Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/kernel/printk.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * Modified to make sys_syslog() more flexible: added commands to | |
7 | * return the last 4k of kernel messages, regardless of whether | |
8 | * they've been read or not. Added option to suppress kernel printk's | |
9 | * to the console. Added hook for sending the console messages | |
10 | * elsewhere, in preparation for a serial line console (someday). | |
11 | * Ted Ts'o, 2/11/93. | |
12 | * Modified for sysctl support, 1/8/97, Chris Horn. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 LT |
15 | * Rewrote bits to get rid of console_lock |
16 | * 01Mar01 Andrew Morton <andrewm@uow.edu.au> | |
17 | */ | |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
1da177e4 LT |
23 | #include <linux/console.h> |
24 | #include <linux/init.h> | |
bfe8df3d RD |
25 | #include <linux/jiffies.h> |
26 | #include <linux/nmi.h> | |
1da177e4 | 27 | #include <linux/module.h> |
3b9c0410 | 28 | #include <linux/moduleparam.h> |
1da177e4 | 29 | #include <linux/interrupt.h> /* For in_interrupt() */ |
1da177e4 LT |
30 | #include <linux/delay.h> |
31 | #include <linux/smp.h> | |
32 | #include <linux/security.h> | |
33 | #include <linux/bootmem.h> | |
34 | #include <linux/syscalls.h> | |
f46c4833 | 35 | #include <linux/jiffies.h> |
1da177e4 LT |
36 | |
37 | #include <asm/uaccess.h> | |
38 | ||
39 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) | |
40 | ||
41 | /* printk's without a loglevel use this.. */ | |
42 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ | |
43 | ||
44 | /* We show everything that is MORE important than this.. */ | |
45 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
46 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
47 | ||
48 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
49 | ||
50 | int console_printk[4] = { | |
51 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
52 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
53 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
54 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
55 | }; | |
56 | ||
1da177e4 | 57 | /* |
0bbfb7c2 | 58 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
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); | |
557240b4 | 70 | static DECLARE_MUTEX(secondary_console_sem); |
1da177e4 LT |
71 | struct console *console_drivers; |
72 | /* | |
73 | * This is used for debugging the mess that is the VT code by | |
74 | * keeping track if we have the console semaphore held. It's | |
75 | * definitely not the perfect debug tool (we don't know if _WE_ | |
76 | * hold it are racing, but it helps tracking those weird code | |
77 | * path in the console code where we end up in places I want | |
78 | * locked without the console sempahore held | |
79 | */ | |
557240b4 | 80 | static int console_locked, console_suspended; |
1da177e4 LT |
81 | |
82 | /* | |
83 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
84 | * It is also used in interesting ways to provide interlocking in | |
85 | * release_console_sem(). | |
86 | */ | |
87 | static DEFINE_SPINLOCK(logbuf_lock); | |
88 | ||
1da177e4 LT |
89 | #define LOG_BUF_MASK (log_buf_len-1) |
90 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) | |
91 | ||
92 | /* | |
93 | * The indices into log_buf are not constrained to log_buf_len - they | |
94 | * must be masked before subscripting | |
95 | */ | |
96 | static unsigned long log_start; /* Index into log_buf: next char to be read by syslog() */ | |
97 | static unsigned long con_start; /* Index into log_buf: next char to be sent to consoles */ | |
98 | static unsigned long log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
99 | |
100 | /* | |
101 | * Array of consoles built from command line options (console=) | |
102 | */ | |
103 | struct console_cmdline | |
104 | { | |
105 | char name[8]; /* Name of the driver */ | |
106 | int index; /* Minor dev. to use */ | |
107 | char *options; /* Options for the driver */ | |
108 | }; | |
109 | ||
110 | #define MAX_CMDLINECONSOLES 8 | |
111 | ||
112 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
113 | static int selected_console = -1; | |
114 | static int preferred_console = -1; | |
115 | ||
116 | /* Flag: console code may call schedule() */ | |
117 | static int console_may_schedule; | |
118 | ||
d59745ce MM |
119 | #ifdef CONFIG_PRINTK |
120 | ||
121 | static char __log_buf[__LOG_BUF_LEN]; | |
122 | static char *log_buf = __log_buf; | |
123 | static int log_buf_len = __LOG_BUF_LEN; | |
124 | static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */ | |
125 | ||
1da177e4 LT |
126 | static int __init log_buf_len_setup(char *str) |
127 | { | |
128 | unsigned long size = memparse(str, &str); | |
129 | unsigned long flags; | |
130 | ||
131 | if (size) | |
132 | size = roundup_pow_of_two(size); | |
133 | if (size > log_buf_len) { | |
134 | unsigned long start, dest_idx, offset; | |
40dc5651 | 135 | char *new_log_buf; |
1da177e4 LT |
136 | |
137 | new_log_buf = alloc_bootmem(size); | |
138 | if (!new_log_buf) { | |
40dc5651 | 139 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
140 | goto out; |
141 | } | |
142 | ||
143 | spin_lock_irqsave(&logbuf_lock, flags); | |
144 | log_buf_len = size; | |
145 | log_buf = new_log_buf; | |
146 | ||
147 | offset = start = min(con_start, log_start); | |
148 | dest_idx = 0; | |
149 | while (start != log_end) { | |
150 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
151 | start++; | |
152 | dest_idx++; | |
153 | } | |
154 | log_start -= offset; | |
155 | con_start -= offset; | |
156 | log_end -= offset; | |
157 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
158 | ||
40dc5651 | 159 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
160 | } |
161 | out: | |
1da177e4 LT |
162 | return 1; |
163 | } | |
164 | ||
165 | __setup("log_buf_len=", log_buf_len_setup); | |
166 | ||
bfe8df3d RD |
167 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
168 | ||
169 | static unsigned int boot_delay; /* msecs delay after each printk during bootup */ | |
170 | static unsigned long long printk_delay_msec; /* per msec, based on boot_delay */ | |
171 | ||
172 | static int __init boot_delay_setup(char *str) | |
173 | { | |
174 | unsigned long lpj; | |
175 | unsigned long long loops_per_msec; | |
176 | ||
177 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
178 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
179 | ||
180 | get_option(&str, &boot_delay); | |
181 | if (boot_delay > 10 * 1000) | |
182 | boot_delay = 0; | |
183 | ||
184 | printk_delay_msec = loops_per_msec; | |
185 | printk(KERN_DEBUG "boot_delay: %u, preset_lpj: %ld, lpj: %lu, " | |
186 | "HZ: %d, printk_delay_msec: %llu\n", | |
187 | boot_delay, preset_lpj, lpj, HZ, printk_delay_msec); | |
188 | return 1; | |
189 | } | |
190 | __setup("boot_delay=", boot_delay_setup); | |
191 | ||
192 | static void boot_delay_msec(void) | |
193 | { | |
194 | unsigned long long k; | |
195 | unsigned long timeout; | |
196 | ||
197 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
198 | return; | |
199 | ||
200 | k = (unsigned long long)printk_delay_msec * boot_delay; | |
201 | ||
202 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
203 | while (k) { | |
204 | k--; | |
205 | cpu_relax(); | |
206 | /* | |
207 | * use (volatile) jiffies to prevent | |
208 | * compiler reduction; loop termination via jiffies | |
209 | * is secondary and may or may not happen. | |
210 | */ | |
211 | if (time_after(jiffies, timeout)) | |
212 | break; | |
213 | touch_nmi_watchdog(); | |
214 | } | |
215 | } | |
216 | #else | |
217 | static inline void boot_delay_msec(void) | |
218 | { | |
219 | } | |
220 | #endif | |
221 | ||
1da177e4 LT |
222 | /* |
223 | * Commands to do_syslog: | |
224 | * | |
225 | * 0 -- Close the log. Currently a NOP. | |
226 | * 1 -- Open the log. Currently a NOP. | |
227 | * 2 -- Read from the log. | |
228 | * 3 -- Read all messages remaining in the ring buffer. | |
229 | * 4 -- Read and clear all messages remaining in the ring buffer | |
230 | * 5 -- Clear ring buffer. | |
231 | * 6 -- Disable printk's to console | |
232 | * 7 -- Enable printk's to console | |
233 | * 8 -- Set level of messages printed to console | |
234 | * 9 -- Return number of unread characters in the log buffer | |
235 | * 10 -- Return size of the log buffer | |
236 | */ | |
40dc5651 | 237 | int do_syslog(int type, char __user *buf, int len) |
1da177e4 LT |
238 | { |
239 | unsigned long i, j, limit, count; | |
240 | int do_clear = 0; | |
241 | char c; | |
242 | int error = 0; | |
243 | ||
244 | error = security_syslog(type); | |
245 | if (error) | |
246 | return error; | |
247 | ||
248 | switch (type) { | |
249 | case 0: /* Close log */ | |
250 | break; | |
251 | case 1: /* Open log */ | |
252 | break; | |
253 | case 2: /* Read from log */ | |
254 | error = -EINVAL; | |
255 | if (!buf || len < 0) | |
256 | goto out; | |
257 | error = 0; | |
258 | if (!len) | |
259 | goto out; | |
260 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
261 | error = -EFAULT; | |
262 | goto out; | |
263 | } | |
40dc5651 JJ |
264 | error = wait_event_interruptible(log_wait, |
265 | (log_start - log_end)); | |
1da177e4 LT |
266 | if (error) |
267 | goto out; | |
268 | i = 0; | |
269 | spin_lock_irq(&logbuf_lock); | |
270 | while (!error && (log_start != log_end) && i < len) { | |
271 | c = LOG_BUF(log_start); | |
272 | log_start++; | |
273 | spin_unlock_irq(&logbuf_lock); | |
274 | error = __put_user(c,buf); | |
275 | buf++; | |
276 | i++; | |
277 | cond_resched(); | |
278 | spin_lock_irq(&logbuf_lock); | |
279 | } | |
280 | spin_unlock_irq(&logbuf_lock); | |
281 | if (!error) | |
282 | error = i; | |
283 | break; | |
284 | case 4: /* Read/clear last kernel messages */ | |
40dc5651 | 285 | do_clear = 1; |
1da177e4 LT |
286 | /* FALL THRU */ |
287 | case 3: /* Read last kernel messages */ | |
288 | error = -EINVAL; | |
289 | if (!buf || len < 0) | |
290 | goto out; | |
291 | error = 0; | |
292 | if (!len) | |
293 | goto out; | |
294 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
295 | error = -EFAULT; | |
296 | goto out; | |
297 | } | |
298 | count = len; | |
299 | if (count > log_buf_len) | |
300 | count = log_buf_len; | |
301 | spin_lock_irq(&logbuf_lock); | |
302 | if (count > logged_chars) | |
303 | count = logged_chars; | |
304 | if (do_clear) | |
305 | logged_chars = 0; | |
306 | limit = log_end; | |
307 | /* | |
308 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 309 | * printk() could overwrite the messages |
1da177e4 LT |
310 | * we try to copy to user space. Therefore |
311 | * the messages are copied in reverse. <manfreds> | |
312 | */ | |
40dc5651 | 313 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
314 | j = limit-1-i; |
315 | if (j + log_buf_len < log_end) | |
316 | break; | |
317 | c = LOG_BUF(j); | |
318 | spin_unlock_irq(&logbuf_lock); | |
319 | error = __put_user(c,&buf[count-1-i]); | |
320 | cond_resched(); | |
321 | spin_lock_irq(&logbuf_lock); | |
322 | } | |
323 | spin_unlock_irq(&logbuf_lock); | |
324 | if (error) | |
325 | break; | |
326 | error = i; | |
40dc5651 | 327 | if (i != count) { |
1da177e4 LT |
328 | int offset = count-error; |
329 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 330 | for (i = 0; i < error; i++) { |
1da177e4 LT |
331 | if (__get_user(c,&buf[i+offset]) || |
332 | __put_user(c,&buf[i])) { | |
333 | error = -EFAULT; | |
334 | break; | |
335 | } | |
336 | cond_resched(); | |
337 | } | |
338 | } | |
339 | break; | |
340 | case 5: /* Clear ring buffer */ | |
341 | logged_chars = 0; | |
342 | break; | |
343 | case 6: /* Disable logging to console */ | |
344 | console_loglevel = minimum_console_loglevel; | |
345 | break; | |
346 | case 7: /* Enable logging to console */ | |
347 | console_loglevel = default_console_loglevel; | |
348 | break; | |
349 | case 8: /* Set level of messages printed to console */ | |
350 | error = -EINVAL; | |
351 | if (len < 1 || len > 8) | |
352 | goto out; | |
353 | if (len < minimum_console_loglevel) | |
354 | len = minimum_console_loglevel; | |
355 | console_loglevel = len; | |
356 | error = 0; | |
357 | break; | |
358 | case 9: /* Number of chars in the log buffer */ | |
359 | error = log_end - log_start; | |
360 | break; | |
361 | case 10: /* Size of the log buffer */ | |
362 | error = log_buf_len; | |
363 | break; | |
364 | default: | |
365 | error = -EINVAL; | |
366 | break; | |
367 | } | |
368 | out: | |
369 | return error; | |
370 | } | |
371 | ||
40dc5651 | 372 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
1da177e4 LT |
373 | { |
374 | return do_syslog(type, buf, len); | |
375 | } | |
376 | ||
377 | /* | |
378 | * Call the console drivers on a range of log_buf | |
379 | */ | |
380 | static void __call_console_drivers(unsigned long start, unsigned long end) | |
381 | { | |
382 | struct console *con; | |
383 | ||
384 | for (con = console_drivers; con; con = con->next) { | |
76a8ad29 ME |
385 | if ((con->flags & CON_ENABLED) && con->write && |
386 | (cpu_online(smp_processor_id()) || | |
387 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
388 | con->write(con, &LOG_BUF(start), end - start); |
389 | } | |
390 | } | |
391 | ||
79290822 IM |
392 | static int __read_mostly ignore_loglevel; |
393 | ||
99eea6a1 | 394 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
395 | { |
396 | ignore_loglevel = 1; | |
397 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
398 | ||
399 | return 1; | |
400 | } | |
401 | ||
402 | __setup("ignore_loglevel", ignore_loglevel_setup); | |
403 | ||
1da177e4 LT |
404 | /* |
405 | * Write out chars from start to end - 1 inclusive | |
406 | */ | |
407 | static void _call_console_drivers(unsigned long start, | |
408 | unsigned long end, int msg_log_level) | |
409 | { | |
79290822 | 410 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
411 | console_drivers && start != end) { |
412 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
413 | /* wrapped write */ | |
414 | __call_console_drivers(start & LOG_BUF_MASK, | |
415 | log_buf_len); | |
416 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
417 | } else { | |
418 | __call_console_drivers(start, end); | |
419 | } | |
420 | } | |
421 | } | |
422 | ||
423 | /* | |
424 | * Call the console drivers, asking them to write out | |
425 | * log_buf[start] to log_buf[end - 1]. | |
426 | * The console_sem must be held. | |
427 | */ | |
428 | static void call_console_drivers(unsigned long start, unsigned long end) | |
429 | { | |
430 | unsigned long cur_index, start_print; | |
431 | static int msg_level = -1; | |
432 | ||
8abd8e29 | 433 | BUG_ON(((long)(start - end)) > 0); |
1da177e4 LT |
434 | |
435 | cur_index = start; | |
436 | start_print = start; | |
437 | while (cur_index != end) { | |
40dc5651 JJ |
438 | if (msg_level < 0 && ((end - cur_index) > 2) && |
439 | LOG_BUF(cur_index + 0) == '<' && | |
440 | LOG_BUF(cur_index + 1) >= '0' && | |
441 | LOG_BUF(cur_index + 1) <= '7' && | |
442 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
443 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
444 | cur_index += 3; | |
445 | start_print = cur_index; | |
446 | } | |
447 | while (cur_index != end) { | |
448 | char c = LOG_BUF(cur_index); | |
1da177e4 | 449 | |
40dc5651 | 450 | cur_index++; |
1da177e4 LT |
451 | if (c == '\n') { |
452 | if (msg_level < 0) { | |
453 | /* | |
454 | * printk() has already given us loglevel tags in | |
455 | * the buffer. This code is here in case the | |
456 | * log buffer has wrapped right round and scribbled | |
457 | * on those tags | |
458 | */ | |
459 | msg_level = default_message_loglevel; | |
460 | } | |
461 | _call_console_drivers(start_print, cur_index, msg_level); | |
462 | msg_level = -1; | |
463 | start_print = cur_index; | |
464 | break; | |
465 | } | |
466 | } | |
467 | } | |
468 | _call_console_drivers(start_print, end, msg_level); | |
469 | } | |
470 | ||
471 | static void emit_log_char(char c) | |
472 | { | |
473 | LOG_BUF(log_end) = c; | |
474 | log_end++; | |
475 | if (log_end - log_start > log_buf_len) | |
476 | log_start = log_end - log_buf_len; | |
477 | if (log_end - con_start > log_buf_len) | |
478 | con_start = log_end - log_buf_len; | |
479 | if (logged_chars < log_buf_len) | |
480 | logged_chars++; | |
481 | } | |
482 | ||
483 | /* | |
484 | * Zap console related locks when oopsing. Only zap at most once | |
485 | * every 10 seconds, to leave time for slow consoles to print a | |
486 | * full oops. | |
487 | */ | |
488 | static void zap_locks(void) | |
489 | { | |
490 | static unsigned long oops_timestamp; | |
491 | ||
492 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 493 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
494 | return; |
495 | ||
496 | oops_timestamp = jiffies; | |
497 | ||
498 | /* If a crash is occurring, make sure we can't deadlock */ | |
499 | spin_lock_init(&logbuf_lock); | |
500 | /* And make sure that we print immediately */ | |
501 | init_MUTEX(&console_sem); | |
502 | } | |
503 | ||
504 | #if defined(CONFIG_PRINTK_TIME) | |
505 | static int printk_time = 1; | |
506 | #else | |
507 | static int printk_time = 0; | |
508 | #endif | |
e84845c4 | 509 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 LT |
510 | |
511 | static int __init printk_time_setup(char *str) | |
512 | { | |
513 | if (*str) | |
514 | return 0; | |
515 | printk_time = 1; | |
e84845c4 RD |
516 | printk(KERN_NOTICE "The 'time' option is deprecated and " |
517 | "is scheduled for removal in early 2008\n"); | |
518 | printk(KERN_NOTICE "Use 'printk.time=<value>' instead\n"); | |
1da177e4 LT |
519 | return 1; |
520 | } | |
521 | ||
522 | __setup("time", printk_time_setup); | |
523 | ||
31f6d9d6 AM |
524 | __attribute__((weak)) unsigned long long printk_clock(void) |
525 | { | |
526 | return sched_clock(); | |
527 | } | |
528 | ||
76a8ad29 ME |
529 | /* Check if we have any console registered that can be called early in boot. */ |
530 | static int have_callable_console(void) | |
531 | { | |
532 | struct console *con; | |
533 | ||
534 | for (con = console_drivers; con; con = con->next) | |
535 | if (con->flags & CON_ANYTIME) | |
536 | return 1; | |
537 | ||
538 | return 0; | |
539 | } | |
540 | ||
ddad86c2 MW |
541 | /** |
542 | * printk - print a kernel message | |
543 | * @fmt: format string | |
544 | * | |
72fd4a35 | 545 | * This is printk(). It can be called from any context. We want it to work. |
1492192b JK |
546 | * Be aware of the fact that if oops_in_progress is not set, we might try to |
547 | * wake klogd up which could deadlock on runqueue lock if printk() is called | |
548 | * from scheduler code. | |
40dc5651 | 549 | * |
1da177e4 LT |
550 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
551 | * call the console drivers. If we fail to get the semaphore we place the output | |
552 | * into the log buffer and return. The current holder of the console_sem will | |
553 | * notice the new output in release_console_sem() and will send it to the | |
554 | * consoles before releasing the semaphore. | |
555 | * | |
556 | * One effect of this deferred printing is that code which calls printk() and | |
557 | * then changes console_loglevel may break. This is because console_loglevel | |
558 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
559 | * |
560 | * See also: | |
561 | * printf(3) | |
1da177e4 | 562 | */ |
d59745ce | 563 | |
1da177e4 LT |
564 | asmlinkage int printk(const char *fmt, ...) |
565 | { | |
566 | va_list args; | |
567 | int r; | |
568 | ||
569 | va_start(args, fmt); | |
570 | r = vprintk(fmt, args); | |
571 | va_end(args); | |
572 | ||
573 | return r; | |
574 | } | |
575 | ||
fe21773d DH |
576 | /* cpu currently holding logbuf_lock */ |
577 | static volatile unsigned int printk_cpu = UINT_MAX; | |
578 | ||
1da177e4 LT |
579 | asmlinkage int vprintk(const char *fmt, va_list args) |
580 | { | |
581 | unsigned long flags; | |
582 | int printed_len; | |
583 | char *p; | |
584 | static char printk_buf[1024]; | |
585 | static int log_level_unknown = 1; | |
586 | ||
bfe8df3d RD |
587 | boot_delay_msec(); |
588 | ||
fe21773d DH |
589 | preempt_disable(); |
590 | if (unlikely(oops_in_progress) && printk_cpu == smp_processor_id()) | |
591 | /* If a crash is occurring during printk() on this CPU, | |
592 | * make sure we can't deadlock */ | |
1da177e4 LT |
593 | zap_locks(); |
594 | ||
595 | /* This stops the holder of console_sem just where we want him */ | |
1efc5da3 | 596 | raw_local_irq_save(flags); |
a0f1ccfd IM |
597 | lockdep_off(); |
598 | spin_lock(&logbuf_lock); | |
fe21773d | 599 | printk_cpu = smp_processor_id(); |
1da177e4 LT |
600 | |
601 | /* Emit the output into the temporary buffer */ | |
602 | printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args); | |
603 | ||
604 | /* | |
605 | * Copy the output into log_buf. If the caller didn't provide | |
606 | * appropriate log level tags, we insert them here | |
607 | */ | |
608 | for (p = printk_buf; *p; p++) { | |
609 | if (log_level_unknown) { | |
610 | /* log_level_unknown signals the start of a new line */ | |
611 | if (printk_time) { | |
612 | int loglev_char; | |
613 | char tbuf[50], *tp; | |
614 | unsigned tlen; | |
615 | unsigned long long t; | |
616 | unsigned long nanosec_rem; | |
617 | ||
618 | /* | |
619 | * force the log level token to be | |
620 | * before the time output. | |
621 | */ | |
622 | if (p[0] == '<' && p[1] >='0' && | |
623 | p[1] <= '7' && p[2] == '>') { | |
624 | loglev_char = p[1]; | |
625 | p += 3; | |
025510cd | 626 | printed_len -= 3; |
1da177e4 LT |
627 | } else { |
628 | loglev_char = default_message_loglevel | |
629 | + '0'; | |
630 | } | |
31f6d9d6 | 631 | t = printk_clock(); |
1da177e4 LT |
632 | nanosec_rem = do_div(t, 1000000000); |
633 | tlen = sprintf(tbuf, | |
634 | "<%c>[%5lu.%06lu] ", | |
635 | loglev_char, | |
636 | (unsigned long)t, | |
637 | nanosec_rem/1000); | |
638 | ||
639 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
640 | emit_log_char(*tp); | |
025510cd | 641 | printed_len += tlen; |
1da177e4 LT |
642 | } else { |
643 | if (p[0] != '<' || p[1] < '0' || | |
644 | p[1] > '7' || p[2] != '>') { | |
645 | emit_log_char('<'); | |
646 | emit_log_char(default_message_loglevel | |
647 | + '0'); | |
648 | emit_log_char('>'); | |
025510cd | 649 | printed_len += 3; |
1da177e4 | 650 | } |
1da177e4 LT |
651 | } |
652 | log_level_unknown = 0; | |
653 | if (!*p) | |
654 | break; | |
655 | } | |
656 | emit_log_char(*p); | |
657 | if (*p == '\n') | |
658 | log_level_unknown = 1; | |
659 | } | |
660 | ||
76a8ad29 | 661 | if (!down_trylock(&console_sem)) { |
1da177e4 | 662 | /* |
76a8ad29 ME |
663 | * We own the drivers. We can drop the spinlock and |
664 | * let release_console_sem() print the text, maybe ... | |
1da177e4 | 665 | */ |
76a8ad29 | 666 | console_locked = 1; |
fe21773d | 667 | printk_cpu = UINT_MAX; |
a0f1ccfd | 668 | spin_unlock(&logbuf_lock); |
76a8ad29 | 669 | |
1da177e4 | 670 | /* |
76a8ad29 ME |
671 | * Console drivers may assume that per-cpu resources have |
672 | * been allocated. So unless they're explicitly marked as | |
673 | * being able to cope (CON_ANYTIME) don't call them until | |
674 | * this CPU is officially up. | |
1da177e4 | 675 | */ |
76a8ad29 ME |
676 | if (cpu_online(smp_processor_id()) || have_callable_console()) { |
677 | console_may_schedule = 0; | |
678 | release_console_sem(); | |
679 | } else { | |
680 | /* Release by hand to avoid flushing the buffer. */ | |
681 | console_locked = 0; | |
682 | up(&console_sem); | |
683 | } | |
a0f1ccfd | 684 | lockdep_on(); |
1efc5da3 | 685 | raw_local_irq_restore(flags); |
1da177e4 LT |
686 | } else { |
687 | /* | |
688 | * Someone else owns the drivers. We drop the spinlock, which | |
689 | * allows the semaphore holder to proceed and to call the | |
690 | * console drivers with the output which we just produced. | |
691 | */ | |
fe21773d | 692 | printk_cpu = UINT_MAX; |
a0f1ccfd IM |
693 | spin_unlock(&logbuf_lock); |
694 | lockdep_on(); | |
1efc5da3 | 695 | raw_local_irq_restore(flags); |
1da177e4 | 696 | } |
76a8ad29 | 697 | |
fe21773d | 698 | preempt_enable(); |
1da177e4 LT |
699 | return printed_len; |
700 | } | |
701 | EXPORT_SYMBOL(printk); | |
702 | EXPORT_SYMBOL(vprintk); | |
703 | ||
d59745ce MM |
704 | #else |
705 | ||
40dc5651 | 706 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
d59745ce | 707 | { |
c36264df | 708 | return -ENOSYS; |
40dc5651 JJ |
709 | } |
710 | ||
711 | static void call_console_drivers(unsigned long start, unsigned long end) | |
712 | { | |
713 | } | |
d59745ce MM |
714 | |
715 | #endif | |
716 | ||
2ea1c539 JB |
717 | /* |
718 | * Set up a list of consoles. Called from init/main.c | |
719 | */ | |
720 | static int __init console_setup(char *str) | |
721 | { | |
eaa944af | 722 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
2ea1c539 JB |
723 | char *s, *options; |
724 | int idx; | |
725 | ||
726 | /* | |
727 | * Decode str into name, index, options. | |
728 | */ | |
729 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
730 | strcpy(buf, "ttyS"); |
731 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 732 | } else { |
eaa944af | 733 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 734 | } |
eaa944af | 735 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
736 | if ((options = strchr(str, ',')) != NULL) |
737 | *(options++) = 0; | |
738 | #ifdef __sparc__ | |
739 | if (!strcmp(str, "ttya")) | |
eaa944af | 740 | strcpy(buf, "ttyS0"); |
2ea1c539 | 741 | if (!strcmp(str, "ttyb")) |
eaa944af | 742 | strcpy(buf, "ttyS1"); |
2ea1c539 | 743 | #endif |
eaa944af | 744 | for (s = buf; *s; s++) |
2ea1c539 JB |
745 | if ((*s >= '0' && *s <= '9') || *s == ',') |
746 | break; | |
747 | idx = simple_strtoul(s, NULL, 10); | |
748 | *s = 0; | |
749 | ||
eaa944af | 750 | add_preferred_console(buf, idx, options); |
2ea1c539 JB |
751 | return 1; |
752 | } | |
753 | __setup("console=", console_setup); | |
754 | ||
3c0547ba MM |
755 | /** |
756 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
757 | * @name: device name |
758 | * @idx: device index | |
759 | * @options: options for this console | |
3c0547ba MM |
760 | * |
761 | * The last preferred console added will be used for kernel messages | |
762 | * and stdin/out/err for init. Normally this is used by console_setup | |
763 | * above to handle user-supplied console arguments; however it can also | |
764 | * be used by arch-specific code either to override the user or more | |
765 | * commonly to provide a default console (ie from PROM variables) when | |
766 | * the user has not supplied one. | |
767 | */ | |
768 | int __init add_preferred_console(char *name, int idx, char *options) | |
769 | { | |
770 | struct console_cmdline *c; | |
771 | int i; | |
772 | ||
773 | /* | |
774 | * See if this tty is not yet registered, and | |
775 | * if we have a slot free. | |
776 | */ | |
eaa944af | 777 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
3c0547ba MM |
778 | if (strcmp(console_cmdline[i].name, name) == 0 && |
779 | console_cmdline[i].index == idx) { | |
780 | selected_console = i; | |
781 | return 0; | |
782 | } | |
783 | if (i == MAX_CMDLINECONSOLES) | |
784 | return -E2BIG; | |
785 | selected_console = i; | |
786 | c = &console_cmdline[i]; | |
787 | memcpy(c->name, name, sizeof(c->name)); | |
788 | c->name[sizeof(c->name) - 1] = 0; | |
789 | c->options = options; | |
790 | c->index = idx; | |
791 | return 0; | |
792 | } | |
793 | ||
b6b1d877 | 794 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
795 | { |
796 | struct console_cmdline *c; | |
797 | int i; | |
798 | ||
799 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
800 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
801 | console_cmdline[i].index == idx) { | |
802 | c = &console_cmdline[i]; | |
803 | memcpy(c->name, name_new, sizeof(c->name)); | |
804 | c->name[sizeof(c->name) - 1] = 0; | |
805 | c->options = options; | |
806 | c->index = idx_new; | |
807 | return i; | |
808 | } | |
809 | /* not found */ | |
810 | return -1; | |
811 | } | |
812 | ||
c8eb8b40 | 813 | #ifndef CONFIG_DISABLE_CONSOLE_SUSPEND |
557240b4 LT |
814 | /** |
815 | * suspend_console - suspend the console subsystem | |
816 | * | |
817 | * This disables printk() while we go into suspend states | |
818 | */ | |
819 | void suspend_console(void) | |
820 | { | |
c8eb8b40 | 821 | printk("Suspending console(s)\n"); |
557240b4 LT |
822 | acquire_console_sem(); |
823 | console_suspended = 1; | |
824 | } | |
825 | ||
826 | void resume_console(void) | |
827 | { | |
828 | console_suspended = 0; | |
829 | release_console_sem(); | |
830 | } | |
c8eb8b40 | 831 | #endif /* CONFIG_DISABLE_CONSOLE_SUSPEND */ |
557240b4 | 832 | |
1da177e4 LT |
833 | /** |
834 | * acquire_console_sem - lock the console system for exclusive use. | |
835 | * | |
836 | * Acquires a semaphore which guarantees that the caller has | |
837 | * exclusive access to the console system and the console_drivers list. | |
838 | * | |
839 | * Can sleep, returns nothing. | |
840 | */ | |
841 | void acquire_console_sem(void) | |
842 | { | |
8abd8e29 | 843 | BUG_ON(in_interrupt()); |
557240b4 LT |
844 | if (console_suspended) { |
845 | down(&secondary_console_sem); | |
846 | return; | |
847 | } | |
1da177e4 LT |
848 | down(&console_sem); |
849 | console_locked = 1; | |
850 | console_may_schedule = 1; | |
851 | } | |
852 | EXPORT_SYMBOL(acquire_console_sem); | |
853 | ||
854 | int try_acquire_console_sem(void) | |
855 | { | |
856 | if (down_trylock(&console_sem)) | |
857 | return -1; | |
858 | console_locked = 1; | |
859 | console_may_schedule = 0; | |
860 | return 0; | |
861 | } | |
862 | EXPORT_SYMBOL(try_acquire_console_sem); | |
863 | ||
864 | int is_console_locked(void) | |
865 | { | |
866 | return console_locked; | |
867 | } | |
1da177e4 | 868 | |
e3e8a75d KK |
869 | void wake_up_klogd(void) |
870 | { | |
871 | if (!oops_in_progress && waitqueue_active(&log_wait)) | |
872 | wake_up_interruptible(&log_wait); | |
873 | } | |
874 | ||
1da177e4 LT |
875 | /** |
876 | * release_console_sem - unlock the console system | |
877 | * | |
878 | * Releases the semaphore which the caller holds on the console system | |
879 | * and the console driver list. | |
880 | * | |
881 | * While the semaphore was held, console output may have been buffered | |
882 | * by printk(). If this is the case, release_console_sem() emits | |
883 | * the output prior to releasing the semaphore. | |
884 | * | |
885 | * If there is output waiting for klogd, we wake it up. | |
886 | * | |
887 | * release_console_sem() may be called from any context. | |
888 | */ | |
889 | void release_console_sem(void) | |
890 | { | |
891 | unsigned long flags; | |
892 | unsigned long _con_start, _log_end; | |
893 | unsigned long wake_klogd = 0; | |
894 | ||
557240b4 LT |
895 | if (console_suspended) { |
896 | up(&secondary_console_sem); | |
897 | return; | |
898 | } | |
78944e54 AD |
899 | |
900 | console_may_schedule = 0; | |
901 | ||
1da177e4 LT |
902 | for ( ; ; ) { |
903 | spin_lock_irqsave(&logbuf_lock, flags); | |
904 | wake_klogd |= log_start - log_end; | |
905 | if (con_start == log_end) | |
906 | break; /* Nothing to print */ | |
907 | _con_start = con_start; | |
908 | _log_end = log_end; | |
909 | con_start = log_end; /* Flush */ | |
910 | spin_unlock(&logbuf_lock); | |
911 | call_console_drivers(_con_start, _log_end); | |
912 | local_irq_restore(flags); | |
913 | } | |
914 | console_locked = 0; | |
1da177e4 LT |
915 | up(&console_sem); |
916 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
917 | if (wake_klogd) |
918 | wake_up_klogd(); | |
1da177e4 LT |
919 | } |
920 | EXPORT_SYMBOL(release_console_sem); | |
921 | ||
ddad86c2 MW |
922 | /** |
923 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
924 | * |
925 | * If the console code is currently allowed to sleep, and | |
926 | * if this CPU should yield the CPU to another task, do | |
927 | * so here. | |
928 | * | |
929 | * Must be called within acquire_console_sem(). | |
930 | */ | |
931 | void __sched console_conditional_schedule(void) | |
932 | { | |
933 | if (console_may_schedule) | |
934 | cond_resched(); | |
935 | } | |
936 | EXPORT_SYMBOL(console_conditional_schedule); | |
937 | ||
938 | void console_print(const char *s) | |
939 | { | |
940 | printk(KERN_EMERG "%s", s); | |
941 | } | |
942 | EXPORT_SYMBOL(console_print); | |
943 | ||
944 | void console_unblank(void) | |
945 | { | |
946 | struct console *c; | |
947 | ||
948 | /* | |
949 | * console_unblank can no longer be called in interrupt context unless | |
950 | * oops_in_progress is set to 1.. | |
951 | */ | |
952 | if (oops_in_progress) { | |
953 | if (down_trylock(&console_sem) != 0) | |
954 | return; | |
955 | } else | |
956 | acquire_console_sem(); | |
957 | ||
958 | console_locked = 1; | |
959 | console_may_schedule = 0; | |
960 | for (c = console_drivers; c != NULL; c = c->next) | |
961 | if ((c->flags & CON_ENABLED) && c->unblank) | |
962 | c->unblank(); | |
963 | release_console_sem(); | |
964 | } | |
1da177e4 LT |
965 | |
966 | /* | |
967 | * Return the console tty driver structure and its associated index | |
968 | */ | |
969 | struct tty_driver *console_device(int *index) | |
970 | { | |
971 | struct console *c; | |
972 | struct tty_driver *driver = NULL; | |
973 | ||
974 | acquire_console_sem(); | |
975 | for (c = console_drivers; c != NULL; c = c->next) { | |
976 | if (!c->device) | |
977 | continue; | |
978 | driver = c->device(c, index); | |
979 | if (driver) | |
980 | break; | |
981 | } | |
982 | release_console_sem(); | |
983 | return driver; | |
984 | } | |
985 | ||
986 | /* | |
987 | * Prevent further output on the passed console device so that (for example) | |
988 | * serial drivers can disable console output before suspending a port, and can | |
989 | * re-enable output afterwards. | |
990 | */ | |
991 | void console_stop(struct console *console) | |
992 | { | |
993 | acquire_console_sem(); | |
994 | console->flags &= ~CON_ENABLED; | |
995 | release_console_sem(); | |
996 | } | |
997 | EXPORT_SYMBOL(console_stop); | |
998 | ||
999 | void console_start(struct console *console) | |
1000 | { | |
1001 | acquire_console_sem(); | |
1002 | console->flags |= CON_ENABLED; | |
1003 | release_console_sem(); | |
1004 | } | |
1005 | EXPORT_SYMBOL(console_start); | |
1006 | ||
1007 | /* | |
1008 | * The console driver calls this routine during kernel initialization | |
1009 | * to register the console printing procedure with printk() and to | |
1010 | * print any messages that were printed by the kernel before the | |
1011 | * console driver was initialized. | |
1012 | */ | |
40dc5651 | 1013 | void register_console(struct console *console) |
1da177e4 | 1014 | { |
40dc5651 | 1015 | int i; |
1da177e4 | 1016 | unsigned long flags; |
69331af7 | 1017 | struct console *bootconsole = NULL; |
1da177e4 | 1018 | |
69331af7 GH |
1019 | if (console_drivers) { |
1020 | if (console->flags & CON_BOOT) | |
1021 | return; | |
1022 | if (console_drivers->flags & CON_BOOT) | |
1023 | bootconsole = console_drivers; | |
1024 | } | |
1025 | ||
1026 | if (preferred_console < 0 || bootconsole || !console_drivers) | |
1da177e4 LT |
1027 | preferred_console = selected_console; |
1028 | ||
18a8bd94 YL |
1029 | if (console->early_setup) |
1030 | console->early_setup(); | |
1031 | ||
1da177e4 LT |
1032 | /* |
1033 | * See if we want to use this console driver. If we | |
1034 | * didn't select a console we take the first one | |
1035 | * that registers here. | |
1036 | */ | |
1037 | if (preferred_console < 0) { | |
1038 | if (console->index < 0) | |
1039 | console->index = 0; | |
1040 | if (console->setup == NULL || | |
1041 | console->setup(console, NULL) == 0) { | |
1042 | console->flags |= CON_ENABLED | CON_CONSDEV; | |
1043 | preferred_console = 0; | |
1044 | } | |
1045 | } | |
1046 | ||
1047 | /* | |
1048 | * See if this console matches one we selected on | |
1049 | * the command line. | |
1050 | */ | |
40dc5651 JJ |
1051 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1052 | i++) { | |
1da177e4 LT |
1053 | if (strcmp(console_cmdline[i].name, console->name) != 0) |
1054 | continue; | |
1055 | if (console->index >= 0 && | |
1056 | console->index != console_cmdline[i].index) | |
1057 | continue; | |
1058 | if (console->index < 0) | |
1059 | console->index = console_cmdline[i].index; | |
1060 | if (console->setup && | |
1061 | console->setup(console, console_cmdline[i].options) != 0) | |
1062 | break; | |
1063 | console->flags |= CON_ENABLED; | |
1064 | console->index = console_cmdline[i].index; | |
ab4af03a | 1065 | if (i == selected_console) { |
1da177e4 | 1066 | console->flags |= CON_CONSDEV; |
ab4af03a GE |
1067 | preferred_console = selected_console; |
1068 | } | |
1da177e4 LT |
1069 | break; |
1070 | } | |
1071 | ||
1072 | if (!(console->flags & CON_ENABLED)) | |
1073 | return; | |
1074 | ||
d37bf60d | 1075 | if (bootconsole && (console->flags & CON_CONSDEV)) { |
69331af7 GH |
1076 | printk(KERN_INFO "console handover: boot [%s%d] -> real [%s%d]\n", |
1077 | bootconsole->name, bootconsole->index, | |
1078 | console->name, console->index); | |
1079 | unregister_console(bootconsole); | |
1da177e4 | 1080 | console->flags &= ~CON_PRINTBUFFER; |
d37bf60d YL |
1081 | } else { |
1082 | printk(KERN_INFO "console [%s%d] enabled\n", | |
1083 | console->name, console->index); | |
1da177e4 LT |
1084 | } |
1085 | ||
1086 | /* | |
1087 | * Put this console in the list - keep the | |
1088 | * preferred driver at the head of the list. | |
1089 | */ | |
1090 | acquire_console_sem(); | |
1091 | if ((console->flags & CON_CONSDEV) || console_drivers == NULL) { | |
1092 | console->next = console_drivers; | |
1093 | console_drivers = console; | |
ab4af03a GE |
1094 | if (console->next) |
1095 | console->next->flags &= ~CON_CONSDEV; | |
1da177e4 LT |
1096 | } else { |
1097 | console->next = console_drivers->next; | |
1098 | console_drivers->next = console; | |
1099 | } | |
1100 | if (console->flags & CON_PRINTBUFFER) { | |
1101 | /* | |
1102 | * release_console_sem() will print out the buffered messages | |
1103 | * for us. | |
1104 | */ | |
1105 | spin_lock_irqsave(&logbuf_lock, flags); | |
1106 | con_start = log_start; | |
1107 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1108 | } | |
1109 | release_console_sem(); | |
1110 | } | |
1111 | EXPORT_SYMBOL(register_console); | |
1112 | ||
40dc5651 | 1113 | int unregister_console(struct console *console) |
1da177e4 | 1114 | { |
40dc5651 | 1115 | struct console *a, *b; |
1da177e4 LT |
1116 | int res = 1; |
1117 | ||
1118 | acquire_console_sem(); | |
1119 | if (console_drivers == console) { | |
1120 | console_drivers=console->next; | |
1121 | res = 0; | |
e9b15b54 | 1122 | } else if (console_drivers) { |
1da177e4 LT |
1123 | for (a=console_drivers->next, b=console_drivers ; |
1124 | a; b=a, a=b->next) { | |
1125 | if (a == console) { | |
1126 | b->next = a->next; | |
1127 | res = 0; | |
1128 | break; | |
40dc5651 | 1129 | } |
1da177e4 LT |
1130 | } |
1131 | } | |
40dc5651 | 1132 | |
69331af7 | 1133 | /* |
ab4af03a GE |
1134 | * If this isn't the last console and it has CON_CONSDEV set, we |
1135 | * need to set it on the next preferred console. | |
1da177e4 | 1136 | */ |
69331af7 | 1137 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1138 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 LT |
1139 | |
1140 | release_console_sem(); | |
1141 | return res; | |
1142 | } | |
1143 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1144 | |
0c5564bd RG |
1145 | static int __init disable_boot_consoles(void) |
1146 | { | |
cb00e99c RG |
1147 | if (console_drivers != NULL) { |
1148 | if (console_drivers->flags & CON_BOOT) { | |
1149 | printk(KERN_INFO "turn off boot console %s%d\n", | |
1150 | console_drivers->name, console_drivers->index); | |
1151 | return unregister_console(console_drivers); | |
1152 | } | |
0c5564bd RG |
1153 | } |
1154 | return 0; | |
1155 | } | |
1156 | late_initcall(disable_boot_consoles); | |
1157 | ||
1da177e4 LT |
1158 | /** |
1159 | * tty_write_message - write a message to a certain tty, not just the console. | |
ddad86c2 MW |
1160 | * @tty: the destination tty_struct |
1161 | * @msg: the message to write | |
1da177e4 LT |
1162 | * |
1163 | * This is used for messages that need to be redirected to a specific tty. | |
1164 | * We don't put it into the syslog queue right now maybe in the future if | |
1165 | * really needed. | |
1166 | */ | |
1167 | void tty_write_message(struct tty_struct *tty, char *msg) | |
1168 | { | |
1169 | if (tty && tty->driver->write) | |
1170 | tty->driver->write(tty, msg, strlen(msg)); | |
1171 | return; | |
1172 | } | |
1173 | ||
1174 | /* | |
1175 | * printk rate limiting, lifted from the networking subsystem. | |
1176 | * | |
1177 | * This enforces a rate limit: not more than one kernel message | |
1178 | * every printk_ratelimit_jiffies to make a denial-of-service | |
1179 | * attack impossible. | |
1180 | */ | |
1181 | int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst) | |
1182 | { | |
1183 | static DEFINE_SPINLOCK(ratelimit_lock); | |
40dc5651 | 1184 | static unsigned long toks = 10 * 5 * HZ; |
1da177e4 LT |
1185 | static unsigned long last_msg; |
1186 | static int missed; | |
1187 | unsigned long flags; | |
1188 | unsigned long now = jiffies; | |
1189 | ||
1190 | spin_lock_irqsave(&ratelimit_lock, flags); | |
1191 | toks += now - last_msg; | |
1192 | last_msg = now; | |
1193 | if (toks > (ratelimit_burst * ratelimit_jiffies)) | |
1194 | toks = ratelimit_burst * ratelimit_jiffies; | |
1195 | if (toks >= ratelimit_jiffies) { | |
1196 | int lost = missed; | |
40dc5651 | 1197 | |
1da177e4 LT |
1198 | missed = 0; |
1199 | toks -= ratelimit_jiffies; | |
1200 | spin_unlock_irqrestore(&ratelimit_lock, flags); | |
1201 | if (lost) | |
1202 | printk(KERN_WARNING "printk: %d messages suppressed.\n", lost); | |
1203 | return 1; | |
1204 | } | |
1205 | missed++; | |
1206 | spin_unlock_irqrestore(&ratelimit_lock, flags); | |
1207 | return 0; | |
1208 | } | |
1209 | EXPORT_SYMBOL(__printk_ratelimit); | |
1210 | ||
1211 | /* minimum time in jiffies between messages */ | |
40dc5651 | 1212 | int printk_ratelimit_jiffies = 5 * HZ; |
1da177e4 LT |
1213 | |
1214 | /* number of messages we send before ratelimiting */ | |
1215 | int printk_ratelimit_burst = 10; | |
1216 | ||
1217 | int printk_ratelimit(void) | |
1218 | { | |
1219 | return __printk_ratelimit(printk_ratelimit_jiffies, | |
1220 | printk_ratelimit_burst); | |
1221 | } | |
1222 | EXPORT_SYMBOL(printk_ratelimit); | |
f46c4833 AM |
1223 | |
1224 | /** | |
1225 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1226 | * @caller_jiffies: pointer to caller's state | |
1227 | * @interval_msecs: minimum interval between prints | |
1228 | * | |
1229 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1230 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1231 | * returned true. | |
1232 | */ | |
1233 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1234 | unsigned int interval_msecs) | |
1235 | { | |
1236 | if (*caller_jiffies == 0 || time_after(jiffies, *caller_jiffies)) { | |
1237 | *caller_jiffies = jiffies + msecs_to_jiffies(interval_msecs); | |
1238 | return true; | |
1239 | } | |
1240 | return false; | |
1241 | } | |
1242 | EXPORT_SYMBOL(printk_timed_ratelimit); |