linux-kernel - Re: [patch 5/5] futex: Cleanup the goto confusion in requeue

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Message-ID: <20151220054602.GK7244@malice.jf.intel.com>
Date:	Sat, 19 Dec 2015 21:46:02 -0800
From:	Darren Hart <dvhart@...radead.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Darren Hart <darren@...art.com>,
	Davidlohr Bueso <dave@...olabs.net>,
	Bhuvanesh_Surachari@...tor.com, Andy Lowe <Andy_Lowe@...tor.com>
Subject: Re: [patch 5/5] futex: Cleanup the goto confusion in requeue_pi()

On Sat, Dec 19, 2015 at 09:15:24PM -0800, Darren Hart wrote:
> 
> As a follow-on, I think it might be worthwhile to create a symmetrical
> get_pi_state() to the put_pi_state(), rather than handling the atomic_inc
> directly.
> 
> And finally, while the break; in futex_requeue works, that function is quite
> long and an explicit out_put_pi_state: label would make the intention clear and
> also avoid inadvertently breaking the implicit behavior of the break.
> 

And while prototyping these changes, I've changed my mind, neither is a
worthwhile change.

The plist_for_each in futex_requeue really isn't that long and the breaks occur
in a logical way and are now well documented with this series. An inadvertent
change to this behavior seems unlikely.

There is only one open coded atomic_inc in futex.c for the pi_state refcount,
hardly worth a wrapper.

Regards,

-- 
Darren Hart
Intel Open Source Technology Center
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