Re: [patch] sgi-xp: nested calls to spin_lock

From:		Andrew Morton <akpm-AT-linux-foundation.org>
To:		Robin Holt <holt-AT-sgi.com>
Subject:		Re: [patch] sgi-xp: nested calls to spin_lock_irqsave()
Date:		Thu, 28 Jun 2012 15:03:42 -0700
Message-ID:		<20120628150342.aaa4ad2d.akpm@linux-foundation.org>
Cc:		Dan Carpenter <dan.carpenter-AT-oracle.com>, linux-kernel-AT-vger.kernel.org, kernel-janitors-AT-vger.kernel.org, Jack Steiner <steiner-AT-sgi.com>
Archive-link:		Article, Thread

On Wed, 27 Jun 2012 08:51:55 -0500
Robin Holt <holt@sgi.com> wrote:

> The code here has a nested spin_lock_irqsave().  It's not needed since
> IRQs are already disabled and it causes a problem because it means that
> IRQs won't be enabled again at the end.  The second call to
> spin_lock_irqsave() will overwrite the value of irq_flags and we can't
> restore the proper settings.

Please find large crayon and write on forehead "when fixing a bug,
be sure to describe the end-user impact of that bug".

Then others will have a chance of deciding whether the fix should be
backported.

> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Robin Holt <holt@sgi.com>

I'm wondering if there should have been a Reported-by:dan in there. 
He's like that.

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Re: [patch] sgi-xp: nested calls to spin_lock_irqsave()