printk: avoid double lock acquire

Commit 4f2a8d3 ("printk: Fix console_sem vs logbuf_lock unlock race") introduced another silly bug where we would want to acquire an already held lock. Avoid this. Reported-by: Andrea Arcangeli <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Cc: Ingo Molnar <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
CamonZ · Dec 9, 2011 · 09dc3cf · 09dc3cf
1 parent c193c82
commit 09dc3cf
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/kernel/printk.c b/kernel/printk.c
@@ -1293,10 +1293,11 @@ void console_unlock(void)
 	raw_spin_lock(&logbuf_lock);
 	if (con_start != log_end)
 		retry = 1;
+	raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+
 	if (retry && console_trylock())
 		goto again;
 
-	raw_spin_unlock_irqrestore(&logbuf_lock, flags);
 	if (wake_klogd)
 		wake_up_klogd();
 }