linux-kernel - Re: [PATCH 2/2] locking/mutex: Use mutex flags macro instead of hard code value

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Message-ID: <20190730080308.GF31381@hirez.programming.kicks-ass.net>
Date:   Tue, 30 Jul 2019 10:03:08 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Mukesh Ojha <mojha@...eaurora.org>
Cc:     mingo@...hat.com, will@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] locking/mutex: Use mutex flags macro instead of hard
 code value

On Tue, Jul 30, 2019 at 01:23:13PM +0530, Mukesh Ojha wrote:
> 
> On 7/29/2019 4:37 PM, Peter Zijlstra wrote:
> > On Mon, Jul 29, 2019 at 04:22:58PM +0530, Mukesh Ojha wrote:
> > > Let's use the mutex flag macro(which got moved from mutex.c
> > > to linux/mutex.h in the last patch) instead of hard code
> > > value which was used in __mutex_owner().
> > > 
> > > Signed-off-by: Mukesh Ojha <mojha@...eaurora.org>
> > > ---
> > >   include/linux/mutex.h | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/include/linux/mutex.h b/include/linux/mutex.h
> > > index 79b28be..c3833ba 100644
> > > --- a/include/linux/mutex.h
> > > +++ b/include/linux/mutex.h
> > > @@ -87,7 +87,7 @@ struct mutex {
> > >    */
> > >   static inline struct task_struct *__mutex_owner(struct mutex *lock)
> > >   {
> > > -	return (struct task_struct *)(atomic_long_read(&lock->owner) & ~0x07);
> > > +	return (struct task_struct *)(atomic_long_read(&lock->owner) & ~MUTEX_FLAGS);
> > >   }
> > I would _much_ rather move __mutex_owner() out of line, you're exposing
> > far too much stuff.
> 
> if i understand you correctly, you want me to move __mutex_owner() to
> mutex.c
> __mutex_owner() is used in mutex_is_locked() and mutex_trylock_recursive
> inside linux/mutex.h.
> 
> Shall i move them as well ?

Yes, then you can make __mutex_owner() static.

Thanks!