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