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Date: Mon, 4 Apr 2016 11:21:43 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>, LKML <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
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Subject: Re: [PATCH 03/11] locking, rwsem: introduce basis for
 down_write_killable
Message-ID: <20160404092143.GX3448@twins.programming.kicks-ass.net>
References: <1459508695-14915-1-git-send-email-mhocko@kernel.org>
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 <20160402044125.GC5329@linux-uzut.site>
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On Mon, Apr 04, 2016 at 11:17:00AM +0200, Michal Hocko wrote:
> > >@@ -486,21 +487,39 @@ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem)
> > >
> > >		/* Block until there are no active lockers. */
> > >		do {
> > >+			if (signal_pending_state(state, current)) {
> > 
> >                           ^^ unlikely()?
> 
> The generated code is identical after I've added unlikely. I haven't
> tried more gcc versions (mine is 5.3.1) but is this worth it?

Both signal_pending() and __fatal_signal_pending() already have an
unlikely(), which is why adding it here is superfluous.