2 * linux/kernel/printk.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
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).
12 * Modified for sysctl support, 1/8/97, Chris Horn.
13 * Fixed SMP synchronization, 08/08/99, Manfred Spraul
14 * manfred@colorfullife.com
15 * Rewrote bits to get rid of console_lock
16 * 01Mar01 Andrew Morton
19 #include <linux/kernel.h>
21 #include <linux/tty.h>
22 #include <linux/tty_driver.h>
23 #include <linux/console.h>
24 #include <linux/init.h>
25 #include <linux/jiffies.h>
26 #include <linux/nmi.h>
27 #include <linux/module.h>
28 #include <linux/moduleparam.h>
29 #include <linux/interrupt.h> /* For in_interrupt() */
30 #include <linux/delay.h>
31 #include <linux/smp.h>
32 #include <linux/security.h>
33 #include <linux/bootmem.h>
34 #include <linux/memblock.h>
35 #include <linux/syscalls.h>
36 #include <linux/kexec.h>
37 #include <linux/kdb.h>
38 #include <linux/ratelimit.h>
39 #include <linux/kmsg_dump.h>
40 #include <linux/syslog.h>
41 #include <linux/cpu.h>
42 #include <linux/notifier.h>
43 #include <linux/rculist.h>
44 #include <linux/poll.h>
46 #include <asm/uaccess.h>
48 #define CREATE_TRACE_POINTS
49 #include <trace/events/printk.h>
52 * Architectures can override it:
54 void asmlinkage
__attribute__((weak
)) early_printk(const char *fmt
, ...)
58 /* printk's without a loglevel use this.. */
59 #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
61 /* We show everything that is MORE important than this.. */
62 #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
63 #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
65 DECLARE_WAIT_QUEUE_HEAD(log_wait
);
67 int console_printk
[4] = {
68 DEFAULT_CONSOLE_LOGLEVEL
, /* console_loglevel */
69 DEFAULT_MESSAGE_LOGLEVEL
, /* default_message_loglevel */
70 MINIMUM_CONSOLE_LOGLEVEL
, /* minimum_console_loglevel */
71 DEFAULT_CONSOLE_LOGLEVEL
, /* default_console_loglevel */
75 * Low level drivers may need that to know if they can schedule in
76 * their unblank() callback or not. So let's export it.
79 EXPORT_SYMBOL(oops_in_progress
);
82 * console_sem protects the console_drivers list, and also
83 * provides serialisation for access to the entire console
86 static DEFINE_SEMAPHORE(console_sem
);
87 struct console
*console_drivers
;
88 EXPORT_SYMBOL_GPL(console_drivers
);
91 static struct lockdep_map console_lock_dep_map
= {
92 .name
= "console_lock"
97 * This is used for debugging the mess that is the VT code by
98 * keeping track if we have the console semaphore held. It's
99 * definitely not the perfect debug tool (we don't know if _WE_
100 * hold it are racing, but it helps tracking those weird code
101 * path in the console code where we end up in places I want
102 * locked without the console sempahore held
104 static int console_locked
, console_suspended
;
107 * If exclusive_console is non-NULL then only this console is to be printed to.
109 static struct console
*exclusive_console
;
112 * Array of consoles built from command line options (console=)
114 struct console_cmdline
116 char name
[8]; /* Name of the driver */
117 int index
; /* Minor dev. to use */
118 char *options
; /* Options for the driver */
119 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
120 char *brl_options
; /* Options for braille driver */
124 #define MAX_CMDLINECONSOLES 8
126 static struct console_cmdline console_cmdline
[MAX_CMDLINECONSOLES
];
127 static int selected_console
= -1;
128 static int preferred_console
= -1;
129 int console_set_on_cmdline
;
130 EXPORT_SYMBOL(console_set_on_cmdline
);
132 /* Flag: console code may call schedule() */
133 static int console_may_schedule
;
136 * The printk log buffer consists of a chain of concatenated variable
137 * length records. Every record starts with a record header, containing
138 * the overall length of the record.
140 * The heads to the first and last entry in the buffer, as well as the
141 * sequence numbers of these both entries are maintained when messages
144 * If the heads indicate available messages, the length in the header
145 * tells the start next message. A length == 0 for the next message
146 * indicates a wrap-around to the beginning of the buffer.
148 * Every record carries the monotonic timestamp in microseconds, as well as
149 * the standard userspace syslog level and syslog facility. The usual
150 * kernel messages use LOG_KERN; userspace-injected messages always carry
151 * a matching syslog facility, by default LOG_USER. The origin of every
152 * message can be reliably determined that way.
154 * The human readable log message directly follows the message header. The
155 * length of the message text is stored in the header, the stored message
158 * Optionally, a message can carry a dictionary of properties (key/value pairs),
159 * to provide userspace with a machine-readable message context.
161 * Examples for well-defined, commonly used property names are:
162 * DEVICE=b12:8 device identifier
166 * +sound:card0 subsystem:devname
167 * SUBSYSTEM=pci driver-core subsystem name
169 * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
170 * follows directly after a '=' character. Every property is terminated by
171 * a '\0' character. The last property is not terminated.
173 * Example of a message structure:
174 * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec
175 * 0008 34 00 record is 52 bytes long
176 * 000a 0b 00 text is 11 bytes long
177 * 000c 1f 00 dictionary is 23 bytes long
178 * 000e 03 00 LOG_KERN (facility) LOG_ERR (level)
179 * 0010 69 74 27 73 20 61 20 6c "it's a l"
181 * 001b 44 45 56 49 43 "DEVIC"
182 * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D"
183 * 52 49 56 45 52 3d 62 75 "RIVER=bu"
185 * 0032 00 00 00 padding to next message header
187 * The 'struct log' buffer header must never be directly exported to
188 * userspace, it is a kernel-private implementation detail that might
189 * need to be changed in the future, when the requirements change.
191 * /dev/kmsg exports the structured data in the following line format:
192 * "level,sequnum,timestamp;<message text>\n"
194 * The optional key/value pairs are attached as continuation lines starting
195 * with a space character and terminated by a newline. All possible
196 * non-prinatable characters are escaped in the "\xff" notation.
198 * Users of the export format should ignore possible additional values
199 * separated by ',', and find the message after the ';' character.
203 LOG_NOCONS
= 1, /* already flushed, do not print to console */
204 LOG_NEWLINE
= 2, /* text ended with a newline */
205 LOG_PREFIX
= 4, /* text started with a prefix */
206 LOG_CONT
= 8, /* text is a fragment of a continuation line */
210 u64 ts_nsec
; /* timestamp in nanoseconds */
211 u16 len
; /* length of entire record */
212 u16 text_len
; /* length of text buffer */
213 u16 dict_len
; /* length of dictionary buffer */
214 u8 facility
; /* syslog facility */
215 u8 flags
:5; /* internal record flags */
216 u8 level
:3; /* syslog level */
220 * The logbuf_lock protects kmsg buffer, indices, counters. It is also
221 * used in interesting ways to provide interlocking in console_unlock();
223 static DEFINE_RAW_SPINLOCK(logbuf_lock
);
226 /* the next printk record to read by syslog(READ) or /proc/kmsg */
227 static u64 syslog_seq
;
228 static u32 syslog_idx
;
229 static enum log_flags syslog_prev
;
230 static size_t syslog_partial
;
232 /* index and sequence number of the first record stored in the buffer */
233 static u64 log_first_seq
;
234 static u32 log_first_idx
;
236 /* index and sequence number of the next record to store in the buffer */
237 static u64 log_next_seq
;
238 static u32 log_next_idx
;
240 /* the next printk record to write to the console */
241 static u64 console_seq
;
242 static u32 console_idx
;
243 static enum log_flags console_prev
;
245 /* the next printk record to read after the last 'clear' command */
246 static u64 clear_seq
;
247 static u32 clear_idx
;
249 #define PREFIX_MAX 32
250 #define LOG_LINE_MAX 1024 - PREFIX_MAX
253 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
256 #define LOG_ALIGN __alignof__(struct log)
258 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
259 static char __log_buf
[__LOG_BUF_LEN
] __aligned(LOG_ALIGN
);
260 static char *log_buf
= __log_buf
;
261 static u32 log_buf_len
= __LOG_BUF_LEN
;
263 /* cpu currently holding logbuf_lock */
264 static volatile unsigned int logbuf_cpu
= UINT_MAX
;
266 /* human readable text of the record */
267 static char *log_text(const struct log
*msg
)
269 return (char *)msg
+ sizeof(struct log
);
272 /* optional key/value pair dictionary attached to the record */
273 static char *log_dict(const struct log
*msg
)
275 return (char *)msg
+ sizeof(struct log
) + msg
->text_len
;
278 /* get record by index; idx must point to valid msg */
279 static struct log
*log_from_idx(u32 idx
)
281 struct log
*msg
= (struct log
*)(log_buf
+ idx
);
284 * A length == 0 record is the end of buffer marker. Wrap around and
285 * read the message at the start of the buffer.
288 return (struct log
*)log_buf
;
292 /* get next record; idx must point to valid msg */
293 static u32
log_next(u32 idx
)
295 struct log
*msg
= (struct log
*)(log_buf
+ idx
);
297 /* length == 0 indicates the end of the buffer; wrap */
299 * A length == 0 record is the end of buffer marker. Wrap around and
300 * read the message at the start of the buffer as *this* one, and
301 * return the one after that.
304 msg
= (struct log
*)log_buf
;
307 return idx
+ msg
->len
;
310 /* insert record into the buffer, discard old ones, update heads */
311 static void log_store(int facility
, int level
,
312 enum log_flags flags
, u64 ts_nsec
,
313 const char *dict
, u16 dict_len
,
314 const char *text
, u16 text_len
)
319 /* number of '\0' padding bytes to next message */
320 size
= sizeof(struct log
) + text_len
+ dict_len
;
321 pad_len
= (-size
) & (LOG_ALIGN
- 1);
324 while (log_first_seq
< log_next_seq
) {
327 if (log_next_idx
> log_first_idx
)
328 free
= max(log_buf_len
- log_next_idx
, log_first_idx
);
330 free
= log_first_idx
- log_next_idx
;
332 if (free
> size
+ sizeof(struct log
))
335 /* drop old messages until we have enough contiuous space */
336 log_first_idx
= log_next(log_first_idx
);
340 if (log_next_idx
+ size
+ sizeof(struct log
) >= log_buf_len
) {
342 * This message + an additional empty header does not fit
343 * at the end of the buffer. Add an empty header with len == 0
344 * to signify a wrap around.
346 memset(log_buf
+ log_next_idx
, 0, sizeof(struct log
));
351 msg
= (struct log
*)(log_buf
+ log_next_idx
);
352 memcpy(log_text(msg
), text
, text_len
);
353 msg
->text_len
= text_len
;
354 memcpy(log_dict(msg
), dict
, dict_len
);
355 msg
->dict_len
= dict_len
;
356 msg
->facility
= facility
;
357 msg
->level
= level
& 7;
358 msg
->flags
= flags
& 0x1f;
360 msg
->ts_nsec
= ts_nsec
;
362 msg
->ts_nsec
= local_clock();
363 memset(log_dict(msg
) + dict_len
, 0, pad_len
);
364 msg
->len
= sizeof(struct log
) + text_len
+ dict_len
+ pad_len
;
367 log_next_idx
+= msg
->len
;
371 /* /dev/kmsg - userspace message inject/listen interface */
372 struct devkmsg_user
{
380 static ssize_t
devkmsg_writev(struct kiocb
*iocb
, const struct iovec
*iv
,
381 unsigned long count
, loff_t pos
)
385 int level
= default_message_loglevel
;
386 int facility
= 1; /* LOG_USER */
387 size_t len
= iov_length(iv
, count
);
390 if (len
> LOG_LINE_MAX
)
392 buf
= kmalloc(len
+1, GFP_KERNEL
);
397 for (i
= 0; i
< count
; i
++) {
398 if (copy_from_user(line
, iv
[i
].iov_base
, iv
[i
].iov_len
)) {
402 line
+= iv
[i
].iov_len
;
406 * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
407 * the decimal value represents 32bit, the lower 3 bit are the log
408 * level, the rest are the log facility.
410 * If no prefix or no userspace facility is specified, we
411 * enforce LOG_USER, to be able to reliably distinguish
412 * kernel-generated messages from userspace-injected ones.
415 if (line
[0] == '<') {
418 i
= simple_strtoul(line
+1, &endp
, 10);
419 if (endp
&& endp
[0] == '>') {
430 printk_emit(facility
, level
, NULL
, 0, "%s", line
);
436 static ssize_t
devkmsg_read(struct file
*file
, char __user
*buf
,
437 size_t count
, loff_t
*ppos
)
439 struct devkmsg_user
*user
= file
->private_data
;
450 ret
= mutex_lock_interruptible(&user
->lock
);
453 raw_spin_lock_irq(&logbuf_lock
);
454 while (user
->seq
== log_next_seq
) {
455 if (file
->f_flags
& O_NONBLOCK
) {
457 raw_spin_unlock_irq(&logbuf_lock
);
461 raw_spin_unlock_irq(&logbuf_lock
);
462 ret
= wait_event_interruptible(log_wait
,
463 user
->seq
!= log_next_seq
);
466 raw_spin_lock_irq(&logbuf_lock
);
469 if (user
->seq
< log_first_seq
) {
470 /* our last seen message is gone, return error and reset */
471 user
->idx
= log_first_idx
;
472 user
->seq
= log_first_seq
;
474 raw_spin_unlock_irq(&logbuf_lock
);
478 msg
= log_from_idx(user
->idx
);
479 ts_usec
= msg
->ts_nsec
;
480 do_div(ts_usec
, 1000);
483 * If we couldn't merge continuation line fragments during the print,
484 * export the stored flags to allow an optional external merge of the
485 * records. Merging the records isn't always neccessarily correct, like
486 * when we hit a race during printing. In most cases though, it produces
487 * better readable output. 'c' in the record flags mark the first
488 * fragment of a line, '+' the following.
490 if (msg
->flags
& LOG_CONT
&& !(user
->prev
& LOG_CONT
))
492 else if ((msg
->flags
& LOG_CONT
) ||
493 ((user
->prev
& LOG_CONT
) && !(msg
->flags
& LOG_PREFIX
)))
496 len
= sprintf(user
->buf
, "%u,%llu,%llu,%c;",
497 (msg
->facility
<< 3) | msg
->level
,
498 user
->seq
, ts_usec
, cont
);
499 user
->prev
= msg
->flags
;
501 /* escape non-printable characters */
502 for (i
= 0; i
< msg
->text_len
; i
++) {
503 unsigned char c
= log_text(msg
)[i
];
505 if (c
< ' ' || c
>= 127 || c
== '\\')
506 len
+= sprintf(user
->buf
+ len
, "\\x%02x", c
);
508 user
->buf
[len
++] = c
;
510 user
->buf
[len
++] = '\n';
515 for (i
= 0; i
< msg
->dict_len
; i
++) {
516 unsigned char c
= log_dict(msg
)[i
];
519 user
->buf
[len
++] = ' ';
524 user
->buf
[len
++] = '\n';
529 if (c
< ' ' || c
>= 127 || c
== '\\') {
530 len
+= sprintf(user
->buf
+ len
, "\\x%02x", c
);
534 user
->buf
[len
++] = c
;
536 user
->buf
[len
++] = '\n';
539 user
->idx
= log_next(user
->idx
);
541 raw_spin_unlock_irq(&logbuf_lock
);
548 if (copy_to_user(buf
, user
->buf
, len
)) {
554 mutex_unlock(&user
->lock
);
558 static loff_t
devkmsg_llseek(struct file
*file
, loff_t offset
, int whence
)
560 struct devkmsg_user
*user
= file
->private_data
;
568 raw_spin_lock_irq(&logbuf_lock
);
571 /* the first record */
572 user
->idx
= log_first_idx
;
573 user
->seq
= log_first_seq
;
577 * The first record after the last SYSLOG_ACTION_CLEAR,
578 * like issued by 'dmesg -c'. Reading /dev/kmsg itself
579 * changes no global state, and does not clear anything.
581 user
->idx
= clear_idx
;
582 user
->seq
= clear_seq
;
585 /* after the last record */
586 user
->idx
= log_next_idx
;
587 user
->seq
= log_next_seq
;
592 raw_spin_unlock_irq(&logbuf_lock
);
596 static unsigned int devkmsg_poll(struct file
*file
, poll_table
*wait
)
598 struct devkmsg_user
*user
= file
->private_data
;
602 return POLLERR
|POLLNVAL
;
604 poll_wait(file
, &log_wait
, wait
);
606 raw_spin_lock_irq(&logbuf_lock
);
607 if (user
->seq
< log_next_seq
) {
608 /* return error when data has vanished underneath us */
609 if (user
->seq
< log_first_seq
)
610 ret
= POLLIN
|POLLRDNORM
|POLLERR
|POLLPRI
;
611 ret
= POLLIN
|POLLRDNORM
;
613 raw_spin_unlock_irq(&logbuf_lock
);
618 static int devkmsg_open(struct inode
*inode
, struct file
*file
)
620 struct devkmsg_user
*user
;
623 /* write-only does not need any file context */
624 if ((file
->f_flags
& O_ACCMODE
) == O_WRONLY
)
627 err
= security_syslog(SYSLOG_ACTION_READ_ALL
);
631 user
= kmalloc(sizeof(struct devkmsg_user
), GFP_KERNEL
);
635 mutex_init(&user
->lock
);
637 raw_spin_lock_irq(&logbuf_lock
);
638 user
->idx
= log_first_idx
;
639 user
->seq
= log_first_seq
;
640 raw_spin_unlock_irq(&logbuf_lock
);
642 file
->private_data
= user
;
646 static int devkmsg_release(struct inode
*inode
, struct file
*file
)
648 struct devkmsg_user
*user
= file
->private_data
;
653 mutex_destroy(&user
->lock
);
658 const struct file_operations kmsg_fops
= {
659 .open
= devkmsg_open
,
660 .read
= devkmsg_read
,
661 .aio_write
= devkmsg_writev
,
662 .llseek
= devkmsg_llseek
,
663 .poll
= devkmsg_poll
,
664 .release
= devkmsg_release
,
669 * This appends the listed symbols to /proc/vmcoreinfo
671 * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
672 * obtain access to symbols that are otherwise very difficult to locate. These
673 * symbols are specifically used so that utilities can access and extract the
674 * dmesg log from a vmcore file after a crash.
676 void log_buf_kexec_setup(void)
678 VMCOREINFO_SYMBOL(log_buf
);
679 VMCOREINFO_SYMBOL(log_buf_len
);
680 VMCOREINFO_SYMBOL(log_first_idx
);
681 VMCOREINFO_SYMBOL(log_next_idx
);
683 * Export struct log size and field offsets. User space tools can
684 * parse it and detect any changes to structure down the line.
686 VMCOREINFO_STRUCT_SIZE(log
);
687 VMCOREINFO_OFFSET(log
, ts_nsec
);
688 VMCOREINFO_OFFSET(log
, len
);
689 VMCOREINFO_OFFSET(log
, text_len
);
690 VMCOREINFO_OFFSET(log
, dict_len
);
694 /* requested log_buf_len from kernel cmdline */
695 static unsigned long __initdata new_log_buf_len
;
697 /* save requested log_buf_len since it's too early to process it */
698 static int __init
log_buf_len_setup(char *str
)
700 unsigned size
= memparse(str
, &str
);
703 size
= roundup_pow_of_two(size
);
704 if (size
> log_buf_len
)
705 new_log_buf_len
= size
;
709 early_param("log_buf_len", log_buf_len_setup
);
711 void __init
setup_log_buf(int early
)
717 if (!new_log_buf_len
)
723 mem
= memblock_alloc(new_log_buf_len
, PAGE_SIZE
);
726 new_log_buf
= __va(mem
);
728 new_log_buf
= alloc_bootmem_nopanic(new_log_buf_len
);
731 if (unlikely(!new_log_buf
)) {
732 pr_err("log_buf_len: %ld bytes not available\n",
737 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
738 log_buf_len
= new_log_buf_len
;
739 log_buf
= new_log_buf
;
741 free
= __LOG_BUF_LEN
- log_next_idx
;
742 memcpy(log_buf
, __log_buf
, __LOG_BUF_LEN
);
743 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
745 pr_info("log_buf_len: %d\n", log_buf_len
);
746 pr_info("early log buf free: %d(%d%%)\n",
747 free
, (free
* 100) / __LOG_BUF_LEN
);
750 #ifdef CONFIG_BOOT_PRINTK_DELAY
752 static int boot_delay
; /* msecs delay after each printk during bootup */
753 static unsigned long long loops_per_msec
; /* based on boot_delay */
755 static int __init
boot_delay_setup(char *str
)
759 lpj
= preset_lpj
? preset_lpj
: 1000000; /* some guess */
760 loops_per_msec
= (unsigned long long)lpj
/ 1000 * HZ
;
762 get_option(&str
, &boot_delay
);
763 if (boot_delay
> 10 * 1000)
766 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
767 "HZ: %d, loops_per_msec: %llu\n",
768 boot_delay
, preset_lpj
, lpj
, HZ
, loops_per_msec
);
771 __setup("boot_delay=", boot_delay_setup
);
773 static void boot_delay_msec(void)
775 unsigned long long k
;
776 unsigned long timeout
;
778 if (boot_delay
== 0 || system_state
!= SYSTEM_BOOTING
)
781 k
= (unsigned long long)loops_per_msec
* boot_delay
;
783 timeout
= jiffies
+ msecs_to_jiffies(boot_delay
);
788 * use (volatile) jiffies to prevent
789 * compiler reduction; loop termination via jiffies
790 * is secondary and may or may not happen.
792 if (time_after(jiffies
, timeout
))
794 touch_nmi_watchdog();
798 static inline void boot_delay_msec(void)
803 #ifdef CONFIG_SECURITY_DMESG_RESTRICT
804 int dmesg_restrict
= 1;
809 static int syslog_action_restricted(int type
)
813 /* Unless restricted, we allow "read all" and "get buffer size" for everybody */
814 return type
!= SYSLOG_ACTION_READ_ALL
&& type
!= SYSLOG_ACTION_SIZE_BUFFER
;
817 static int check_syslog_permissions(int type
, bool from_file
)
820 * If this is from /proc/kmsg and we've already opened it, then we've
821 * already done the capabilities checks at open time.
823 if (from_file
&& type
!= SYSLOG_ACTION_OPEN
)
826 if (syslog_action_restricted(type
)) {
827 if (capable(CAP_SYSLOG
))
829 /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */
830 if (capable(CAP_SYS_ADMIN
)) {
831 printk_once(KERN_WARNING
"%s (%d): "
832 "Attempt to access syslog with CAP_SYS_ADMIN "
833 "but no CAP_SYSLOG (deprecated).\n",
834 current
->comm
, task_pid_nr(current
));
842 #if defined(CONFIG_PRINTK_TIME)
843 static bool printk_time
= 1;
845 static bool printk_time
;
847 module_param_named(time
, printk_time
, bool, S_IRUGO
| S_IWUSR
);
849 static size_t print_time(u64 ts
, char *buf
)
851 unsigned long rem_nsec
;
859 rem_nsec
= do_div(ts
, 1000000000);
860 return sprintf(buf
, "[%5lu.%06lu] ",
861 (unsigned long)ts
, rem_nsec
/ 1000);
864 static size_t print_prefix(const struct log
*msg
, bool syslog
, char *buf
)
867 unsigned int prefix
= (msg
->facility
<< 3) | msg
->level
;
871 len
+= sprintf(buf
, "<%u>", prefix
);
876 else if (prefix
> 99)
883 len
+= print_time(msg
->ts_nsec
, buf
? buf
+ len
: NULL
);
887 static size_t msg_print_text(const struct log
*msg
, enum log_flags prev
,
888 bool syslog
, char *buf
, size_t size
)
890 const char *text
= log_text(msg
);
891 size_t text_size
= msg
->text_len
;
896 if ((prev
& LOG_CONT
) && !(msg
->flags
& LOG_PREFIX
))
899 if (msg
->flags
& LOG_CONT
) {
900 if ((prev
& LOG_CONT
) && !(prev
& LOG_NEWLINE
))
903 if (!(msg
->flags
& LOG_NEWLINE
))
908 const char *next
= memchr(text
, '\n', text_size
);
912 text_len
= next
- text
;
914 text_size
-= next
- text
;
916 text_len
= text_size
;
920 if (print_prefix(msg
, syslog
, NULL
) +
921 text_len
+ 1 >= size
- len
)
925 len
+= print_prefix(msg
, syslog
, buf
+ len
);
926 memcpy(buf
+ len
, text
, text_len
);
931 /* SYSLOG_ACTION_* buffer size only calculation */
933 len
+= print_prefix(msg
, syslog
, NULL
);
946 static int syslog_print(char __user
*buf
, int size
)
952 text
= kmalloc(LOG_LINE_MAX
+ PREFIX_MAX
, GFP_KERNEL
);
960 raw_spin_lock_irq(&logbuf_lock
);
961 if (syslog_seq
< log_first_seq
) {
962 /* messages are gone, move to first one */
963 syslog_seq
= log_first_seq
;
964 syslog_idx
= log_first_idx
;
968 if (syslog_seq
== log_next_seq
) {
969 raw_spin_unlock_irq(&logbuf_lock
);
973 skip
= syslog_partial
;
974 msg
= log_from_idx(syslog_idx
);
975 n
= msg_print_text(msg
, syslog_prev
, true, text
,
976 LOG_LINE_MAX
+ PREFIX_MAX
);
977 if (n
- syslog_partial
<= size
) {
978 /* message fits into buffer, move forward */
979 syslog_idx
= log_next(syslog_idx
);
981 syslog_prev
= msg
->flags
;
985 /* partial read(), remember position */
990 raw_spin_unlock_irq(&logbuf_lock
);
995 if (copy_to_user(buf
, text
+ skip
, n
)) {
1010 static int syslog_print_all(char __user
*buf
, int size
, bool clear
)
1015 text
= kmalloc(LOG_LINE_MAX
+ PREFIX_MAX
, GFP_KERNEL
);
1019 raw_spin_lock_irq(&logbuf_lock
);
1024 enum log_flags prev
;
1026 if (clear_seq
< log_first_seq
) {
1027 /* messages are gone, move to first available one */
1028 clear_seq
= log_first_seq
;
1029 clear_idx
= log_first_idx
;
1033 * Find first record that fits, including all following records,
1034 * into the user-provided buffer for this dump.
1039 while (seq
< log_next_seq
) {
1040 struct log
*msg
= log_from_idx(idx
);
1042 len
+= msg_print_text(msg
, prev
, true, NULL
, 0);
1044 idx
= log_next(idx
);
1048 /* move first record forward until length fits into the buffer */
1052 while (len
> size
&& seq
< log_next_seq
) {
1053 struct log
*msg
= log_from_idx(idx
);
1055 len
-= msg_print_text(msg
, prev
, true, NULL
, 0);
1057 idx
= log_next(idx
);
1061 /* last message fitting into this dump */
1062 next_seq
= log_next_seq
;
1066 while (len
>= 0 && seq
< next_seq
) {
1067 struct log
*msg
= log_from_idx(idx
);
1070 textlen
= msg_print_text(msg
, prev
, true, text
,
1071 LOG_LINE_MAX
+ PREFIX_MAX
);
1076 idx
= log_next(idx
);
1080 raw_spin_unlock_irq(&logbuf_lock
);
1081 if (copy_to_user(buf
+ len
, text
, textlen
))
1085 raw_spin_lock_irq(&logbuf_lock
);
1087 if (seq
< log_first_seq
) {
1088 /* messages are gone, move to next one */
1089 seq
= log_first_seq
;
1090 idx
= log_first_idx
;
1097 clear_seq
= log_next_seq
;
1098 clear_idx
= log_next_idx
;
1100 raw_spin_unlock_irq(&logbuf_lock
);
1106 int do_syslog(int type
, char __user
*buf
, int len
, bool from_file
)
1109 static int saved_console_loglevel
= -1;
1112 error
= check_syslog_permissions(type
, from_file
);
1116 error
= security_syslog(type
);
1121 case SYSLOG_ACTION_CLOSE
: /* Close log */
1123 case SYSLOG_ACTION_OPEN
: /* Open log */
1125 case SYSLOG_ACTION_READ
: /* Read from log */
1127 if (!buf
|| len
< 0)
1132 if (!access_ok(VERIFY_WRITE
, buf
, len
)) {
1136 error
= wait_event_interruptible(log_wait
,
1137 syslog_seq
!= log_next_seq
);
1140 error
= syslog_print(buf
, len
);
1142 /* Read/clear last kernel messages */
1143 case SYSLOG_ACTION_READ_CLEAR
:
1146 /* Read last kernel messages */
1147 case SYSLOG_ACTION_READ_ALL
:
1149 if (!buf
|| len
< 0)
1154 if (!access_ok(VERIFY_WRITE
, buf
, len
)) {
1158 error
= syslog_print_all(buf
, len
, clear
);
1160 /* Clear ring buffer */
1161 case SYSLOG_ACTION_CLEAR
:
1162 syslog_print_all(NULL
, 0, true);
1164 /* Disable logging to console */
1165 case SYSLOG_ACTION_CONSOLE_OFF
:
1166 if (saved_console_loglevel
== -1)
1167 saved_console_loglevel
= console_loglevel
;
1168 console_loglevel
= minimum_console_loglevel
;
1170 /* Enable logging to console */
1171 case SYSLOG_ACTION_CONSOLE_ON
:
1172 if (saved_console_loglevel
!= -1) {
1173 console_loglevel
= saved_console_loglevel
;
1174 saved_console_loglevel
= -1;
1177 /* Set level of messages printed to console */
1178 case SYSLOG_ACTION_CONSOLE_LEVEL
:
1180 if (len
< 1 || len
> 8)
1182 if (len
< minimum_console_loglevel
)
1183 len
= minimum_console_loglevel
;
1184 console_loglevel
= len
;
1185 /* Implicitly re-enable logging to console */
1186 saved_console_loglevel
= -1;
1189 /* Number of chars in the log buffer */
1190 case SYSLOG_ACTION_SIZE_UNREAD
:
1191 raw_spin_lock_irq(&logbuf_lock
);
1192 if (syslog_seq
< log_first_seq
) {
1193 /* messages are gone, move to first one */
1194 syslog_seq
= log_first_seq
;
1195 syslog_idx
= log_first_idx
;
1201 * Short-cut for poll(/"proc/kmsg") which simply checks
1202 * for pending data, not the size; return the count of
1203 * records, not the length.
1205 error
= log_next_idx
- syslog_idx
;
1207 u64 seq
= syslog_seq
;
1208 u32 idx
= syslog_idx
;
1209 enum log_flags prev
= syslog_prev
;
1212 while (seq
< log_next_seq
) {
1213 struct log
*msg
= log_from_idx(idx
);
1215 error
+= msg_print_text(msg
, prev
, true, NULL
, 0);
1216 idx
= log_next(idx
);
1220 error
-= syslog_partial
;
1222 raw_spin_unlock_irq(&logbuf_lock
);
1224 /* Size of the log buffer */
1225 case SYSLOG_ACTION_SIZE_BUFFER
:
1226 error
= log_buf_len
;
1236 SYSCALL_DEFINE3(syslog
, int, type
, char __user
*, buf
, int, len
)
1238 return do_syslog(type
, buf
, len
, SYSLOG_FROM_CALL
);
1241 static bool __read_mostly ignore_loglevel
;
1243 static int __init
ignore_loglevel_setup(char *str
)
1245 ignore_loglevel
= 1;
1246 printk(KERN_INFO
"debug: ignoring loglevel setting.\n");
1251 early_param("ignore_loglevel", ignore_loglevel_setup
);
1252 module_param(ignore_loglevel
, bool, S_IRUGO
| S_IWUSR
);
1253 MODULE_PARM_DESC(ignore_loglevel
, "ignore loglevel setting, to"
1254 "print all kernel messages to the console.");
1257 * Call the console drivers, asking them to write out
1258 * log_buf[start] to log_buf[end - 1].
1259 * The console_lock must be held.
1261 static void call_console_drivers(int level
, const char *text
, size_t len
)
1263 struct console
*con
;
1265 trace_console(text
, 0, len
, len
);
1267 if (level
>= console_loglevel
&& !ignore_loglevel
)
1269 if (!console_drivers
)
1272 for_each_console(con
) {
1273 if (exclusive_console
&& con
!= exclusive_console
)
1275 if (!(con
->flags
& CON_ENABLED
))
1279 if (!cpu_online(smp_processor_id()) &&
1280 !(con
->flags
& CON_ANYTIME
))
1282 con
->write(con
, text
, len
);
1287 * Zap console related locks when oopsing. Only zap at most once
1288 * every 10 seconds, to leave time for slow consoles to print a
1291 static void zap_locks(void)
1293 static unsigned long oops_timestamp
;
1295 if (time_after_eq(jiffies
, oops_timestamp
) &&
1296 !time_after(jiffies
, oops_timestamp
+ 30 * HZ
))
1299 oops_timestamp
= jiffies
;
1302 /* If a crash is occurring, make sure we can't deadlock */
1303 raw_spin_lock_init(&logbuf_lock
);
1304 /* And make sure that we print immediately */
1305 sema_init(&console_sem
, 1);
1308 /* Check if we have any console registered that can be called early in boot. */
1309 static int have_callable_console(void)
1311 struct console
*con
;
1313 for_each_console(con
)
1314 if (con
->flags
& CON_ANYTIME
)
1321 * Can we actually use the console at this time on this cpu?
1323 * Console drivers may assume that per-cpu resources have
1324 * been allocated. So unless they're explicitly marked as
1325 * being able to cope (CON_ANYTIME) don't call them until
1326 * this CPU is officially up.
1328 static inline int can_use_console(unsigned int cpu
)
1330 return cpu_online(cpu
) || have_callable_console();
1334 * Try to get console ownership to actually show the kernel
1335 * messages from a 'printk'. Return true (and with the
1336 * console_lock held, and 'console_locked' set) if it
1337 * is successful, false otherwise.
1339 * This gets called with the 'logbuf_lock' spinlock held and
1340 * interrupts disabled. It should return with 'lockbuf_lock'
1341 * released but interrupts still disabled.
1343 static int console_trylock_for_printk(unsigned int cpu
)
1344 __releases(&logbuf_lock
)
1346 int retval
= 0, wake
= 0;
1348 if (console_trylock()) {
1352 * If we can't use the console, we need to release
1353 * the console semaphore by hand to avoid flushing
1354 * the buffer. We need to hold the console semaphore
1355 * in order to do this test safely.
1357 if (!can_use_console(cpu
)) {
1363 logbuf_cpu
= UINT_MAX
;
1366 raw_spin_unlock(&logbuf_lock
);
1370 int printk_delay_msec __read_mostly
;
1372 static inline void printk_delay(void)
1374 if (unlikely(printk_delay_msec
)) {
1375 int m
= printk_delay_msec
;
1379 touch_nmi_watchdog();
1385 * Continuation lines are buffered, and not committed to the record buffer
1386 * until the line is complete, or a race forces it. The line fragments
1387 * though, are printed immediately to the consoles to ensure everything has
1388 * reached the console in case of a kernel crash.
1390 static struct cont
{
1391 char buf
[LOG_LINE_MAX
];
1392 size_t len
; /* length == 0 means unused buffer */
1393 size_t cons
; /* bytes written to console */
1394 struct task_struct
*owner
; /* task of first print*/
1395 u64 ts_nsec
; /* time of first print */
1396 u8 level
; /* log level of first message */
1397 u8 facility
; /* log level of first message */
1398 enum log_flags flags
; /* prefix, newline flags */
1399 bool flushed
:1; /* buffer sealed and committed */
1402 static void cont_flush(enum log_flags flags
)
1411 * If a fragment of this line was directly flushed to the
1412 * console; wait for the console to pick up the rest of the
1413 * line. LOG_NOCONS suppresses a duplicated output.
1415 log_store(cont
.facility
, cont
.level
, flags
| LOG_NOCONS
,
1416 cont
.ts_nsec
, NULL
, 0, cont
.buf
, cont
.len
);
1418 cont
.flushed
= true;
1421 * If no fragment of this line ever reached the console,
1422 * just submit it to the store and free the buffer.
1424 log_store(cont
.facility
, cont
.level
, flags
, 0,
1425 NULL
, 0, cont
.buf
, cont
.len
);
1430 static bool cont_add(int facility
, int level
, const char *text
, size_t len
)
1432 if (cont
.len
&& cont
.flushed
)
1435 if (cont
.len
+ len
> sizeof(cont
.buf
)) {
1436 /* the line gets too long, split it up in separate records */
1437 cont_flush(LOG_CONT
);
1442 cont
.facility
= facility
;
1444 cont
.owner
= current
;
1445 cont
.ts_nsec
= local_clock();
1448 cont
.flushed
= false;
1451 memcpy(cont
.buf
+ cont
.len
, text
, len
);
1454 if (cont
.len
> (sizeof(cont
.buf
) * 80) / 100)
1455 cont_flush(LOG_CONT
);
1460 static size_t cont_print_text(char *text
, size_t size
)
1465 if (cont
.cons
== 0 && (console_prev
& LOG_NEWLINE
)) {
1466 textlen
+= print_time(cont
.ts_nsec
, text
);
1470 len
= cont
.len
- cont
.cons
;
1474 memcpy(text
+ textlen
, cont
.buf
+ cont
.cons
, len
);
1476 cont
.cons
= cont
.len
;
1480 if (cont
.flags
& LOG_NEWLINE
)
1481 text
[textlen
++] = '\n';
1482 /* got everything, release buffer */
1488 asmlinkage
int vprintk_emit(int facility
, int level
,
1489 const char *dict
, size_t dictlen
,
1490 const char *fmt
, va_list args
)
1492 static int recursion_bug
;
1493 static char textbuf
[LOG_LINE_MAX
];
1494 char *text
= textbuf
;
1496 enum log_flags lflags
= 0;
1497 unsigned long flags
;
1499 int printed_len
= 0;
1504 /* This stops the holder of console_sem just where we want him */
1505 local_irq_save(flags
);
1506 this_cpu
= smp_processor_id();
1509 * Ouch, printk recursed into itself!
1511 if (unlikely(logbuf_cpu
== this_cpu
)) {
1513 * If a crash is occurring during printk() on this CPU,
1514 * then try to get the crash message out but make sure
1515 * we can't deadlock. Otherwise just return to avoid the
1516 * recursion and return - but flag the recursion so that
1517 * it can be printed at the next appropriate moment:
1519 if (!oops_in_progress
&& !lockdep_recursing(current
)) {
1521 goto out_restore_irqs
;
1527 raw_spin_lock(&logbuf_lock
);
1528 logbuf_cpu
= this_cpu
;
1530 if (recursion_bug
) {
1531 static const char recursion_msg
[] =
1532 "BUG: recent printk recursion!";
1535 printed_len
+= strlen(recursion_msg
);
1536 /* emit KERN_CRIT message */
1537 log_store(0, 2, LOG_PREFIX
|LOG_NEWLINE
, 0,
1538 NULL
, 0, recursion_msg
, printed_len
);
1542 * The printf needs to come first; we need the syslog
1543 * prefix which might be passed-in as a parameter.
1545 text_len
= vscnprintf(text
, sizeof(textbuf
), fmt
, args
);
1547 /* mark and strip a trailing newline */
1548 if (text_len
&& text
[text_len
-1] == '\n') {
1550 lflags
|= LOG_NEWLINE
;
1553 /* strip kernel syslog prefix and extract log level or control flags */
1554 if (facility
== 0) {
1555 int kern_level
= printk_get_level(text
);
1558 const char *end_of_header
= printk_skip_level(text
);
1559 switch (kern_level
) {
1562 level
= kern_level
- '0';
1563 case 'd': /* KERN_DEFAULT */
1564 lflags
|= LOG_PREFIX
;
1565 case 'c': /* KERN_CONT */
1568 text_len
-= end_of_header
- text
;
1569 text
= (char *)end_of_header
;
1574 level
= default_message_loglevel
;
1577 lflags
|= LOG_PREFIX
|LOG_NEWLINE
;
1579 if (!(lflags
& LOG_NEWLINE
)) {
1581 * Flush the conflicting buffer. An earlier newline was missing,
1582 * or another task also prints continuation lines.
1584 if (cont
.len
&& (lflags
& LOG_PREFIX
|| cont
.owner
!= current
))
1585 cont_flush(LOG_NEWLINE
);
1587 /* buffer line if possible, otherwise store it right away */
1588 if (!cont_add(facility
, level
, text
, text_len
))
1589 log_store(facility
, level
, lflags
| LOG_CONT
, 0,
1590 dict
, dictlen
, text
, text_len
);
1592 bool stored
= false;
1595 * If an earlier newline was missing and it was the same task,
1596 * either merge it with the current buffer and flush, or if
1597 * there was a race with interrupts (prefix == true) then just
1598 * flush it out and store this line separately.
1600 if (cont
.len
&& cont
.owner
== current
) {
1601 if (!(lflags
& LOG_PREFIX
))
1602 stored
= cont_add(facility
, level
, text
, text_len
);
1603 cont_flush(LOG_NEWLINE
);
1607 log_store(facility
, level
, lflags
, 0,
1608 dict
, dictlen
, text
, text_len
);
1610 printed_len
+= text_len
;
1613 * Try to acquire and then immediately release the console semaphore.
1614 * The release will print out buffers and wake up /dev/kmsg and syslog()
1617 * The console_trylock_for_printk() function will release 'logbuf_lock'
1618 * regardless of whether it actually gets the console semaphore or not.
1620 if (console_trylock_for_printk(this_cpu
))
1625 local_irq_restore(flags
);
1629 EXPORT_SYMBOL(vprintk_emit
);
1631 asmlinkage
int vprintk(const char *fmt
, va_list args
)
1633 return vprintk_emit(0, -1, NULL
, 0, fmt
, args
);
1635 EXPORT_SYMBOL(vprintk
);
1637 asmlinkage
int printk_emit(int facility
, int level
,
1638 const char *dict
, size_t dictlen
,
1639 const char *fmt
, ...)
1644 va_start(args
, fmt
);
1645 r
= vprintk_emit(facility
, level
, dict
, dictlen
, fmt
, args
);
1650 EXPORT_SYMBOL(printk_emit
);
1653 * printk - print a kernel message
1654 * @fmt: format string
1656 * This is printk(). It can be called from any context. We want it to work.
1658 * We try to grab the console_lock. If we succeed, it's easy - we log the
1659 * output and call the console drivers. If we fail to get the semaphore, we
1660 * place the output into the log buffer and return. The current holder of
1661 * the console_sem will notice the new output in console_unlock(); and will
1662 * send it to the consoles before releasing the lock.
1664 * One effect of this deferred printing is that code which calls printk() and
1665 * then changes console_loglevel may break. This is because console_loglevel
1666 * is inspected when the actual printing occurs.
1671 * See the vsnprintf() documentation for format string extensions over C99.
1673 asmlinkage
int printk(const char *fmt
, ...)
1678 #ifdef CONFIG_KGDB_KDB
1679 if (unlikely(kdb_trap_printk
)) {
1680 va_start(args
, fmt
);
1681 r
= vkdb_printf(fmt
, args
);
1686 va_start(args
, fmt
);
1687 r
= vprintk_emit(0, -1, NULL
, 0, fmt
, args
);
1692 EXPORT_SYMBOL(printk
);
1694 #else /* CONFIG_PRINTK */
1696 #define LOG_LINE_MAX 0
1697 #define PREFIX_MAX 0
1698 #define LOG_LINE_MAX 0
1699 static u64 syslog_seq
;
1700 static u32 syslog_idx
;
1701 static u64 console_seq
;
1702 static u32 console_idx
;
1703 static enum log_flags syslog_prev
;
1704 static u64 log_first_seq
;
1705 static u32 log_first_idx
;
1706 static u64 log_next_seq
;
1707 static enum log_flags console_prev
;
1708 static struct cont
{
1714 static struct log
*log_from_idx(u32 idx
) { return NULL
; }
1715 static u32
log_next(u32 idx
) { return 0; }
1716 static void call_console_drivers(int level
, const char *text
, size_t len
) {}
1717 static size_t msg_print_text(const struct log
*msg
, enum log_flags prev
,
1718 bool syslog
, char *buf
, size_t size
) { return 0; }
1719 static size_t cont_print_text(char *text
, size_t size
) { return 0; }
1721 #endif /* CONFIG_PRINTK */
1723 static int __add_preferred_console(char *name
, int idx
, char *options
,
1726 struct console_cmdline
*c
;
1730 * See if this tty is not yet registered, and
1731 * if we have a slot free.
1733 for (i
= 0; i
< MAX_CMDLINECONSOLES
&& console_cmdline
[i
].name
[0]; i
++)
1734 if (strcmp(console_cmdline
[i
].name
, name
) == 0 &&
1735 console_cmdline
[i
].index
== idx
) {
1737 selected_console
= i
;
1740 if (i
== MAX_CMDLINECONSOLES
)
1743 selected_console
= i
;
1744 c
= &console_cmdline
[i
];
1745 strlcpy(c
->name
, name
, sizeof(c
->name
));
1746 c
->options
= options
;
1747 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1748 c
->brl_options
= brl_options
;
1754 * Set up a list of consoles. Called from init/main.c
1756 static int __init
console_setup(char *str
)
1758 char buf
[sizeof(console_cmdline
[0].name
) + 4]; /* 4 for index */
1759 char *s
, *options
, *brl_options
= NULL
;
1762 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1763 if (!memcmp(str
, "brl,", 4)) {
1766 } else if (!memcmp(str
, "brl=", 4)) {
1767 brl_options
= str
+ 4;
1768 str
= strchr(brl_options
, ',');
1770 printk(KERN_ERR
"need port name after brl=\n");
1778 * Decode str into name, index, options.
1780 if (str
[0] >= '0' && str
[0] <= '9') {
1781 strcpy(buf
, "ttyS");
1782 strncpy(buf
+ 4, str
, sizeof(buf
) - 5);
1784 strncpy(buf
, str
, sizeof(buf
) - 1);
1786 buf
[sizeof(buf
) - 1] = 0;
1787 if ((options
= strchr(str
, ',')) != NULL
)
1790 if (!strcmp(str
, "ttya"))
1791 strcpy(buf
, "ttyS0");
1792 if (!strcmp(str
, "ttyb"))
1793 strcpy(buf
, "ttyS1");
1795 for (s
= buf
; *s
; s
++)
1796 if ((*s
>= '0' && *s
<= '9') || *s
== ',')
1798 idx
= simple_strtoul(s
, NULL
, 10);
1801 __add_preferred_console(buf
, idx
, options
, brl_options
);
1802 console_set_on_cmdline
= 1;
1805 __setup("console=", console_setup
);
1808 * add_preferred_console - add a device to the list of preferred consoles.
1809 * @name: device name
1810 * @idx: device index
1811 * @options: options for this console
1813 * The last preferred console added will be used for kernel messages
1814 * and stdin/out/err for init. Normally this is used by console_setup
1815 * above to handle user-supplied console arguments; however it can also
1816 * be used by arch-specific code either to override the user or more
1817 * commonly to provide a default console (ie from PROM variables) when
1818 * the user has not supplied one.
1820 int add_preferred_console(char *name
, int idx
, char *options
)
1822 return __add_preferred_console(name
, idx
, options
, NULL
);
1825 int update_console_cmdline(char *name
, int idx
, char *name_new
, int idx_new
, char *options
)
1827 struct console_cmdline
*c
;
1830 for (i
= 0; i
< MAX_CMDLINECONSOLES
&& console_cmdline
[i
].name
[0]; i
++)
1831 if (strcmp(console_cmdline
[i
].name
, name
) == 0 &&
1832 console_cmdline
[i
].index
== idx
) {
1833 c
= &console_cmdline
[i
];
1834 strlcpy(c
->name
, name_new
, sizeof(c
->name
));
1835 c
->name
[sizeof(c
->name
) - 1] = 0;
1836 c
->options
= options
;
1844 bool console_suspend_enabled
= 1;
1845 EXPORT_SYMBOL(console_suspend_enabled
);
1847 static int __init
console_suspend_disable(char *str
)
1849 console_suspend_enabled
= 0;
1852 __setup("no_console_suspend", console_suspend_disable
);
1853 module_param_named(console_suspend
, console_suspend_enabled
,
1854 bool, S_IRUGO
| S_IWUSR
);
1855 MODULE_PARM_DESC(console_suspend
, "suspend console during suspend"
1856 " and hibernate operations");
1859 * suspend_console - suspend the console subsystem
1861 * This disables printk() while we go into suspend states
1863 void suspend_console(void)
1865 if (!console_suspend_enabled
)
1867 printk("Suspending console(s) (use no_console_suspend to debug)\n");
1869 console_suspended
= 1;
1873 void resume_console(void)
1875 if (!console_suspend_enabled
)
1878 console_suspended
= 0;
1883 * console_cpu_notify - print deferred console messages after CPU hotplug
1884 * @self: notifier struct
1885 * @action: CPU hotplug event
1888 * If printk() is called from a CPU that is not online yet, the messages
1889 * will be spooled but will not show up on the console. This function is
1890 * called when a new CPU comes online (or fails to come up), and ensures
1891 * that any such output gets printed.
1893 static int __cpuinit
console_cpu_notify(struct notifier_block
*self
,
1894 unsigned long action
, void *hcpu
)
1899 case CPU_DOWN_FAILED
:
1900 case CPU_UP_CANCELED
:
1908 * console_lock - lock the console system for exclusive use.
1910 * Acquires a lock which guarantees that the caller has
1911 * exclusive access to the console system and the console_drivers list.
1913 * Can sleep, returns nothing.
1915 void console_lock(void)
1920 if (console_suspended
)
1923 console_may_schedule
= 1;
1924 mutex_acquire(&console_lock_dep_map
, 0, 0, _RET_IP_
);
1926 EXPORT_SYMBOL(console_lock
);
1929 * console_trylock - try to lock the console system for exclusive use.
1931 * Tried to acquire a lock which guarantees that the caller has
1932 * exclusive access to the console system and the console_drivers list.
1934 * returns 1 on success, and 0 on failure to acquire the lock.
1936 int console_trylock(void)
1938 if (down_trylock(&console_sem
))
1940 if (console_suspended
) {
1945 console_may_schedule
= 0;
1946 mutex_acquire(&console_lock_dep_map
, 0, 1, _RET_IP_
);
1949 EXPORT_SYMBOL(console_trylock
);
1951 int is_console_locked(void)
1953 return console_locked
;
1957 * Delayed printk version, for scheduler-internal messages:
1959 #define PRINTK_BUF_SIZE 512
1961 #define PRINTK_PENDING_WAKEUP 0x01
1962 #define PRINTK_PENDING_SCHED 0x02
1964 static DEFINE_PER_CPU(int, printk_pending
);
1965 static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE
], printk_sched_buf
);
1967 void printk_tick(void)
1969 if (__this_cpu_read(printk_pending
)) {
1970 int pending
= __this_cpu_xchg(printk_pending
, 0);
1971 if (pending
& PRINTK_PENDING_SCHED
) {
1972 char *buf
= __get_cpu_var(printk_sched_buf
);
1973 printk(KERN_WARNING
"[sched_delayed] %s", buf
);
1975 if (pending
& PRINTK_PENDING_WAKEUP
)
1976 wake_up_interruptible(&log_wait
);
1980 int printk_needs_cpu(int cpu
)
1982 if (cpu_is_offline(cpu
))
1984 return __this_cpu_read(printk_pending
);
1987 void wake_up_klogd(void)
1989 if (waitqueue_active(&log_wait
))
1990 this_cpu_or(printk_pending
, PRINTK_PENDING_WAKEUP
);
1993 static void console_cont_flush(char *text
, size_t size
)
1995 unsigned long flags
;
1998 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2004 * We still queue earlier records, likely because the console was
2005 * busy. The earlier ones need to be printed before this one, we
2006 * did not flush any fragment so far, so just let it queue up.
2008 if (console_seq
< log_next_seq
&& !cont
.cons
)
2011 len
= cont_print_text(text
, size
);
2012 raw_spin_unlock(&logbuf_lock
);
2013 stop_critical_timings();
2014 call_console_drivers(cont
.level
, text
, len
);
2015 start_critical_timings();
2016 local_irq_restore(flags
);
2019 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2023 * console_unlock - unlock the console system
2025 * Releases the console_lock which the caller holds on the console system
2026 * and the console driver list.
2028 * While the console_lock was held, console output may have been buffered
2029 * by printk(). If this is the case, console_unlock(); emits
2030 * the output prior to releasing the lock.
2032 * If there is output waiting, we wake /dev/kmsg and syslog() users.
2034 * console_unlock(); may be called from any context.
2036 void console_unlock(void)
2038 static char text
[LOG_LINE_MAX
+ PREFIX_MAX
];
2039 static u64 seen_seq
;
2040 unsigned long flags
;
2041 bool wake_klogd
= false;
2044 if (console_suspended
) {
2049 console_may_schedule
= 0;
2051 /* flush buffered message fragment immediately to console */
2052 console_cont_flush(text
, sizeof(text
));
2059 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2060 if (seen_seq
!= log_next_seq
) {
2062 seen_seq
= log_next_seq
;
2065 if (console_seq
< log_first_seq
) {
2066 /* messages are gone, move to first one */
2067 console_seq
= log_first_seq
;
2068 console_idx
= log_first_idx
;
2072 if (console_seq
== log_next_seq
)
2075 msg
= log_from_idx(console_idx
);
2076 if (msg
->flags
& LOG_NOCONS
) {
2078 * Skip record we have buffered and already printed
2079 * directly to the console when we received it.
2081 console_idx
= log_next(console_idx
);
2084 * We will get here again when we register a new
2085 * CON_PRINTBUFFER console. Clear the flag so we
2086 * will properly dump everything later.
2088 msg
->flags
&= ~LOG_NOCONS
;
2089 console_prev
= msg
->flags
;
2094 len
= msg_print_text(msg
, console_prev
, false,
2095 text
, sizeof(text
));
2096 console_idx
= log_next(console_idx
);
2098 console_prev
= msg
->flags
;
2099 raw_spin_unlock(&logbuf_lock
);
2101 stop_critical_timings(); /* don't trace print latency */
2102 call_console_drivers(level
, text
, len
);
2103 start_critical_timings();
2104 local_irq_restore(flags
);
2107 mutex_release(&console_lock_dep_map
, 1, _RET_IP_
);
2109 /* Release the exclusive_console once it is used */
2110 if (unlikely(exclusive_console
))
2111 exclusive_console
= NULL
;
2113 raw_spin_unlock(&logbuf_lock
);
2118 * Someone could have filled up the buffer again, so re-check if there's
2119 * something to flush. In case we cannot trylock the console_sem again,
2120 * there's a new owner and the console_unlock() from them will do the
2121 * flush, no worries.
2123 raw_spin_lock(&logbuf_lock
);
2124 retry
= console_seq
!= log_next_seq
;
2125 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2127 if (retry
&& console_trylock())
2133 EXPORT_SYMBOL(console_unlock
);
2136 * console_conditional_schedule - yield the CPU if required
2138 * If the console code is currently allowed to sleep, and
2139 * if this CPU should yield the CPU to another task, do
2142 * Must be called within console_lock();.
2144 void __sched
console_conditional_schedule(void)
2146 if (console_may_schedule
)
2149 EXPORT_SYMBOL(console_conditional_schedule
);
2151 void console_unblank(void)
2156 * console_unblank can no longer be called in interrupt context unless
2157 * oops_in_progress is set to 1..
2159 if (oops_in_progress
) {
2160 if (down_trylock(&console_sem
) != 0)
2166 console_may_schedule
= 0;
2168 if ((c
->flags
& CON_ENABLED
) && c
->unblank
)
2174 * Return the console tty driver structure and its associated index
2176 struct tty_driver
*console_device(int *index
)
2179 struct tty_driver
*driver
= NULL
;
2182 for_each_console(c
) {
2185 driver
= c
->device(c
, index
);
2194 * Prevent further output on the passed console device so that (for example)
2195 * serial drivers can disable console output before suspending a port, and can
2196 * re-enable output afterwards.
2198 void console_stop(struct console
*console
)
2201 console
->flags
&= ~CON_ENABLED
;
2204 EXPORT_SYMBOL(console_stop
);
2206 void console_start(struct console
*console
)
2209 console
->flags
|= CON_ENABLED
;
2212 EXPORT_SYMBOL(console_start
);
2214 static int __read_mostly keep_bootcon
;
2216 static int __init
keep_bootcon_setup(char *str
)
2219 printk(KERN_INFO
"debug: skip boot console de-registration.\n");
2224 early_param("keep_bootcon", keep_bootcon_setup
);
2227 * The console driver calls this routine during kernel initialization
2228 * to register the console printing procedure with printk() and to
2229 * print any messages that were printed by the kernel before the
2230 * console driver was initialized.
2232 * This can happen pretty early during the boot process (because of
2233 * early_printk) - sometimes before setup_arch() completes - be careful
2234 * of what kernel features are used - they may not be initialised yet.
2236 * There are two types of consoles - bootconsoles (early_printk) and
2237 * "real" consoles (everything which is not a bootconsole) which are
2238 * handled differently.
2239 * - Any number of bootconsoles can be registered at any time.
2240 * - As soon as a "real" console is registered, all bootconsoles
2241 * will be unregistered automatically.
2242 * - Once a "real" console is registered, any attempt to register a
2243 * bootconsoles will be rejected
2245 void register_console(struct console
*newcon
)
2248 unsigned long flags
;
2249 struct console
*bcon
= NULL
;
2252 * before we register a new CON_BOOT console, make sure we don't
2253 * already have a valid console
2255 if (console_drivers
&& newcon
->flags
& CON_BOOT
) {
2256 /* find the last or real console */
2257 for_each_console(bcon
) {
2258 if (!(bcon
->flags
& CON_BOOT
)) {
2259 printk(KERN_INFO
"Too late to register bootconsole %s%d\n",
2260 newcon
->name
, newcon
->index
);
2266 if (console_drivers
&& console_drivers
->flags
& CON_BOOT
)
2267 bcon
= console_drivers
;
2269 if (preferred_console
< 0 || bcon
|| !console_drivers
)
2270 preferred_console
= selected_console
;
2272 if (newcon
->early_setup
)
2273 newcon
->early_setup();
2276 * See if we want to use this console driver. If we
2277 * didn't select a console we take the first one
2278 * that registers here.
2280 if (preferred_console
< 0) {
2281 if (newcon
->index
< 0)
2283 if (newcon
->setup
== NULL
||
2284 newcon
->setup(newcon
, NULL
) == 0) {
2285 newcon
->flags
|= CON_ENABLED
;
2286 if (newcon
->device
) {
2287 newcon
->flags
|= CON_CONSDEV
;
2288 preferred_console
= 0;
2294 * See if this console matches one we selected on
2297 for (i
= 0; i
< MAX_CMDLINECONSOLES
&& console_cmdline
[i
].name
[0];
2299 if (strcmp(console_cmdline
[i
].name
, newcon
->name
) != 0)
2301 if (newcon
->index
>= 0 &&
2302 newcon
->index
!= console_cmdline
[i
].index
)
2304 if (newcon
->index
< 0)
2305 newcon
->index
= console_cmdline
[i
].index
;
2306 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
2307 if (console_cmdline
[i
].brl_options
) {
2308 newcon
->flags
|= CON_BRL
;
2309 braille_register_console(newcon
,
2310 console_cmdline
[i
].index
,
2311 console_cmdline
[i
].options
,
2312 console_cmdline
[i
].brl_options
);
2316 if (newcon
->setup
&&
2317 newcon
->setup(newcon
, console_cmdline
[i
].options
) != 0)
2319 newcon
->flags
|= CON_ENABLED
;
2320 newcon
->index
= console_cmdline
[i
].index
;
2321 if (i
== selected_console
) {
2322 newcon
->flags
|= CON_CONSDEV
;
2323 preferred_console
= selected_console
;
2328 if (!(newcon
->flags
& CON_ENABLED
))
2332 * If we have a bootconsole, and are switching to a real console,
2333 * don't print everything out again, since when the boot console, and
2334 * the real console are the same physical device, it's annoying to
2335 * see the beginning boot messages twice
2337 if (bcon
&& ((newcon
->flags
& (CON_CONSDEV
| CON_BOOT
)) == CON_CONSDEV
))
2338 newcon
->flags
&= ~CON_PRINTBUFFER
;
2341 * Put this console in the list - keep the
2342 * preferred driver at the head of the list.
2345 if ((newcon
->flags
& CON_CONSDEV
) || console_drivers
== NULL
) {
2346 newcon
->next
= console_drivers
;
2347 console_drivers
= newcon
;
2349 newcon
->next
->flags
&= ~CON_CONSDEV
;
2351 newcon
->next
= console_drivers
->next
;
2352 console_drivers
->next
= newcon
;
2354 if (newcon
->flags
& CON_PRINTBUFFER
) {
2356 * console_unlock(); will print out the buffered messages
2359 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2360 console_seq
= syslog_seq
;
2361 console_idx
= syslog_idx
;
2362 console_prev
= syslog_prev
;
2363 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2365 * We're about to replay the log buffer. Only do this to the
2366 * just-registered console to avoid excessive message spam to
2367 * the already-registered consoles.
2369 exclusive_console
= newcon
;
2372 console_sysfs_notify();
2375 * By unregistering the bootconsoles after we enable the real console
2376 * we get the "console xxx enabled" message on all the consoles -
2377 * boot consoles, real consoles, etc - this is to ensure that end
2378 * users know there might be something in the kernel's log buffer that
2379 * went to the bootconsole (that they do not see on the real console)
2382 ((newcon
->flags
& (CON_CONSDEV
| CON_BOOT
)) == CON_CONSDEV
) &&
2384 /* we need to iterate through twice, to make sure we print
2385 * everything out, before we unregister the console(s)
2387 printk(KERN_INFO
"console [%s%d] enabled, bootconsole disabled\n",
2388 newcon
->name
, newcon
->index
);
2389 for_each_console(bcon
)
2390 if (bcon
->flags
& CON_BOOT
)
2391 unregister_console(bcon
);
2393 printk(KERN_INFO
"%sconsole [%s%d] enabled\n",
2394 (newcon
->flags
& CON_BOOT
) ? "boot" : "" ,
2395 newcon
->name
, newcon
->index
);
2398 EXPORT_SYMBOL(register_console
);
2400 int unregister_console(struct console
*console
)
2402 struct console
*a
, *b
;
2405 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
2406 if (console
->flags
& CON_BRL
)
2407 return braille_unregister_console(console
);
2411 if (console_drivers
== console
) {
2412 console_drivers
=console
->next
;
2414 } else if (console_drivers
) {
2415 for (a
=console_drivers
->next
, b
=console_drivers
;
2416 a
; b
=a
, a
=b
->next
) {
2426 * If this isn't the last console and it has CON_CONSDEV set, we
2427 * need to set it on the next preferred console.
2429 if (console_drivers
!= NULL
&& console
->flags
& CON_CONSDEV
)
2430 console_drivers
->flags
|= CON_CONSDEV
;
2433 console_sysfs_notify();
2436 EXPORT_SYMBOL(unregister_console
);
2438 static int __init
printk_late_init(void)
2440 struct console
*con
;
2442 for_each_console(con
) {
2443 if (!keep_bootcon
&& con
->flags
& CON_BOOT
) {
2444 printk(KERN_INFO
"turn off boot console %s%d\n",
2445 con
->name
, con
->index
);
2446 unregister_console(con
);
2449 hotcpu_notifier(console_cpu_notify
, 0);
2452 late_initcall(printk_late_init
);
2454 #if defined CONFIG_PRINTK
2456 int printk_sched(const char *fmt
, ...)
2458 unsigned long flags
;
2463 local_irq_save(flags
);
2464 buf
= __get_cpu_var(printk_sched_buf
);
2466 va_start(args
, fmt
);
2467 r
= vsnprintf(buf
, PRINTK_BUF_SIZE
, fmt
, args
);
2470 __this_cpu_or(printk_pending
, PRINTK_PENDING_SCHED
);
2471 local_irq_restore(flags
);
2477 * printk rate limiting, lifted from the networking subsystem.
2479 * This enforces a rate limit: not more than 10 kernel messages
2480 * every 5s to make a denial-of-service attack impossible.
2482 DEFINE_RATELIMIT_STATE(printk_ratelimit_state
, 5 * HZ
, 10);
2484 int __printk_ratelimit(const char *func
)
2486 return ___ratelimit(&printk_ratelimit_state
, func
);
2488 EXPORT_SYMBOL(__printk_ratelimit
);
2491 * printk_timed_ratelimit - caller-controlled printk ratelimiting
2492 * @caller_jiffies: pointer to caller's state
2493 * @interval_msecs: minimum interval between prints
2495 * printk_timed_ratelimit() returns true if more than @interval_msecs
2496 * milliseconds have elapsed since the last time printk_timed_ratelimit()
2499 bool printk_timed_ratelimit(unsigned long *caller_jiffies
,
2500 unsigned int interval_msecs
)
2502 if (*caller_jiffies
== 0
2503 || !time_in_range(jiffies
, *caller_jiffies
,
2505 + msecs_to_jiffies(interval_msecs
))) {
2506 *caller_jiffies
= jiffies
;
2511 EXPORT_SYMBOL(printk_timed_ratelimit
);
2513 static DEFINE_SPINLOCK(dump_list_lock
);
2514 static LIST_HEAD(dump_list
);
2517 * kmsg_dump_register - register a kernel log dumper.
2518 * @dumper: pointer to the kmsg_dumper structure
2520 * Adds a kernel log dumper to the system. The dump callback in the
2521 * structure will be called when the kernel oopses or panics and must be
2522 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
2524 int kmsg_dump_register(struct kmsg_dumper
*dumper
)
2526 unsigned long flags
;
2529 /* The dump callback needs to be set */
2533 spin_lock_irqsave(&dump_list_lock
, flags
);
2534 /* Don't allow registering multiple times */
2535 if (!dumper
->registered
) {
2536 dumper
->registered
= 1;
2537 list_add_tail_rcu(&dumper
->list
, &dump_list
);
2540 spin_unlock_irqrestore(&dump_list_lock
, flags
);
2544 EXPORT_SYMBOL_GPL(kmsg_dump_register
);
2547 * kmsg_dump_unregister - unregister a kmsg dumper.
2548 * @dumper: pointer to the kmsg_dumper structure
2550 * Removes a dump device from the system. Returns zero on success and
2551 * %-EINVAL otherwise.
2553 int kmsg_dump_unregister(struct kmsg_dumper
*dumper
)
2555 unsigned long flags
;
2558 spin_lock_irqsave(&dump_list_lock
, flags
);
2559 if (dumper
->registered
) {
2560 dumper
->registered
= 0;
2561 list_del_rcu(&dumper
->list
);
2564 spin_unlock_irqrestore(&dump_list_lock
, flags
);
2569 EXPORT_SYMBOL_GPL(kmsg_dump_unregister
);
2571 static bool always_kmsg_dump
;
2572 module_param_named(always_kmsg_dump
, always_kmsg_dump
, bool, S_IRUGO
| S_IWUSR
);
2575 * kmsg_dump - dump kernel log to kernel message dumpers.
2576 * @reason: the reason (oops, panic etc) for dumping
2578 * Call each of the registered dumper's dump() callback, which can
2579 * retrieve the kmsg records with kmsg_dump_get_line() or
2580 * kmsg_dump_get_buffer().
2582 void kmsg_dump(enum kmsg_dump_reason reason
)
2584 struct kmsg_dumper
*dumper
;
2585 unsigned long flags
;
2587 if ((reason
> KMSG_DUMP_OOPS
) && !always_kmsg_dump
)
2591 list_for_each_entry_rcu(dumper
, &dump_list
, list
) {
2592 if (dumper
->max_reason
&& reason
> dumper
->max_reason
)
2595 /* initialize iterator with data about the stored records */
2596 dumper
->active
= true;
2598 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2599 dumper
->cur_seq
= clear_seq
;
2600 dumper
->cur_idx
= clear_idx
;
2601 dumper
->next_seq
= log_next_seq
;
2602 dumper
->next_idx
= log_next_idx
;
2603 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2605 /* invoke dumper which will iterate over records */
2606 dumper
->dump(dumper
, reason
);
2608 /* reset iterator */
2609 dumper
->active
= false;
2615 * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
2616 * @dumper: registered kmsg dumper
2617 * @syslog: include the "<4>" prefixes
2618 * @line: buffer to copy the line to
2619 * @size: maximum size of the buffer
2620 * @len: length of line placed into buffer
2622 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2623 * record, and copy one record into the provided buffer.
2625 * Consecutive calls will return the next available record moving
2626 * towards the end of the buffer with the youngest messages.
2628 * A return value of FALSE indicates that there are no more records to
2631 * The function is similar to kmsg_dump_get_line(), but grabs no locks.
2633 bool kmsg_dump_get_line_nolock(struct kmsg_dumper
*dumper
, bool syslog
,
2634 char *line
, size_t size
, size_t *len
)
2640 if (!dumper
->active
)
2643 if (dumper
->cur_seq
< log_first_seq
) {
2644 /* messages are gone, move to first available one */
2645 dumper
->cur_seq
= log_first_seq
;
2646 dumper
->cur_idx
= log_first_idx
;
2650 if (dumper
->cur_seq
>= log_next_seq
)
2653 msg
= log_from_idx(dumper
->cur_idx
);
2654 l
= msg_print_text(msg
, 0, syslog
, line
, size
);
2656 dumper
->cur_idx
= log_next(dumper
->cur_idx
);
2666 * kmsg_dump_get_line - retrieve one kmsg log line
2667 * @dumper: registered kmsg dumper
2668 * @syslog: include the "<4>" prefixes
2669 * @line: buffer to copy the line to
2670 * @size: maximum size of the buffer
2671 * @len: length of line placed into buffer
2673 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2674 * record, and copy one record into the provided buffer.
2676 * Consecutive calls will return the next available record moving
2677 * towards the end of the buffer with the youngest messages.
2679 * A return value of FALSE indicates that there are no more records to
2682 bool kmsg_dump_get_line(struct kmsg_dumper
*dumper
, bool syslog
,
2683 char *line
, size_t size
, size_t *len
)
2685 unsigned long flags
;
2688 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2689 ret
= kmsg_dump_get_line_nolock(dumper
, syslog
, line
, size
, len
);
2690 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2694 EXPORT_SYMBOL_GPL(kmsg_dump_get_line
);
2697 * kmsg_dump_get_buffer - copy kmsg log lines
2698 * @dumper: registered kmsg dumper
2699 * @syslog: include the "<4>" prefixes
2700 * @buf: buffer to copy the line to
2701 * @size: maximum size of the buffer
2702 * @len: length of line placed into buffer
2704 * Start at the end of the kmsg buffer and fill the provided buffer
2705 * with as many of the the *youngest* kmsg records that fit into it.
2706 * If the buffer is large enough, all available kmsg records will be
2707 * copied with a single call.
2709 * Consecutive calls will fill the buffer with the next block of
2710 * available older records, not including the earlier retrieved ones.
2712 * A return value of FALSE indicates that there are no more records to
2715 bool kmsg_dump_get_buffer(struct kmsg_dumper
*dumper
, bool syslog
,
2716 char *buf
, size_t size
, size_t *len
)
2718 unsigned long flags
;
2723 enum log_flags prev
;
2727 if (!dumper
->active
)
2730 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2731 if (dumper
->cur_seq
< log_first_seq
) {
2732 /* messages are gone, move to first available one */
2733 dumper
->cur_seq
= log_first_seq
;
2734 dumper
->cur_idx
= log_first_idx
;
2738 if (dumper
->cur_seq
>= dumper
->next_seq
) {
2739 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2743 /* calculate length of entire buffer */
2744 seq
= dumper
->cur_seq
;
2745 idx
= dumper
->cur_idx
;
2747 while (seq
< dumper
->next_seq
) {
2748 struct log
*msg
= log_from_idx(idx
);
2750 l
+= msg_print_text(msg
, prev
, true, NULL
, 0);
2751 idx
= log_next(idx
);
2756 /* move first record forward until length fits into the buffer */
2757 seq
= dumper
->cur_seq
;
2758 idx
= dumper
->cur_idx
;
2760 while (l
> size
&& seq
< dumper
->next_seq
) {
2761 struct log
*msg
= log_from_idx(idx
);
2763 l
-= msg_print_text(msg
, prev
, true, NULL
, 0);
2764 idx
= log_next(idx
);
2769 /* last message in next interation */
2775 while (seq
< dumper
->next_seq
) {
2776 struct log
*msg
= log_from_idx(idx
);
2778 l
+= msg_print_text(msg
, prev
, syslog
, buf
+ l
, size
- l
);
2779 idx
= log_next(idx
);
2784 dumper
->next_seq
= next_seq
;
2785 dumper
->next_idx
= next_idx
;
2787 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2793 EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer
);
2796 * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
2797 * @dumper: registered kmsg dumper
2799 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2800 * kmsg_dump_get_buffer() can be called again and used multiple
2801 * times within the same dumper.dump() callback.
2803 * The function is similar to kmsg_dump_rewind(), but grabs no locks.
2805 void kmsg_dump_rewind_nolock(struct kmsg_dumper
*dumper
)
2807 dumper
->cur_seq
= clear_seq
;
2808 dumper
->cur_idx
= clear_idx
;
2809 dumper
->next_seq
= log_next_seq
;
2810 dumper
->next_idx
= log_next_idx
;
2814 * kmsg_dump_rewind - reset the interator
2815 * @dumper: registered kmsg dumper
2817 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2818 * kmsg_dump_get_buffer() can be called again and used multiple
2819 * times within the same dumper.dump() callback.
2821 void kmsg_dump_rewind(struct kmsg_dumper
*dumper
)
2823 unsigned long flags
;
2825 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2826 kmsg_dump_rewind_nolock(dumper
);
2827 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2829 EXPORT_SYMBOL_GPL(kmsg_dump_rewind
);