[alsa-devel] [patch 1/2] OSS: soundcard: locking bug in sound_ioctl()

[Arnd Bergmann]

On Tuesday 12 October 2010 00:23:08 Josh Triplett wrote:
> Assuming that the underlying function only returns zero/non-zero and
> that the actual return value doesn't matter, then you can use the
> __cond_lock macro from compiler.h for this:
> 
> # define __cond_lock(x,c)       ((c) ? ({ __acquire(x); 1; }) : 0)
> 

The return from mutex_lock_{killable,interruptible} is an error
value, not true/false, so it actually matters. We know that the only
possible error that is currently returned is -EINTR though, so we
could do a similar trick and define another

#define __cond_mutex(x, c)	((!c) ? ({ __acquire(x); 0; }) : -EINTR)

My fear was that this would impact code generation.

	Arnd