On (10/25/16 10:55), Sergey Senozhatsky wrote:
> I think cont_flush() should grab the logbuf_lock lock, because
> it does log_store() and touches the cont.len. so something like
> this perhaps
>
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index c7f490f..47f887c 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1608,13 +1608,20 @@ static struct cont {
>
> static bool cont_flush(void)
> {
> + unsigned long flags;
> + bool flushed = false;
> +
> + raw_spin_lock_irqsave(&logbuf_lock, flags);
> if (!cont.len)
> - return false;
> + goto out;
>
> log_store(cont.facility, cont.level, cont.flags, cont.ts_nsec,
> NULL, 0, cont.buf, cont.len);
> cont.len = 0;
> - return true;
> + flushed = true;
> +out:
> + raw_spin_unlock_irqrestore(&logbuf_lock, flags);
> + return flushed;
> }
... clearly, wasn't tested at all! sorry about that.
what I meant was cont_flush() from deferred_cont_flush()->flush_timer().
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index c7f490f..bd7841c 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1619,7 +1619,14 @@ static bool cont_flush(void)
static void flush_timer(unsigned long data)
{
- if (cont_flush())
+ unsigned long flags;
+ bool flushed;
+
+ raw_spin_lock_irqsave(&logbuf_lock, flags);
+ flushed = cont_flush();
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+
+ if (flushed)
wake_up_klogd();
}
-ss
