Re: a competition when some threads acquire futex

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: a competition when some threads acquire futex
Date	2017-09-06 10:40 +0200
Message-ID	<umE2m-7tt-9@gated-at.bofh.it> (permalink)
References	<umbjH-4I1-5@gated-at.bofh.it> <umrRv-76q-15@gated-at.bofh.it> <umwo9-1Oc-1@gated-at.bofh.it>
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On Wed, 6 Sep 2017, chengjian (D) wrote:

> > > diff --git a/kernel/futex.c b/kernel/futex.c
> > > index 3d38eaf..0b2d17a 100644
> > > --- a/kernel/futex.c
> > > +++ b/kernel/futex.c
> > > @@ -1545,6 +1545,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32
> > > uval,
> > > struct futex_pi_state *pi_
> > >    	spin_unlock(&hb->lock);
> > >   	wake_up_q(&wake_q);
> > > +        _cond_resched( );
> > 

> I wrote _cond_resched( ) in futex_wake( ) which will be called to wake up
> waiters
> when the process release the futex.
> 
> 
> But the patch producted by git format-patch displayed in wake_futex_pi( ).

Ok. Still that patch has issues.

1) It's white space damaged. Please use TAB not spaces for
   indentation. checkpatch.pl would have told you.

2) Why are you using _cond_resched() instead of plain cond_resched().

   cond_resched() is what you want to use.

Thanks,

	tglx

Thread

a competition when some threads acquire futex "chengjian (D)" <cj.chengjian@huawei.com> - 2017-09-05 04:00 +0200
  Re: a competition when some threads acquire futex Thomas Gleixner <tglx@linutronix.de> - 2017-09-05 21:40 +0200
    Re: a competition when some threads acquire futex "chengjian (D)" <cj.chengjian@huawei.com> - 2017-09-06 02:30 +0200
      Re: a competition when some threads acquire futex Thomas Gleixner <tglx@linutronix.de> - 2017-09-06 10:40 +0200
        Re: a competition when some threads acquire futex Peter Zijlstra <peterz@infradead.org> - 2017-09-06 11:00 +0200
          Re: a competition when some threads acquire futex Peter Zijlstra <peterz@infradead.org> - 2017-09-06 11:10 +0200
        Re: a competition when some threads acquire futex "chengjian (D)" <cj.chengjian@huawei.com> - 2017-09-06 11:20 +0200

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