Commit | Line | Data |
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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. | |
13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul | |
14 | * manfreds@colorfullife.com | |
15 | * Rewrote bits to get rid of console_lock | |
16 | * 01Mar01 Andrew Morton <andrewm@uow.edu.au> | |
17 | */ | |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
23 | #include <linux/smp_lock.h> | |
24 | #include <linux/console.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/interrupt.h> /* For in_interrupt() */ | |
28 | #include <linux/config.h> | |
29 | #include <linux/delay.h> | |
30 | #include <linux/smp.h> | |
31 | #include <linux/security.h> | |
32 | #include <linux/bootmem.h> | |
33 | #include <linux/syscalls.h> | |
34 | ||
35 | #include <asm/uaccess.h> | |
36 | ||
37 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) | |
38 | ||
39 | /* printk's without a loglevel use this.. */ | |
40 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ | |
41 | ||
42 | /* We show everything that is MORE important than this.. */ | |
43 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
44 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
45 | ||
46 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
47 | ||
48 | int console_printk[4] = { | |
49 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
50 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
51 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
52 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
53 | }; | |
54 | ||
55 | EXPORT_SYMBOL(console_printk); | |
56 | ||
57 | /* | |
58 | * Low lever drivers may need that to know if they can schedule in | |
59 | * their unblank() callback or not. So let's export it. | |
60 | */ | |
61 | int oops_in_progress; | |
62 | EXPORT_SYMBOL(oops_in_progress); | |
63 | ||
64 | /* | |
65 | * console_sem protects the console_drivers list, and also | |
66 | * provides serialisation for access to the entire console | |
67 | * driver system. | |
68 | */ | |
69 | static DECLARE_MUTEX(console_sem); | |
70 | struct console *console_drivers; | |
71 | /* | |
72 | * This is used for debugging the mess that is the VT code by | |
73 | * keeping track if we have the console semaphore held. It's | |
74 | * definitely not the perfect debug tool (we don't know if _WE_ | |
75 | * hold it are racing, but it helps tracking those weird code | |
76 | * path in the console code where we end up in places I want | |
77 | * locked without the console sempahore held | |
78 | */ | |
79 | static int console_locked; | |
80 | ||
81 | /* | |
82 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
83 | * It is also used in interesting ways to provide interlocking in | |
84 | * release_console_sem(). | |
85 | */ | |
86 | static DEFINE_SPINLOCK(logbuf_lock); | |
87 | ||
1da177e4 LT |
88 | #define LOG_BUF_MASK (log_buf_len-1) |
89 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) | |
90 | ||
91 | /* | |
92 | * The indices into log_buf are not constrained to log_buf_len - they | |
93 | * must be masked before subscripting | |
94 | */ | |
95 | static unsigned long log_start; /* Index into log_buf: next char to be read by syslog() */ | |
96 | static unsigned long con_start; /* Index into log_buf: next char to be sent to consoles */ | |
97 | static unsigned long log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
98 | |
99 | /* | |
100 | * Array of consoles built from command line options (console=) | |
101 | */ | |
102 | struct console_cmdline | |
103 | { | |
104 | char name[8]; /* Name of the driver */ | |
105 | int index; /* Minor dev. to use */ | |
106 | char *options; /* Options for the driver */ | |
107 | }; | |
108 | ||
109 | #define MAX_CMDLINECONSOLES 8 | |
110 | ||
111 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
112 | static int selected_console = -1; | |
113 | static int preferred_console = -1; | |
114 | ||
115 | /* Flag: console code may call schedule() */ | |
116 | static int console_may_schedule; | |
117 | ||
d59745ce MM |
118 | #ifdef CONFIG_PRINTK |
119 | ||
120 | static char __log_buf[__LOG_BUF_LEN]; | |
121 | static char *log_buf = __log_buf; | |
122 | static int log_buf_len = __LOG_BUF_LEN; | |
123 | static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */ | |
124 | ||
1da177e4 LT |
125 | /* |
126 | * Setup a list of consoles. Called from init/main.c | |
127 | */ | |
128 | static int __init console_setup(char *str) | |
129 | { | |
130 | char name[sizeof(console_cmdline[0].name)]; | |
131 | char *s, *options; | |
132 | int idx; | |
133 | ||
134 | /* | |
135 | * Decode str into name, index, options. | |
136 | */ | |
137 | if (str[0] >= '0' && str[0] <= '9') { | |
138 | strcpy(name, "ttyS"); | |
139 | strncpy(name + 4, str, sizeof(name) - 5); | |
140 | } else | |
141 | strncpy(name, str, sizeof(name) - 1); | |
142 | name[sizeof(name) - 1] = 0; | |
143 | if ((options = strchr(str, ',')) != NULL) | |
144 | *(options++) = 0; | |
145 | #ifdef __sparc__ | |
146 | if (!strcmp(str, "ttya")) | |
147 | strcpy(name, "ttyS0"); | |
148 | if (!strcmp(str, "ttyb")) | |
149 | strcpy(name, "ttyS1"); | |
150 | #endif | |
151 | for(s = name; *s; s++) | |
152 | if ((*s >= '0' && *s <= '9') || *s == ',') | |
153 | break; | |
154 | idx = simple_strtoul(s, NULL, 10); | |
155 | *s = 0; | |
156 | ||
157 | add_preferred_console(name, idx, options); | |
158 | return 1; | |
159 | } | |
160 | ||
161 | __setup("console=", console_setup); | |
162 | ||
163 | /** | |
164 | * add_preferred_console - add a device to the list of preferred consoles. | |
165 | * | |
166 | * The last preferred console added will be used for kernel messages | |
167 | * and stdin/out/err for init. Normally this is used by console_setup | |
168 | * above to handle user-supplied console arguments; however it can also | |
169 | * be used by arch-specific code either to override the user or more | |
170 | * commonly to provide a default console (ie from PROM variables) when | |
171 | * the user has not supplied one. | |
172 | */ | |
173 | int __init add_preferred_console(char *name, int idx, char *options) | |
174 | { | |
175 | struct console_cmdline *c; | |
176 | int i; | |
177 | ||
178 | /* | |
179 | * See if this tty is not yet registered, and | |
180 | * if we have a slot free. | |
181 | */ | |
182 | for(i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
183 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
184 | console_cmdline[i].index == idx) { | |
185 | selected_console = i; | |
186 | return 0; | |
187 | } | |
188 | if (i == MAX_CMDLINECONSOLES) | |
189 | return -E2BIG; | |
190 | selected_console = i; | |
191 | c = &console_cmdline[i]; | |
192 | memcpy(c->name, name, sizeof(c->name)); | |
193 | c->name[sizeof(c->name) - 1] = 0; | |
194 | c->options = options; | |
195 | c->index = idx; | |
196 | return 0; | |
197 | } | |
198 | ||
199 | static int __init log_buf_len_setup(char *str) | |
200 | { | |
201 | unsigned long size = memparse(str, &str); | |
202 | unsigned long flags; | |
203 | ||
204 | if (size) | |
205 | size = roundup_pow_of_two(size); | |
206 | if (size > log_buf_len) { | |
207 | unsigned long start, dest_idx, offset; | |
208 | char * new_log_buf; | |
209 | ||
210 | new_log_buf = alloc_bootmem(size); | |
211 | if (!new_log_buf) { | |
212 | printk("log_buf_len: allocation failed\n"); | |
213 | goto out; | |
214 | } | |
215 | ||
216 | spin_lock_irqsave(&logbuf_lock, flags); | |
217 | log_buf_len = size; | |
218 | log_buf = new_log_buf; | |
219 | ||
220 | offset = start = min(con_start, log_start); | |
221 | dest_idx = 0; | |
222 | while (start != log_end) { | |
223 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
224 | start++; | |
225 | dest_idx++; | |
226 | } | |
227 | log_start -= offset; | |
228 | con_start -= offset; | |
229 | log_end -= offset; | |
230 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
231 | ||
232 | printk("log_buf_len: %d\n", log_buf_len); | |
233 | } | |
234 | out: | |
235 | ||
236 | return 1; | |
237 | } | |
238 | ||
239 | __setup("log_buf_len=", log_buf_len_setup); | |
240 | ||
241 | /* | |
242 | * Commands to do_syslog: | |
243 | * | |
244 | * 0 -- Close the log. Currently a NOP. | |
245 | * 1 -- Open the log. Currently a NOP. | |
246 | * 2 -- Read from the log. | |
247 | * 3 -- Read all messages remaining in the ring buffer. | |
248 | * 4 -- Read and clear all messages remaining in the ring buffer | |
249 | * 5 -- Clear ring buffer. | |
250 | * 6 -- Disable printk's to console | |
251 | * 7 -- Enable printk's to console | |
252 | * 8 -- Set level of messages printed to console | |
253 | * 9 -- Return number of unread characters in the log buffer | |
254 | * 10 -- Return size of the log buffer | |
255 | */ | |
256 | int do_syslog(int type, char __user * buf, int len) | |
257 | { | |
258 | unsigned long i, j, limit, count; | |
259 | int do_clear = 0; | |
260 | char c; | |
261 | int error = 0; | |
262 | ||
263 | error = security_syslog(type); | |
264 | if (error) | |
265 | return error; | |
266 | ||
267 | switch (type) { | |
268 | case 0: /* Close log */ | |
269 | break; | |
270 | case 1: /* Open log */ | |
271 | break; | |
272 | case 2: /* Read from log */ | |
273 | error = -EINVAL; | |
274 | if (!buf || len < 0) | |
275 | goto out; | |
276 | error = 0; | |
277 | if (!len) | |
278 | goto out; | |
279 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
280 | error = -EFAULT; | |
281 | goto out; | |
282 | } | |
283 | error = wait_event_interruptible(log_wait, (log_start - log_end)); | |
284 | if (error) | |
285 | goto out; | |
286 | i = 0; | |
287 | spin_lock_irq(&logbuf_lock); | |
288 | while (!error && (log_start != log_end) && i < len) { | |
289 | c = LOG_BUF(log_start); | |
290 | log_start++; | |
291 | spin_unlock_irq(&logbuf_lock); | |
292 | error = __put_user(c,buf); | |
293 | buf++; | |
294 | i++; | |
295 | cond_resched(); | |
296 | spin_lock_irq(&logbuf_lock); | |
297 | } | |
298 | spin_unlock_irq(&logbuf_lock); | |
299 | if (!error) | |
300 | error = i; | |
301 | break; | |
302 | case 4: /* Read/clear last kernel messages */ | |
303 | do_clear = 1; | |
304 | /* FALL THRU */ | |
305 | case 3: /* Read last kernel messages */ | |
306 | error = -EINVAL; | |
307 | if (!buf || len < 0) | |
308 | goto out; | |
309 | error = 0; | |
310 | if (!len) | |
311 | goto out; | |
312 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
313 | error = -EFAULT; | |
314 | goto out; | |
315 | } | |
316 | count = len; | |
317 | if (count > log_buf_len) | |
318 | count = log_buf_len; | |
319 | spin_lock_irq(&logbuf_lock); | |
320 | if (count > logged_chars) | |
321 | count = logged_chars; | |
322 | if (do_clear) | |
323 | logged_chars = 0; | |
324 | limit = log_end; | |
325 | /* | |
326 | * __put_user() could sleep, and while we sleep | |
327 | * printk() could overwrite the messages | |
328 | * we try to copy to user space. Therefore | |
329 | * the messages are copied in reverse. <manfreds> | |
330 | */ | |
331 | for(i = 0; i < count && !error; i++) { | |
332 | j = limit-1-i; | |
333 | if (j + log_buf_len < log_end) | |
334 | break; | |
335 | c = LOG_BUF(j); | |
336 | spin_unlock_irq(&logbuf_lock); | |
337 | error = __put_user(c,&buf[count-1-i]); | |
338 | cond_resched(); | |
339 | spin_lock_irq(&logbuf_lock); | |
340 | } | |
341 | spin_unlock_irq(&logbuf_lock); | |
342 | if (error) | |
343 | break; | |
344 | error = i; | |
345 | if(i != count) { | |
346 | int offset = count-error; | |
347 | /* buffer overflow during copy, correct user buffer. */ | |
348 | for(i=0;i<error;i++) { | |
349 | if (__get_user(c,&buf[i+offset]) || | |
350 | __put_user(c,&buf[i])) { | |
351 | error = -EFAULT; | |
352 | break; | |
353 | } | |
354 | cond_resched(); | |
355 | } | |
356 | } | |
357 | break; | |
358 | case 5: /* Clear ring buffer */ | |
359 | logged_chars = 0; | |
360 | break; | |
361 | case 6: /* Disable logging to console */ | |
362 | console_loglevel = minimum_console_loglevel; | |
363 | break; | |
364 | case 7: /* Enable logging to console */ | |
365 | console_loglevel = default_console_loglevel; | |
366 | break; | |
367 | case 8: /* Set level of messages printed to console */ | |
368 | error = -EINVAL; | |
369 | if (len < 1 || len > 8) | |
370 | goto out; | |
371 | if (len < minimum_console_loglevel) | |
372 | len = minimum_console_loglevel; | |
373 | console_loglevel = len; | |
374 | error = 0; | |
375 | break; | |
376 | case 9: /* Number of chars in the log buffer */ | |
377 | error = log_end - log_start; | |
378 | break; | |
379 | case 10: /* Size of the log buffer */ | |
380 | error = log_buf_len; | |
381 | break; | |
382 | default: | |
383 | error = -EINVAL; | |
384 | break; | |
385 | } | |
386 | out: | |
387 | return error; | |
388 | } | |
389 | ||
390 | asmlinkage long sys_syslog(int type, char __user * buf, int len) | |
391 | { | |
392 | return do_syslog(type, buf, len); | |
393 | } | |
394 | ||
395 | /* | |
396 | * Call the console drivers on a range of log_buf | |
397 | */ | |
398 | static void __call_console_drivers(unsigned long start, unsigned long end) | |
399 | { | |
400 | struct console *con; | |
401 | ||
402 | for (con = console_drivers; con; con = con->next) { | |
403 | if ((con->flags & CON_ENABLED) && con->write) | |
404 | con->write(con, &LOG_BUF(start), end - start); | |
405 | } | |
406 | } | |
407 | ||
408 | /* | |
409 | * Write out chars from start to end - 1 inclusive | |
410 | */ | |
411 | static void _call_console_drivers(unsigned long start, | |
412 | unsigned long end, int msg_log_level) | |
413 | { | |
414 | if (msg_log_level < console_loglevel && | |
415 | console_drivers && start != end) { | |
416 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
417 | /* wrapped write */ | |
418 | __call_console_drivers(start & LOG_BUF_MASK, | |
419 | log_buf_len); | |
420 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
421 | } else { | |
422 | __call_console_drivers(start, end); | |
423 | } | |
424 | } | |
425 | } | |
426 | ||
427 | /* | |
428 | * Call the console drivers, asking them to write out | |
429 | * log_buf[start] to log_buf[end - 1]. | |
430 | * The console_sem must be held. | |
431 | */ | |
432 | static void call_console_drivers(unsigned long start, unsigned long end) | |
433 | { | |
434 | unsigned long cur_index, start_print; | |
435 | static int msg_level = -1; | |
436 | ||
437 | if (((long)(start - end)) > 0) | |
438 | BUG(); | |
439 | ||
440 | cur_index = start; | |
441 | start_print = start; | |
442 | while (cur_index != end) { | |
443 | if ( msg_level < 0 && | |
444 | ((end - cur_index) > 2) && | |
445 | LOG_BUF(cur_index + 0) == '<' && | |
446 | LOG_BUF(cur_index + 1) >= '0' && | |
447 | LOG_BUF(cur_index + 1) <= '7' && | |
448 | LOG_BUF(cur_index + 2) == '>') | |
449 | { | |
450 | msg_level = LOG_BUF(cur_index + 1) - '0'; | |
451 | cur_index += 3; | |
452 | start_print = cur_index; | |
453 | } | |
454 | while (cur_index != end) { | |
455 | char c = LOG_BUF(cur_index); | |
456 | cur_index++; | |
457 | ||
458 | if (c == '\n') { | |
459 | if (msg_level < 0) { | |
460 | /* | |
461 | * printk() has already given us loglevel tags in | |
462 | * the buffer. This code is here in case the | |
463 | * log buffer has wrapped right round and scribbled | |
464 | * on those tags | |
465 | */ | |
466 | msg_level = default_message_loglevel; | |
467 | } | |
468 | _call_console_drivers(start_print, cur_index, msg_level); | |
469 | msg_level = -1; | |
470 | start_print = cur_index; | |
471 | break; | |
472 | } | |
473 | } | |
474 | } | |
475 | _call_console_drivers(start_print, end, msg_level); | |
476 | } | |
477 | ||
478 | static void emit_log_char(char c) | |
479 | { | |
480 | LOG_BUF(log_end) = c; | |
481 | log_end++; | |
482 | if (log_end - log_start > log_buf_len) | |
483 | log_start = log_end - log_buf_len; | |
484 | if (log_end - con_start > log_buf_len) | |
485 | con_start = log_end - log_buf_len; | |
486 | if (logged_chars < log_buf_len) | |
487 | logged_chars++; | |
488 | } | |
489 | ||
490 | /* | |
491 | * Zap console related locks when oopsing. Only zap at most once | |
492 | * every 10 seconds, to leave time for slow consoles to print a | |
493 | * full oops. | |
494 | */ | |
495 | static void zap_locks(void) | |
496 | { | |
497 | static unsigned long oops_timestamp; | |
498 | ||
499 | if (time_after_eq(jiffies, oops_timestamp) && | |
500 | !time_after(jiffies, oops_timestamp + 30*HZ)) | |
501 | return; | |
502 | ||
503 | oops_timestamp = jiffies; | |
504 | ||
505 | /* If a crash is occurring, make sure we can't deadlock */ | |
506 | spin_lock_init(&logbuf_lock); | |
507 | /* And make sure that we print immediately */ | |
508 | init_MUTEX(&console_sem); | |
509 | } | |
510 | ||
511 | #if defined(CONFIG_PRINTK_TIME) | |
512 | static int printk_time = 1; | |
513 | #else | |
514 | static int printk_time = 0; | |
515 | #endif | |
516 | ||
517 | static int __init printk_time_setup(char *str) | |
518 | { | |
519 | if (*str) | |
520 | return 0; | |
521 | printk_time = 1; | |
522 | return 1; | |
523 | } | |
524 | ||
525 | __setup("time", printk_time_setup); | |
526 | ||
527 | /* | |
528 | * This is printk. It can be called from any context. We want it to work. | |
529 | * | |
530 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and | |
531 | * call the console drivers. If we fail to get the semaphore we place the output | |
532 | * into the log buffer and return. The current holder of the console_sem will | |
533 | * notice the new output in release_console_sem() and will send it to the | |
534 | * consoles before releasing the semaphore. | |
535 | * | |
536 | * One effect of this deferred printing is that code which calls printk() and | |
537 | * then changes console_loglevel may break. This is because console_loglevel | |
538 | * is inspected when the actual printing occurs. | |
539 | */ | |
d59745ce | 540 | |
1da177e4 LT |
541 | asmlinkage int printk(const char *fmt, ...) |
542 | { | |
543 | va_list args; | |
544 | int r; | |
545 | ||
546 | va_start(args, fmt); | |
547 | r = vprintk(fmt, args); | |
548 | va_end(args); | |
549 | ||
550 | return r; | |
551 | } | |
552 | ||
553 | asmlinkage int vprintk(const char *fmt, va_list args) | |
554 | { | |
555 | unsigned long flags; | |
556 | int printed_len; | |
557 | char *p; | |
558 | static char printk_buf[1024]; | |
559 | static int log_level_unknown = 1; | |
560 | ||
561 | if (unlikely(oops_in_progress)) | |
562 | zap_locks(); | |
563 | ||
564 | /* This stops the holder of console_sem just where we want him */ | |
565 | spin_lock_irqsave(&logbuf_lock, flags); | |
566 | ||
567 | /* Emit the output into the temporary buffer */ | |
568 | printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args); | |
569 | ||
570 | /* | |
571 | * Copy the output into log_buf. If the caller didn't provide | |
572 | * appropriate log level tags, we insert them here | |
573 | */ | |
574 | for (p = printk_buf; *p; p++) { | |
575 | if (log_level_unknown) { | |
576 | /* log_level_unknown signals the start of a new line */ | |
577 | if (printk_time) { | |
578 | int loglev_char; | |
579 | char tbuf[50], *tp; | |
580 | unsigned tlen; | |
581 | unsigned long long t; | |
582 | unsigned long nanosec_rem; | |
583 | ||
584 | /* | |
585 | * force the log level token to be | |
586 | * before the time output. | |
587 | */ | |
588 | if (p[0] == '<' && p[1] >='0' && | |
589 | p[1] <= '7' && p[2] == '>') { | |
590 | loglev_char = p[1]; | |
591 | p += 3; | |
592 | printed_len += 3; | |
593 | } else { | |
594 | loglev_char = default_message_loglevel | |
595 | + '0'; | |
596 | } | |
597 | t = sched_clock(); | |
598 | nanosec_rem = do_div(t, 1000000000); | |
599 | tlen = sprintf(tbuf, | |
600 | "<%c>[%5lu.%06lu] ", | |
601 | loglev_char, | |
602 | (unsigned long)t, | |
603 | nanosec_rem/1000); | |
604 | ||
605 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
606 | emit_log_char(*tp); | |
607 | printed_len += tlen - 3; | |
608 | } else { | |
609 | if (p[0] != '<' || p[1] < '0' || | |
610 | p[1] > '7' || p[2] != '>') { | |
611 | emit_log_char('<'); | |
612 | emit_log_char(default_message_loglevel | |
613 | + '0'); | |
614 | emit_log_char('>'); | |
615 | } | |
616 | printed_len += 3; | |
617 | } | |
618 | log_level_unknown = 0; | |
619 | if (!*p) | |
620 | break; | |
621 | } | |
622 | emit_log_char(*p); | |
623 | if (*p == '\n') | |
624 | log_level_unknown = 1; | |
625 | } | |
626 | ||
627 | if (!cpu_online(smp_processor_id()) && | |
628 | system_state != SYSTEM_RUNNING) { | |
629 | /* | |
630 | * Some console drivers may assume that per-cpu resources have | |
631 | * been allocated. So don't allow them to be called by this | |
632 | * CPU until it is officially up. We shouldn't be calling into | |
633 | * random console drivers on a CPU which doesn't exist yet.. | |
634 | */ | |
635 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
636 | goto out; | |
637 | } | |
638 | if (!down_trylock(&console_sem)) { | |
639 | console_locked = 1; | |
640 | /* | |
641 | * We own the drivers. We can drop the spinlock and let | |
642 | * release_console_sem() print the text | |
643 | */ | |
644 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
645 | console_may_schedule = 0; | |
646 | release_console_sem(); | |
647 | } else { | |
648 | /* | |
649 | * Someone else owns the drivers. We drop the spinlock, which | |
650 | * allows the semaphore holder to proceed and to call the | |
651 | * console drivers with the output which we just produced. | |
652 | */ | |
653 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
654 | } | |
655 | out: | |
656 | return printed_len; | |
657 | } | |
658 | EXPORT_SYMBOL(printk); | |
659 | EXPORT_SYMBOL(vprintk); | |
660 | ||
d59745ce MM |
661 | #else |
662 | ||
663 | asmlinkage long sys_syslog(int type, char __user * buf, int len) | |
664 | { | |
665 | return 0; | |
666 | } | |
667 | ||
668 | int do_syslog(int type, char __user * buf, int len) { return 0; } | |
669 | static void call_console_drivers(unsigned long start, unsigned long end) {} | |
670 | ||
671 | #endif | |
672 | ||
1da177e4 LT |
673 | /** |
674 | * acquire_console_sem - lock the console system for exclusive use. | |
675 | * | |
676 | * Acquires a semaphore which guarantees that the caller has | |
677 | * exclusive access to the console system and the console_drivers list. | |
678 | * | |
679 | * Can sleep, returns nothing. | |
680 | */ | |
681 | void acquire_console_sem(void) | |
682 | { | |
683 | if (in_interrupt()) | |
684 | BUG(); | |
685 | down(&console_sem); | |
686 | console_locked = 1; | |
687 | console_may_schedule = 1; | |
688 | } | |
689 | EXPORT_SYMBOL(acquire_console_sem); | |
690 | ||
691 | int try_acquire_console_sem(void) | |
692 | { | |
693 | if (down_trylock(&console_sem)) | |
694 | return -1; | |
695 | console_locked = 1; | |
696 | console_may_schedule = 0; | |
697 | return 0; | |
698 | } | |
699 | EXPORT_SYMBOL(try_acquire_console_sem); | |
700 | ||
701 | int is_console_locked(void) | |
702 | { | |
703 | return console_locked; | |
704 | } | |
705 | EXPORT_SYMBOL(is_console_locked); | |
706 | ||
707 | /** | |
708 | * release_console_sem - unlock the console system | |
709 | * | |
710 | * Releases the semaphore which the caller holds on the console system | |
711 | * and the console driver list. | |
712 | * | |
713 | * While the semaphore was held, console output may have been buffered | |
714 | * by printk(). If this is the case, release_console_sem() emits | |
715 | * the output prior to releasing the semaphore. | |
716 | * | |
717 | * If there is output waiting for klogd, we wake it up. | |
718 | * | |
719 | * release_console_sem() may be called from any context. | |
720 | */ | |
721 | void release_console_sem(void) | |
722 | { | |
723 | unsigned long flags; | |
724 | unsigned long _con_start, _log_end; | |
725 | unsigned long wake_klogd = 0; | |
726 | ||
727 | for ( ; ; ) { | |
728 | spin_lock_irqsave(&logbuf_lock, flags); | |
729 | wake_klogd |= log_start - log_end; | |
730 | if (con_start == log_end) | |
731 | break; /* Nothing to print */ | |
732 | _con_start = con_start; | |
733 | _log_end = log_end; | |
734 | con_start = log_end; /* Flush */ | |
735 | spin_unlock(&logbuf_lock); | |
736 | call_console_drivers(_con_start, _log_end); | |
737 | local_irq_restore(flags); | |
738 | } | |
739 | console_locked = 0; | |
740 | console_may_schedule = 0; | |
741 | up(&console_sem); | |
742 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
743 | if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait)) | |
744 | wake_up_interruptible(&log_wait); | |
745 | } | |
746 | EXPORT_SYMBOL(release_console_sem); | |
747 | ||
748 | /** console_conditional_schedule - yield the CPU if required | |
749 | * | |
750 | * If the console code is currently allowed to sleep, and | |
751 | * if this CPU should yield the CPU to another task, do | |
752 | * so here. | |
753 | * | |
754 | * Must be called within acquire_console_sem(). | |
755 | */ | |
756 | void __sched console_conditional_schedule(void) | |
757 | { | |
758 | if (console_may_schedule) | |
759 | cond_resched(); | |
760 | } | |
761 | EXPORT_SYMBOL(console_conditional_schedule); | |
762 | ||
763 | void console_print(const char *s) | |
764 | { | |
765 | printk(KERN_EMERG "%s", s); | |
766 | } | |
767 | EXPORT_SYMBOL(console_print); | |
768 | ||
769 | void console_unblank(void) | |
770 | { | |
771 | struct console *c; | |
772 | ||
773 | /* | |
774 | * console_unblank can no longer be called in interrupt context unless | |
775 | * oops_in_progress is set to 1.. | |
776 | */ | |
777 | if (oops_in_progress) { | |
778 | if (down_trylock(&console_sem) != 0) | |
779 | return; | |
780 | } else | |
781 | acquire_console_sem(); | |
782 | ||
783 | console_locked = 1; | |
784 | console_may_schedule = 0; | |
785 | for (c = console_drivers; c != NULL; c = c->next) | |
786 | if ((c->flags & CON_ENABLED) && c->unblank) | |
787 | c->unblank(); | |
788 | release_console_sem(); | |
789 | } | |
790 | EXPORT_SYMBOL(console_unblank); | |
791 | ||
792 | /* | |
793 | * Return the console tty driver structure and its associated index | |
794 | */ | |
795 | struct tty_driver *console_device(int *index) | |
796 | { | |
797 | struct console *c; | |
798 | struct tty_driver *driver = NULL; | |
799 | ||
800 | acquire_console_sem(); | |
801 | for (c = console_drivers; c != NULL; c = c->next) { | |
802 | if (!c->device) | |
803 | continue; | |
804 | driver = c->device(c, index); | |
805 | if (driver) | |
806 | break; | |
807 | } | |
808 | release_console_sem(); | |
809 | return driver; | |
810 | } | |
811 | ||
812 | /* | |
813 | * Prevent further output on the passed console device so that (for example) | |
814 | * serial drivers can disable console output before suspending a port, and can | |
815 | * re-enable output afterwards. | |
816 | */ | |
817 | void console_stop(struct console *console) | |
818 | { | |
819 | acquire_console_sem(); | |
820 | console->flags &= ~CON_ENABLED; | |
821 | release_console_sem(); | |
822 | } | |
823 | EXPORT_SYMBOL(console_stop); | |
824 | ||
825 | void console_start(struct console *console) | |
826 | { | |
827 | acquire_console_sem(); | |
828 | console->flags |= CON_ENABLED; | |
829 | release_console_sem(); | |
830 | } | |
831 | EXPORT_SYMBOL(console_start); | |
832 | ||
833 | /* | |
834 | * The console driver calls this routine during kernel initialization | |
835 | * to register the console printing procedure with printk() and to | |
836 | * print any messages that were printed by the kernel before the | |
837 | * console driver was initialized. | |
838 | */ | |
839 | void register_console(struct console * console) | |
840 | { | |
841 | int i; | |
842 | unsigned long flags; | |
843 | ||
844 | if (preferred_console < 0) | |
845 | preferred_console = selected_console; | |
846 | ||
847 | /* | |
848 | * See if we want to use this console driver. If we | |
849 | * didn't select a console we take the first one | |
850 | * that registers here. | |
851 | */ | |
852 | if (preferred_console < 0) { | |
853 | if (console->index < 0) | |
854 | console->index = 0; | |
855 | if (console->setup == NULL || | |
856 | console->setup(console, NULL) == 0) { | |
857 | console->flags |= CON_ENABLED | CON_CONSDEV; | |
858 | preferred_console = 0; | |
859 | } | |
860 | } | |
861 | ||
862 | /* | |
863 | * See if this console matches one we selected on | |
864 | * the command line. | |
865 | */ | |
866 | for(i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) { | |
867 | if (strcmp(console_cmdline[i].name, console->name) != 0) | |
868 | continue; | |
869 | if (console->index >= 0 && | |
870 | console->index != console_cmdline[i].index) | |
871 | continue; | |
872 | if (console->index < 0) | |
873 | console->index = console_cmdline[i].index; | |
874 | if (console->setup && | |
875 | console->setup(console, console_cmdline[i].options) != 0) | |
876 | break; | |
877 | console->flags |= CON_ENABLED; | |
878 | console->index = console_cmdline[i].index; | |
879 | if (i == preferred_console) | |
880 | console->flags |= CON_CONSDEV; | |
881 | break; | |
882 | } | |
883 | ||
884 | if (!(console->flags & CON_ENABLED)) | |
885 | return; | |
886 | ||
887 | if (console_drivers && (console_drivers->flags & CON_BOOT)) { | |
888 | unregister_console(console_drivers); | |
889 | console->flags &= ~CON_PRINTBUFFER; | |
890 | } | |
891 | ||
892 | /* | |
893 | * Put this console in the list - keep the | |
894 | * preferred driver at the head of the list. | |
895 | */ | |
896 | acquire_console_sem(); | |
897 | if ((console->flags & CON_CONSDEV) || console_drivers == NULL) { | |
898 | console->next = console_drivers; | |
899 | console_drivers = console; | |
900 | } else { | |
901 | console->next = console_drivers->next; | |
902 | console_drivers->next = console; | |
903 | } | |
904 | if (console->flags & CON_PRINTBUFFER) { | |
905 | /* | |
906 | * release_console_sem() will print out the buffered messages | |
907 | * for us. | |
908 | */ | |
909 | spin_lock_irqsave(&logbuf_lock, flags); | |
910 | con_start = log_start; | |
911 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
912 | } | |
913 | release_console_sem(); | |
914 | } | |
915 | EXPORT_SYMBOL(register_console); | |
916 | ||
917 | int unregister_console(struct console * console) | |
918 | { | |
919 | struct console *a,*b; | |
920 | int res = 1; | |
921 | ||
922 | acquire_console_sem(); | |
923 | if (console_drivers == console) { | |
924 | console_drivers=console->next; | |
925 | res = 0; | |
926 | } else { | |
927 | for (a=console_drivers->next, b=console_drivers ; | |
928 | a; b=a, a=b->next) { | |
929 | if (a == console) { | |
930 | b->next = a->next; | |
931 | res = 0; | |
932 | break; | |
933 | } | |
934 | } | |
935 | } | |
936 | ||
937 | /* If last console is removed, we re-enable picking the first | |
938 | * one that gets registered. Without that, pmac early boot console | |
939 | * would prevent fbcon from taking over. | |
940 | */ | |
941 | if (console_drivers == NULL) | |
942 | preferred_console = selected_console; | |
943 | ||
944 | ||
945 | release_console_sem(); | |
946 | return res; | |
947 | } | |
948 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 949 | |
1da177e4 LT |
950 | /** |
951 | * tty_write_message - write a message to a certain tty, not just the console. | |
952 | * | |
953 | * This is used for messages that need to be redirected to a specific tty. | |
954 | * We don't put it into the syslog queue right now maybe in the future if | |
955 | * really needed. | |
956 | */ | |
957 | void tty_write_message(struct tty_struct *tty, char *msg) | |
958 | { | |
959 | if (tty && tty->driver->write) | |
960 | tty->driver->write(tty, msg, strlen(msg)); | |
961 | return; | |
962 | } | |
963 | ||
964 | /* | |
965 | * printk rate limiting, lifted from the networking subsystem. | |
966 | * | |
967 | * This enforces a rate limit: not more than one kernel message | |
968 | * every printk_ratelimit_jiffies to make a denial-of-service | |
969 | * attack impossible. | |
970 | */ | |
971 | int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst) | |
972 | { | |
973 | static DEFINE_SPINLOCK(ratelimit_lock); | |
974 | static unsigned long toks = 10*5*HZ; | |
975 | static unsigned long last_msg; | |
976 | static int missed; | |
977 | unsigned long flags; | |
978 | unsigned long now = jiffies; | |
979 | ||
980 | spin_lock_irqsave(&ratelimit_lock, flags); | |
981 | toks += now - last_msg; | |
982 | last_msg = now; | |
983 | if (toks > (ratelimit_burst * ratelimit_jiffies)) | |
984 | toks = ratelimit_burst * ratelimit_jiffies; | |
985 | if (toks >= ratelimit_jiffies) { | |
986 | int lost = missed; | |
987 | missed = 0; | |
988 | toks -= ratelimit_jiffies; | |
989 | spin_unlock_irqrestore(&ratelimit_lock, flags); | |
990 | if (lost) | |
991 | printk(KERN_WARNING "printk: %d messages suppressed.\n", lost); | |
992 | return 1; | |
993 | } | |
994 | missed++; | |
995 | spin_unlock_irqrestore(&ratelimit_lock, flags); | |
996 | return 0; | |
997 | } | |
998 | EXPORT_SYMBOL(__printk_ratelimit); | |
999 | ||
1000 | /* minimum time in jiffies between messages */ | |
1001 | int printk_ratelimit_jiffies = 5*HZ; | |
1002 | ||
1003 | /* number of messages we send before ratelimiting */ | |
1004 | int printk_ratelimit_burst = 10; | |
1005 | ||
1006 | int printk_ratelimit(void) | |
1007 | { | |
1008 | return __printk_ratelimit(printk_ratelimit_jiffies, | |
1009 | printk_ratelimit_burst); | |
1010 | } | |
1011 | EXPORT_SYMBOL(printk_ratelimit); |