From: Jens Axboe <axboe@suse.de>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: linux-ide@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: PATCH (for comment): ide-cd possible race in PIO mode
Date: Wed, 17 Nov 2004 21:56:02 +0100 [thread overview]
Message-ID: <20041117205602.GO26240@suse.de> (raw)
In-Reply-To: <1100708728.420.68.camel@localhost.localdomain>
On Wed, Nov 17 2004, Alan Cox wrote:
> On Mer, 2004-11-17 at 15:37, Jens Axboe wrote:
> > > - HWIF(drive)->OUTB(WIN_PACKETCMD, IDE_COMMAND_REG);
> > > + spin_lock_irqsave(&ide_lock, flags);
> > > + HWIF(drive)->OUTBSYNC(WIN_PACKETCMD, IDE_COMMAND_REG);
> > > + ndelay(400);
> > > + spin_unlock_irqsave(&ide_lock, flags);
> > > return (*handler) (drive);
> > > }
> > > }
> >
> > What good does the lock do?
>
> The same as in ide_execute_command - make sure we don't take an IDE
> interrupt that tries to read the state during the delay. That is the old
> 2.4 "may drives shared IRQ random fails" fix and why the lock is taken
> in ide_execute_command.
Ah I see, makes sense. I didn't think about the shared irq case.
--
Jens Axboe
next prev parent reply other threads:[~2004-11-17 20:56 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-11-17 13:19 PATCH (for comment): ide-cd possible race in PIO mode Alan Cox
2004-11-17 15:37 ` Jens Axboe
2004-11-17 16:25 ` Alan Cox
2004-11-17 20:56 ` Jens Axboe [this message]
2004-11-22 7:58 ` Jens Axboe
2004-11-24 11:35 ` Alan Cox
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