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| author | Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> | 2018-04-19 10:42:50 +0900 |
|---|---|---|
| committer | Petr Mladek <pmladek@suse.com> | 2018-04-25 13:26:02 +0200 |
| commit | 43a17111c2553925f65e7be9b9c3f9d90cf29a8b (patch) | |
| tree | 3e14a2ad36779608bc6d4d3bfbdb12ef6c5482d2 /kernel/printk | |
| parent | 357aa6aefebe888c712152cb83c9e700f98eebd1 (diff) | |
| download | linux-43a17111c2553925f65e7be9b9c3f9d90cf29a8b.tar.gz linux-43a17111c2553925f65e7be9b9c3f9d90cf29a8b.tar.bz2 linux-43a17111c2553925f65e7be9b9c3f9d90cf29a8b.zip | |
printk: wake up klogd in vprintk_emit
We wake up klogd very late - only when current console_sem owner
is done pushing pending kernel messages to the serial/net consoles.
In some cases this results in lost syslog messages, because kernel
log buffer is a circular buffer and if we don't wakeup syslog long
enough there are chances that logbuf simply will wrap around.
The patch moves the klogd wake up call to vprintk_emit(), which is
the only legit way for a kernel message to appear in the logbuf,
right after the attempt to handle consoles. As a result, klogd
will get waken either after flushing the new message to consoles
or immediately when consoles are still busy with older messages.
Link: http://lkml.kernel.org/r/20180419014250.5692-1-sergey.senozhatsky@gmail.com
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Diffstat (limited to 'kernel/printk')
| -rw-r--r-- | kernel/printk/printk.c | 14 |
1 files changed, 2 insertions, 12 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 704e55129c3a..fba995b305b1 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1907,6 +1907,7 @@ asmlinkage int vprintk_emit(int facility, int level, preempt_enable(); } + wake_up_klogd(); return printed_len; } EXPORT_SYMBOL(vprintk_emit); @@ -2288,9 +2289,7 @@ void console_unlock(void) { static char ext_text[CONSOLE_EXT_LOG_MAX]; static char text[LOG_LINE_MAX + PREFIX_MAX]; - static u64 seen_seq; unsigned long flags; - bool wake_klogd = false; bool do_cond_resched, retry; if (console_suspended) { @@ -2334,11 +2333,6 @@ again: printk_safe_enter_irqsave(flags); raw_spin_lock(&logbuf_lock); - if (seen_seq != log_next_seq) { - wake_klogd = true; - seen_seq = log_next_seq; - } - if (console_seq < log_first_seq) { len = sprintf(text, "** %u printk messages dropped **\n", (unsigned)(log_first_seq - console_seq)); @@ -2396,7 +2390,7 @@ skip: if (console_lock_spinning_disable_and_check()) { printk_safe_exit_irqrestore(flags); - goto out; + return; } printk_safe_exit_irqrestore(flags); @@ -2428,10 +2422,6 @@ skip: if (retry && console_trylock()) goto again; - -out: - if (wake_klogd) - wake_up_klogd(); } EXPORT_SYMBOL(console_unlock); |