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Date: Wed, 10 Aug 2011 10:33:25 +0200
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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To: "Michael S. Tsirkin" <mst@redhat.com>
CC: Chris Wright <chrisw@redhat.com>, "Hans J. Koch" <hjk@hansjkoch.de>,
        Jesse Barnes <jbarnes@virtuousgeek.org>,
        Greg Kroah-Hartman <gregkh@suse.de>,
        Anthony Foiani <anthony.foiani@gmail.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] uio/gen-pci: don't enable interrupts in ISR
References: <20110804204606.GA19724@linutronix.de> <20110804210413.GA29222@redhat.com> <20110805191842.GA4224@linutronix.de> <20110808064050.GC5182@redhat.com> <4E411D72.7000604@linutronix.de> <20110809120206.GB524@redhat.com>
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Michael S. Tsirkin wrote:
> Let's assume we start with e.g. io enable bit cleared.
> 
> 
>     user                                kernel
>  read config                               |
>  set io enable                             |
>      |                                  interrupt                                                
>      |                              read + set interrupt mask
>  write config back                         |
> 					write
> 
> 
> 
> We end up with io enable bit cleared. Locking around rmw
> that we have fixes this race.

Okay, forgot about the SMP case, sorry.

Sebastian