console: use might_sleep in console_lock
authorDaniel Vetter <daniel.vetter@ffwll.ch>
Mon, 17 Sep 2012 23:03:31 +0000 (23:03 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 24 Oct 2012 03:14:55 +0000 (20:14 -0700)
commit6b898c07cb1d5bd8344a8044288bb4ae3873da74
tree746c283ebf35c7e038b28fee4f7a094f1b885db2
parentecbbfd44a08fa80e0d664814efd4c187721b85f6
console: use might_sleep in console_lock

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 <airlied@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernel/printk.c