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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. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 | 15 | * Rewrote bits to get rid of console_lock |
e1f8e874 | 16 | * 01Mar01 Andrew Morton |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
1da177e4 LT |
23 | #include <linux/console.h> |
24 | #include <linux/init.h> | |
bfe8df3d RD |
25 | #include <linux/jiffies.h> |
26 | #include <linux/nmi.h> | |
1da177e4 | 27 | #include <linux/module.h> |
3b9c0410 | 28 | #include <linux/moduleparam.h> |
1da177e4 | 29 | #include <linux/interrupt.h> /* For in_interrupt() */ |
1da177e4 LT |
30 | #include <linux/delay.h> |
31 | #include <linux/smp.h> | |
32 | #include <linux/security.h> | |
33 | #include <linux/bootmem.h> | |
34 | #include <linux/syscalls.h> | |
35 | ||
36 | #include <asm/uaccess.h> | |
37 | ||
076f9776 IM |
38 | /* |
39 | * Architectures can override it: | |
40 | */ | |
e17ba73b | 41 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
076f9776 IM |
42 | { |
43 | } | |
44 | ||
1da177e4 LT |
45 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
46 | ||
47 | /* printk's without a loglevel use this.. */ | |
48 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ | |
49 | ||
50 | /* We show everything that is MORE important than this.. */ | |
51 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
52 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
53 | ||
54 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
55 | ||
56 | int console_printk[4] = { | |
57 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
58 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
59 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
60 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
61 | }; | |
62 | ||
1da177e4 | 63 | /* |
0bbfb7c2 | 64 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
65 | * their unblank() callback or not. So let's export it. |
66 | */ | |
67 | int oops_in_progress; | |
68 | EXPORT_SYMBOL(oops_in_progress); | |
69 | ||
70 | /* | |
71 | * console_sem protects the console_drivers list, and also | |
72 | * provides serialisation for access to the entire console | |
73 | * driver system. | |
74 | */ | |
75 | static DECLARE_MUTEX(console_sem); | |
557240b4 | 76 | static DECLARE_MUTEX(secondary_console_sem); |
1da177e4 | 77 | struct console *console_drivers; |
a29d1cfe IM |
78 | EXPORT_SYMBOL_GPL(console_drivers); |
79 | ||
1da177e4 LT |
80 | /* |
81 | * This is used for debugging the mess that is the VT code by | |
82 | * keeping track if we have the console semaphore held. It's | |
83 | * definitely not the perfect debug tool (we don't know if _WE_ | |
84 | * hold it are racing, but it helps tracking those weird code | |
85 | * path in the console code where we end up in places I want | |
86 | * locked without the console sempahore held | |
87 | */ | |
557240b4 | 88 | static int console_locked, console_suspended; |
1da177e4 LT |
89 | |
90 | /* | |
91 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
92 | * It is also used in interesting ways to provide interlocking in | |
93 | * release_console_sem(). | |
94 | */ | |
95 | static DEFINE_SPINLOCK(logbuf_lock); | |
96 | ||
eed4a2ab | 97 | #define LOG_BUF_MASK (log_buf_len-1) |
1da177e4 LT |
98 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
99 | ||
100 | /* | |
101 | * The indices into log_buf are not constrained to log_buf_len - they | |
102 | * must be masked before subscripting | |
103 | */ | |
eed4a2ab DV |
104 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
105 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ | |
106 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
107 | |
108 | /* | |
109 | * Array of consoles built from command line options (console=) | |
110 | */ | |
111 | struct console_cmdline | |
112 | { | |
113 | char name[8]; /* Name of the driver */ | |
114 | int index; /* Minor dev. to use */ | |
115 | char *options; /* Options for the driver */ | |
f7511d5f ST |
116 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
117 | char *brl_options; /* Options for braille driver */ | |
118 | #endif | |
1da177e4 LT |
119 | }; |
120 | ||
121 | #define MAX_CMDLINECONSOLES 8 | |
122 | ||
123 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
124 | static int selected_console = -1; | |
125 | static int preferred_console = -1; | |
9e124fe1 MA |
126 | int console_set_on_cmdline; |
127 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
128 | |
129 | /* Flag: console code may call schedule() */ | |
130 | static int console_may_schedule; | |
131 | ||
d59745ce MM |
132 | #ifdef CONFIG_PRINTK |
133 | ||
134 | static char __log_buf[__LOG_BUF_LEN]; | |
135 | static char *log_buf = __log_buf; | |
136 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 137 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
d59745ce | 138 | |
1da177e4 LT |
139 | static int __init log_buf_len_setup(char *str) |
140 | { | |
eed4a2ab | 141 | unsigned size = memparse(str, &str); |
1da177e4 LT |
142 | unsigned long flags; |
143 | ||
144 | if (size) | |
145 | size = roundup_pow_of_two(size); | |
146 | if (size > log_buf_len) { | |
eed4a2ab | 147 | unsigned start, dest_idx, offset; |
40dc5651 | 148 | char *new_log_buf; |
1da177e4 LT |
149 | |
150 | new_log_buf = alloc_bootmem(size); | |
151 | if (!new_log_buf) { | |
40dc5651 | 152 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
153 | goto out; |
154 | } | |
155 | ||
156 | spin_lock_irqsave(&logbuf_lock, flags); | |
157 | log_buf_len = size; | |
158 | log_buf = new_log_buf; | |
159 | ||
160 | offset = start = min(con_start, log_start); | |
161 | dest_idx = 0; | |
162 | while (start != log_end) { | |
163 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
164 | start++; | |
165 | dest_idx++; | |
166 | } | |
167 | log_start -= offset; | |
168 | con_start -= offset; | |
169 | log_end -= offset; | |
170 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
171 | ||
40dc5651 | 172 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
173 | } |
174 | out: | |
1da177e4 LT |
175 | return 1; |
176 | } | |
177 | ||
178 | __setup("log_buf_len=", log_buf_len_setup); | |
179 | ||
bfe8df3d RD |
180 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
181 | ||
182 | static unsigned int boot_delay; /* msecs delay after each printk during bootup */ | |
183 | static unsigned long long printk_delay_msec; /* per msec, based on boot_delay */ | |
184 | ||
185 | static int __init boot_delay_setup(char *str) | |
186 | { | |
187 | unsigned long lpj; | |
188 | unsigned long long loops_per_msec; | |
189 | ||
190 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
191 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
192 | ||
193 | get_option(&str, &boot_delay); | |
194 | if (boot_delay > 10 * 1000) | |
195 | boot_delay = 0; | |
196 | ||
197 | printk_delay_msec = loops_per_msec; | |
198 | printk(KERN_DEBUG "boot_delay: %u, preset_lpj: %ld, lpj: %lu, " | |
199 | "HZ: %d, printk_delay_msec: %llu\n", | |
200 | boot_delay, preset_lpj, lpj, HZ, printk_delay_msec); | |
201 | return 1; | |
202 | } | |
203 | __setup("boot_delay=", boot_delay_setup); | |
204 | ||
205 | static void boot_delay_msec(void) | |
206 | { | |
207 | unsigned long long k; | |
208 | unsigned long timeout; | |
209 | ||
210 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
211 | return; | |
212 | ||
213 | k = (unsigned long long)printk_delay_msec * boot_delay; | |
214 | ||
215 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
216 | while (k) { | |
217 | k--; | |
218 | cpu_relax(); | |
219 | /* | |
220 | * use (volatile) jiffies to prevent | |
221 | * compiler reduction; loop termination via jiffies | |
222 | * is secondary and may or may not happen. | |
223 | */ | |
224 | if (time_after(jiffies, timeout)) | |
225 | break; | |
226 | touch_nmi_watchdog(); | |
227 | } | |
228 | } | |
229 | #else | |
230 | static inline void boot_delay_msec(void) | |
231 | { | |
232 | } | |
233 | #endif | |
234 | ||
0b15d04a MF |
235 | /* |
236 | * Return the number of unread characters in the log buffer. | |
237 | */ | |
7f6f3a39 | 238 | static int log_buf_get_len(void) |
0b15d04a MF |
239 | { |
240 | return logged_chars; | |
241 | } | |
242 | ||
243 | /* | |
244 | * Copy a range of characters from the log buffer. | |
245 | */ | |
246 | int log_buf_copy(char *dest, int idx, int len) | |
247 | { | |
248 | int ret, max; | |
249 | bool took_lock = false; | |
250 | ||
251 | if (!oops_in_progress) { | |
252 | spin_lock_irq(&logbuf_lock); | |
253 | took_lock = true; | |
254 | } | |
255 | ||
256 | max = log_buf_get_len(); | |
257 | if (idx < 0 || idx >= max) { | |
258 | ret = -1; | |
259 | } else { | |
260 | if (len > max) | |
261 | len = max; | |
262 | ret = len; | |
263 | idx += (log_end - max); | |
264 | while (len-- > 0) | |
265 | dest[len] = LOG_BUF(idx + len); | |
266 | } | |
267 | ||
268 | if (took_lock) | |
269 | spin_unlock_irq(&logbuf_lock); | |
270 | ||
271 | return ret; | |
272 | } | |
273 | ||
1da177e4 LT |
274 | /* |
275 | * Commands to do_syslog: | |
276 | * | |
277 | * 0 -- Close the log. Currently a NOP. | |
278 | * 1 -- Open the log. Currently a NOP. | |
279 | * 2 -- Read from the log. | |
280 | * 3 -- Read all messages remaining in the ring buffer. | |
281 | * 4 -- Read and clear all messages remaining in the ring buffer | |
282 | * 5 -- Clear ring buffer. | |
283 | * 6 -- Disable printk's to console | |
284 | * 7 -- Enable printk's to console | |
285 | * 8 -- Set level of messages printed to console | |
286 | * 9 -- Return number of unread characters in the log buffer | |
287 | * 10 -- Return size of the log buffer | |
288 | */ | |
40dc5651 | 289 | int do_syslog(int type, char __user *buf, int len) |
1da177e4 | 290 | { |
eed4a2ab | 291 | unsigned i, j, limit, count; |
1da177e4 LT |
292 | int do_clear = 0; |
293 | char c; | |
294 | int error = 0; | |
295 | ||
296 | error = security_syslog(type); | |
297 | if (error) | |
298 | return error; | |
299 | ||
300 | switch (type) { | |
301 | case 0: /* Close log */ | |
302 | break; | |
303 | case 1: /* Open log */ | |
304 | break; | |
305 | case 2: /* Read from log */ | |
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 | } | |
40dc5651 JJ |
316 | error = wait_event_interruptible(log_wait, |
317 | (log_start - log_end)); | |
1da177e4 LT |
318 | if (error) |
319 | goto out; | |
320 | i = 0; | |
321 | spin_lock_irq(&logbuf_lock); | |
322 | while (!error && (log_start != log_end) && i < len) { | |
323 | c = LOG_BUF(log_start); | |
324 | log_start++; | |
325 | spin_unlock_irq(&logbuf_lock); | |
326 | error = __put_user(c,buf); | |
327 | buf++; | |
328 | i++; | |
329 | cond_resched(); | |
330 | spin_lock_irq(&logbuf_lock); | |
331 | } | |
332 | spin_unlock_irq(&logbuf_lock); | |
333 | if (!error) | |
334 | error = i; | |
335 | break; | |
336 | case 4: /* Read/clear last kernel messages */ | |
40dc5651 | 337 | do_clear = 1; |
1da177e4 LT |
338 | /* FALL THRU */ |
339 | case 3: /* Read last kernel messages */ | |
340 | error = -EINVAL; | |
341 | if (!buf || len < 0) | |
342 | goto out; | |
343 | error = 0; | |
344 | if (!len) | |
345 | goto out; | |
346 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
347 | error = -EFAULT; | |
348 | goto out; | |
349 | } | |
350 | count = len; | |
351 | if (count > log_buf_len) | |
352 | count = log_buf_len; | |
353 | spin_lock_irq(&logbuf_lock); | |
354 | if (count > logged_chars) | |
355 | count = logged_chars; | |
356 | if (do_clear) | |
357 | logged_chars = 0; | |
358 | limit = log_end; | |
359 | /* | |
360 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 361 | * printk() could overwrite the messages |
1da177e4 LT |
362 | * we try to copy to user space. Therefore |
363 | * the messages are copied in reverse. <manfreds> | |
364 | */ | |
40dc5651 | 365 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
366 | j = limit-1-i; |
367 | if (j + log_buf_len < log_end) | |
368 | break; | |
369 | c = LOG_BUF(j); | |
370 | spin_unlock_irq(&logbuf_lock); | |
371 | error = __put_user(c,&buf[count-1-i]); | |
372 | cond_resched(); | |
373 | spin_lock_irq(&logbuf_lock); | |
374 | } | |
375 | spin_unlock_irq(&logbuf_lock); | |
376 | if (error) | |
377 | break; | |
378 | error = i; | |
40dc5651 | 379 | if (i != count) { |
1da177e4 LT |
380 | int offset = count-error; |
381 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 382 | for (i = 0; i < error; i++) { |
1da177e4 LT |
383 | if (__get_user(c,&buf[i+offset]) || |
384 | __put_user(c,&buf[i])) { | |
385 | error = -EFAULT; | |
386 | break; | |
387 | } | |
388 | cond_resched(); | |
389 | } | |
390 | } | |
391 | break; | |
392 | case 5: /* Clear ring buffer */ | |
393 | logged_chars = 0; | |
394 | break; | |
395 | case 6: /* Disable logging to console */ | |
396 | console_loglevel = minimum_console_loglevel; | |
397 | break; | |
398 | case 7: /* Enable logging to console */ | |
399 | console_loglevel = default_console_loglevel; | |
400 | break; | |
401 | case 8: /* Set level of messages printed to console */ | |
402 | error = -EINVAL; | |
403 | if (len < 1 || len > 8) | |
404 | goto out; | |
405 | if (len < minimum_console_loglevel) | |
406 | len = minimum_console_loglevel; | |
407 | console_loglevel = len; | |
408 | error = 0; | |
409 | break; | |
410 | case 9: /* Number of chars in the log buffer */ | |
411 | error = log_end - log_start; | |
412 | break; | |
413 | case 10: /* Size of the log buffer */ | |
414 | error = log_buf_len; | |
415 | break; | |
416 | default: | |
417 | error = -EINVAL; | |
418 | break; | |
419 | } | |
420 | out: | |
421 | return error; | |
422 | } | |
423 | ||
40dc5651 | 424 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
1da177e4 LT |
425 | { |
426 | return do_syslog(type, buf, len); | |
427 | } | |
428 | ||
429 | /* | |
430 | * Call the console drivers on a range of log_buf | |
431 | */ | |
eed4a2ab | 432 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
433 | { |
434 | struct console *con; | |
435 | ||
436 | for (con = console_drivers; con; con = con->next) { | |
76a8ad29 ME |
437 | if ((con->flags & CON_ENABLED) && con->write && |
438 | (cpu_online(smp_processor_id()) || | |
439 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
440 | con->write(con, &LOG_BUF(start), end - start); |
441 | } | |
442 | } | |
443 | ||
79290822 IM |
444 | static int __read_mostly ignore_loglevel; |
445 | ||
99eea6a1 | 446 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
447 | { |
448 | ignore_loglevel = 1; | |
449 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
450 | ||
c4772d99 | 451 | return 0; |
79290822 IM |
452 | } |
453 | ||
c4772d99 | 454 | early_param("ignore_loglevel", ignore_loglevel_setup); |
79290822 | 455 | |
1da177e4 LT |
456 | /* |
457 | * Write out chars from start to end - 1 inclusive | |
458 | */ | |
eed4a2ab DV |
459 | static void _call_console_drivers(unsigned start, |
460 | unsigned end, int msg_log_level) | |
1da177e4 | 461 | { |
79290822 | 462 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
463 | console_drivers && start != end) { |
464 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
465 | /* wrapped write */ | |
466 | __call_console_drivers(start & LOG_BUF_MASK, | |
467 | log_buf_len); | |
468 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
469 | } else { | |
470 | __call_console_drivers(start, end); | |
471 | } | |
472 | } | |
473 | } | |
474 | ||
475 | /* | |
476 | * Call the console drivers, asking them to write out | |
477 | * log_buf[start] to log_buf[end - 1]. | |
478 | * The console_sem must be held. | |
479 | */ | |
eed4a2ab | 480 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 481 | { |
eed4a2ab | 482 | unsigned cur_index, start_print; |
1da177e4 LT |
483 | static int msg_level = -1; |
484 | ||
eed4a2ab | 485 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
486 | |
487 | cur_index = start; | |
488 | start_print = start; | |
489 | while (cur_index != end) { | |
40dc5651 JJ |
490 | if (msg_level < 0 && ((end - cur_index) > 2) && |
491 | LOG_BUF(cur_index + 0) == '<' && | |
492 | LOG_BUF(cur_index + 1) >= '0' && | |
493 | LOG_BUF(cur_index + 1) <= '7' && | |
494 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
495 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
496 | cur_index += 3; | |
497 | start_print = cur_index; | |
498 | } | |
499 | while (cur_index != end) { | |
500 | char c = LOG_BUF(cur_index); | |
1da177e4 | 501 | |
40dc5651 | 502 | cur_index++; |
1da177e4 LT |
503 | if (c == '\n') { |
504 | if (msg_level < 0) { | |
505 | /* | |
506 | * printk() has already given us loglevel tags in | |
507 | * the buffer. This code is here in case the | |
508 | * log buffer has wrapped right round and scribbled | |
509 | * on those tags | |
510 | */ | |
511 | msg_level = default_message_loglevel; | |
512 | } | |
513 | _call_console_drivers(start_print, cur_index, msg_level); | |
514 | msg_level = -1; | |
515 | start_print = cur_index; | |
516 | break; | |
517 | } | |
518 | } | |
519 | } | |
520 | _call_console_drivers(start_print, end, msg_level); | |
521 | } | |
522 | ||
523 | static void emit_log_char(char c) | |
524 | { | |
525 | LOG_BUF(log_end) = c; | |
526 | log_end++; | |
527 | if (log_end - log_start > log_buf_len) | |
528 | log_start = log_end - log_buf_len; | |
529 | if (log_end - con_start > log_buf_len) | |
530 | con_start = log_end - log_buf_len; | |
531 | if (logged_chars < log_buf_len) | |
532 | logged_chars++; | |
533 | } | |
534 | ||
535 | /* | |
536 | * Zap console related locks when oopsing. Only zap at most once | |
537 | * every 10 seconds, to leave time for slow consoles to print a | |
538 | * full oops. | |
539 | */ | |
540 | static void zap_locks(void) | |
541 | { | |
542 | static unsigned long oops_timestamp; | |
543 | ||
544 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 545 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
546 | return; |
547 | ||
548 | oops_timestamp = jiffies; | |
549 | ||
550 | /* If a crash is occurring, make sure we can't deadlock */ | |
551 | spin_lock_init(&logbuf_lock); | |
552 | /* And make sure that we print immediately */ | |
553 | init_MUTEX(&console_sem); | |
554 | } | |
555 | ||
556 | #if defined(CONFIG_PRINTK_TIME) | |
557 | static int printk_time = 1; | |
558 | #else | |
559 | static int printk_time = 0; | |
560 | #endif | |
e84845c4 | 561 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 562 | |
76a8ad29 ME |
563 | /* Check if we have any console registered that can be called early in boot. */ |
564 | static int have_callable_console(void) | |
565 | { | |
566 | struct console *con; | |
567 | ||
568 | for (con = console_drivers; con; con = con->next) | |
569 | if (con->flags & CON_ANYTIME) | |
570 | return 1; | |
571 | ||
572 | return 0; | |
573 | } | |
574 | ||
ddad86c2 MW |
575 | /** |
576 | * printk - print a kernel message | |
577 | * @fmt: format string | |
578 | * | |
72fd4a35 | 579 | * This is printk(). It can be called from any context. We want it to work. |
1492192b JK |
580 | * Be aware of the fact that if oops_in_progress is not set, we might try to |
581 | * wake klogd up which could deadlock on runqueue lock if printk() is called | |
582 | * from scheduler code. | |
40dc5651 | 583 | * |
1da177e4 LT |
584 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
585 | * call the console drivers. If we fail to get the semaphore we place the output | |
586 | * into the log buffer and return. The current holder of the console_sem will | |
587 | * notice the new output in release_console_sem() and will send it to the | |
588 | * consoles before releasing the semaphore. | |
589 | * | |
590 | * One effect of this deferred printing is that code which calls printk() and | |
591 | * then changes console_loglevel may break. This is because console_loglevel | |
592 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
593 | * |
594 | * See also: | |
595 | * printf(3) | |
1da177e4 | 596 | */ |
d59745ce | 597 | |
1da177e4 LT |
598 | asmlinkage int printk(const char *fmt, ...) |
599 | { | |
600 | va_list args; | |
601 | int r; | |
602 | ||
603 | va_start(args, fmt); | |
604 | r = vprintk(fmt, args); | |
605 | va_end(args); | |
606 | ||
607 | return r; | |
608 | } | |
609 | ||
fe21773d DH |
610 | /* cpu currently holding logbuf_lock */ |
611 | static volatile unsigned int printk_cpu = UINT_MAX; | |
612 | ||
266c2e0a LT |
613 | /* |
614 | * Can we actually use the console at this time on this cpu? | |
615 | * | |
616 | * Console drivers may assume that per-cpu resources have | |
617 | * been allocated. So unless they're explicitly marked as | |
618 | * being able to cope (CON_ANYTIME) don't call them until | |
619 | * this CPU is officially up. | |
620 | */ | |
621 | static inline int can_use_console(unsigned int cpu) | |
622 | { | |
623 | return cpu_online(cpu) || have_callable_console(); | |
624 | } | |
625 | ||
626 | /* | |
627 | * Try to get console ownership to actually show the kernel | |
628 | * messages from a 'printk'. Return true (and with the | |
629 | * console_semaphore held, and 'console_locked' set) if it | |
630 | * is successful, false otherwise. | |
631 | * | |
632 | * This gets called with the 'logbuf_lock' spinlock held and | |
633 | * interrupts disabled. It should return with 'lockbuf_lock' | |
634 | * released but interrupts still disabled. | |
635 | */ | |
636 | static int acquire_console_semaphore_for_printk(unsigned int cpu) | |
637 | { | |
638 | int retval = 0; | |
639 | ||
093a07e2 LT |
640 | if (!try_acquire_console_sem()) { |
641 | retval = 1; | |
642 | ||
643 | /* | |
644 | * If we can't use the console, we need to release | |
645 | * the console semaphore by hand to avoid flushing | |
646 | * the buffer. We need to hold the console semaphore | |
647 | * in order to do this test safely. | |
648 | */ | |
649 | if (!can_use_console(cpu)) { | |
650 | console_locked = 0; | |
651 | up(&console_sem); | |
652 | retval = 0; | |
653 | } | |
654 | } | |
266c2e0a LT |
655 | printk_cpu = UINT_MAX; |
656 | spin_unlock(&logbuf_lock); | |
657 | return retval; | |
658 | } | |
3b8945e8 TH |
659 | static const char recursion_bug_msg [] = |
660 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
661 | static int recursion_bug; | |
ac60ad74 | 662 | static int new_text_line = 1; |
3b8945e8 | 663 | static char printk_buf[1024]; |
32a76006 | 664 | |
1da177e4 LT |
665 | asmlinkage int vprintk(const char *fmt, va_list args) |
666 | { | |
32a76006 | 667 | int printed_len = 0; |
09159308 | 668 | int current_log_level = default_message_loglevel; |
ac60ad74 | 669 | unsigned long flags; |
32a76006 | 670 | int this_cpu; |
1da177e4 | 671 | char *p; |
1da177e4 | 672 | |
bfe8df3d RD |
673 | boot_delay_msec(); |
674 | ||
fe21773d | 675 | preempt_disable(); |
1da177e4 | 676 | /* This stops the holder of console_sem just where we want him */ |
1efc5da3 | 677 | raw_local_irq_save(flags); |
32a76006 IM |
678 | this_cpu = smp_processor_id(); |
679 | ||
680 | /* | |
681 | * Ouch, printk recursed into itself! | |
682 | */ | |
683 | if (unlikely(printk_cpu == this_cpu)) { | |
684 | /* | |
685 | * If a crash is occurring during printk() on this CPU, | |
686 | * then try to get the crash message out but make sure | |
687 | * we can't deadlock. Otherwise just return to avoid the | |
688 | * recursion and return - but flag the recursion so that | |
689 | * it can be printed at the next appropriate moment: | |
690 | */ | |
691 | if (!oops_in_progress) { | |
3b8945e8 | 692 | recursion_bug = 1; |
32a76006 IM |
693 | goto out_restore_irqs; |
694 | } | |
695 | zap_locks(); | |
696 | } | |
697 | ||
a0f1ccfd IM |
698 | lockdep_off(); |
699 | spin_lock(&logbuf_lock); | |
32a76006 | 700 | printk_cpu = this_cpu; |
1da177e4 | 701 | |
3b8945e8 TH |
702 | if (recursion_bug) { |
703 | recursion_bug = 0; | |
704 | strcpy(printk_buf, recursion_bug_msg); | |
705 | printed_len = sizeof(recursion_bug_msg); | |
32a76006 | 706 | } |
1da177e4 | 707 | /* Emit the output into the temporary buffer */ |
32a76006 | 708 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 709 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 710 | |
ac60ad74 | 711 | |
1da177e4 LT |
712 | /* |
713 | * Copy the output into log_buf. If the caller didn't provide | |
714 | * appropriate log level tags, we insert them here | |
715 | */ | |
716 | for (p = printk_buf; *p; p++) { | |
ac60ad74 | 717 | if (new_text_line) { |
ac60ad74 NA |
718 | /* If a token, set current_log_level and skip over */ |
719 | if (p[0] == '<' && p[1] >= '0' && p[1] <= '7' && | |
720 | p[2] == '>') { | |
721 | current_log_level = p[1] - '0'; | |
722 | p += 3; | |
723 | printed_len -= 3; | |
724 | } | |
725 | ||
726 | /* Always output the token */ | |
727 | emit_log_char('<'); | |
728 | emit_log_char(current_log_level + '0'); | |
729 | emit_log_char('>'); | |
730 | printed_len += 3; | |
731 | new_text_line = 0; | |
732 | ||
1da177e4 | 733 | if (printk_time) { |
ac60ad74 | 734 | /* Follow the token with the time */ |
1da177e4 LT |
735 | char tbuf[50], *tp; |
736 | unsigned tlen; | |
737 | unsigned long long t; | |
738 | unsigned long nanosec_rem; | |
739 | ||
326e96b9 | 740 | t = cpu_clock(printk_cpu); |
1da177e4 | 741 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
742 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
743 | (unsigned long) t, | |
744 | nanosec_rem / 1000); | |
1da177e4 LT |
745 | |
746 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
747 | emit_log_char(*tp); | |
025510cd | 748 | printed_len += tlen; |
1da177e4 | 749 | } |
ac60ad74 | 750 | |
1da177e4 LT |
751 | if (!*p) |
752 | break; | |
753 | } | |
ac60ad74 | 754 | |
1da177e4 LT |
755 | emit_log_char(*p); |
756 | if (*p == '\n') | |
ac60ad74 | 757 | new_text_line = 1; |
1da177e4 LT |
758 | } |
759 | ||
266c2e0a LT |
760 | /* |
761 | * Try to acquire and then immediately release the | |
762 | * console semaphore. The release will do all the | |
763 | * actual magic (print out buffers, wake up klogd, | |
764 | * etc). | |
765 | * | |
766 | * The acquire_console_semaphore_for_printk() function | |
767 | * will release 'logbuf_lock' regardless of whether it | |
768 | * actually gets the semaphore or not. | |
769 | */ | |
770 | if (acquire_console_semaphore_for_printk(this_cpu)) | |
771 | release_console_sem(); | |
76a8ad29 | 772 | |
266c2e0a | 773 | lockdep_on(); |
32a76006 | 774 | out_restore_irqs: |
266c2e0a | 775 | raw_local_irq_restore(flags); |
76a8ad29 | 776 | |
fe21773d | 777 | preempt_enable(); |
1da177e4 LT |
778 | return printed_len; |
779 | } | |
780 | EXPORT_SYMBOL(printk); | |
781 | EXPORT_SYMBOL(vprintk); | |
782 | ||
d59745ce MM |
783 | #else |
784 | ||
40dc5651 | 785 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
d59745ce | 786 | { |
c36264df | 787 | return -ENOSYS; |
40dc5651 JJ |
788 | } |
789 | ||
eed4a2ab | 790 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
791 | { |
792 | } | |
d59745ce MM |
793 | |
794 | #endif | |
795 | ||
f7511d5f ST |
796 | static int __add_preferred_console(char *name, int idx, char *options, |
797 | char *brl_options) | |
798 | { | |
799 | struct console_cmdline *c; | |
800 | int i; | |
801 | ||
802 | /* | |
803 | * See if this tty is not yet registered, and | |
804 | * if we have a slot free. | |
805 | */ | |
806 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
807 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
808 | console_cmdline[i].index == idx) { | |
809 | if (!brl_options) | |
810 | selected_console = i; | |
811 | return 0; | |
812 | } | |
813 | if (i == MAX_CMDLINECONSOLES) | |
814 | return -E2BIG; | |
815 | if (!brl_options) | |
816 | selected_console = i; | |
817 | c = &console_cmdline[i]; | |
818 | strlcpy(c->name, name, sizeof(c->name)); | |
819 | c->options = options; | |
820 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
821 | c->brl_options = brl_options; | |
822 | #endif | |
823 | c->index = idx; | |
824 | return 0; | |
825 | } | |
2ea1c539 JB |
826 | /* |
827 | * Set up a list of consoles. Called from init/main.c | |
828 | */ | |
829 | static int __init console_setup(char *str) | |
830 | { | |
eaa944af | 831 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 832 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
833 | int idx; |
834 | ||
f7511d5f ST |
835 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
836 | if (!memcmp(str, "brl,", 4)) { | |
837 | brl_options = ""; | |
838 | str += 4; | |
839 | } else if (!memcmp(str, "brl=", 4)) { | |
840 | brl_options = str + 4; | |
841 | str = strchr(brl_options, ','); | |
842 | if (!str) { | |
843 | printk(KERN_ERR "need port name after brl=\n"); | |
844 | return 1; | |
845 | } | |
846 | *(str++) = 0; | |
847 | } | |
848 | #endif | |
849 | ||
2ea1c539 JB |
850 | /* |
851 | * Decode str into name, index, options. | |
852 | */ | |
853 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
854 | strcpy(buf, "ttyS"); |
855 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 856 | } else { |
eaa944af | 857 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 858 | } |
eaa944af | 859 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
860 | if ((options = strchr(str, ',')) != NULL) |
861 | *(options++) = 0; | |
862 | #ifdef __sparc__ | |
863 | if (!strcmp(str, "ttya")) | |
eaa944af | 864 | strcpy(buf, "ttyS0"); |
2ea1c539 | 865 | if (!strcmp(str, "ttyb")) |
eaa944af | 866 | strcpy(buf, "ttyS1"); |
2ea1c539 | 867 | #endif |
eaa944af | 868 | for (s = buf; *s; s++) |
2ea1c539 JB |
869 | if ((*s >= '0' && *s <= '9') || *s == ',') |
870 | break; | |
871 | idx = simple_strtoul(s, NULL, 10); | |
872 | *s = 0; | |
873 | ||
f7511d5f | 874 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 875 | console_set_on_cmdline = 1; |
2ea1c539 JB |
876 | return 1; |
877 | } | |
878 | __setup("console=", console_setup); | |
879 | ||
3c0547ba MM |
880 | /** |
881 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
882 | * @name: device name |
883 | * @idx: device index | |
884 | * @options: options for this console | |
3c0547ba MM |
885 | * |
886 | * The last preferred console added will be used for kernel messages | |
887 | * and stdin/out/err for init. Normally this is used by console_setup | |
888 | * above to handle user-supplied console arguments; however it can also | |
889 | * be used by arch-specific code either to override the user or more | |
890 | * commonly to provide a default console (ie from PROM variables) when | |
891 | * the user has not supplied one. | |
892 | */ | |
fb445ee5 | 893 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 894 | { |
f7511d5f | 895 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
896 | } |
897 | ||
b6b1d877 | 898 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
899 | { |
900 | struct console_cmdline *c; | |
901 | int i; | |
902 | ||
903 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
904 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
905 | console_cmdline[i].index == idx) { | |
906 | c = &console_cmdline[i]; | |
f735295b | 907 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
908 | c->name[sizeof(c->name) - 1] = 0; |
909 | c->options = options; | |
910 | c->index = idx_new; | |
911 | return i; | |
912 | } | |
913 | /* not found */ | |
914 | return -1; | |
915 | } | |
916 | ||
8f4ce8c3 AS |
917 | int console_suspend_enabled = 1; |
918 | EXPORT_SYMBOL(console_suspend_enabled); | |
919 | ||
920 | static int __init console_suspend_disable(char *str) | |
921 | { | |
922 | console_suspend_enabled = 0; | |
923 | return 1; | |
924 | } | |
925 | __setup("no_console_suspend", console_suspend_disable); | |
926 | ||
557240b4 LT |
927 | /** |
928 | * suspend_console - suspend the console subsystem | |
929 | * | |
930 | * This disables printk() while we go into suspend states | |
931 | */ | |
932 | void suspend_console(void) | |
933 | { | |
8f4ce8c3 AS |
934 | if (!console_suspend_enabled) |
935 | return; | |
0d63081d | 936 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
557240b4 LT |
937 | acquire_console_sem(); |
938 | console_suspended = 1; | |
939 | } | |
940 | ||
941 | void resume_console(void) | |
942 | { | |
8f4ce8c3 AS |
943 | if (!console_suspend_enabled) |
944 | return; | |
557240b4 LT |
945 | console_suspended = 0; |
946 | release_console_sem(); | |
947 | } | |
948 | ||
1da177e4 LT |
949 | /** |
950 | * acquire_console_sem - lock the console system for exclusive use. | |
951 | * | |
952 | * Acquires a semaphore which guarantees that the caller has | |
953 | * exclusive access to the console system and the console_drivers list. | |
954 | * | |
955 | * Can sleep, returns nothing. | |
956 | */ | |
957 | void acquire_console_sem(void) | |
958 | { | |
8abd8e29 | 959 | BUG_ON(in_interrupt()); |
557240b4 LT |
960 | if (console_suspended) { |
961 | down(&secondary_console_sem); | |
962 | return; | |
963 | } | |
1da177e4 LT |
964 | down(&console_sem); |
965 | console_locked = 1; | |
966 | console_may_schedule = 1; | |
967 | } | |
968 | EXPORT_SYMBOL(acquire_console_sem); | |
969 | ||
970 | int try_acquire_console_sem(void) | |
971 | { | |
972 | if (down_trylock(&console_sem)) | |
973 | return -1; | |
974 | console_locked = 1; | |
975 | console_may_schedule = 0; | |
976 | return 0; | |
977 | } | |
978 | EXPORT_SYMBOL(try_acquire_console_sem); | |
979 | ||
980 | int is_console_locked(void) | |
981 | { | |
982 | return console_locked; | |
983 | } | |
1da177e4 | 984 | |
e3e8a75d KK |
985 | void wake_up_klogd(void) |
986 | { | |
987 | if (!oops_in_progress && waitqueue_active(&log_wait)) | |
988 | wake_up_interruptible(&log_wait); | |
989 | } | |
990 | ||
1da177e4 LT |
991 | /** |
992 | * release_console_sem - unlock the console system | |
993 | * | |
994 | * Releases the semaphore which the caller holds on the console system | |
995 | * and the console driver list. | |
996 | * | |
997 | * While the semaphore was held, console output may have been buffered | |
998 | * by printk(). If this is the case, release_console_sem() emits | |
999 | * the output prior to releasing the semaphore. | |
1000 | * | |
1001 | * If there is output waiting for klogd, we wake it up. | |
1002 | * | |
1003 | * release_console_sem() may be called from any context. | |
1004 | */ | |
1005 | void release_console_sem(void) | |
1006 | { | |
1007 | unsigned long flags; | |
eed4a2ab DV |
1008 | unsigned _con_start, _log_end; |
1009 | unsigned wake_klogd = 0; | |
1da177e4 | 1010 | |
557240b4 LT |
1011 | if (console_suspended) { |
1012 | up(&secondary_console_sem); | |
1013 | return; | |
1014 | } | |
78944e54 AD |
1015 | |
1016 | console_may_schedule = 0; | |
1017 | ||
1da177e4 LT |
1018 | for ( ; ; ) { |
1019 | spin_lock_irqsave(&logbuf_lock, flags); | |
1020 | wake_klogd |= log_start - log_end; | |
1021 | if (con_start == log_end) | |
1022 | break; /* Nothing to print */ | |
1023 | _con_start = con_start; | |
1024 | _log_end = log_end; | |
1025 | con_start = log_end; /* Flush */ | |
1026 | spin_unlock(&logbuf_lock); | |
81d68a96 | 1027 | stop_critical_timings(); /* don't trace print latency */ |
1da177e4 | 1028 | call_console_drivers(_con_start, _log_end); |
81d68a96 | 1029 | start_critical_timings(); |
1da177e4 LT |
1030 | local_irq_restore(flags); |
1031 | } | |
1032 | console_locked = 0; | |
1da177e4 LT |
1033 | up(&console_sem); |
1034 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
1035 | if (wake_klogd) |
1036 | wake_up_klogd(); | |
1da177e4 LT |
1037 | } |
1038 | EXPORT_SYMBOL(release_console_sem); | |
1039 | ||
ddad86c2 MW |
1040 | /** |
1041 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1042 | * |
1043 | * If the console code is currently allowed to sleep, and | |
1044 | * if this CPU should yield the CPU to another task, do | |
1045 | * so here. | |
1046 | * | |
1047 | * Must be called within acquire_console_sem(). | |
1048 | */ | |
1049 | void __sched console_conditional_schedule(void) | |
1050 | { | |
1051 | if (console_may_schedule) | |
1052 | cond_resched(); | |
1053 | } | |
1054 | EXPORT_SYMBOL(console_conditional_schedule); | |
1055 | ||
1056 | void console_print(const char *s) | |
1057 | { | |
1058 | printk(KERN_EMERG "%s", s); | |
1059 | } | |
1060 | EXPORT_SYMBOL(console_print); | |
1061 | ||
1062 | void console_unblank(void) | |
1063 | { | |
1064 | struct console *c; | |
1065 | ||
1066 | /* | |
1067 | * console_unblank can no longer be called in interrupt context unless | |
1068 | * oops_in_progress is set to 1.. | |
1069 | */ | |
1070 | if (oops_in_progress) { | |
1071 | if (down_trylock(&console_sem) != 0) | |
1072 | return; | |
1073 | } else | |
1074 | acquire_console_sem(); | |
1075 | ||
1076 | console_locked = 1; | |
1077 | console_may_schedule = 0; | |
1078 | for (c = console_drivers; c != NULL; c = c->next) | |
1079 | if ((c->flags & CON_ENABLED) && c->unblank) | |
1080 | c->unblank(); | |
1081 | release_console_sem(); | |
1082 | } | |
1da177e4 LT |
1083 | |
1084 | /* | |
1085 | * Return the console tty driver structure and its associated index | |
1086 | */ | |
1087 | struct tty_driver *console_device(int *index) | |
1088 | { | |
1089 | struct console *c; | |
1090 | struct tty_driver *driver = NULL; | |
1091 | ||
1092 | acquire_console_sem(); | |
1093 | for (c = console_drivers; c != NULL; c = c->next) { | |
1094 | if (!c->device) | |
1095 | continue; | |
1096 | driver = c->device(c, index); | |
1097 | if (driver) | |
1098 | break; | |
1099 | } | |
1100 | release_console_sem(); | |
1101 | return driver; | |
1102 | } | |
1103 | ||
1104 | /* | |
1105 | * Prevent further output on the passed console device so that (for example) | |
1106 | * serial drivers can disable console output before suspending a port, and can | |
1107 | * re-enable output afterwards. | |
1108 | */ | |
1109 | void console_stop(struct console *console) | |
1110 | { | |
1111 | acquire_console_sem(); | |
1112 | console->flags &= ~CON_ENABLED; | |
1113 | release_console_sem(); | |
1114 | } | |
1115 | EXPORT_SYMBOL(console_stop); | |
1116 | ||
1117 | void console_start(struct console *console) | |
1118 | { | |
1119 | acquire_console_sem(); | |
1120 | console->flags |= CON_ENABLED; | |
1121 | release_console_sem(); | |
1122 | } | |
1123 | EXPORT_SYMBOL(console_start); | |
1124 | ||
1125 | /* | |
1126 | * The console driver calls this routine during kernel initialization | |
1127 | * to register the console printing procedure with printk() and to | |
1128 | * print any messages that were printed by the kernel before the | |
1129 | * console driver was initialized. | |
1130 | */ | |
40dc5651 | 1131 | void register_console(struct console *console) |
1da177e4 | 1132 | { |
40dc5651 | 1133 | int i; |
1da177e4 | 1134 | unsigned long flags; |
69331af7 | 1135 | struct console *bootconsole = NULL; |
1da177e4 | 1136 | |
69331af7 GH |
1137 | if (console_drivers) { |
1138 | if (console->flags & CON_BOOT) | |
1139 | return; | |
1140 | if (console_drivers->flags & CON_BOOT) | |
1141 | bootconsole = console_drivers; | |
1142 | } | |
1143 | ||
1144 | if (preferred_console < 0 || bootconsole || !console_drivers) | |
1da177e4 LT |
1145 | preferred_console = selected_console; |
1146 | ||
18a8bd94 YL |
1147 | if (console->early_setup) |
1148 | console->early_setup(); | |
1149 | ||
1da177e4 LT |
1150 | /* |
1151 | * See if we want to use this console driver. If we | |
1152 | * didn't select a console we take the first one | |
1153 | * that registers here. | |
1154 | */ | |
1155 | if (preferred_console < 0) { | |
1156 | if (console->index < 0) | |
1157 | console->index = 0; | |
1158 | if (console->setup == NULL || | |
1159 | console->setup(console, NULL) == 0) { | |
cd3a1b85 JK |
1160 | console->flags |= CON_ENABLED; |
1161 | if (console->device) { | |
1162 | console->flags |= CON_CONSDEV; | |
1163 | preferred_console = 0; | |
1164 | } | |
1da177e4 LT |
1165 | } |
1166 | } | |
1167 | ||
1168 | /* | |
1169 | * See if this console matches one we selected on | |
1170 | * the command line. | |
1171 | */ | |
40dc5651 JJ |
1172 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1173 | i++) { | |
1da177e4 LT |
1174 | if (strcmp(console_cmdline[i].name, console->name) != 0) |
1175 | continue; | |
1176 | if (console->index >= 0 && | |
1177 | console->index != console_cmdline[i].index) | |
1178 | continue; | |
1179 | if (console->index < 0) | |
1180 | console->index = console_cmdline[i].index; | |
f7511d5f ST |
1181 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1182 | if (console_cmdline[i].brl_options) { | |
1183 | console->flags |= CON_BRL; | |
1184 | braille_register_console(console, | |
1185 | console_cmdline[i].index, | |
1186 | console_cmdline[i].options, | |
1187 | console_cmdline[i].brl_options); | |
1188 | return; | |
1189 | } | |
1190 | #endif | |
1da177e4 LT |
1191 | if (console->setup && |
1192 | console->setup(console, console_cmdline[i].options) != 0) | |
1193 | break; | |
1194 | console->flags |= CON_ENABLED; | |
1195 | console->index = console_cmdline[i].index; | |
ab4af03a | 1196 | if (i == selected_console) { |
1da177e4 | 1197 | console->flags |= CON_CONSDEV; |
ab4af03a GE |
1198 | preferred_console = selected_console; |
1199 | } | |
1da177e4 LT |
1200 | break; |
1201 | } | |
1202 | ||
1203 | if (!(console->flags & CON_ENABLED)) | |
1204 | return; | |
1205 | ||
d37bf60d | 1206 | if (bootconsole && (console->flags & CON_CONSDEV)) { |
69331af7 GH |
1207 | printk(KERN_INFO "console handover: boot [%s%d] -> real [%s%d]\n", |
1208 | bootconsole->name, bootconsole->index, | |
1209 | console->name, console->index); | |
1210 | unregister_console(bootconsole); | |
1da177e4 | 1211 | console->flags &= ~CON_PRINTBUFFER; |
d37bf60d YL |
1212 | } else { |
1213 | printk(KERN_INFO "console [%s%d] enabled\n", | |
1214 | console->name, console->index); | |
1da177e4 LT |
1215 | } |
1216 | ||
1217 | /* | |
1218 | * Put this console in the list - keep the | |
1219 | * preferred driver at the head of the list. | |
1220 | */ | |
1221 | acquire_console_sem(); | |
1222 | if ((console->flags & CON_CONSDEV) || console_drivers == NULL) { | |
1223 | console->next = console_drivers; | |
1224 | console_drivers = console; | |
ab4af03a GE |
1225 | if (console->next) |
1226 | console->next->flags &= ~CON_CONSDEV; | |
1da177e4 LT |
1227 | } else { |
1228 | console->next = console_drivers->next; | |
1229 | console_drivers->next = console; | |
1230 | } | |
1231 | if (console->flags & CON_PRINTBUFFER) { | |
1232 | /* | |
1233 | * release_console_sem() will print out the buffered messages | |
1234 | * for us. | |
1235 | */ | |
1236 | spin_lock_irqsave(&logbuf_lock, flags); | |
1237 | con_start = log_start; | |
1238 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1239 | } | |
1240 | release_console_sem(); | |
1241 | } | |
1242 | EXPORT_SYMBOL(register_console); | |
1243 | ||
40dc5651 | 1244 | int unregister_console(struct console *console) |
1da177e4 | 1245 | { |
40dc5651 | 1246 | struct console *a, *b; |
1da177e4 LT |
1247 | int res = 1; |
1248 | ||
f7511d5f ST |
1249 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1250 | if (console->flags & CON_BRL) | |
1251 | return braille_unregister_console(console); | |
1252 | #endif | |
1253 | ||
1da177e4 LT |
1254 | acquire_console_sem(); |
1255 | if (console_drivers == console) { | |
1256 | console_drivers=console->next; | |
1257 | res = 0; | |
e9b15b54 | 1258 | } else if (console_drivers) { |
1da177e4 LT |
1259 | for (a=console_drivers->next, b=console_drivers ; |
1260 | a; b=a, a=b->next) { | |
1261 | if (a == console) { | |
1262 | b->next = a->next; | |
1263 | res = 0; | |
1264 | break; | |
40dc5651 | 1265 | } |
1da177e4 LT |
1266 | } |
1267 | } | |
40dc5651 | 1268 | |
69331af7 | 1269 | /* |
ab4af03a GE |
1270 | * If this isn't the last console and it has CON_CONSDEV set, we |
1271 | * need to set it on the next preferred console. | |
1da177e4 | 1272 | */ |
69331af7 | 1273 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1274 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 LT |
1275 | |
1276 | release_console_sem(); | |
1277 | return res; | |
1278 | } | |
1279 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1280 | |
0c5564bd RG |
1281 | static int __init disable_boot_consoles(void) |
1282 | { | |
cb00e99c RG |
1283 | if (console_drivers != NULL) { |
1284 | if (console_drivers->flags & CON_BOOT) { | |
1285 | printk(KERN_INFO "turn off boot console %s%d\n", | |
1286 | console_drivers->name, console_drivers->index); | |
1287 | return unregister_console(console_drivers); | |
1288 | } | |
0c5564bd RG |
1289 | } |
1290 | return 0; | |
1291 | } | |
1292 | late_initcall(disable_boot_consoles); | |
1293 | ||
7ef3d2fd | 1294 | #if defined CONFIG_PRINTK |
717115e1 | 1295 | |
1da177e4 LT |
1296 | /* |
1297 | * printk rate limiting, lifted from the networking subsystem. | |
1298 | * | |
641de9d8 UKK |
1299 | * This enforces a rate limit: not more than 10 kernel messages |
1300 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 1301 | */ |
641de9d8 UKK |
1302 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1303 | ||
1da177e4 LT |
1304 | int printk_ratelimit(void) |
1305 | { | |
717115e1 | 1306 | return __ratelimit(&printk_ratelimit_state); |
1da177e4 LT |
1307 | } |
1308 | EXPORT_SYMBOL(printk_ratelimit); | |
f46c4833 AM |
1309 | |
1310 | /** | |
1311 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1312 | * @caller_jiffies: pointer to caller's state | |
1313 | * @interval_msecs: minimum interval between prints | |
1314 | * | |
1315 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1316 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1317 | * returned true. | |
1318 | */ | |
1319 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1320 | unsigned int interval_msecs) | |
1321 | { | |
1322 | if (*caller_jiffies == 0 || time_after(jiffies, *caller_jiffies)) { | |
1323 | *caller_jiffies = jiffies + msecs_to_jiffies(interval_msecs); | |
1324 | return true; | |
1325 | } | |
1326 | return false; | |
1327 | } | |
1328 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
7ef3d2fd | 1329 | #endif |