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 klog wake up call to vprintk_emit(), which is
the only legit way for a kernel message to appear in the logbuf,
right before we attempt to grab the console_sem (possibly spinning
on it waiting for the hand off) and call console drivers.
Signed-off-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com>
---
kernel/printk/printk.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 2f4af216bd6e..86f0b337cbf6 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1888,6 +1888,7 @@ asmlinkage int vprintk_emit(int facility, int level,
printed_len = log_output(facility, level, lflags, dict, dictlen, text,
text_len);
+ wake_up_klogd();
logbuf_unlock_irqrestore(flags);
/* If called from the scheduler, we can not call up(). */
@@ -2289,9 +2290,7 @@ 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) {
@@ -2335,11 +2334,6 @@ void console_unlock(void)
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));
@@ -2397,7 +2391,7 @@ void console_unlock(void)
if (console_lock_spinning_disable_and_check()) {
printk_safe_exit_irqrestore(flags);
- goto out;
+ return;
}
printk_safe_exit_irqrestore(flags);
@@ -2429,10 +2423,6 @@ void console_unlock(void)
if (retry && console_trylock())
goto again;
-
-out:
- if (wake_klogd)
- wake_up_klogd();
}
EXPORT_SYMBOL(console_unlock);
--
2.17.0
