console: use might_sleep in console_lock

danvet · gregkh · commit 6b898c07cb1d · 2012-10-23T20:14:55.000-07:00
Instead of BUG_ON(in_interrupt()), since that doesn't check for all
the newfangled stuff like preempt.

Note that this is valid since the console_sem is essentially used like
a real mutex with only two twists:
- we allow trylock from hardirq context
- across suspend/resume we lock the logical console_lock, but drop the
  semaphore protecting the locking state.

Now that doesn't guarantee that no one is playing tricks in
single-thread atomic contexts at suspend/resume/boot time, but
- I couldn't find anything suspicious with some grepping,
- might_sleep shouldn't die,
- and I think the upside of catching more potential issues is worth
  the risk of getting a might_sleep backtrace that would have been
  save (and then dealing with that fallout).

Cc: Dave Airlie &lt;airlied@gmail.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Alan Cox &lt;alan@lxorguk.ukuu.org.uk&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
diff --git a/kernel/printk.c b/kernel/printk.c
@@ -1914,7 +1914,8 @@ static int __cpuinit console_cpu_notify(struct notifier_block *self,
  */
 void console_lock(void)
 {
-	BUG_ON(in_interrupt());
+	might_sleep();
+
 	down(&console_sem);
 	if (console_suspended)
 		return;
