Annotation of /alx-src/tags/kernel26-2.6.12-alx-r9/kernel/printk.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 25804 byte(s)
Tag kernel26-2.6.12-alx-r9
1 | niro | 628 | /* |
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 | |||
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 */ | ||
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 | |||
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 | |||
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 | static int __init log_buf_len_setup(char *str) | ||
164 | { | ||
165 | unsigned long size = memparse(str, &str); | ||
166 | unsigned long flags; | ||
167 | |||
168 | if (size) | ||
169 | size = roundup_pow_of_two(size); | ||
170 | if (size > log_buf_len) { | ||
171 | unsigned long start, dest_idx, offset; | ||
172 | char * new_log_buf; | ||
173 | |||
174 | new_log_buf = alloc_bootmem(size); | ||
175 | if (!new_log_buf) { | ||
176 | printk("log_buf_len: allocation failed\n"); | ||
177 | goto out; | ||
178 | } | ||
179 | |||
180 | spin_lock_irqsave(&logbuf_lock, flags); | ||
181 | log_buf_len = size; | ||
182 | log_buf = new_log_buf; | ||
183 | |||
184 | offset = start = min(con_start, log_start); | ||
185 | dest_idx = 0; | ||
186 | while (start != log_end) { | ||
187 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | ||
188 | start++; | ||
189 | dest_idx++; | ||
190 | } | ||
191 | log_start -= offset; | ||
192 | con_start -= offset; | ||
193 | log_end -= offset; | ||
194 | spin_unlock_irqrestore(&logbuf_lock, flags); | ||
195 | |||
196 | printk("log_buf_len: %d\n", log_buf_len); | ||
197 | } | ||
198 | out: | ||
199 | |||
200 | return 1; | ||
201 | } | ||
202 | |||
203 | __setup("log_buf_len=", log_buf_len_setup); | ||
204 | |||
205 | /* | ||
206 | * Commands to do_syslog: | ||
207 | * | ||
208 | * 0 -- Close the log. Currently a NOP. | ||
209 | * 1 -- Open the log. Currently a NOP. | ||
210 | * 2 -- Read from the log. | ||
211 | * 3 -- Read all messages remaining in the ring buffer. | ||
212 | * 4 -- Read and clear all messages remaining in the ring buffer | ||
213 | * 5 -- Clear ring buffer. | ||
214 | * 6 -- Disable printk's to console | ||
215 | * 7 -- Enable printk's to console | ||
216 | * 8 -- Set level of messages printed to console | ||
217 | * 9 -- Return number of unread characters in the log buffer | ||
218 | * 10 -- Return size of the log buffer | ||
219 | */ | ||
220 | int do_syslog(int type, char __user * buf, int len) | ||
221 | { | ||
222 | unsigned long i, j, limit, count; | ||
223 | int do_clear = 0; | ||
224 | char c; | ||
225 | int error = 0; | ||
226 | |||
227 | error = security_syslog(type); | ||
228 | if (error) | ||
229 | return error; | ||
230 | |||
231 | switch (type) { | ||
232 | case 0: /* Close log */ | ||
233 | break; | ||
234 | case 1: /* Open log */ | ||
235 | break; | ||
236 | case 2: /* Read from log */ | ||
237 | error = -EINVAL; | ||
238 | if (!buf || len < 0) | ||
239 | goto out; | ||
240 | error = 0; | ||
241 | if (!len) | ||
242 | goto out; | ||
243 | if (!access_ok(VERIFY_WRITE, buf, len)) { | ||
244 | error = -EFAULT; | ||
245 | goto out; | ||
246 | } | ||
247 | error = wait_event_interruptible(log_wait, (log_start - log_end)); | ||
248 | if (error) | ||
249 | goto out; | ||
250 | i = 0; | ||
251 | spin_lock_irq(&logbuf_lock); | ||
252 | while (!error && (log_start != log_end) && i < len) { | ||
253 | c = LOG_BUF(log_start); | ||
254 | log_start++; | ||
255 | spin_unlock_irq(&logbuf_lock); | ||
256 | error = __put_user(c,buf); | ||
257 | buf++; | ||
258 | i++; | ||
259 | cond_resched(); | ||
260 | spin_lock_irq(&logbuf_lock); | ||
261 | } | ||
262 | spin_unlock_irq(&logbuf_lock); | ||
263 | if (!error) | ||
264 | error = i; | ||
265 | break; | ||
266 | case 4: /* Read/clear last kernel messages */ | ||
267 | do_clear = 1; | ||
268 | /* FALL THRU */ | ||
269 | case 3: /* Read last kernel messages */ | ||
270 | error = -EINVAL; | ||
271 | if (!buf || len < 0) | ||
272 | goto out; | ||
273 | error = 0; | ||
274 | if (!len) | ||
275 | goto out; | ||
276 | if (!access_ok(VERIFY_WRITE, buf, len)) { | ||
277 | error = -EFAULT; | ||
278 | goto out; | ||
279 | } | ||
280 | count = len; | ||
281 | if (count > log_buf_len) | ||
282 | count = log_buf_len; | ||
283 | spin_lock_irq(&logbuf_lock); | ||
284 | if (count > logged_chars) | ||
285 | count = logged_chars; | ||
286 | if (do_clear) | ||
287 | logged_chars = 0; | ||
288 | limit = log_end; | ||
289 | /* | ||
290 | * __put_user() could sleep, and while we sleep | ||
291 | * printk() could overwrite the messages | ||
292 | * we try to copy to user space. Therefore | ||
293 | * the messages are copied in reverse. <manfreds> | ||
294 | */ | ||
295 | for(i = 0; i < count && !error; i++) { | ||
296 | j = limit-1-i; | ||
297 | if (j + log_buf_len < log_end) | ||
298 | break; | ||
299 | c = LOG_BUF(j); | ||
300 | spin_unlock_irq(&logbuf_lock); | ||
301 | error = __put_user(c,&buf[count-1-i]); | ||
302 | cond_resched(); | ||
303 | spin_lock_irq(&logbuf_lock); | ||
304 | } | ||
305 | spin_unlock_irq(&logbuf_lock); | ||
306 | if (error) | ||
307 | break; | ||
308 | error = i; | ||
309 | if(i != count) { | ||
310 | int offset = count-error; | ||
311 | /* buffer overflow during copy, correct user buffer. */ | ||
312 | for(i=0;i<error;i++) { | ||
313 | if (__get_user(c,&buf[i+offset]) || | ||
314 | __put_user(c,&buf[i])) { | ||
315 | error = -EFAULT; | ||
316 | break; | ||
317 | } | ||
318 | cond_resched(); | ||
319 | } | ||
320 | } | ||
321 | break; | ||
322 | case 5: /* Clear ring buffer */ | ||
323 | logged_chars = 0; | ||
324 | break; | ||
325 | case 6: /* Disable logging to console */ | ||
326 | console_loglevel = minimum_console_loglevel; | ||
327 | break; | ||
328 | case 7: /* Enable logging to console */ | ||
329 | console_loglevel = default_console_loglevel; | ||
330 | break; | ||
331 | case 8: /* Set level of messages printed to console */ | ||
332 | error = -EINVAL; | ||
333 | if (len < 1 || len > 8) | ||
334 | goto out; | ||
335 | if (len < minimum_console_loglevel) | ||
336 | len = minimum_console_loglevel; | ||
337 | console_loglevel = len; | ||
338 | error = 0; | ||
339 | break; | ||
340 | case 9: /* Number of chars in the log buffer */ | ||
341 | error = log_end - log_start; | ||
342 | break; | ||
343 | case 10: /* Size of the log buffer */ | ||
344 | error = log_buf_len; | ||
345 | break; | ||
346 | default: | ||
347 | error = -EINVAL; | ||
348 | break; | ||
349 | } | ||
350 | out: | ||
351 | return error; | ||
352 | } | ||
353 | |||
354 | asmlinkage long sys_syslog(int type, char __user * buf, int len) | ||
355 | { | ||
356 | return do_syslog(type, buf, len); | ||
357 | } | ||
358 | |||
359 | /* | ||
360 | * Call the console drivers on a range of log_buf | ||
361 | */ | ||
362 | static void __call_console_drivers(unsigned long start, unsigned long end) | ||
363 | { | ||
364 | struct console *con; | ||
365 | |||
366 | for (con = console_drivers; con; con = con->next) { | ||
367 | if ((con->flags & CON_ENABLED) && con->write) | ||
368 | con->write(con, &LOG_BUF(start), end - start); | ||
369 | } | ||
370 | } | ||
371 | |||
372 | /* | ||
373 | * Write out chars from start to end - 1 inclusive | ||
374 | */ | ||
375 | static void _call_console_drivers(unsigned long start, | ||
376 | unsigned long end, int msg_log_level) | ||
377 | { | ||
378 | if (msg_log_level < console_loglevel && | ||
379 | console_drivers && start != end) { | ||
380 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | ||
381 | /* wrapped write */ | ||
382 | __call_console_drivers(start & LOG_BUF_MASK, | ||
383 | log_buf_len); | ||
384 | __call_console_drivers(0, end & LOG_BUF_MASK); | ||
385 | } else { | ||
386 | __call_console_drivers(start, end); | ||
387 | } | ||
388 | } | ||
389 | } | ||
390 | |||
391 | /* | ||
392 | * Call the console drivers, asking them to write out | ||
393 | * log_buf[start] to log_buf[end - 1]. | ||
394 | * The console_sem must be held. | ||
395 | */ | ||
396 | static void call_console_drivers(unsigned long start, unsigned long end) | ||
397 | { | ||
398 | unsigned long cur_index, start_print; | ||
399 | static int msg_level = -1; | ||
400 | |||
401 | if (((long)(start - end)) > 0) | ||
402 | BUG(); | ||
403 | |||
404 | cur_index = start; | ||
405 | start_print = start; | ||
406 | while (cur_index != end) { | ||
407 | if ( msg_level < 0 && | ||
408 | ((end - cur_index) > 2) && | ||
409 | LOG_BUF(cur_index + 0) == '<' && | ||
410 | LOG_BUF(cur_index + 1) >= '0' && | ||
411 | LOG_BUF(cur_index + 1) <= '7' && | ||
412 | LOG_BUF(cur_index + 2) == '>') | ||
413 | { | ||
414 | msg_level = LOG_BUF(cur_index + 1) - '0'; | ||
415 | cur_index += 3; | ||
416 | start_print = cur_index; | ||
417 | } | ||
418 | while (cur_index != end) { | ||
419 | char c = LOG_BUF(cur_index); | ||
420 | cur_index++; | ||
421 | |||
422 | if (c == '\n') { | ||
423 | if (msg_level < 0) { | ||
424 | /* | ||
425 | * printk() has already given us loglevel tags in | ||
426 | * the buffer. This code is here in case the | ||
427 | * log buffer has wrapped right round and scribbled | ||
428 | * on those tags | ||
429 | */ | ||
430 | msg_level = default_message_loglevel; | ||
431 | } | ||
432 | _call_console_drivers(start_print, cur_index, msg_level); | ||
433 | msg_level = -1; | ||
434 | start_print = cur_index; | ||
435 | break; | ||
436 | } | ||
437 | } | ||
438 | } | ||
439 | _call_console_drivers(start_print, end, msg_level); | ||
440 | } | ||
441 | |||
442 | static void emit_log_char(char c) | ||
443 | { | ||
444 | LOG_BUF(log_end) = c; | ||
445 | log_end++; | ||
446 | if (log_end - log_start > log_buf_len) | ||
447 | log_start = log_end - log_buf_len; | ||
448 | if (log_end - con_start > log_buf_len) | ||
449 | con_start = log_end - log_buf_len; | ||
450 | if (logged_chars < log_buf_len) | ||
451 | logged_chars++; | ||
452 | } | ||
453 | |||
454 | /* | ||
455 | * Zap console related locks when oopsing. Only zap at most once | ||
456 | * every 10 seconds, to leave time for slow consoles to print a | ||
457 | * full oops. | ||
458 | */ | ||
459 | static void zap_locks(void) | ||
460 | { | ||
461 | static unsigned long oops_timestamp; | ||
462 | |||
463 | if (time_after_eq(jiffies, oops_timestamp) && | ||
464 | !time_after(jiffies, oops_timestamp + 30*HZ)) | ||
465 | return; | ||
466 | |||
467 | oops_timestamp = jiffies; | ||
468 | |||
469 | /* If a crash is occurring, make sure we can't deadlock */ | ||
470 | spin_lock_init(&logbuf_lock); | ||
471 | /* And make sure that we print immediately */ | ||
472 | init_MUTEX(&console_sem); | ||
473 | } | ||
474 | |||
475 | #if defined(CONFIG_PRINTK_TIME) | ||
476 | static int printk_time = 1; | ||
477 | #else | ||
478 | static int printk_time = 0; | ||
479 | #endif | ||
480 | |||
481 | static int __init printk_time_setup(char *str) | ||
482 | { | ||
483 | if (*str) | ||
484 | return 0; | ||
485 | printk_time = 1; | ||
486 | return 1; | ||
487 | } | ||
488 | |||
489 | __setup("time", printk_time_setup); | ||
490 | |||
491 | /* | ||
492 | * This is printk. It can be called from any context. We want it to work. | ||
493 | * | ||
494 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and | ||
495 | * call the console drivers. If we fail to get the semaphore we place the output | ||
496 | * into the log buffer and return. The current holder of the console_sem will | ||
497 | * notice the new output in release_console_sem() and will send it to the | ||
498 | * consoles before releasing the semaphore. | ||
499 | * | ||
500 | * One effect of this deferred printing is that code which calls printk() and | ||
501 | * then changes console_loglevel may break. This is because console_loglevel | ||
502 | * is inspected when the actual printing occurs. | ||
503 | */ | ||
504 | |||
505 | asmlinkage int printk(const char *fmt, ...) | ||
506 | { | ||
507 | va_list args; | ||
508 | int r; | ||
509 | |||
510 | va_start(args, fmt); | ||
511 | r = vprintk(fmt, args); | ||
512 | va_end(args); | ||
513 | |||
514 | return r; | ||
515 | } | ||
516 | |||
517 | asmlinkage int vprintk(const char *fmt, va_list args) | ||
518 | { | ||
519 | unsigned long flags; | ||
520 | int printed_len; | ||
521 | char *p; | ||
522 | static char printk_buf[1024]; | ||
523 | static int log_level_unknown = 1; | ||
524 | |||
525 | if (unlikely(oops_in_progress)) | ||
526 | zap_locks(); | ||
527 | |||
528 | /* This stops the holder of console_sem just where we want him */ | ||
529 | spin_lock_irqsave(&logbuf_lock, flags); | ||
530 | |||
531 | /* Emit the output into the temporary buffer */ | ||
532 | printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args); | ||
533 | |||
534 | /* | ||
535 | * Copy the output into log_buf. If the caller didn't provide | ||
536 | * appropriate log level tags, we insert them here | ||
537 | */ | ||
538 | for (p = printk_buf; *p; p++) { | ||
539 | if (log_level_unknown) { | ||
540 | /* log_level_unknown signals the start of a new line */ | ||
541 | if (printk_time) { | ||
542 | int loglev_char; | ||
543 | char tbuf[50], *tp; | ||
544 | unsigned tlen; | ||
545 | unsigned long long t; | ||
546 | unsigned long nanosec_rem; | ||
547 | |||
548 | /* | ||
549 | * force the log level token to be | ||
550 | * before the time output. | ||
551 | */ | ||
552 | if (p[0] == '<' && p[1] >='0' && | ||
553 | p[1] <= '7' && p[2] == '>') { | ||
554 | loglev_char = p[1]; | ||
555 | p += 3; | ||
556 | printed_len += 3; | ||
557 | } else { | ||
558 | loglev_char = default_message_loglevel | ||
559 | + '0'; | ||
560 | } | ||
561 | t = sched_clock(); | ||
562 | nanosec_rem = do_div(t, 1000000000); | ||
563 | tlen = sprintf(tbuf, | ||
564 | "<%c>[%5lu.%06lu] ", | ||
565 | loglev_char, | ||
566 | (unsigned long)t, | ||
567 | nanosec_rem/1000); | ||
568 | |||
569 | for (tp = tbuf; tp < tbuf + tlen; tp++) | ||
570 | emit_log_char(*tp); | ||
571 | printed_len += tlen - 3; | ||
572 | } else { | ||
573 | if (p[0] != '<' || p[1] < '0' || | ||
574 | p[1] > '7' || p[2] != '>') { | ||
575 | emit_log_char('<'); | ||
576 | emit_log_char(default_message_loglevel | ||
577 | + '0'); | ||
578 | emit_log_char('>'); | ||
579 | } | ||
580 | printed_len += 3; | ||
581 | } | ||
582 | log_level_unknown = 0; | ||
583 | if (!*p) | ||
584 | break; | ||
585 | } | ||
586 | emit_log_char(*p); | ||
587 | if (*p == '\n') | ||
588 | log_level_unknown = 1; | ||
589 | } | ||
590 | |||
591 | if (!cpu_online(smp_processor_id()) && | ||
592 | system_state != SYSTEM_RUNNING) { | ||
593 | /* | ||
594 | * Some console drivers may assume that per-cpu resources have | ||
595 | * been allocated. So don't allow them to be called by this | ||
596 | * CPU until it is officially up. We shouldn't be calling into | ||
597 | * random console drivers on a CPU which doesn't exist yet.. | ||
598 | */ | ||
599 | spin_unlock_irqrestore(&logbuf_lock, flags); | ||
600 | goto out; | ||
601 | } | ||
602 | if (!down_trylock(&console_sem)) { | ||
603 | console_locked = 1; | ||
604 | /* | ||
605 | * We own the drivers. We can drop the spinlock and let | ||
606 | * release_console_sem() print the text | ||
607 | */ | ||
608 | spin_unlock_irqrestore(&logbuf_lock, flags); | ||
609 | console_may_schedule = 0; | ||
610 | release_console_sem(); | ||
611 | } else { | ||
612 | /* | ||
613 | * Someone else owns the drivers. We drop the spinlock, which | ||
614 | * allows the semaphore holder to proceed and to call the | ||
615 | * console drivers with the output which we just produced. | ||
616 | */ | ||
617 | spin_unlock_irqrestore(&logbuf_lock, flags); | ||
618 | } | ||
619 | out: | ||
620 | return printed_len; | ||
621 | } | ||
622 | EXPORT_SYMBOL(printk); | ||
623 | EXPORT_SYMBOL(vprintk); | ||
624 | |||
625 | #else | ||
626 | |||
627 | asmlinkage long sys_syslog(int type, char __user * buf, int len) | ||
628 | { | ||
629 | return 0; | ||
630 | } | ||
631 | |||
632 | int do_syslog(int type, char __user * buf, int len) { return 0; } | ||
633 | static void call_console_drivers(unsigned long start, unsigned long end) {} | ||
634 | |||
635 | #endif | ||
636 | |||
637 | /** | ||
638 | * add_preferred_console - add a device to the list of preferred consoles. | ||
639 | * | ||
640 | * The last preferred console added will be used for kernel messages | ||
641 | * and stdin/out/err for init. Normally this is used by console_setup | ||
642 | * above to handle user-supplied console arguments; however it can also | ||
643 | * be used by arch-specific code either to override the user or more | ||
644 | * commonly to provide a default console (ie from PROM variables) when | ||
645 | * the user has not supplied one. | ||
646 | */ | ||
647 | int __init add_preferred_console(char *name, int idx, char *options) | ||
648 | { | ||
649 | struct console_cmdline *c; | ||
650 | int i; | ||
651 | |||
652 | /* | ||
653 | * See if this tty is not yet registered, and | ||
654 | * if we have a slot free. | ||
655 | */ | ||
656 | for(i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | ||
657 | if (strcmp(console_cmdline[i].name, name) == 0 && | ||
658 | console_cmdline[i].index == idx) { | ||
659 | selected_console = i; | ||
660 | return 0; | ||
661 | } | ||
662 | if (i == MAX_CMDLINECONSOLES) | ||
663 | return -E2BIG; | ||
664 | selected_console = i; | ||
665 | c = &console_cmdline[i]; | ||
666 | memcpy(c->name, name, sizeof(c->name)); | ||
667 | c->name[sizeof(c->name) - 1] = 0; | ||
668 | c->options = options; | ||
669 | c->index = idx; | ||
670 | return 0; | ||
671 | } | ||
672 | |||
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); | ||
949 | |||
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); |