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author | Mike Frysinger <vapier.adi@gmail.com> | 2007-10-16 23:26:43 -0700 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-17 08:42:50 -0700 |
commit | 0b15d04af3dd996035d8fa81fc849d049171f9c3 (patch) | |
tree | cb0dc973b6485edb6fdf0bcdf4a2eeef9a48adad /kernel/printk.c | |
parent | d823e3e7541c39b4dfe9c79dbf052b4c39da2965 (diff) | |
download | linux-0b15d04af3dd996035d8fa81fc849d049171f9c3.tar.gz linux-0b15d04af3dd996035d8fa81fc849d049171f9c3.tar.bz2 linux-0b15d04af3dd996035d8fa81fc849d049171f9c3.zip |
printk: add interfaces for external access to the log buffer
Add two new functions for reading the kernel log buffer. The intention is for
them to be used by recovery/dump/debug code so the kernel log can be easily
retrieved/parsed in a crash scenario, but they are generic enough for other
people to dream up other fun uses.
[akpm@linux-foundation.org: buncha fixes]
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Robin Getz <rgetz@blackfin.uclinux.org>
Cc: Greg Ungerer <gerg@snapgear.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul Mundt <lethal@linux-sh.org>
Acked-by: Tim Bird <tim.bird@am.sony.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/printk.c')
-rw-r--r-- | kernel/printk.c | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/kernel/printk.c b/kernel/printk.c index b2b5c3a22a36..52493474f0ab 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -220,6 +220,58 @@ static inline void boot_delay_msec(void) #endif /* + * Return the number of unread characters in the log buffer. + */ +int log_buf_get_len(void) +{ + return logged_chars; +} + +/* + * Copy a range of characters from the log buffer. + */ +int log_buf_copy(char *dest, int idx, int len) +{ + int ret, max; + bool took_lock = false; + + if (!oops_in_progress) { + spin_lock_irq(&logbuf_lock); + took_lock = true; + } + + max = log_buf_get_len(); + if (idx < 0 || idx >= max) { + ret = -1; + } else { + if (len > max) + len = max; + ret = len; + idx += (log_end - max); + while (len-- > 0) + dest[len] = LOG_BUF(idx + len); + } + + if (took_lock) + spin_unlock_irq(&logbuf_lock); + + return ret; +} + +/* + * Extract a single character from the log buffer. + */ +int log_buf_read(int idx) +{ + char ret; + + if (log_buf_copy(&ret, idx, 1) == 1) + return ret; + else + return -1; +} + +/* * Commands to do_syslog: * * 0 -- Close the log. Currently a NOP. |