Contents 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, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 25804 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | |
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); |