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From: Tejun Heo <htejun@gmail.com>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: linux-ide@vger.kernel.org, jeff@garzik.org
Subject: Re: [PATCH 2/2] block: add function for waiting for a specific free tag
Date: Wed, 20 May 2009 20:55:40 +0900	[thread overview]
Message-ID: <4A13EFBC.4010005@gmail.com> (raw)
In-Reply-To: <20090520070104.GF11363@kernel.dk>

Jens Axboe wrote:
> We need this in libata to ensure that we don't race between internal
> tag usage and the block layer usage.

Hmm... I can't think of a race condition.  Can you please elaborate
what can cause such race condition and how it can get resolved by
waiting for in-flight tag?  Currently, libata reserves a qc for EH so
there won't be any race around it (the old-EH path is broken if
invoked with commands in flight anyway, so doesn't matter).  Also, as
all failed rq's are on hold till EH finishes, if there's a race
condition around a tag, it will become a deadlock.

Thanks.

-- 
tejun

  reply	other threads:[~2009-05-20 11:55 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-20  6:59 [PATCH 0/2] libata: switch to block layer tagging Jens Axboe
2009-05-20  7:00 ` [PATCH 1/2] libata: switch to using block layer tagging support Jens Axboe
2009-05-20 11:53   ` Tejun Heo
2009-05-20 17:10   ` Grant Grundler
2009-05-20 18:08     ` Gwendal Grignou
2009-05-20 18:50       ` James Bottomley
2009-05-20 18:58         ` Jeff Garzik
2009-05-20 19:04           ` Jeff Garzik
2009-05-20 19:42             ` Gwendal Grignou
2009-05-20 19:47               ` Jeff Garzik
2009-05-21 13:44               ` Mark Lord
2009-05-21 17:27                 ` Jeff Garzik
2009-05-20 18:51       ` Jeff Garzik
2009-05-20 19:09     ` Jeff Garzik
2009-06-10 15:11   ` Jeff Garzik
2009-06-11  2:10     ` Tejun Heo
2009-05-20  7:01 ` [PATCH 2/2] block: add function for waiting for a specific free tag Jens Axboe
2009-05-20 11:55   ` Tejun Heo [this message]
2009-05-20 19:34     ` old-EH and SAS (was Re: [PATCH 2/2] block: add function for waiting for a specific free tag) Jeff Garzik
2009-05-21 16:34       ` Brian King
2009-05-20 17:28   ` [PATCH 2/2] block: add function for waiting for a specific free tag Grant Grundler
2009-05-20  7:53 ` [PATCH 0/2] libata: switch to block layer tagging Jeff Garzik
2009-05-20  7:57   ` Jens Axboe

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