest, int idx, int len) | |
243 | { | |
244 | int ret, max; | |
245 | bool took_lock = false; | |
246 | ||
247 | if (!oops_in_progress) { | |
248 | spin_lock_irq(&logbuf_lock); | |
249 | took_lock = true; | |
250 | } | |
251 | ||
252 | max = log_buf_get_len(); | |
253 | if (idx < 0 || idx >= max) { | |
254 | ret = -1; | |
255 | } else { | |
256 | if (len > max) | |
257 | len = max; | |
258 | ret = len; | |
259 | idx += (log_end - max); | |
260 | while (len-- > 0) | |
261 | dest[len] = LOG_BUF(idx + len); | |
262 | } | |
263 | ||
264 | if (took_lock) | |
265 | spin_unlock_irq(&logbuf_lock); | |
266 | ||
267 | return ret; | |
268 | } | |
269 | ||
1da177e4 LT |
270 | /* |
271 | * Commands to do_syslog: | |
272 | * | |
273 | * 0 -- Close the log. Currently a NOP. | |
274 | * 1 -- Open the log. Currently a NOP. | |
275 | * 2 -- Read from the log. | |
276 | * 3 -- Read all messages remaining in the ring buffer. | |
277 | * 4 -- Read and clear all messages remaining in the ring buffer | |
278 | * 5 -- Clear ring buffer. | |
279 | * 6 -- Disable printk's to console | |
280 | * 7 -- Enable printk's to console | |
281 | * 8 -- Set level of messages printed to console | |
282 | * 9 -- Return number of unread characters in the log buffer | |
283 | * 10 -- Return size of the log buffer | |
284 | */ | |
40dc5651 | 285 | int do_syslog(int type, char __user *buf, int len) |
1da177e4 | 286 | { |
eed4a2ab | 287 | unsigned i, j, limit, count; |
1da177e4 LT |
288 | int do_clear = 0; |
289 | char c; | |
290 | int error = 0; | |
291 | ||
292 | error = security_syslog(type); | |
293 | if (error) | |
294 | return error; | |
295 | ||
296 | switch (type) { | |
297 | case 0: /* Close log */ | |
298 | break; | |
299 | case 1: /* Open log */ | |
300 | break; | |
301 | case 2: /* Read from log */ | |
302 | error = -EINVAL; | |
303 | if (!buf || len < 0) | |
304 | goto out; | |
305 | error = 0; | |
306 | if (!len) | |
307 | goto out; | |
308 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
309 | error = -EFAULT; | |
310 | goto out; | |
311 | } | |
40dc5651 JJ |
312 | error = wait_event_interruptible(log_wait, |
313 | (log_start - log_end)); | |
1da177e4 LT |
314 | if (error) |
315 | goto out; | |
316 | i = 0; | |
317 | spin_lock_irq(&logbuf_lock); | |
318 | while (!error && (log_start != log_end) && i < len) { | |
319 | c = LOG_BUF(log_start); | |
320 | log_start++; | |
321 | spin_unlock_irq(&logbuf_lock); | |
322 | error = __put_user(c,buf); | |
323 | buf++; | |
324 | i++; | |
325 | cond_resched(); | |
326 | spin_lock_irq(&logbuf_lock); | |
327 | } | |
328 | spin_unlock_irq(&logbuf_lock); | |
329 | if (!error) | |
330 | error = i; | |
331 | break; | |
332 | case 4: /* Read/clear last kernel messages */ | |
40dc5651 | 333 | do_clear = 1; |
1da177e4 LT |
334 | /* FALL THRU */ |
335 | case 3: /* Read last kernel messages */ | |
336 | error = -EINVAL; | |
337 | if (!buf || len < 0) | |
338 | goto out; | |
339 | error = 0; | |
340 | if (!len) | |
341 | goto out; | |
342 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
343 | error = -EFAULT; | |
344 | goto out; | |
345 | } | |
346 | count = len; | |
347 | if (count > log_buf_len) | |
348 | count = log_buf_len; | |
349 | spin_lock_irq(&logbuf_lock); | |
350 | if (count > logged_chars) | |
351 | count = logged_chars; | |
352 | if (do_clear) | |
353 | logged_chars = 0; | |
354 | limit = log_end; | |
355 | /* | |
356 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 357 | * printk() could overwrite the messages |
1da177e4 LT |
358 | * we try to copy to user space. Therefore |
359 | * the messages are copied in reverse. <manfreds> | |
360 | */ | |
40dc5651 | 361 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
362 | j = limit-1-i; |
363 | if (j + log_buf_len < log_end) | |
364 | break; | |
365 | c = LOG_BUF(j); | |
366 | spin_unlock_irq(&logbuf_lock); | |
367 | error = __put_user(c,&buf[count-1-i]); | |
368 | cond_resched(); | |
369 | spin_lock_irq(&logbuf_lock); | |
370 | } | |
371 | spin_unlock_irq(&logbuf_lock); | |
372 | if (error) | |
373 | break; | |
374 | error = i; | |
40dc5651 | 375 | if (i != count) { |
1da177e4 LT |
376 | int offset = count-error; |
377 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 378 | for (i = 0; i < error; i++) { |
1da177e4 LT |
379 | if (__get_user(c,&buf[i+offset]) || |
380 | __put_user(c,&buf[i])) { | |
381 | error = -EFAULT; | |
382 | break; | |
383 | } | |
384 | cond_resched(); | |
385 | } | |
386 | } | |
387 | break; | |
388 | case 5: /* Clear ring buffer */ | |
389 | logged_chars = 0; | |
390 | break; | |
391 | case 6: /* Disable logging to console */ | |
392 | console_loglevel = minimum_console_loglevel; | |
393 | break; | |
394 | case 7: /* Enable logging to console */ | |
395 | console_loglevel = default_console_loglevel; | |
396 | break; | |
397 | case 8: /* Set level of messages printed to console */ | |
398 | error = -EINVAL; | |
399 | if (len < 1 || len > 8) | |
400 | goto out; | |
401 | if (len < minimum_console_loglevel) | |
402 | len = minimum_console_loglevel; | |
403 | console_loglevel = len; | |
404 | error = 0; | |
405 | break; | |
406 | case 9: /* Number of chars in the log buffer */ | |
407 | error = log_end - log_start; | |
408 | break; | |
409 | case 10: /* Size of the log buffer */ | |
410 | error = log_buf_len; | |
411 | break; | |
412 | default: | |
413 | error = -EINVAL; | |
414 | break; | |
415 | } | |
416 | out: | |
417 | return error; | |
418 | } | |
419 | ||
40dc5651 | 420 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
1da177e4 LT |
421 | { |
422 | return do_syslog(type, buf, len); | |
423 | } | |
424 | ||
425 | /* | |
426 | * Call the console drivers on a range of log_buf | |
427 | */ | |
eed4a2ab | 428 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
429 | { |
430 | struct console *con; | |
431 | ||
432 | for (con = console_drivers; con; con = con->next) { | |
76a8ad29 ME |
433 | if ((con->flags & CON_ENABLED) && con->write && |
434 | (cpu_online(smp_processor_id()) || | |
435 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
436 | con->write(con, &LOG_BUF(start), end - start); |
437 | } | |
438 | } | |
439 | ||
79290822 IM |
440 | static int __read_mostly ignore_loglevel; |
441 | ||
99eea6a1 | 442 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
443 | { |
444 | ignore_loglevel = 1; | |
445 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
446 | ||
c4772d99 | 447 | return 0; |
79290822 IM |
448 | } |
449 | ||
c4772d99 | 450 | early_param("ignore_loglevel", ignore_loglevel_setup); |
79290822 | 451 | |
1da177e4 LT |
452 | /* |
453 | * Write out chars from start to end - 1 inclusive | |
454 | */ | |
eed4a2ab DV |
455 | static void _call_console_drivers(unsigned start, |
456 | unsigned end, int msg_log_level) | |
1da177e4 | 457 | { |
79290822 | 458 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
459 | console_drivers && start != end) { |
460 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
461 | /* wrapped write */ | |
462 | __call_console_drivers(start & LOG_BUF_MASK, | |
463 | log_buf_len); | |
464 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
465 | } else { | |
466 | __call_console_drivers(start, end); | |
467 | } | |
468 | } | |
469 | } | |
470 | ||
471 | /* | |
472 | * Call the console drivers, asking them to write out | |
473 | * log_buf[start] to log_buf[end - 1]. | |
474 | * The console_sem must be held. | |
475 | */ | |
eed4a2ab | 476 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 477 | { |
eed4a2ab | 478 | unsigned cur_index, start_print; |
1da177e4 LT |
479 | static int msg_level = -1; |
480 | ||
eed4a2ab | 481 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
482 | |
483 | cur_index = start; | |
484 | start_print = start; | |
485 | while (cur_index != end) { | |
40dc5651 JJ |
486 | if (msg_level < 0 && ((end - cur_index) > 2) && |
487 | LOG_BUF(cur_index + 0) == '<' && | |
488 | LOG_BUF(cur_index + 1) >= '0' && | |
489 | LOG_BUF(cur_index + 1) <= '7' && | |
490 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
491 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
492 | cur_index += 3; | |
493 | start_print = cur_index; | |
494 | } | |
495 | while (cur_index != end) { | |
496 | char c = LOG_BUF(cur_index); | |
1da177e4 | 497 | |
40dc5651 | 498 | cur_index++; |
1da177e4 LT |
499 | if (c == '\n') { |
500 | if (msg_level < 0) { | |
501 | /* | |
502 | * printk() has already given us loglevel tags in | |
503 | * the buffer. This code is here in case the | |
504 | * log buffer has wrapped right round and scribbled | |
505 | * on those tags | |
506 | */ | |
507 | msg_level = default_message_loglevel; | |
508 | } | |
509 | _call_console_drivers(start_print, cur_index, msg_level); | |
510 | msg_level = -1; | |
511 | start_print = cur_index; | |
512 | break; | |
513 | } | |
514 | } | |
515 | } | |
516 | _call_console_drivers(start_print, end, msg_level); | |
517 | } | |
518 | ||
519 | static void emit_log_char(char c) | |
520 | { | |
521 | LOG_BUF(log_end) = c; | |
522 | log_end++; | |
523 | if (log_end - log_start > log_buf_len) | |
524 | log_start = log_end - log_buf_len; | |
525 | if (log_end - con_start > log_buf_len) | |
526 | con_start = log_end - log_buf_len; | |
527 | if (logged_chars < log_buf_len) | |
528 | logged_chars++; | |
529 | } | |
530 | ||
531 | /* | |
532 | * Zap console related locks when oopsing. Only zap at most once | |
533 | * every 10 seconds, to leave time for slow consoles to print a | |
534 | * full oops. | |
535 | */ | |
536 | static void zap_locks(void) | |
537 | { | |
538 | static unsigned long oops_timestamp; | |
539 | ||
540 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 541 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
542 | return; |
543 | ||
544 | oops_timestamp = jiffies; | |
545 | ||
546 | /* If a crash is occurring, make sure we can't deadlock */ | |
547 | spin_lock_init(&logbuf_lock); | |
548 | /* And make sure that we print immediately */ | |
549 | init_MUTEX(&console_sem); | |
550 | } | |
551 | ||
552 | #if defined(CONFIG_PRINTK_TIME) | |
553 | static int printk_time = 1; | |
554 | #else | |
555 | static int printk_time = 0; | |
556 | #endif | |
e84845c4 | 557 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 558 | |
76a8ad29 ME |
559 | /* Check if we have any console registered that can be called early in boot. */ |
560 | static int have_callable_console(void) | |
561 | { | |
562 | struct console *con; | |
563 | ||
564 | for (con = console_drivers; con; con = con->next) | |
565 | if (con->flags & CON_ANYTIME) | |
566 | return 1; | |
567 | ||
568 | return 0; | |
569 | } | |
570 | ||
ddad86c2 MW |
571 | /** |
572 | * printk - print a kernel message | |
573 | * @fmt: format string | |
574 | * | |
72fd4a35 | 575 | * This is printk(). It can be called from any context. We want it to work. |
1492192b JK |
576 | * Be aware of the fact that if oops_in_progress is not set, we might try to |
577 | * wake klogd up which could deadlock on runqueue lock if printk() is called | |
578 | * from scheduler code. | |
40dc5651 | 579 | * |
1da177e4 LT |
580 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
581 | * call the console drivers. If we fail to get the semaphore we place the output | |
582 | * into the log buffer and return. The current holder of the console_sem will | |
583 | * notice the new output in release_console_sem() and will send it to the | |
584 | * consoles before releasing the semaphore. | |
585 | * | |
586 | * One effect of this deferred printing is that code which calls printk() and | |
587 | * then changes console_loglevel may break. This is because console_loglevel | |
588 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
589 | * |
590 | * See also: | |
591 | * printf(3) | |
1da177e4 | 592 | */ |
d59745ce | 593 | |
1da177e4 LT |
594 | asmlinkage int printk(const char *fmt, ...) |
595 | { | |
596 | va_list args; | |
597 | int r; | |
598 | ||
599 | va_start(args, fmt); | |
600 | r = vprintk(fmt, args); | |
601 | va_end(args); | |
602 | ||
603 | return r; | |
604 | } | |
605 | ||
fe21773d DH |
606 | /* cpu currently holding logbuf_lock */ |
607 | static volatile unsigned int printk_cpu = UINT_MAX; | |
608 | ||
266c2e0a LT |
609 | /* |
610 | * Can we actually use the console at this time on this cpu? | |
611 | * | |
612 | * Console drivers may assume that per-cpu resources have | |
613 | * been allocated. So unless they're explicitly marked as | |
614 | * being able to cope (CON_ANYTIME) don't call them until | |
615 | * this CPU is officially up. | |
616 | */ | |
617 | static inline int can_use_console(unsigned int cpu) | |
618 | { | |
619 | return cpu_online(cpu) || have_callable_console(); | |
620 | } | |
621 | ||
622 | /* | |
623 | * Try to get console ownership to actually show the kernel | |
624 | * messages from a 'printk'. Return true (and with the | |
625 | * console_semaphore held, and 'console_locked' set) if it | |
626 | * is successful, false otherwise. | |
627 | * | |
628 | * This gets called with the 'logbuf_lock' spinlock held and | |
629 | * interrupts disabled. It should return with 'lockbuf_lock' | |
630 | * released but interrupts still disabled. | |
631 | */ | |
632 | static int acquire_console_semaphore_for_printk(unsigned int cpu) | |
633 | { | |
634 | int retval = 0; | |
635 | ||
093a07e2 LT |
636 | if (!try_acquire_console_sem()) { |
637 | retval = 1; | |
638 | ||
639 | /* | |
640 | * If we can't use the console, we need to release | |
641 | * the console semaphore by hand to avoid flushing | |
642 | * the buffer. We need to hold the console semaphore | |
643 | * in order to do this test safely. | |
644 | */ | |
645 | if (!can_use_console(cpu)) { | |
646 | console_locked = 0; | |
647 | up(&console_sem); | |
648 | retval = 0; | |
649 | } | |
650 | } | |
266c2e0a LT |
651 | printk_cpu = UINT_MAX; |
652 | spin_unlock(&logbuf_lock); | |
653 | return retval; | |
654 | } | |
3b8945e8 TH |
655 | static const char recursion_bug_msg [] = |
656 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
657 | static int recursion_bug; | |
ac60ad74 | 658 | static int new_text_line = 1; |
3b8945e8 | 659 | static char printk_buf[1024]; |
32a76006 | 660 | |
1da177e4 LT |
661 | asmlinkage int vprintk(const char *fmt, va_list args) |
662 | { | |
32a76006 | 663 | int printed_len = 0; |
ac60ad74 | 664 | unsigned long flags; |
32a76006 | 665 | int this_cpu; |
1da177e4 | 666 | char *p; |
1da177e4 | 667 | |
bfe8df3d RD |
668 | boot_delay_msec(); |
669 | ||
fe21773d | 670 | preempt_disable(); |
1da177e4 | 671 | /* This stops the holder of console_sem just where we want him */ |
1efc5da3 | 672 | raw_local_irq_save(flags); |
32a76006 IM |
673 | this_cpu = smp_processor_id(); |
674 | ||
675 | /* | |
676 | * Ouch, printk recursed into itself! | |
677 | */ | |
678 | if (unlikely(printk_cpu == this_cpu)) { | |
679 | /* | |
680 | * If a crash is occurring during printk() on this CPU, | |
681 | * then try to get the crash message out but make sure | |
682 | * we can't deadlock. Otherwise just return to avoid the | |
683 | * recursion and return - but flag the recursion so that | |
684 | * it can be printed at the next appropriate moment: | |
685 | */ | |
686 | if (!oops_in_progress) { | |
3b8945e8 | 687 | recursion_bug = 1; |
32a76006 IM |
688 | goto out_restore_irqs; |
689 | } | |
690 | zap_locks(); | |
691 | } | |
692 | ||
a0f1ccfd IM |
693 | lockdep_off(); |
694 | spin_lock(&logbuf_lock); | |
32a76006 | 695 | printk_cpu = this_cpu; |
1da177e4 | 696 | |
3b8945e8 TH |
697 | if (recursion_bug) { |
698 | recursion_bug = 0; | |
699 | strcpy(printk_buf, recursion_bug_msg); | |
700 | printed_len = sizeof(recursion_bug_msg); | |
32a76006 | 701 | } |
1da177e4 | 702 | /* Emit the output into the temporary buffer */ |
32a76006 | 703 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 704 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 705 | |
ac60ad74 | 706 | |
1da177e4 LT |
707 | /* |
708 | * Copy the output into log_buf. If the caller didn't provide | |
709 | * appropriate log level tags, we insert them here | |
710 | */ | |
711 | for (p = printk_buf; *p; p++) { | |
ac60ad74 NA |
712 | if (new_text_line) { |
713 | int current_log_level = default_message_loglevel; | |
714 | /* If a token, set current_log_level and skip over */ | |
715 | if (p[0] == '<' && p[1] >= '0' && p[1] <= '7' && | |
716 | p[2] == '>') { | |
717 | current_log_level = p[1] - '0'; | |
718 | p += 3; | |
719 | printed_len -= 3; | |
720 | } | |
721 | ||
722 | /* Always output the token */ | |
723 | emit_log_char('<'); | |
724 | emit_log_char(current_log_level + '0'); | |
725 | emit_log_char('>'); | |
726 | printed_len += 3; | |
727 | new_text_line = 0; | |
728 | ||
1da177e4 | 729 | if (printk_time) { |
ac60ad74 | 730 | /* Follow the token with the time */ |
1da177e4 LT |
731 | char tbuf[50], *tp; |
732 | unsigned tlen; | |
733 | unsigned long long t; | |
734 | unsigned long nanosec_rem; | |
735 | ||
326e96b9 | 736 | t = cpu_clock(printk_cpu); |
1da177e4 | 737 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
738 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
739 | (unsigned long) t, | |
740 | nanosec_rem / 1000); | |
1da177e4 LT |
741 | |
742 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
743 | emit_log_char(*tp); | |
025510cd | 744 | printed_len += tlen; |
1da177e4 | 745 | } |
ac60ad74 | 746 | |
1da177e4 LT |
747 | if (!*p) |
748 | break; | |
749 | } | |
ac60ad74 | 750 | |
1da177e4 LT |
751 | emit_log_char(*p); |
752 | if (*p == '\n') | |
ac60ad74 | 753 | new_text_line = 1; |
1da177e4 LT |
754 | } |
755 | ||
266c2e0a LT |
756 | /* |
757 | * Try to acquire and then immediately release the | |
758 | * console semaphore. The release will do all the | |
759 | * actual magic (print out buffers, wake up klogd, | |
760 | * etc). | |
761 | * | |
762 | * The acquire_console_semaphore_for_printk() function | |
763 | * will release 'logbuf_lock' regardless of whether it | |
764 | * actually gets the semaphore or not. | |
765 | */ | |
766 | if (acquire_console_semaphore_for_printk(this_cpu)) | |
767 | release_console_sem(); | |
76a8ad29 | 768 | |
266c2e0a | 769 | lockdep_on(); |
32a76006 | 770 | out_restore_irqs: |
266c2e0a | 771 | raw_local_irq_restore(flags); |
76a8ad29 | 772 | |
fe21773d | 773 | preempt_enable(); |
1da177e4 LT |
774 | return printed_len; |
775 | } | |
776 | EXPORT_SYMBOL(printk); | |
777 | EXPORT_SYMBOL(vprintk); | |
778 | ||
d59745ce MM |
779 | #else |
780 | ||
40dc5651 | 781 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
d59745ce | 782 | { |
c36264df | 783 | return -ENOSYS; |
40dc5651 JJ |
784 | } |
785 | ||
eed4a2ab | 786 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
787 | { |
788 | } | |
d59745ce MM |
789 | |
790 | #endif | |
791 | ||
f7511d5f ST |
792 | static int __add_preferred_console(char *name, int idx, char *options, |
793 | char *brl_options) | |
794 | { | |
795 | struct console_cmdline *c; | |
796 | int i; | |
797 | ||
798 | /* | |
799 | * See if this tty is not yet registered, and | |
800 | * if we have a slot free. | |
801 | */ | |
802 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
803 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
804 | console_cmdline[i].index == idx) { | |
805 | if (!brl_options) | |
806 | selected_console = i; | |
807 | return 0; | |
808 | } | |
809 | if (i == MAX_CMDLINECONSOLES) | |
810 | return -E2BIG; | |
811 | if (!brl_options) | |
812 | selected_console = i; | |
813 | c = &console_cmdline[i]; | |
814 | strlcpy(c->name, name, sizeof(c->name)); | |
815 | c->options = options; | |
816 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
817 | c->brl_options = brl_options; | |
818 | #endif | |
819 | c->index = idx; | |
820 | return 0; | |
821 | } | |
2ea1c539 JB |
822 | /* |
823 | * Set up a list of consoles. Called from init/main.c | |
824 | */ | |
825 | static int __init console_setup(char *str) | |
826 | { | |
eaa944af | 827 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 828 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
829 | int idx; |
830 | ||
f7511d5f ST |
831 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
832 | if (!memcmp(str, "brl,", 4)) { | |
833 | brl_options = ""; | |
834 | str += 4; | |
835 | } else if (!memcmp(str, "brl=", 4)) { | |
836 | brl_options = str + 4; | |
837 | str = strchr(brl_options, ','); | |
838 | if (!str) { | |
839 | printk(KERN_ERR "need port name after brl=\n"); | |
840 | return 1; | |
841 | } | |
842 | *(str++) = 0; | |
843 | } | |
844 | #endif | |
845 | ||
2ea1c539 JB |
846 | /* |
847 | * Decode str into name, index, options. | |
848 | */ | |
849 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
850 | strcpy(buf, "ttyS"); |
851 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 852 | } else { |
eaa944af | 853 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 854 | } |
eaa944af | 855 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
856 | if ((options = strchr(str, ',')) != NULL) |
857 | *(options++) = 0; | |
858 | #ifdef __sparc__ | |
859 | if (!strcmp(str, "ttya")) | |
eaa944af | 860 | strcpy(buf, "ttyS0"); |
2ea1c539 | 861 | if (!strcmp(str, "ttyb")) |
eaa944af | 862 | strcpy(buf, "ttyS1"); |
2ea1c539 | 863 | #endif |
eaa944af | 864 | for (s = buf; *s; s++) |
2ea1c539 JB |
865 | if ((*s >= '0' && *s <= '9') || *s == ',') |
866 | break; | |
867 | idx = simple_strtoul(s, NULL, 10); | |
868 | *s = 0; | |
869 | ||
f7511d5f | 870 | __add_preferred_console(buf, idx, options, brl_options); |
2ea1c539 JB |
871 | return 1; |
872 | } | |
873 | __setup("console=", console_setup); | |
874 | ||
3c0547ba MM |
875 | /** |
876 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
877 | * @name: device name |
878 | * @idx: device index | |
879 | * @options: options for this console | |
3c0547ba MM |
880 | * |
881 | * The last preferred console added will be used for kernel messages | |
882 | * and stdin/out/err for init. Normally this is used by console_setup | |
883 | * above to handle user-supplied console arguments; however it can also | |
884 | * be used by arch-specific code either to override the user or more | |
885 | * commonly to provide a default console (ie from PROM variables) when | |
886 | * the user has not supplied one. | |
887 | */ | |
fb445ee5 | 888 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 889 | { |
f7511d5f | 890 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
891 | } |
892 | ||
b6b1d877 | 893 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
894 | { |
895 | struct console_cmdline *c; | |
896 | int i; | |
897 | ||
898 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
899 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
900 | console_cmdline[i].index == idx) { | |
901 | c = &console_cmdline[i]; | |
f735295b | 902 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
903 | c->name[sizeof(c->name) - 1] = 0; |
904 | c->options = options; | |
905 | c->index = idx_new; | |
906 | return i; | |
907 | } | |
908 | /* not found */ | |
909 | return -1; | |
910 | } | |
911 | ||
8f4ce8c3 AS |
912 | int console_suspend_enabled = 1; |
913 | EXPORT_SYMBOL(console_suspend_enabled); | |
914 | ||
915 | static int __init console_suspend_disable(char *str) | |
916 | { | |
917 | console_suspend_enabled = 0; | |
918 | return 1; | |
919 | } | |
920 | __setup("no_console_suspend", console_suspend_disable); | |
921 | ||
557240b4 LT |
922 | /** |
923 | * suspend_console - suspend the console subsystem | |
924 | * | |
925 | * This disables printk() while we go into suspend states | |
926 | */ | |
927 | void suspend_console(void) | |
928 | { | |
8f4ce8c3 AS |
929 | if (!console_suspend_enabled) |
930 | return; | |
c8eb8b40 | 931 | printk("Suspending console(s)\n"); |
557240b4 LT |
932 | acquire_console_sem(); |
933 | console_suspended = 1; | |
934 | } | |
935 | ||
936 | void resume_console(void) | |
937 | { | |
8f4ce8c3 AS |
938 | if (!console_suspend_enabled) |
939 | return; | |
557240b4 LT |
940 | console_suspended = 0; |
941 | release_console_sem(); | |
942 | } | |
943 | ||
1da177e4 LT |
944 | /** |
945 | * acquire_console_sem - lock the console system for exclusive use. | |
946 | * | |
947 | * Acquires a semaphore which guarantees that the caller has | |
948 | * exclusive access to the console system and the console_drivers list. | |
949 | * | |
950 | * Can sleep, returns nothing. | |
951 | */ | |
952 | void acquire_console_sem(void) | |
953 | { | |
8abd8e29 | 954 | BUG_ON(in_interrupt()); |
557240b4 LT |
955 | if (console_suspended) { |
956 | down(&secondary_console_sem); | |
957 | return; | |
958 | } | |
1da177e4 LT |
959 | down(&console_sem); |
960 | console_locked = 1; | |
961 | console_may_schedule = 1; | |
962 | } | |
963 | EXPORT_SYMBOL(acquire_console_sem); | |
964 | ||
965 | int try_acquire_console_sem(void) | |
966 | { | |
967 | if (down_trylock(&console_sem)) | |
968 | return -1; | |
969 | console_locked = 1; | |
970 | console_may_schedule = 0; | |
971 | return 0; | |
972 | } | |
973 | EXPORT_SYMBOL(try_acquire_console_sem); | |
974 | ||
975 | int is_console_locked(void) | |
976 | { | |
977 | return console_locked; | |
978 | } | |
1da177e4 | 979 | |
e3e8a75d KK |
980 | void wake_up_klogd(void) |
981 | { | |
982 | if (!oops_in_progress && waitqueue_active(&log_wait)) | |
983 | wake_up_interruptible(&log_wait); | |
984 | } | |
985 | ||
1da177e4 LT |
986 | /** |
987 | * release_console_sem - unlock the console system | |
988 | * | |
989 | * Releases the semaphore which the caller holds on the console system | |
990 | * and the console driver list. | |
991 | * | |
992 | * While the semaphore was held, console output may have been buffered | |
993 | * by printk(). If this is the case, release_console_sem() emits | |
994 | * the output prior to releasing the semaphore. | |
995 | * | |
996 | * If there is output waiting for klogd, we wake it up. | |
997 | * | |
998 | * release_console_sem() may be called from any context. | |
999 | */ | |
1000 | void release_console_sem(void) | |
1001 | { | |
1002 | unsigned long flags; | |
eed4a2ab DV |
1003 | unsigned _con_start, _log_end; |
1004 | unsigned wake_klogd = 0; | |
1da177e4 | 1005 | |
557240b4 LT |
1006 | if (console_suspended) { |
1007 | up(&secondary_console_sem); | |
1008 | return; | |
1009 | } | |
78944e54 AD |
1010 | |
1011 | console_may_schedule = 0; | |
1012 | ||
1da177e4 LT |
1013 | for ( ; ; ) { |
1014 | spin_lock_irqsave(&logbuf_lock, flags); | |
1015 | wake_klogd |= log_start - log_end; | |
1016 | if (con_start == log_end) | |
1017 | break; /* Nothing to print */ | |
1018 | _con_start = con_start; | |
1019 | _log_end = log_end; | |
1020 | con_start = log_end; /* Flush */ | |
1021 | spin_unlock(&logbuf_lock); | |
1022 | call_console_drivers(_con_start, _log_end); | |
1023 | local_irq_restore(flags); | |
1024 | } | |
1025 | console_locked = 0; | |
1da177e4 LT |
1026 | up(&console_sem); |
1027 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
1028 | if (wake_klogd) |
1029 | wake_up_klogd(); | |
1da177e4 LT |
1030 | } |
1031 | EXPORT_SYMBOL(release_console_sem); | |
1032 | ||
ddad86c2 MW |
1033 | /** |
1034 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1035 | * |
1036 | * If the console code is currently allowed to sleep, and | |
1037 | * if this CPU should yield the CPU to another task, do | |
1038 | * so here. | |
1039 | * | |
1040 | * Must be called within acquire_console_sem(). | |
1041 | */ | |
1042 | void __sched console_conditional_schedule(void) | |
1043 | { | |
1044 | if (console_may_schedule) | |
1045 | cond_resched(); | |
1046 | } | |
1047 | EXPORT_SYMBOL(console_conditional_schedule); | |
1048 | ||
1049 | void console_print(const char *s) | |
1050 | { | |
1051 | printk(KERN_EMERG "%s", s); | |
1052 | } | |
1053 | EXPORT_SYMBOL(console_print); | |
1054 | ||
1055 | void console_unblank(void) | |
1056 | { | |
1057 | struct console *c; | |
1058 | ||
1059 | /* | |
1060 | * console_unblank can no longer be called in interrupt context unless | |
1061 | * oops_in_progress is set to 1.. | |
1062 | */ | |
1063 | if (oops_in_progress) { | |
1064 | if (down_trylock(&console_sem) != 0) | |
1065 | return; | |
1066 | } else | |
1067 | acquire_console_sem(); | |
1068 | ||
1069 | console_locked = 1; | |
1070 | console_may_schedule = 0; | |
1071 | for (c = console_drivers; c != NULL; c = c->next) | |
1072 | if ((c->flags & CON_ENABLED) && c->unblank) | |
1073 | c->unblank(); | |
1074 | release_console_sem(); | |
1075 | } | |
1da177e4 LT |
1076 | |
1077 | /* | |
1078 | * Return the console tty driver structure and its associated index | |
1079 | */ | |
1080 | struct tty_driver *console_device(int *index) | |
1081 | { | |
1082 | struct console *c; | |
1083 | struct tty_driver *driver = NULL; | |
1084 | ||
1085 | acquire_console_sem(); | |
1086 | for (c = console_drivers; c != NULL; c = c->next) { | |
1087 | if (!c->device) | |
1088 | continue; | |
1089 | driver = c->device(c, index); | |
1090 | if (driver) | |
1091 | break; | |
1092 | } | |
1093 | release_console_sem(); | |
1094 | return driver; | |
1095 | } | |
1096 | ||
1097 | /* | |
1098 | * Prevent further output on the passed console device so that (for example) | |
1099 | * serial drivers can disable console output before suspending a port, and can | |
1100 | * re-enable output afterwards. | |
1101 | */ | |
1102 | void console_stop(struct console *console) | |
1103 | { | |
1104 | acquire_console_sem(); | |
1105 | console->flags &= ~CON_ENABLED; | |
1106 | release_console_sem(); | |
1107 | } | |
1108 | EXPORT_SYMBOL(console_stop); | |
1109 | ||
1110 | void console_start(struct console *console) | |
1111 | { | |
1112 | acquire_console_sem(); | |
1113 | console->flags |= CON_ENABLED; | |
1114 | release_console_sem(); | |
1115 | } | |
1116 | EXPORT_SYMBOL(console_start); | |
1117 | ||
1118 | /* | |
1119 | * The console driver calls this routine during kernel initialization | |
1120 | * to register the console printing procedure with printk() and to | |
1121 | * print any messages that were printed by the kernel before the | |
1122 | * console driver was initialized. | |
1123 | */ | |
40dc5651 | 1124 | void register_console(struct console *console) |
1da177e4 | 1125 | { |
40dc5651 | 1126 | int i; |
1da177e4 | 1127 | unsigned long flags; |
69331af7 | 1128 | struct console *bootconsole = NULL; |
1da177e4 | 1129 | |
69331af7 GH |
1130 | if (console_drivers) { |
1131 | if (console->flags & CON_BOOT) | |
1132 | return; | |
1133 | if (console_drivers->flags & CON_BOOT) | |
1134 | bootconsole = console_drivers; | |
1135 | } | |
1136 | ||
1137 | if (preferred_console < 0 || bootconsole || !console_drivers) | |
1da177e4 LT |
1138 | preferred_console = selected_console; |
1139 | ||
18a8bd94 YL |
1140 | if (console->early_setup) |
1141 | console->early_setup(); | |
1142 | ||
1da177e4 LT |
1143 | /* |
1144 | * See if we want to use this console driver. If we | |
1145 | * didn't select a console we take the first one | |
1146 | * that registers here. | |
1147 | */ | |
1148 | if (preferred_console < 0) { | |
1149 | if (console->index < 0) | |
1150 | console->index = 0; | |
1151 | if (console->setup == NULL || | |
1152 | console->setup(console, NULL) == 0) { | |
cd3a1b85 JK |
1153 | console->flags |= CON_ENABLED; |
1154 | if (console->device) { | |
1155 | console->flags |= CON_CONSDEV; | |
1156 | preferred_console = 0; | |
1157 | } | |
1da177e4 LT |
1158 | } |
1159 | } | |
1160 | ||
1161 | /* | |
1162 | * See if this console matches one we selected on | |
1163 | * the command line. | |
1164 | */ | |
40dc5651 JJ |
1165 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1166 | i++) { | |
1da177e4 LT |
1167 | if (strcmp(console_cmdline[i].name, console->name) != 0) |
1168 | continue; | |
1169 | if (console->index >= 0 && | |
1170 | console->index != console_cmdline[i].index) | |
1171 | continue; | |
1172 | if (console->index < 0) | |
1173 | console->index = console_cmdline[i].index; | |
f7511d5f ST |
1174 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1175 | if (console_cmdline[i].brl_options) { | |
1176 | console->flags |= CON_BRL; | |
1177 | braille_register_console(console, | |
1178 | console_cmdline[i].index, | |
1179 | console_cmdline[i].options, | |
1180 | console_cmdline[i].brl_options); | |
1181 | return; | |
1182 | } | |
1183 | #endif | |
1da177e4 LT |
1184 | if (console->setup && |
1185 | console->setup(console, console_cmdline[i].options) != 0) | |
1186 | break; | |
1187 | console->flags |= CON_ENABLED; | |
1188 | console->index = console_cmdline[i].index; | |
ab4af03a | 1189 | if (i == selected_console) { |
1da177e4 | 1190 | console->flags |= CON_CONSDEV; |
ab4af03a GE |
1191 | preferred_console = selected_console; |
1192 | } | |
1da177e4 LT |
1193 | break; |
1194 | } | |
1195 | ||
1196 | if (!(console->flags & CON_ENABLED)) | |
1197 | return; | |
1198 | ||
d37bf60d | 1199 | if (bootconsole && (console->flags & CON_CONSDEV)) { |
69331af7 GH |
1200 | printk(KERN_INFO "console handover: boot [%s%d] -> real [%s%d]\n", |
1201 | bootconsole->name, bootconsole->index, | |
1202 | console->name, console->index); | |
1203 | unregister_console(bootconsole); | |
1da177e4 | 1204 | console->flags &= ~CON_PRINTBUFFER; |
d37bf60d YL |
1205 | } else { |
1206 | printk(KERN_INFO "console [%s%d] enabled\n", | |
1207 | console->name, console->index); | |
1da177e4 LT |
1208 | } |
1209 | ||
1210 | /* | |
1211 | * Put this console in the list - keep the | |
1212 | * preferred driver at the head of the list. | |
1213 | */ | |
1214 | acquire_console_sem(); | |
1215 | if ((console->flags & CON_CONSDEV) || console_drivers == NULL) { | |
1216 | console->next = console_drivers; | |
1217 | console_drivers = console; | |
ab4af03a GE |
1218 | if (console->next) |
1219 | console->next->flags &= ~CON_CONSDEV; | |
1da177e4 LT |
1220 | } else { |
1221 | console->next = console_drivers->next; | |
1222 | console_drivers->next = console; | |
1223 | } | |
1224 | if (console->flags & CON_PRINTBUFFER) { | |
1225 | /* | |
1226 | * release_console_sem() will print out the buffered messages | |
1227 | * for us. | |
1228 | */ | |
1229 | spin_lock_irqsave(&logbuf_lock, flags); | |
1230 | con_start = log_start; | |
1231 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1232 | } | |
1233 | release_console_sem(); | |
1234 | } | |
1235 | EXPORT_SYMBOL(register_console); | |
1236 | ||
40dc5651 | 1237 | int unregister_console(struct console *console) |
1da177e4 | 1238 | { |
40dc5651 | 1239 | struct console *a, *b; |
1da177e4 LT |
1240 | int res = 1; |
1241 | ||
f7511d5f ST |
1242 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1243 | if (console->flags & CON_BRL) | |
1244 | return braille_unregister_console(console); | |
1245 | #endif | |
1246 | ||
1da177e4 LT |
1247 | acquire_console_sem(); |
1248 | if (console_drivers == console) { | |
1249 | console_drivers=console->next; | |
1250 | res = 0; | |
e9b15b54 | 1251 | } else if (console_drivers) { |
1da177e4 LT |
1252 | for (a=console_drivers->next, b=console_drivers ; |
1253 | a; b=a, a=b->next) { | |
1254 | if (a == console) { | |
1255 | b->next = a->next; | |
1256 | res = 0; | |
1257 | break; | |
40dc5651 | 1258 | } |
1da177e4 LT |
1259 | } |
1260 | } | |
40dc5651 | 1261 | |
69331af7 | 1262 | /* |
ab4af03a GE |
1263 | * If this isn't the last console and it has CON_CONSDEV set, we |
1264 | * need to set it on the next preferred console. | |
1da177e4 | 1265 | */ |
69331af7 | 1266 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1267 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 LT |
1268 | |
1269 | release_console_sem(); | |
1270 | return res; | |
1271 | } | |
1272 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1273 | |
0c5564bd RG |
1274 | static int __init disable_boot_consoles(void) |
1275 | { | |
cb00e99c RG |
1276 | if (console_drivers != NULL) { |
1277 | if (console_drivers->flags & CON_BOOT) { | |
1278 | printk(KERN_INFO "turn off boot console %s%d\n", | |
1279 | console_drivers->name, console_drivers->index); | |
1280 | return unregister_console(console_drivers); | |
1281 | } | |
0c5564bd RG |
1282 | } |
1283 | return 0; | |
1284 | } | |
1285 | late_initcall(disable_boot_consoles); | |
1286 | ||
1da177e4 LT |
1287 | /** |
1288 | * tty_write_message - write a message to a certain tty, not just the console. | |
ddad86c2 MW |
1289 | * @tty: the destination tty_struct |
1290 | * @msg: the message to write | |
1da177e4 LT |
1291 | * |
1292 | * This is used for messages that need to be redirected to a specific tty. | |
1293 | * We don't put it into the syslog queue right now maybe in the future if | |
1294 | * really needed. | |
1295 | */ | |
1296 | void tty_write_message(struct tty_struct *tty, char *msg) | |
1297 | { | |
f34d7a5b AC |
1298 | if (tty && tty->ops->write) |
1299 | tty->ops->write(tty, msg, strlen(msg)); | |
1da177e4 LT |
1300 | return; |
1301 | } | |
1302 | ||
7ef3d2fd | 1303 | #if defined CONFIG_PRINTK |
1da177e4 LT |
1304 | /* |
1305 | * printk rate limiting, lifted from the networking subsystem. | |
1306 | * | |
1307 | * This enforces a rate limit: not more than one kernel message | |
1308 | * every printk_ratelimit_jiffies to make a denial-of-service | |
1309 | * attack impossible. | |
1310 | */ | |
1311 | int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst) | |
1312 | { | |
5f97a5a8 | 1313 | return __ratelimit(ratelimit_jiffies, ratelimit_burst); |
1da177e4 LT |
1314 | } |
1315 | EXPORT_SYMBOL(__printk_ratelimit); | |
1316 | ||
1317 | /* minimum time in jiffies between messages */ | |
40dc5651 | 1318 | int printk_ratelimit_jiffies = 5 * HZ; |
1da177e4 LT |
1319 | |
1320 | /* number of messages we send before ratelimiting */ | |
1321 | int printk_ratelimit_burst = 10; | |
1322 | ||
1323 | int printk_ratelimit(void) | |
1324 | { | |
1325 | return __printk_ratelimit(printk_ratelimit_jiffies, | |
1326 | printk_ratelimit_burst); | |
1327 | } | |
1328 | EXPORT_SYMBOL(printk_ratelimit); | |
f46c4833 AM |
1329 | |
1330 | /** | |
1331 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1332 | * @caller_jiffies: pointer to caller's state | |
1333 | * @interval_msecs: minimum interval between prints | |
1334 | * | |
1335 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1336 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1337 | * returned true. | |
1338 | */ | |
1339 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1340 | unsigned int interval_msecs) | |
1341 | { | |
1342 | if (*caller_jiffies == 0 || time_after(jiffies, *caller_jiffies)) { | |
1343 | *caller_jiffies = jiffies + msecs_to_jiffies(interval_msecs); | |
1344 | return true; | |
1345 | } | |
1346 | return false; | |
1347 | } | |
1348 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
7ef3d2fd | 1349 | #endif |