From: James Bottomley <James.Bottomley@SteelEye.com>
To: brking@us.ibm.com
Cc: SCSI Mailing List <linux-scsi@vger.kernel.org>
Subject: Re: [PATCH] p00001_scsi_tcq_queue_lock
Date: 06 Aug 2004 21:09:49 -0700 [thread overview]
Message-ID: <1091815154.2421.15.camel@mulgrave> (raw)
In-Reply-To: <410FD03E.6040305@us.ibm.com>
On Tue, 2004-08-03 at 10:49, Brian King wrote:
> Add locking to scsi_activate_tcq and scsi_deactivate_tcq to fix a race
> condition that can occur when disabling tcqing with commands in flight.
It's possible to do it like this. However, we should really quiesce the
SCSI device before disabling tcq. It is not legal in the scsi spec to
have both tagged and untagged commands outstanding. Most drives do the
right thing and return BUSY to an untagged request if they have tags in
flight. Also, we have to wait until all tags return before freeing the
block layer tag structures...and there's always the devices that do
strange things in this situation...
James
next prev parent reply other threads:[~2004-08-07 4:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-03 17:49 [PATCH] p00001_scsi_tcq_queue_lock Brian King
2004-08-07 4:09 ` James Bottomley [this message]
2004-08-09 14:04 ` Brian King
2004-08-09 14:14 ` Brian King
2004-09-17 17:55 ` Brian King
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