Re: [PATCH] net: wireless: airo semaphore to mutex

[Matthew Wilcox <matthew@wil.cx>]

On Mon, May 26, 2008 at 09:34:41PM -0700, Daniel Walker wrote:
> 
> On Mon, 2008-05-26 at 20:15 -0600, Matthew Wilcox wrote:
> > On Tue, May 27, 2008 at 11:17:22AM +1000, Rusty Russell wrote:
> > > On Tuesday 27 May 2008 03:29:14 Michal Schmidt wrote:
> > > > Mutexes are not allowed in interrupt context, not even mutex_trylock.
> > > 
> > > As an aside, does anyone know why?  I know the documentation says so, but it 
> > > wasn't immediately obvious to me.  I asked before to no response...
> > 
> > Because mutexes have an owner.  In interrupt context, there is no owner.
> > This owner is used to do priority boosts as well as debugging.
> 
> I don't think regular mutexes do boosting, the rtmutex does tho .. I
> think it's more a issue with lockdep complaining about the context, but
> that exists to just plain disallow this type of usage on principal .

You're right, I got confused, it's only rtmutexes that do priority
inheritance.

I suppose we could have a special 'interrupt context' owner for
the purposes of LOCKDEP.  Ingo?

-- 
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