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 | 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> | |
04d491ab | 35 | #include <linux/kexec.h> |
d37d39ae | 36 | #include <linux/kdb.h> |
3fff4c42 | 37 | #include <linux/ratelimit.h> |
456b565c | 38 | #include <linux/kmsg_dump.h> |
00234592 | 39 | #include <linux/syslog.h> |
034260d6 KC |
40 | #include <linux/cpu.h> |
41 | #include <linux/notifier.h> | |
fb842b00 | 42 | #include <linux/rculist.h> |
1da177e4 LT |
43 | |
44 | #include <asm/uaccess.h> | |
45 | ||
076f9776 IM |
46 | /* |
47 | * Architectures can override it: | |
48 | */ | |
e17ba73b | 49 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
076f9776 IM |
50 | { |
51 | } | |
52 | ||
1da177e4 LT |
53 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
54 | ||
55 | /* printk's without a loglevel use this.. */ | |
56 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ | |
57 | ||
58 | /* We show everything that is MORE important than this.. */ | |
59 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
60 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
61 | ||
62 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
63 | ||
64 | int console_printk[4] = { | |
65 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
66 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
67 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
68 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
69 | }; | |
70 | ||
1da177e4 | 71 | /* |
0bbfb7c2 | 72 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
73 | * their unblank() callback or not. So let's export it. |
74 | */ | |
75 | int oops_in_progress; | |
76 | EXPORT_SYMBOL(oops_in_progress); | |
77 | ||
78 | /* | |
79 | * console_sem protects the console_drivers list, and also | |
80 | * provides serialisation for access to the entire console | |
81 | * driver system. | |
82 | */ | |
5b8c4f23 | 83 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 84 | struct console *console_drivers; |
a29d1cfe IM |
85 | EXPORT_SYMBOL_GPL(console_drivers); |
86 | ||
1da177e4 LT |
87 | /* |
88 | * This is used for debugging the mess that is the VT code by | |
89 | * keeping track if we have the console semaphore held. It's | |
90 | * definitely not the perfect debug tool (we don't know if _WE_ | |
91 | * hold it are racing, but it helps tracking those weird code | |
92 | * path in the console code where we end up in places I want | |
93 | * locked without the console sempahore held | |
94 | */ | |
557240b4 | 95 | static int console_locked, console_suspended; |
1da177e4 LT |
96 | |
97 | /* | |
98 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
99 | * It is also used in interesting ways to provide interlocking in | |
ac751efa | 100 | * console_unlock();. |
1da177e4 LT |
101 | */ |
102 | static DEFINE_SPINLOCK(logbuf_lock); | |
103 | ||
eed4a2ab | 104 | #define LOG_BUF_MASK (log_buf_len-1) |
1da177e4 LT |
105 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
106 | ||
107 | /* | |
108 | * The indices into log_buf are not constrained to log_buf_len - they | |
109 | * must be masked before subscripting | |
110 | */ | |
eed4a2ab DV |
111 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
112 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ | |
113 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
114 | |
115 | /* | |
116 | * Array of consoles built from command line options (console=) | |
117 | */ | |
118 | struct console_cmdline | |
119 | { | |
120 | char name[8]; /* Name of the driver */ | |
121 | int index; /* Minor dev. to use */ | |
122 | char *options; /* Options for the driver */ | |
f7511d5f ST |
123 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
124 | char *brl_options; /* Options for braille driver */ | |
125 | #endif | |
1da177e4 LT |
126 | }; |
127 | ||
128 | #define MAX_CMDLINECONSOLES 8 | |
129 | ||
130 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
131 | static int selected_console = -1; | |
132 | static int preferred_console = -1; | |
9e124fe1 MA |
133 | int console_set_on_cmdline; |
134 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
135 | |
136 | /* Flag: console code may call schedule() */ | |
137 | static int console_may_schedule; | |
138 | ||
d59745ce MM |
139 | #ifdef CONFIG_PRINTK |
140 | ||
141 | static char __log_buf[__LOG_BUF_LEN]; | |
142 | static char *log_buf = __log_buf; | |
143 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 144 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
cea83886 | 145 | static int saved_console_loglevel = -1; |
d59745ce | 146 | |
04d491ab NH |
147 | #ifdef CONFIG_KEXEC |
148 | /* | |
149 | * This appends the listed symbols to /proc/vmcoreinfo | |
150 | * | |
151 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
152 | * obtain access to symbols that are otherwise very difficult to locate. These | |
153 | * symbols are specifically used so that utilities can access and extract the | |
154 | * dmesg log from a vmcore file after a crash. | |
155 | */ | |
156 | void log_buf_kexec_setup(void) | |
157 | { | |
158 | VMCOREINFO_SYMBOL(log_buf); | |
159 | VMCOREINFO_SYMBOL(log_end); | |
160 | VMCOREINFO_SYMBOL(log_buf_len); | |
161 | VMCOREINFO_SYMBOL(logged_chars); | |
162 | } | |
163 | #endif | |
164 | ||
1da177e4 LT |
165 | static int __init log_buf_len_setup(char *str) |
166 | { | |
eed4a2ab | 167 | unsigned size = memparse(str, &str); |
1da177e4 LT |
168 | unsigned long flags; |
169 | ||
170 | if (size) | |
171 | size = roundup_pow_of_two(size); | |
172 | if (size > log_buf_len) { | |
eed4a2ab | 173 | unsigned start, dest_idx, offset; |
40dc5651 | 174 | char *new_log_buf; |
1da177e4 LT |
175 | |
176 | new_log_buf = alloc_bootmem(size); | |
177 | if (!new_log_buf) { | |
40dc5651 | 178 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
179 | goto out; |
180 | } | |
181 | ||
182 | spin_lock_irqsave(&logbuf_lock, flags); | |
183 | log_buf_len = size; | |
184 | log_buf = new_log_buf; | |
185 | ||
186 | offset = start = min(con_start, log_start); | |
187 | dest_idx = 0; | |
188 | while (start != log_end) { | |
189 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
190 | start++; | |
191 | dest_idx++; | |
192 | } | |
193 | log_start -= offset; | |
194 | con_start -= offset; | |
195 | log_end -= offset; | |
196 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
197 | ||
40dc5651 | 198 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
199 | } |
200 | out: | |
1da177e4 LT |
201 | return 1; |
202 | } | |
203 | ||
204 | __setup("log_buf_len=", log_buf_len_setup); | |
205 | ||
bfe8df3d RD |
206 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
207 | ||
674dff65 | 208 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 209 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
210 | |
211 | static int __init boot_delay_setup(char *str) | |
212 | { | |
213 | unsigned long lpj; | |
bfe8df3d RD |
214 | |
215 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
216 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
217 | ||
218 | get_option(&str, &boot_delay); | |
219 | if (boot_delay > 10 * 1000) | |
220 | boot_delay = 0; | |
221 | ||
3a3b6ed2 DY |
222 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
223 | "HZ: %d, loops_per_msec: %llu\n", | |
224 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
bfe8df3d RD |
225 | return 1; |
226 | } | |
227 | __setup("boot_delay=", boot_delay_setup); | |
228 | ||
229 | static void boot_delay_msec(void) | |
230 | { | |
231 | unsigned long long k; | |
232 | unsigned long timeout; | |
233 | ||
234 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
235 | return; | |
236 | ||
3a3b6ed2 | 237 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
238 | |
239 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
240 | while (k) { | |
241 | k--; | |
242 | cpu_relax(); | |
243 | /* | |
244 | * use (volatile) jiffies to prevent | |
245 | * compiler reduction; loop termination via jiffies | |
246 | * is secondary and may or may not happen. | |
247 | */ | |
248 | if (time_after(jiffies, timeout)) | |
249 | break; | |
250 | touch_nmi_watchdog(); | |
251 | } | |
252 | } | |
253 | #else | |
254 | static inline void boot_delay_msec(void) | |
255 | { | |
256 | } | |
257 | #endif | |
258 | ||
eaf06b24 DR |
259 | #ifdef CONFIG_SECURITY_DMESG_RESTRICT |
260 | int dmesg_restrict = 1; | |
261 | #else | |
262 | int dmesg_restrict; | |
263 | #endif | |
264 | ||
ee24aebf LT |
265 | static int syslog_action_restricted(int type) |
266 | { | |
267 | if (dmesg_restrict) | |
268 | return 1; | |
269 | /* Unless restricted, we allow "read all" and "get buffer size" for everybody */ | |
270 | return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; | |
271 | } | |
272 | ||
273 | static int check_syslog_permissions(int type, bool from_file) | |
274 | { | |
275 | /* | |
276 | * If this is from /proc/kmsg and we've already opened it, then we've | |
277 | * already done the capabilities checks at open time. | |
278 | */ | |
279 | if (from_file && type != SYSLOG_ACTION_OPEN) | |
280 | return 0; | |
281 | ||
282 | if (syslog_action_restricted(type)) { | |
283 | if (capable(CAP_SYSLOG)) | |
284 | return 0; | |
285 | /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */ | |
286 | if (capable(CAP_SYS_ADMIN)) { | |
287 | WARN_ONCE(1, "Attempt to access syslog with CAP_SYS_ADMIN " | |
288 | "but no CAP_SYSLOG (deprecated).\n"); | |
289 | return 0; | |
290 | } | |
291 | return -EPERM; | |
292 | } | |
293 | return 0; | |
294 | } | |
295 | ||
00234592 | 296 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
1da177e4 | 297 | { |
eed4a2ab | 298 | unsigned i, j, limit, count; |
1da177e4 LT |
299 | int do_clear = 0; |
300 | char c; | |
ee24aebf | 301 | int error; |
1da177e4 | 302 | |
ee24aebf LT |
303 | error = check_syslog_permissions(type, from_file); |
304 | if (error) | |
305 | goto out; | |
12b3052c EP |
306 | |
307 | error = security_syslog(type); | |
1da177e4 LT |
308 | if (error) |
309 | return error; | |
310 | ||
311 | switch (type) { | |
d78ca3cd | 312 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 313 | break; |
d78ca3cd | 314 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 315 | break; |
d78ca3cd | 316 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 LT |
317 | error = -EINVAL; |
318 | if (!buf || len < 0) | |
319 | goto out; | |
320 | error = 0; | |
321 | if (!len) | |
322 | goto out; | |
323 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
324 | error = -EFAULT; | |
325 | goto out; | |
326 | } | |
40dc5651 JJ |
327 | error = wait_event_interruptible(log_wait, |
328 | (log_start - log_end)); | |
1da177e4 LT |
329 | if (error) |
330 | goto out; | |
331 | i = 0; | |
332 | spin_lock_irq(&logbuf_lock); | |
333 | while (!error && (log_start != log_end) && i < len) { | |
334 | c = LOG_BUF(log_start); | |
335 | log_start++; | |
336 | spin_unlock_irq(&logbuf_lock); | |
337 | error = __put_user(c,buf); | |
338 | buf++; | |
339 | i++; | |
340 | cond_resched(); | |
341 | spin_lock_irq(&logbuf_lock); | |
342 | } | |
343 | spin_unlock_irq(&logbuf_lock); | |
344 | if (!error) | |
345 | error = i; | |
346 | break; | |
d78ca3cd KC |
347 | /* Read/clear last kernel messages */ |
348 | case SYSLOG_ACTION_READ_CLEAR: | |
40dc5651 | 349 | do_clear = 1; |
1da177e4 | 350 | /* FALL THRU */ |
d78ca3cd KC |
351 | /* Read last kernel messages */ |
352 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 LT |
353 | error = -EINVAL; |
354 | if (!buf || len < 0) | |
355 | goto out; | |
356 | error = 0; | |
357 | if (!len) | |
358 | goto out; | |
359 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
360 | error = -EFAULT; | |
361 | goto out; | |
362 | } | |
363 | count = len; | |
364 | if (count > log_buf_len) | |
365 | count = log_buf_len; | |
366 | spin_lock_irq(&logbuf_lock); | |
367 | if (count > logged_chars) | |
368 | count = logged_chars; | |
369 | if (do_clear) | |
370 | logged_chars = 0; | |
371 | limit = log_end; | |
372 | /* | |
373 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 374 | * printk() could overwrite the messages |
1da177e4 LT |
375 | * we try to copy to user space. Therefore |
376 | * the messages are copied in reverse. <manfreds> | |
377 | */ | |
40dc5651 | 378 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
379 | j = limit-1-i; |
380 | if (j + log_buf_len < log_end) | |
381 | break; | |
382 | c = LOG_BUF(j); | |
383 | spin_unlock_irq(&logbuf_lock); | |
384 | error = __put_user(c,&buf[count-1-i]); | |
385 | cond_resched(); | |
386 | spin_lock_irq(&logbuf_lock); | |
387 | } | |
388 | spin_unlock_irq(&logbuf_lock); | |
389 | if (error) | |
390 | break; | |
391 | error = i; | |
40dc5651 | 392 | if (i != count) { |
1da177e4 LT |
393 | int offset = count-error; |
394 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 395 | for (i = 0; i < error; i++) { |
1da177e4 LT |
396 | if (__get_user(c,&buf[i+offset]) || |
397 | __put_user(c,&buf[i])) { | |
398 | error = -EFAULT; | |
399 | break; | |
400 | } | |
401 | cond_resched(); | |
402 | } | |
403 | } | |
404 | break; | |
d78ca3cd KC |
405 | /* Clear ring buffer */ |
406 | case SYSLOG_ACTION_CLEAR: | |
1da177e4 LT |
407 | logged_chars = 0; |
408 | break; | |
d78ca3cd KC |
409 | /* Disable logging to console */ |
410 | case SYSLOG_ACTION_CONSOLE_OFF: | |
1aaad49e FP |
411 | if (saved_console_loglevel == -1) |
412 | saved_console_loglevel = console_loglevel; | |
1da177e4 LT |
413 | console_loglevel = minimum_console_loglevel; |
414 | break; | |
d78ca3cd KC |
415 | /* Enable logging to console */ |
416 | case SYSLOG_ACTION_CONSOLE_ON: | |
1aaad49e FP |
417 | if (saved_console_loglevel != -1) { |
418 | console_loglevel = saved_console_loglevel; | |
419 | saved_console_loglevel = -1; | |
420 | } | |
1da177e4 | 421 | break; |
d78ca3cd KC |
422 | /* Set level of messages printed to console */ |
423 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 LT |
424 | error = -EINVAL; |
425 | if (len < 1 || len > 8) | |
426 | goto out; | |
427 | if (len < minimum_console_loglevel) | |
428 | len = minimum_console_loglevel; | |
429 | console_loglevel = len; | |
1aaad49e FP |
430 | /* Implicitly re-enable logging to console */ |
431 | saved_console_loglevel = -1; | |
1da177e4 LT |
432 | error = 0; |
433 | break; | |
d78ca3cd KC |
434 | /* Number of chars in the log buffer */ |
435 | case SYSLOG_ACTION_SIZE_UNREAD: | |
1da177e4 LT |
436 | error = log_end - log_start; |
437 | break; | |
d78ca3cd KC |
438 | /* Size of the log buffer */ |
439 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
440 | error = log_buf_len; |
441 | break; | |
442 | default: | |
443 | error = -EINVAL; | |
444 | break; | |
445 | } | |
446 | out: | |
447 | return error; | |
448 | } | |
449 | ||
1e7bfb21 | 450 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 451 | { |
00234592 | 452 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
1da177e4 LT |
453 | } |
454 | ||
67fc4e0c JW |
455 | #ifdef CONFIG_KGDB_KDB |
456 | /* kdb dmesg command needs access to the syslog buffer. do_syslog() | |
457 | * uses locks so it cannot be used during debugging. Just tell kdb | |
458 | * where the start and end of the physical and logical logs are. This | |
459 | * is equivalent to do_syslog(3). | |
460 | */ | |
461 | void kdb_syslog_data(char *syslog_data[4]) | |
462 | { | |
463 | syslog_data[0] = log_buf; | |
464 | syslog_data[1] = log_buf + log_buf_len; | |
465 | syslog_data[2] = log_buf + log_end - | |
466 | (logged_chars < log_buf_len ? logged_chars : log_buf_len); | |
467 | syslog_data[3] = log_buf + log_end; | |
468 | } | |
469 | #endif /* CONFIG_KGDB_KDB */ | |
470 | ||
1da177e4 LT |
471 | /* |
472 | * Call the console drivers on a range of log_buf | |
473 | */ | |
eed4a2ab | 474 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
475 | { |
476 | struct console *con; | |
477 | ||
4d091611 | 478 | for_each_console(con) { |
76a8ad29 ME |
479 | if ((con->flags & CON_ENABLED) && con->write && |
480 | (cpu_online(smp_processor_id()) || | |
481 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
482 | con->write(con, &LOG_BUF(start), end - start); |
483 | } | |
484 | } | |
485 | ||
79290822 IM |
486 | static int __read_mostly ignore_loglevel; |
487 | ||
99eea6a1 | 488 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
489 | { |
490 | ignore_loglevel = 1; | |
491 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
492 | ||
c4772d99 | 493 | return 0; |
79290822 IM |
494 | } |
495 | ||
c4772d99 | 496 | early_param("ignore_loglevel", ignore_loglevel_setup); |
79290822 | 497 | |
1da177e4 LT |
498 | /* |
499 | * Write out chars from start to end - 1 inclusive | |
500 | */ | |
eed4a2ab DV |
501 | static void _call_console_drivers(unsigned start, |
502 | unsigned end, int msg_log_level) | |
1da177e4 | 503 | { |
79290822 | 504 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
505 | console_drivers && start != end) { |
506 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
507 | /* wrapped write */ | |
508 | __call_console_drivers(start & LOG_BUF_MASK, | |
509 | log_buf_len); | |
510 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
511 | } else { | |
512 | __call_console_drivers(start, end); | |
513 | } | |
514 | } | |
515 | } | |
516 | ||
517 | /* | |
518 | * Call the console drivers, asking them to write out | |
519 | * log_buf[start] to log_buf[end - 1]. | |
ac751efa | 520 | * The console_lock must be held. |
1da177e4 | 521 | */ |
eed4a2ab | 522 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 523 | { |
eed4a2ab | 524 | unsigned cur_index, start_print; |
1da177e4 LT |
525 | static int msg_level = -1; |
526 | ||
eed4a2ab | 527 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
528 | |
529 | cur_index = start; | |
530 | start_print = start; | |
531 | while (cur_index != end) { | |
40dc5651 JJ |
532 | if (msg_level < 0 && ((end - cur_index) > 2) && |
533 | LOG_BUF(cur_index + 0) == '<' && | |
534 | LOG_BUF(cur_index + 1) >= '0' && | |
535 | LOG_BUF(cur_index + 1) <= '7' && | |
536 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
537 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
538 | cur_index += 3; | |
539 | start_print = cur_index; | |
540 | } | |
541 | while (cur_index != end) { | |
542 | char c = LOG_BUF(cur_index); | |
1da177e4 | 543 | |
40dc5651 | 544 | cur_index++; |
1da177e4 LT |
545 | if (c == '\n') { |
546 | if (msg_level < 0) { | |
547 | /* | |
548 | * printk() has already given us loglevel tags in | |
549 | * the buffer. This code is here in case the | |
550 | * log buffer has wrapped right round and scribbled | |
551 | * on those tags | |
552 | */ | |
553 | msg_level = default_message_loglevel; | |
554 | } | |
555 | _call_console_drivers(start_print, cur_index, msg_level); | |
556 | msg_level = -1; | |
557 | start_print = cur_index; | |
558 | break; | |
559 | } | |
560 | } | |
561 | } | |
562 | _call_console_drivers(start_print, end, msg_level); | |
563 | } | |
564 | ||
565 | static void emit_log_char(char c) | |
566 | { | |
567 | LOG_BUF(log_end) = c; | |
568 | log_end++; | |
569 | if (log_end - log_start > log_buf_len) | |
570 | log_start = log_end - log_buf_len; | |
571 | if (log_end - con_start > log_buf_len) | |
572 | con_start = log_end - log_buf_len; | |
573 | if (logged_chars < log_buf_len) | |
574 | logged_chars++; | |
575 | } | |
576 | ||
577 | /* | |
578 | * Zap console related locks when oopsing. Only zap at most once | |
579 | * every 10 seconds, to leave time for slow consoles to print a | |
580 | * full oops. | |
581 | */ | |
582 | static void zap_locks(void) | |
583 | { | |
584 | static unsigned long oops_timestamp; | |
585 | ||
586 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 587 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
588 | return; |
589 | ||
590 | oops_timestamp = jiffies; | |
591 | ||
592 | /* If a crash is occurring, make sure we can't deadlock */ | |
593 | spin_lock_init(&logbuf_lock); | |
594 | /* And make sure that we print immediately */ | |
5b8c4f23 | 595 | sema_init(&console_sem, 1); |
1da177e4 LT |
596 | } |
597 | ||
598 | #if defined(CONFIG_PRINTK_TIME) | |
599 | static int printk_time = 1; | |
600 | #else | |
601 | static int printk_time = 0; | |
602 | #endif | |
e84845c4 | 603 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 604 | |
76a8ad29 ME |
605 | /* Check if we have any console registered that can be called early in boot. */ |
606 | static int have_callable_console(void) | |
607 | { | |
608 | struct console *con; | |
609 | ||
4d091611 | 610 | for_each_console(con) |
76a8ad29 ME |
611 | if (con->flags & CON_ANYTIME) |
612 | return 1; | |
613 | ||
614 | return 0; | |
615 | } | |
616 | ||
ddad86c2 MW |
617 | /** |
618 | * printk - print a kernel message | |
619 | * @fmt: format string | |
620 | * | |
72fd4a35 | 621 | * This is printk(). It can be called from any context. We want it to work. |
40dc5651 | 622 | * |
ac751efa | 623 | * We try to grab the console_lock. If we succeed, it's easy - we log the output and |
1da177e4 LT |
624 | * call the console drivers. If we fail to get the semaphore we place the output |
625 | * into the log buffer and return. The current holder of the console_sem will | |
ac751efa TH |
626 | * notice the new output in console_unlock(); and will send it to the |
627 | * consoles before releasing the lock. | |
1da177e4 LT |
628 | * |
629 | * One effect of this deferred printing is that code which calls printk() and | |
630 | * then changes console_loglevel may break. This is because console_loglevel | |
631 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
632 | * |
633 | * See also: | |
634 | * printf(3) | |
20036fdc AK |
635 | * |
636 | * See the vsnprintf() documentation for format string extensions over C99. | |
1da177e4 | 637 | */ |
d59745ce | 638 | |
1da177e4 LT |
639 | asmlinkage int printk(const char *fmt, ...) |
640 | { | |
641 | va_list args; | |
642 | int r; | |
643 | ||
d37d39ae JW |
644 | #ifdef CONFIG_KGDB_KDB |
645 | if (unlikely(kdb_trap_printk)) { | |
646 | va_start(args, fmt); | |
647 | r = vkdb_printf(fmt, args); | |
648 | va_end(args); | |
649 | return r; | |
650 | } | |
651 | #endif | |
1da177e4 LT |
652 | va_start(args, fmt); |
653 | r = vprintk(fmt, args); | |
654 | va_end(args); | |
655 | ||
656 | return r; | |
657 | } | |
658 | ||
fe21773d DH |
659 | /* cpu currently holding logbuf_lock */ |
660 | static volatile unsigned int printk_cpu = UINT_MAX; | |
661 | ||
266c2e0a LT |
662 | /* |
663 | * Can we actually use the console at this time on this cpu? | |
664 | * | |
665 | * Console drivers may assume that per-cpu resources have | |
666 | * been allocated. So unless they're explicitly marked as | |
667 | * being able to cope (CON_ANYTIME) don't call them until | |
668 | * this CPU is officially up. | |
669 | */ | |
670 | static inline int can_use_console(unsigned int cpu) | |
671 | { | |
672 | return cpu_online(cpu) || have_callable_console(); | |
673 | } | |
674 | ||
675 | /* | |
676 | * Try to get console ownership to actually show the kernel | |
677 | * messages from a 'printk'. Return true (and with the | |
ac751efa | 678 | * console_lock held, and 'console_locked' set) if it |
266c2e0a LT |
679 | * is successful, false otherwise. |
680 | * | |
681 | * This gets called with the 'logbuf_lock' spinlock held and | |
682 | * interrupts disabled. It should return with 'lockbuf_lock' | |
683 | * released but interrupts still disabled. | |
684 | */ | |
ac751efa | 685 | static int console_trylock_for_printk(unsigned int cpu) |
8155c02a | 686 | __releases(&logbuf_lock) |
266c2e0a LT |
687 | { |
688 | int retval = 0; | |
689 | ||
ac751efa | 690 | if (console_trylock()) { |
093a07e2 LT |
691 | retval = 1; |
692 | ||
693 | /* | |
694 | * If we can't use the console, we need to release | |
695 | * the console semaphore by hand to avoid flushing | |
696 | * the buffer. We need to hold the console semaphore | |
697 | * in order to do this test safely. | |
698 | */ | |
699 | if (!can_use_console(cpu)) { | |
700 | console_locked = 0; | |
701 | up(&console_sem); | |
702 | retval = 0; | |
703 | } | |
704 | } | |
266c2e0a LT |
705 | printk_cpu = UINT_MAX; |
706 | spin_unlock(&logbuf_lock); | |
707 | return retval; | |
708 | } | |
3b8945e8 TH |
709 | static const char recursion_bug_msg [] = |
710 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
711 | static int recursion_bug; | |
edb123e1 | 712 | static int new_text_line = 1; |
3b8945e8 | 713 | static char printk_buf[1024]; |
32a76006 | 714 | |
af91322e DY |
715 | int printk_delay_msec __read_mostly; |
716 | ||
717 | static inline void printk_delay(void) | |
718 | { | |
719 | if (unlikely(printk_delay_msec)) { | |
720 | int m = printk_delay_msec; | |
721 | ||
722 | while (m--) { | |
723 | mdelay(1); | |
724 | touch_nmi_watchdog(); | |
725 | } | |
726 | } | |
727 | } | |
728 | ||
1da177e4 LT |
729 | asmlinkage int vprintk(const char *fmt, va_list args) |
730 | { | |
32a76006 | 731 | int printed_len = 0; |
09159308 | 732 | int current_log_level = default_message_loglevel; |
ac60ad74 | 733 | unsigned long flags; |
32a76006 | 734 | int this_cpu; |
1da177e4 | 735 | char *p; |
1da177e4 | 736 | |
bfe8df3d | 737 | boot_delay_msec(); |
af91322e | 738 | printk_delay(); |
bfe8df3d | 739 | |
fe21773d | 740 | preempt_disable(); |
1da177e4 | 741 | /* This stops the holder of console_sem just where we want him */ |
1efc5da3 | 742 | raw_local_irq_save(flags); |
32a76006 IM |
743 | this_cpu = smp_processor_id(); |
744 | ||
745 | /* | |
746 | * Ouch, printk recursed into itself! | |
747 | */ | |
748 | if (unlikely(printk_cpu == this_cpu)) { | |
749 | /* | |
750 | * If a crash is occurring during printk() on this CPU, | |
751 | * then try to get the crash message out but make sure | |
752 | * we can't deadlock. Otherwise just return to avoid the | |
753 | * recursion and return - but flag the recursion so that | |
754 | * it can be printed at the next appropriate moment: | |
755 | */ | |
756 | if (!oops_in_progress) { | |
3b8945e8 | 757 | recursion_bug = 1; |
32a76006 IM |
758 | goto out_restore_irqs; |
759 | } | |
760 | zap_locks(); | |
761 | } | |
762 | ||
a0f1ccfd IM |
763 | lockdep_off(); |
764 | spin_lock(&logbuf_lock); | |
32a76006 | 765 | printk_cpu = this_cpu; |
1da177e4 | 766 | |
3b8945e8 TH |
767 | if (recursion_bug) { |
768 | recursion_bug = 0; | |
769 | strcpy(printk_buf, recursion_bug_msg); | |
26cc271d | 770 | printed_len = strlen(recursion_bug_msg); |
32a76006 | 771 | } |
1da177e4 | 772 | /* Emit the output into the temporary buffer */ |
32a76006 | 773 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 774 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 775 | |
ac60ad74 | 776 | |
5fd29d6c LT |
777 | p = printk_buf; |
778 | ||
779 | /* Do we have a loglevel in the string? */ | |
780 | if (p[0] == '<') { | |
781 | unsigned char c = p[1]; | |
782 | if (c && p[2] == '>') { | |
783 | switch (c) { | |
784 | case '0' ... '7': /* loglevel */ | |
785 | current_log_level = c - '0'; | |
e28d7137 LT |
786 | /* Fallthrough - make sure we're on a new line */ |
787 | case 'd': /* KERN_DEFAULT */ | |
5fd29d6c LT |
788 | if (!new_text_line) { |
789 | emit_log_char('\n'); | |
790 | new_text_line = 1; | |
791 | } | |
792 | /* Fallthrough - skip the loglevel */ | |
793 | case 'c': /* KERN_CONT */ | |
794 | p += 3; | |
795 | break; | |
796 | } | |
797 | } | |
798 | } | |
799 | ||
1da177e4 LT |
800 | /* |
801 | * Copy the output into log_buf. If the caller didn't provide | |
802 | * appropriate log level tags, we insert them here | |
803 | */ | |
5fd29d6c | 804 | for ( ; *p; p++) { |
ac60ad74 | 805 | if (new_text_line) { |
ac60ad74 NA |
806 | /* Always output the token */ |
807 | emit_log_char('<'); | |
808 | emit_log_char(current_log_level + '0'); | |
809 | emit_log_char('>'); | |
810 | printed_len += 3; | |
811 | new_text_line = 0; | |
812 | ||
1da177e4 | 813 | if (printk_time) { |
ac60ad74 | 814 | /* Follow the token with the time */ |
1da177e4 LT |
815 | char tbuf[50], *tp; |
816 | unsigned tlen; | |
817 | unsigned long long t; | |
818 | unsigned long nanosec_rem; | |
819 | ||
326e96b9 | 820 | t = cpu_clock(printk_cpu); |
1da177e4 | 821 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
822 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
823 | (unsigned long) t, | |
824 | nanosec_rem / 1000); | |
1da177e4 LT |
825 | |
826 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
827 | emit_log_char(*tp); | |
025510cd | 828 | printed_len += tlen; |
1da177e4 | 829 | } |
ac60ad74 | 830 | |
1da177e4 LT |
831 | if (!*p) |
832 | break; | |
833 | } | |
ac60ad74 | 834 | |
1da177e4 LT |
835 | emit_log_char(*p); |
836 | if (*p == '\n') | |
ac60ad74 | 837 | new_text_line = 1; |
1da177e4 LT |
838 | } |
839 | ||
266c2e0a LT |
840 | /* |
841 | * Try to acquire and then immediately release the | |
842 | * console semaphore. The release will do all the | |
843 | * actual magic (print out buffers, wake up klogd, | |
844 | * etc). | |
845 | * | |
ac751efa | 846 | * The console_trylock_for_printk() function |
266c2e0a LT |
847 | * will release 'logbuf_lock' regardless of whether it |
848 | * actually gets the semaphore or not. | |
849 | */ | |
ac751efa TH |
850 | if (console_trylock_for_printk(this_cpu)) |
851 | console_unlock(); | |
76a8ad29 | 852 | |
266c2e0a | 853 | lockdep_on(); |
32a76006 | 854 | out_restore_irqs: |
266c2e0a | 855 | raw_local_irq_restore(flags); |
76a8ad29 | 856 | |
fe21773d | 857 | preempt_enable(); |
1da177e4 LT |
858 | return printed_len; |
859 | } | |
860 | EXPORT_SYMBOL(printk); | |
861 | EXPORT_SYMBOL(vprintk); | |
862 | ||
d59745ce MM |
863 | #else |
864 | ||
eed4a2ab | 865 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
866 | { |
867 | } | |
d59745ce MM |
868 | |
869 | #endif | |
870 | ||
f7511d5f ST |
871 | static int __add_preferred_console(char *name, int idx, char *options, |
872 | char *brl_options) | |
873 | { | |
874 | struct console_cmdline *c; | |
875 | int i; | |
876 | ||
877 | /* | |
878 | * See if this tty is not yet registered, and | |
879 | * if we have a slot free. | |
880 | */ | |
881 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
882 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
883 | console_cmdline[i].index == idx) { | |
884 | if (!brl_options) | |
885 | selected_console = i; | |
886 | return 0; | |
887 | } | |
888 | if (i == MAX_CMDLINECONSOLES) | |
889 | return -E2BIG; | |
890 | if (!brl_options) | |
891 | selected_console = i; | |
892 | c = &console_cmdline[i]; | |
893 | strlcpy(c->name, name, sizeof(c->name)); | |
894 | c->options = options; | |
895 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
896 | c->brl_options = brl_options; | |
897 | #endif | |
898 | c->index = idx; | |
899 | return 0; | |
900 | } | |
2ea1c539 JB |
901 | /* |
902 | * Set up a list of consoles. Called from init/main.c | |
903 | */ | |
904 | static int __init console_setup(char *str) | |
905 | { | |
eaa944af | 906 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 907 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
908 | int idx; |
909 | ||
f7511d5f ST |
910 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
911 | if (!memcmp(str, "brl,", 4)) { | |
912 | brl_options = ""; | |
913 | str += 4; | |
914 | } else if (!memcmp(str, "brl=", 4)) { | |
915 | brl_options = str + 4; | |
916 | str = strchr(brl_options, ','); | |
917 | if (!str) { | |
918 | printk(KERN_ERR "need port name after brl=\n"); | |
919 | return 1; | |
920 | } | |
921 | *(str++) = 0; | |
922 | } | |
923 | #endif | |
924 | ||
2ea1c539 JB |
925 | /* |
926 | * Decode str into name, index, options. | |
927 | */ | |
928 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
929 | strcpy(buf, "ttyS"); |
930 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 931 | } else { |
eaa944af | 932 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 933 | } |
eaa944af | 934 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
935 | if ((options = strchr(str, ',')) != NULL) |
936 | *(options++) = 0; | |
937 | #ifdef __sparc__ | |
938 | if (!strcmp(str, "ttya")) | |
eaa944af | 939 | strcpy(buf, "ttyS0"); |
2ea1c539 | 940 | if (!strcmp(str, "ttyb")) |
eaa944af | 941 | strcpy(buf, "ttyS1"); |
2ea1c539 | 942 | #endif |
eaa944af | 943 | for (s = buf; *s; s++) |
2ea1c539 JB |
944 | if ((*s >= '0' && *s <= '9') || *s == ',') |
945 | break; | |
946 | idx = simple_strtoul(s, NULL, 10); | |
947 | *s = 0; | |
948 | ||
f7511d5f | 949 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 950 | console_set_on_cmdline = 1; |
2ea1c539 JB |
951 | return 1; |
952 | } | |
953 | __setup("console=", console_setup); | |
954 | ||
3c0547ba MM |
955 | /** |
956 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
957 | * @name: device name |
958 | * @idx: device index | |
959 | * @options: options for this console | |
3c0547ba MM |
960 | * |
961 | * The last preferred console added will be used for kernel messages | |
962 | * and stdin/out/err for init. Normally this is used by console_setup | |
963 | * above to handle user-supplied console arguments; however it can also | |
964 | * be used by arch-specific code either to override the user or more | |
965 | * commonly to provide a default console (ie from PROM variables) when | |
966 | * the user has not supplied one. | |
967 | */ | |
fb445ee5 | 968 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 969 | { |
f7511d5f | 970 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
971 | } |
972 | ||
b6b1d877 | 973 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
974 | { |
975 | struct console_cmdline *c; | |
976 | int i; | |
977 | ||
978 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
979 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
980 | console_cmdline[i].index == idx) { | |
981 | c = &console_cmdline[i]; | |
f735295b | 982 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
983 | c->name[sizeof(c->name) - 1] = 0; |
984 | c->options = options; | |
985 | c->index = idx_new; | |
986 | return i; | |
987 | } | |
988 | /* not found */ | |
989 | return -1; | |
990 | } | |
991 | ||
8f4ce8c3 AS |
992 | int console_suspend_enabled = 1; |
993 | EXPORT_SYMBOL(console_suspend_enabled); | |
994 | ||
995 | static int __init console_suspend_disable(char *str) | |
996 | { | |
997 | console_suspend_enabled = 0; | |
998 | return 1; | |
999 | } | |
1000 | __setup("no_console_suspend", console_suspend_disable); | |
1001 | ||
557240b4 LT |
1002 | /** |
1003 | * suspend_console - suspend the console subsystem | |
1004 | * | |
1005 | * This disables printk() while we go into suspend states | |
1006 | */ | |
1007 | void suspend_console(void) | |
1008 | { | |
8f4ce8c3 AS |
1009 | if (!console_suspend_enabled) |
1010 | return; | |
0d63081d | 1011 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
ac751efa | 1012 | console_lock(); |
557240b4 | 1013 | console_suspended = 1; |
403f3075 | 1014 | up(&console_sem); |
557240b4 LT |
1015 | } |
1016 | ||
1017 | void resume_console(void) | |
1018 | { | |
8f4ce8c3 AS |
1019 | if (!console_suspend_enabled) |
1020 | return; | |
403f3075 | 1021 | down(&console_sem); |
557240b4 | 1022 | console_suspended = 0; |
ac751efa | 1023 | console_unlock(); |
557240b4 LT |
1024 | } |
1025 | ||
034260d6 KC |
1026 | /** |
1027 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
1028 | * @self: notifier struct | |
1029 | * @action: CPU hotplug event | |
1030 | * @hcpu: unused | |
1031 | * | |
1032 | * If printk() is called from a CPU that is not online yet, the messages | |
1033 | * will be spooled but will not show up on the console. This function is | |
1034 | * called when a new CPU comes online (or fails to come up), and ensures | |
1035 | * that any such output gets printed. | |
1036 | */ | |
1037 | static int __cpuinit console_cpu_notify(struct notifier_block *self, | |
1038 | unsigned long action, void *hcpu) | |
1039 | { | |
1040 | switch (action) { | |
1041 | case CPU_ONLINE: | |
1042 | case CPU_DEAD: | |
1043 | case CPU_DYING: | |
1044 | case CPU_DOWN_FAILED: | |
1045 | case CPU_UP_CANCELED: | |
ac751efa TH |
1046 | console_lock(); |
1047 | console_unlock(); | |
034260d6 KC |
1048 | } |
1049 | return NOTIFY_OK; | |
1050 | } | |
1051 | ||
1da177e4 | 1052 | /** |
ac751efa | 1053 | * console_lock - lock the console system for exclusive use. |
1da177e4 | 1054 | * |
ac751efa | 1055 | * Acquires a lock which guarantees that the caller has |
1da177e4 LT |
1056 | * exclusive access to the console system and the console_drivers list. |
1057 | * | |
1058 | * Can sleep, returns nothing. | |
1059 | */ | |
ac751efa | 1060 | void console_lock(void) |
1da177e4 | 1061 | { |
8abd8e29 | 1062 | BUG_ON(in_interrupt()); |
1da177e4 | 1063 | down(&console_sem); |
403f3075 AH |
1064 | if (console_suspended) |
1065 | return; | |
1da177e4 LT |
1066 | console_locked = 1; |
1067 | console_may_schedule = 1; | |
1068 | } | |
ac751efa | 1069 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 1070 | |
ac751efa TH |
1071 | /** |
1072 | * console_trylock - try to lock the console system for exclusive use. | |
1073 | * | |
1074 | * Tried to acquire a lock which guarantees that the caller has | |
1075 | * exclusive access to the console system and the console_drivers list. | |
1076 | * | |
1077 | * returns 1 on success, and 0 on failure to acquire the lock. | |
1078 | */ | |
1079 | int console_trylock(void) | |
1da177e4 LT |
1080 | { |
1081 | if (down_trylock(&console_sem)) | |
ac751efa | 1082 | return 0; |
403f3075 AH |
1083 | if (console_suspended) { |
1084 | up(&console_sem); | |
ac751efa | 1085 | return 0; |
403f3075 | 1086 | } |
1da177e4 LT |
1087 | console_locked = 1; |
1088 | console_may_schedule = 0; | |
ac751efa | 1089 | return 1; |
1da177e4 | 1090 | } |
ac751efa | 1091 | EXPORT_SYMBOL(console_trylock); |
1da177e4 LT |
1092 | |
1093 | int is_console_locked(void) | |
1094 | { | |
1095 | return console_locked; | |
1096 | } | |
1da177e4 | 1097 | |
b845b517 PZ |
1098 | static DEFINE_PER_CPU(int, printk_pending); |
1099 | ||
1100 | void printk_tick(void) | |
e3e8a75d | 1101 | { |
40dc11ff ED |
1102 | if (__this_cpu_read(printk_pending)) { |
1103 | __this_cpu_write(printk_pending, 0); | |
e3e8a75d | 1104 | wake_up_interruptible(&log_wait); |
b845b517 PZ |
1105 | } |
1106 | } | |
1107 | ||
1108 | int printk_needs_cpu(int cpu) | |
1109 | { | |
40dc11ff | 1110 | if (cpu_is_offline(cpu)) |
61ab2544 | 1111 | printk_tick(); |
40dc11ff | 1112 | return __this_cpu_read(printk_pending); |
b845b517 PZ |
1113 | } |
1114 | ||
1115 | void wake_up_klogd(void) | |
1116 | { | |
1117 | if (waitqueue_active(&log_wait)) | |
49f41383 | 1118 | this_cpu_write(printk_pending, 1); |
e3e8a75d KK |
1119 | } |
1120 | ||
1da177e4 | 1121 | /** |
ac751efa | 1122 | * console_unlock - unlock the console system |
1da177e4 | 1123 | * |
ac751efa | 1124 | * Releases the console_lock which the caller holds on the console system |
1da177e4 LT |
1125 | * and the console driver list. |
1126 | * | |
ac751efa TH |
1127 | * While the console_lock was held, console output may have been buffered |
1128 | * by printk(). If this is the case, console_unlock(); emits | |
1129 | * the output prior to releasing the lock. | |
1da177e4 LT |
1130 | * |
1131 | * If there is output waiting for klogd, we wake it up. | |
1132 | * | |
ac751efa | 1133 | * console_unlock(); may be called from any context. |
1da177e4 | 1134 | */ |
ac751efa | 1135 | void console_unlock(void) |
1da177e4 LT |
1136 | { |
1137 | unsigned long flags; | |
eed4a2ab DV |
1138 | unsigned _con_start, _log_end; |
1139 | unsigned wake_klogd = 0; | |
1da177e4 | 1140 | |
557240b4 | 1141 | if (console_suspended) { |
403f3075 | 1142 | up(&console_sem); |
557240b4 LT |
1143 | return; |
1144 | } | |
78944e54 AD |
1145 | |
1146 | console_may_schedule = 0; | |
1147 | ||
1da177e4 LT |
1148 | for ( ; ; ) { |
1149 | spin_lock_irqsave(&logbuf_lock, flags); | |
1150 | wake_klogd |= log_start - log_end; | |
1151 | if (con_start == log_end) | |
1152 | break; /* Nothing to print */ | |
1153 | _con_start = con_start; | |
1154 | _log_end = log_end; | |
1155 | con_start = log_end; /* Flush */ | |
1156 | spin_unlock(&logbuf_lock); | |
81d68a96 | 1157 | stop_critical_timings(); /* don't trace print latency */ |
1da177e4 | 1158 | call_console_drivers(_con_start, _log_end); |
81d68a96 | 1159 | start_critical_timings(); |
1da177e4 LT |
1160 | local_irq_restore(flags); |
1161 | } | |
1162 | console_locked = 0; | |
1da177e4 LT |
1163 | up(&console_sem); |
1164 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
1165 | if (wake_klogd) |
1166 | wake_up_klogd(); | |
1da177e4 | 1167 | } |
ac751efa | 1168 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 1169 | |
ddad86c2 MW |
1170 | /** |
1171 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1172 | * |
1173 | * If the console code is currently allowed to sleep, and | |
1174 | * if this CPU should yield the CPU to another task, do | |
1175 | * so here. | |
1176 | * | |
ac751efa | 1177 | * Must be called within console_lock();. |
1da177e4 LT |
1178 | */ |
1179 | void __sched console_conditional_schedule(void) | |
1180 | { | |
1181 | if (console_may_schedule) | |
1182 | cond_resched(); | |
1183 | } | |
1184 | EXPORT_SYMBOL(console_conditional_schedule); | |
1185 | ||
1da177e4 LT |
1186 | void console_unblank(void) |
1187 | { | |
1188 | struct console *c; | |
1189 | ||
1190 | /* | |
1191 | * console_unblank can no longer be called in interrupt context unless | |
1192 | * oops_in_progress is set to 1.. | |
1193 | */ | |
1194 | if (oops_in_progress) { | |
1195 | if (down_trylock(&console_sem) != 0) | |
1196 | return; | |
1197 | } else | |
ac751efa | 1198 | console_lock(); |
1da177e4 LT |
1199 | |
1200 | console_locked = 1; | |
1201 | console_may_schedule = 0; | |
4d091611 | 1202 | for_each_console(c) |
1da177e4 LT |
1203 | if ((c->flags & CON_ENABLED) && c->unblank) |
1204 | c->unblank(); | |
ac751efa | 1205 | console_unlock(); |
1da177e4 | 1206 | } |
1da177e4 LT |
1207 | |
1208 | /* | |
1209 | * Return the console tty driver structure and its associated index | |
1210 | */ | |
1211 | struct tty_driver *console_device(int *index) | |
1212 | { | |
1213 | struct console *c; | |
1214 | struct tty_driver *driver = NULL; | |
1215 | ||
ac751efa | 1216 | console_lock(); |
4d091611 | 1217 | for_each_console(c) { |
1da177e4 LT |
1218 | if (!c->device) |
1219 | continue; | |
1220 | driver = c->device(c, index); | |
1221 | if (driver) | |
1222 | break; | |
1223 | } | |
ac751efa | 1224 | console_unlock(); |
1da177e4 LT |
1225 | return driver; |
1226 | } | |
1227 | ||
1228 | /* | |
1229 | * Prevent further output on the passed console device so that (for example) | |
1230 | * serial drivers can disable console output before suspending a port, and can | |
1231 | * re-enable output afterwards. | |
1232 | */ | |
1233 | void console_stop(struct console *console) | |
1234 | { | |
ac751efa | 1235 | console_lock(); |
1da177e4 | 1236 | console->flags &= ~CON_ENABLED; |
ac751efa | 1237 | console_unlock(); |
1da177e4 LT |
1238 | } |
1239 | EXPORT_SYMBOL(console_stop); | |
1240 | ||
1241 | void console_start(struct console *console) | |
1242 | { | |
ac751efa | 1243 | console_lock(); |
1da177e4 | 1244 | console->flags |= CON_ENABLED; |
ac751efa | 1245 | console_unlock(); |
1da177e4 LT |
1246 | } |
1247 | EXPORT_SYMBOL(console_start); | |
1248 | ||
1249 | /* | |
1250 | * The console driver calls this routine during kernel initialization | |
1251 | * to register the console printing procedure with printk() and to | |
1252 | * print any messages that were printed by the kernel before the | |
1253 | * console driver was initialized. | |
4d091611 RG |
1254 | * |
1255 | * This can happen pretty early during the boot process (because of | |
1256 | * early_printk) - sometimes before setup_arch() completes - be careful | |
1257 | * of what kernel features are used - they may not be initialised yet. | |
1258 | * | |
1259 | * There are two types of consoles - bootconsoles (early_printk) and | |
1260 | * "real" consoles (everything which is not a bootconsole) which are | |
1261 | * handled differently. | |
1262 | * - Any number of bootconsoles can be registered at any time. | |
1263 | * - As soon as a "real" console is registered, all bootconsoles | |
1264 | * will be unregistered automatically. | |
1265 | * - Once a "real" console is registered, any attempt to register a | |
1266 | * bootconsoles will be rejected | |
1da177e4 | 1267 | */ |
4d091611 | 1268 | void register_console(struct console *newcon) |
1da177e4 | 1269 | { |
40dc5651 | 1270 | int i; |
1da177e4 | 1271 | unsigned long flags; |
4d091611 | 1272 | struct console *bcon = NULL; |
1da177e4 | 1273 | |
4d091611 RG |
1274 | /* |
1275 | * before we register a new CON_BOOT console, make sure we don't | |
1276 | * already have a valid console | |
1277 | */ | |
1278 | if (console_drivers && newcon->flags & CON_BOOT) { | |
1279 | /* find the last or real console */ | |
1280 | for_each_console(bcon) { | |
1281 | if (!(bcon->flags & CON_BOOT)) { | |
1282 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", | |
1283 | newcon->name, newcon->index); | |
1284 | return; | |
1285 | } | |
1286 | } | |
69331af7 GH |
1287 | } |
1288 | ||
4d091611 RG |
1289 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1290 | bcon = console_drivers; | |
1291 | ||
1292 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
1293 | preferred_console = selected_console; |
1294 | ||
4d091611 RG |
1295 | if (newcon->early_setup) |
1296 | newcon->early_setup(); | |
18a8bd94 | 1297 | |
1da177e4 LT |
1298 | /* |
1299 | * See if we want to use this console driver. If we | |
1300 | * didn't select a console we take the first one | |
1301 | * that registers here. | |
1302 | */ | |
1303 | if (preferred_console < 0) { | |
4d091611 RG |
1304 | if (newcon->index < 0) |
1305 | newcon->index = 0; | |
1306 | if (newcon->setup == NULL || | |
1307 | newcon->setup(newcon, NULL) == 0) { | |
1308 | newcon->flags |= CON_ENABLED; | |
1309 | if (newcon->device) { | |
1310 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
1311 | preferred_console = 0; |
1312 | } | |
1da177e4 LT |
1313 | } |
1314 | } | |
1315 | ||
1316 | /* | |
1317 | * See if this console matches one we selected on | |
1318 | * the command line. | |
1319 | */ | |
40dc5651 JJ |
1320 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1321 | i++) { | |
4d091611 | 1322 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1da177e4 | 1323 | continue; |
4d091611 RG |
1324 | if (newcon->index >= 0 && |
1325 | newcon->index != console_cmdline[i].index) | |
1da177e4 | 1326 | continue; |
4d091611 RG |
1327 | if (newcon->index < 0) |
1328 | newcon->index = console_cmdline[i].index; | |
f7511d5f ST |
1329 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1330 | if (console_cmdline[i].brl_options) { | |
4d091611 RG |
1331 | newcon->flags |= CON_BRL; |
1332 | braille_register_console(newcon, | |
f7511d5f ST |
1333 | console_cmdline[i].index, |
1334 | console_cmdline[i].options, | |
1335 | console_cmdline[i].brl_options); | |
1336 | return; | |
1337 | } | |
1338 | #endif | |
4d091611 RG |
1339 | if (newcon->setup && |
1340 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 1341 | break; |
4d091611 RG |
1342 | newcon->flags |= CON_ENABLED; |
1343 | newcon->index = console_cmdline[i].index; | |
ab4af03a | 1344 | if (i == selected_console) { |
4d091611 | 1345 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
1346 | preferred_console = selected_console; |
1347 | } | |
1da177e4 LT |
1348 | break; |
1349 | } | |
1350 | ||
4d091611 | 1351 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
1352 | return; |
1353 | ||
8259cf43 RG |
1354 | /* |
1355 | * If we have a bootconsole, and are switching to a real console, | |
1356 | * don't print everything out again, since when the boot console, and | |
1357 | * the real console are the same physical device, it's annoying to | |
1358 | * see the beginning boot messages twice | |
1359 | */ | |
1360 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 1361 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
1362 | |
1363 | /* | |
1364 | * Put this console in the list - keep the | |
1365 | * preferred driver at the head of the list. | |
1366 | */ | |
ac751efa | 1367 | console_lock(); |
4d091611 RG |
1368 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1369 | newcon->next = console_drivers; | |
1370 | console_drivers = newcon; | |
1371 | if (newcon->next) | |
1372 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 1373 | } else { |
4d091611 RG |
1374 | newcon->next = console_drivers->next; |
1375 | console_drivers->next = newcon; | |
1da177e4 | 1376 | } |
4d091611 | 1377 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 | 1378 | /* |
ac751efa | 1379 | * console_unlock(); will print out the buffered messages |
1da177e4 LT |
1380 | * for us. |
1381 | */ | |
1382 | spin_lock_irqsave(&logbuf_lock, flags); | |
1383 | con_start = log_start; | |
1384 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1385 | } | |
ac751efa | 1386 | console_unlock(); |
fbc92a34 | 1387 | console_sysfs_notify(); |
8259cf43 RG |
1388 | |
1389 | /* | |
1390 | * By unregistering the bootconsoles after we enable the real console | |
1391 | * we get the "console xxx enabled" message on all the consoles - | |
1392 | * boot consoles, real consoles, etc - this is to ensure that end | |
1393 | * users know there might be something in the kernel's log buffer that | |
1394 | * went to the bootconsole (that they do not see on the real console) | |
1395 | */ | |
1396 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) { | |
1397 | /* we need to iterate through twice, to make sure we print | |
1398 | * everything out, before we unregister the console(s) | |
1399 | */ | |
1400 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", | |
1401 | newcon->name, newcon->index); | |
1402 | for_each_console(bcon) | |
1403 | if (bcon->flags & CON_BOOT) | |
1404 | unregister_console(bcon); | |
1405 | } else { | |
1406 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", | |
1407 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
1408 | newcon->name, newcon->index); | |
1409 | } | |
1da177e4 LT |
1410 | } |
1411 | EXPORT_SYMBOL(register_console); | |
1412 | ||
40dc5651 | 1413 | int unregister_console(struct console *console) |
1da177e4 | 1414 | { |
40dc5651 | 1415 | struct console *a, *b; |
1da177e4 LT |
1416 | int res = 1; |
1417 | ||
f7511d5f ST |
1418 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1419 | if (console->flags & CON_BRL) | |
1420 | return braille_unregister_console(console); | |
1421 | #endif | |
1422 | ||
ac751efa | 1423 | console_lock(); |
1da177e4 LT |
1424 | if (console_drivers == console) { |
1425 | console_drivers=console->next; | |
1426 | res = 0; | |
e9b15b54 | 1427 | } else if (console_drivers) { |
1da177e4 LT |
1428 | for (a=console_drivers->next, b=console_drivers ; |
1429 | a; b=a, a=b->next) { | |
1430 | if (a == console) { | |
1431 | b->next = a->next; | |
1432 | res = 0; | |
1433 | break; | |
40dc5651 | 1434 | } |
1da177e4 LT |
1435 | } |
1436 | } | |
40dc5651 | 1437 | |
69331af7 | 1438 | /* |
ab4af03a GE |
1439 | * If this isn't the last console and it has CON_CONSDEV set, we |
1440 | * need to set it on the next preferred console. | |
1da177e4 | 1441 | */ |
69331af7 | 1442 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1443 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 | 1444 | |
ac751efa | 1445 | console_unlock(); |
fbc92a34 | 1446 | console_sysfs_notify(); |
1da177e4 LT |
1447 | return res; |
1448 | } | |
1449 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1450 | |
034260d6 | 1451 | static int __init printk_late_init(void) |
0c5564bd | 1452 | { |
4d091611 RG |
1453 | struct console *con; |
1454 | ||
1455 | for_each_console(con) { | |
1456 | if (con->flags & CON_BOOT) { | |
cb00e99c | 1457 | printk(KERN_INFO "turn off boot console %s%d\n", |
4d091611 | 1458 | con->name, con->index); |
42c2c8c8 | 1459 | unregister_console(con); |
cb00e99c | 1460 | } |
0c5564bd | 1461 | } |
034260d6 | 1462 | hotcpu_notifier(console_cpu_notify, 0); |
0c5564bd RG |
1463 | return 0; |
1464 | } | |
034260d6 | 1465 | late_initcall(printk_late_init); |
0c5564bd | 1466 | |
7ef3d2fd | 1467 | #if defined CONFIG_PRINTK |
717115e1 | 1468 | |
1da177e4 LT |
1469 | /* |
1470 | * printk rate limiting, lifted from the networking subsystem. | |
1471 | * | |
641de9d8 UKK |
1472 | * This enforces a rate limit: not more than 10 kernel messages |
1473 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 1474 | */ |
641de9d8 UKK |
1475 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1476 | ||
5c828713 | 1477 | int __printk_ratelimit(const char *func) |
1da177e4 | 1478 | { |
5c828713 | 1479 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 1480 | } |
5c828713 | 1481 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
1482 | |
1483 | /** | |
1484 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1485 | * @caller_jiffies: pointer to caller's state | |
1486 | * @interval_msecs: minimum interval between prints | |
1487 | * | |
1488 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1489 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1490 | * returned true. | |
1491 | */ | |
1492 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1493 | unsigned int interval_msecs) | |
1494 | { | |
f2d28a2e GK |
1495 | if (*caller_jiffies == 0 |
1496 | || !time_in_range(jiffies, *caller_jiffies, | |
1497 | *caller_jiffies | |
1498 | + msecs_to_jiffies(interval_msecs))) { | |
1499 | *caller_jiffies = jiffies; | |
f46c4833 AM |
1500 | return true; |
1501 | } | |
1502 | return false; | |
1503 | } | |
1504 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
1505 | |
1506 | static DEFINE_SPINLOCK(dump_list_lock); | |
1507 | static LIST_HEAD(dump_list); | |
1508 | ||
1509 | /** | |
1510 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 1511 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1512 | * |
1513 | * Adds a kernel log dumper to the system. The dump callback in the | |
1514 | * structure will be called when the kernel oopses or panics and must be | |
1515 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
1516 | */ | |
1517 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
1518 | { | |
1519 | unsigned long flags; | |
1520 | int err = -EBUSY; | |
1521 | ||
1522 | /* The dump callback needs to be set */ | |
1523 | if (!dumper->dump) | |
1524 | return -EINVAL; | |
1525 | ||
1526 | spin_lock_irqsave(&dump_list_lock, flags); | |
1527 | /* Don't allow registering multiple times */ | |
1528 | if (!dumper->registered) { | |
1529 | dumper->registered = 1; | |
fb842b00 | 1530 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
1531 | err = 0; |
1532 | } | |
1533 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1534 | ||
1535 | return err; | |
1536 | } | |
1537 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
1538 | ||
1539 | /** | |
1540 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 1541 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1542 | * |
1543 | * Removes a dump device from the system. Returns zero on success and | |
1544 | * %-EINVAL otherwise. | |
1545 | */ | |
1546 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
1547 | { | |
1548 | unsigned long flags; | |
1549 | int err = -EINVAL; | |
1550 | ||
1551 | spin_lock_irqsave(&dump_list_lock, flags); | |
1552 | if (dumper->registered) { | |
1553 | dumper->registered = 0; | |
fb842b00 | 1554 | list_del_rcu(&dumper->list); |
456b565c SK |
1555 | err = 0; |
1556 | } | |
1557 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 1558 | synchronize_rcu(); |
456b565c SK |
1559 | |
1560 | return err; | |
1561 | } | |
1562 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
1563 | ||
456b565c SK |
1564 | /** |
1565 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
1566 | * @reason: the reason (oops, panic etc) for dumping | |
1567 | * | |
1568 | * Iterate through each of the dump devices and call the oops/panic | |
1569 | * callbacks with the log buffer. | |
1570 | */ | |
1571 | void kmsg_dump(enum kmsg_dump_reason reason) | |
1572 | { | |
1573 | unsigned long end; | |
1574 | unsigned chars; | |
1575 | struct kmsg_dumper *dumper; | |
1576 | const char *s1, *s2; | |
1577 | unsigned long l1, l2; | |
1578 | unsigned long flags; | |
1579 | ||
1580 | /* Theoretically, the log could move on after we do this, but | |
1581 | there's not a lot we can do about that. The new messages | |
1582 | will overwrite the start of what we dump. */ | |
1583 | spin_lock_irqsave(&logbuf_lock, flags); | |
1584 | end = log_end & LOG_BUF_MASK; | |
1585 | chars = logged_chars; | |
1586 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1587 | ||
8c4af38e AK |
1588 | if (chars > end) { |
1589 | s1 = log_buf + log_buf_len - chars + end; | |
1590 | l1 = chars - end; | |
456b565c SK |
1591 | |
1592 | s2 = log_buf; | |
1593 | l2 = end; | |
1594 | } else { | |
1595 | s1 = ""; | |
1596 | l1 = 0; | |
1597 | ||
8c4af38e AK |
1598 | s2 = log_buf + end - chars; |
1599 | l2 = chars; | |
456b565c SK |
1600 | } |
1601 | ||
fb842b00 HY |
1602 | rcu_read_lock(); |
1603 | list_for_each_entry_rcu(dumper, &dump_list, list) | |
456b565c | 1604 | dumper->dump(dumper, reason, s1, l1, s2, l2); |
fb842b00 | 1605 | rcu_read_unlock(); |
456b565c | 1606 | } |
7ef3d2fd | 1607 | #endif |