linux-kernel - Re: [PATCH 1/2] IB/hfi1: Use preempt_{dis,en}able

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Message-ID: <alpine.DEB.2.20.1710051726490.2083@nanos>
Date:   Thu, 5 Oct 2017 17:27:30 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Julia Cartwright <julia@...com>
cc:     Arnaldo Carvalho de Melo <acme@...nel.org>, bigeasy@...utronix.de,
        linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Clark Williams <williams@...hat.com>,
        Dean Luick <dean.luick@...el.com>,
        Dennis Dalessandro <dennis.dalessandro@...el.com>,
        Doug Ledford <dledford@...hat.com>,
        Kaike Wan <kaike.wan@...el.com>,
        Leon Romanovsky <leonro@...lanox.com>,
        linux-rdma@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
        Sebastian Andrzej Siewior <sebastian.siewior@...utronix.de>,
        Sebastian Sanchez <sebastian.sanchez@...el.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH 1/2] IB/hfi1: Use preempt_{dis,en}able_nort()

On Thu, 5 Oct 2017, Julia Cartwright wrote:
> On Tue, Oct 03, 2017 at 12:49:19PM -0300, Arnaldo Carvalho de Melo wrote:
> > -	preempt_disable();
> > +	preempt_disable_nort();
> >  	this_cpu_inc(*sc->buffers_allocated);
> 
> Have you tried this on RT w/ CONFIG_DEBUG_PREEMPT?  I believe that the
> this_cpu_* operations perform a preemption check, which we'd trip.

Good point. Changing this to migrate_disable() would do the trick.

Thanks,

	tglx