From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751716AbZKCO6u (ORCPT ); Tue, 3 Nov 2009 09:58:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751171AbZKCO6u (ORCPT ); Tue, 3 Nov 2009 09:58:50 -0500 Received: from mail-pz0-f188.google.com ([209.85.222.188]:51115 "EHLO mail-pz0-f188.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750938AbZKCO6t convert rfc822-to-8bit (ORCPT ); Tue, 3 Nov 2009 09:58:49 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=j3AR2ERWJVzYmMw9CdBV4BqLR2T2Go1GHheXW7NeC+Wjh5vFARw2hZ6rj9zrgJFo/1 bvuQhZ9NteiQpZLwjIKPWeg9nOOEa56Lr5CJEjXd2d2VoMe4CsGwldz7w8ao8xBQdehi iECjk5oj3qVgH5ZPZnKT63KJN5rytiwJ8tOnM= MIME-Version: 1.0 In-Reply-To: <20091103134342.24414.82986.sendpatchset@prarit.bos.redhat.com> References: <20091103134342.24414.82986.sendpatchset@prarit.bos.redhat.com> Date: Tue, 3 Nov 2009 22:58:54 +0800 Message-ID: <2674af740911030658m76b702cfxb67723984286c4bb@mail.gmail.com> Subject: Re: [PATCH]: use spin_lock_irqsave in try_one_irq() From: Yong Zhang To: Prarit Bhargava Cc: linux-kernel@vger.kernel.org, ebiederm@xmission.com, akpm@linux-foundation.org, Ingo Molnar , Thomas Gleixner Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > This happens because the &desc->lock is taken with spin_lock_irqsave and > just a spin_lock.  In the try_one_irq(), this lock really should be a > spin_lock_irqsave(). > Cc'ed Ingo and Thomas. The reason is that try_one_irq() is called both from hardirq context and softirq context. And by default the timer handler poll_all_shared_irqs() is called with irq enabled. Then the two usage will cause inconsistent. So I think the following patch is also workable to you. diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c index 114e704..11affbc 100644 --- a/kernel/irq/spurious.c +++ b/kernel/irq/spurious.c @@ -111,6 +111,7 @@ static void poll_all_shared_irqs(void) for_each_irq_desc(i, desc) { unsigned int status; + unsigned long flags; if (!i) continue; @@ -121,7 +122,9 @@ static void poll_all_shared_irqs(void) if (!(status & IRQ_SPURIOUS_DISABLED)) continue; + local_irq_save(flags); try_one_irq(i, desc); + local_irq_restore(flags); } } > I have not yet narrowed down the reason for the spurious interrupt (although > I suspect it maybe to do with the radeon driver). > > Successfully tested by me. > > Signed-off-by: Prarit Bhargava > > --- linux-2.6.31.x86_64.orig/kernel/irq/spurious.c      2009-09-09 18:13:59.000000000 -0400 > +++ linux-2.6.31.x86_64/kernel/irq/spurious.c   2009-10-26 10:55:56.709845786 -0400 > @@ -27,8 +27,9 @@ static int try_one_irq(int irq, struct i >  { >        struct irqaction *action; >        int ok = 0, work = 0; > +       unsigned long flags; > > -       spin_lock(&desc->lock); > +       spin_lock_irqsave(&desc->lock, flags); >        /* Already running on another processor */ >        if (desc->status & IRQ_INPROGRESS) { >                /* > @@ -37,13 +38,13 @@ static int try_one_irq(int irq, struct i >                 */ >                if (desc->action && (desc->action->flags & IRQF_SHARED)) >                        desc->status |= IRQ_PENDING; > -               spin_unlock(&desc->lock); > +               spin_unlock_irqrestore(&desc->lock, flags); >                return ok; >        } >        /* Honour the normal IRQ locking */ >        desc->status |= IRQ_INPROGRESS; >        action = desc->action; > -       spin_unlock(&desc->lock); > +       spin_unlock_irqrestore(&desc->lock, flags); > >        while (action) { >                /* Only shared IRQ handlers are safe to call */ > @@ -56,7 +57,7 @@ static int try_one_irq(int irq, struct i >        } >        local_irq_disable(); >        /* Now clean up the flags */ > -       spin_lock(&desc->lock); > +       spin_lock_irqsave(&desc->lock, flags); >        action = desc->action; > >        /* > @@ -68,9 +69,9 @@ static int try_one_irq(int irq, struct i >                 * Perform real IRQ processing for the IRQ we deferred >                 */ >                work = 1; > -               spin_unlock(&desc->lock); > +               spin_unlock_irqrestore(&desc->lock, flags); >                handle_IRQ_event(irq, action); > -               spin_lock(&desc->lock); > +               spin_lock_irqsave(&desc->lock, flags); >                desc->status &= ~IRQ_PENDING; >        } >        desc->status &= ~IRQ_INPROGRESS; > @@ -80,7 +81,7 @@ static int try_one_irq(int irq, struct i >         */ >        if (work && desc->chip && desc->chip->end) >                desc->chip->end(irq); > -       spin_unlock(&desc->lock); > +       spin_unlock_irqrestore(&desc->lock, flags); > >        return ok; >  } > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at  http://vger.kernel.org/majordomo-info.html > Please read the FAQ at  http://www.tux.org/lkml/ >