From: Jeff Garzik <jgarzik@pobox.com>
To: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Tejun Heo <htejun@gmail.com>, Jens Axboe <axboe@suse.de>,
SCSI Mailing List <linux-scsi@vger.kernel.org>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH scsi-misc-2.6 04/08] scsi: remove meaningless volatile qualifiers from structure definitions
Date: Tue, 22 Mar 2005 23:22:23 -0500 [thread overview]
Message-ID: <4240EEFF.8030703@pobox.com> (raw)
In-Reply-To: <1111551327.5520.99.camel@mulgrave>
James Bottomley wrote:
> On Wed, 2005-03-23 at 11:14 +0900, Tejun Heo wrote:
>
>> scsi_device->device_busy, Scsi_Host->host_busy and
>> ->host_failed have volatile qualifiers, but the qualifiers
>> don't serve any purpose. Kill them. While at it, protect
>> ->host_failed update in scsi_error for consistency and clarity.
>
>
> Well ... the data here is volatile so what you're advocating is a move
> away from a volatile variable model to a protected variable one ... did
> you audit all users of both of these to make sure we have protection on
> all of them? It looks like the sata strategy handlers would still rely
> on the volatile data.
volatile is almost always (a) buggy, or (b) hiding bugs. At the very
least, barriers are usually needed.
Almost every case really wants to be inside a spinlock, or atomic_t, or
similarly protected.
Specifically for SATA, I am making the presumption that SCSI is smart
enough not to mess with host_failed until my error handler completes.
Jeff
next prev parent reply other threads:[~2005-03-23 4:22 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-23 2:14 [PATCH scsi-misc-2.6 00/08] scsi: small fixes & cleanups Tejun Heo
2005-03-23 2:14 ` [PATCH scsi-misc-2.6 01/08] scsi: remove unused bounce-buffer release path Tejun Heo
2005-03-23 4:07 ` James Bottomley
2005-03-23 6:08 ` Tejun Heo
2005-03-23 15:27 ` Jens Axboe
2005-03-23 2:14 ` [PATCH scsi-misc-2.6 02/08] scsi: don't use blk_insert_request() for requeueing Tejun Heo
2005-03-23 2:14 ` [PATCH scsi-misc-2.6 03/08] scsi: remove unused scsi_cmnd->internal_timeout field Tejun Heo
2005-03-23 2:14 ` [PATCH scsi-misc-2.6 04/08] scsi: remove meaningless volatile qualifiers from structure definitions Tejun Heo
2005-03-23 4:15 ` James Bottomley
2005-03-23 4:22 ` Jeff Garzik [this message]
2005-03-23 5:28 ` Tejun Heo
2005-03-23 15:16 ` James Bottomley
2005-03-23 2:14 ` [PATCH scsi-misc-2.6 05/08] scsi: remove a timer race from scsi_queue_insert() and cleanup timer Tejun Heo
2005-03-23 2:14 ` [PATCH scsi-misc-2.6 06/08] scsi: remove meaningless scsi_cmnd->serial_number_at_timeout field Tejun Heo
2005-03-23 2:14 ` [PATCH scsi-misc-2.6 07/08] scsi: remove bogus {get|put}_device() calls Tejun Heo
2005-03-23 4:15 ` James Bottomley
2005-03-23 9:13 ` Tejun Heo
2005-03-29 17:02 ` Patrick Mansfield
2005-03-23 2:14 ` [PATCH scsi-misc-2.6 08/08] scsi: fix hot unplug sequence Tejun Heo
2005-03-23 4:08 ` James Bottomley
2005-03-23 4:50 ` Tejun Heo
2005-03-23 7:19 ` Jens Axboe
2005-03-23 15:20 ` James Bottomley
2005-03-23 15:25 ` Jens Axboe
2005-03-25 0:45 ` James Bottomley
2005-03-25 3:15 ` Tejun Heo
2005-03-25 5:02 ` James Bottomley
2005-03-25 5:38 ` Tejun Heo
2005-03-25 19:19 ` James Bottomley
2005-03-25 21:43 ` Tejun Heo
2005-03-25 22:49 ` James Bottomley
2005-03-26 7:27 ` Kai Makisara
2005-03-26 14:48 ` James Bottomley
2005-03-23 15:12 ` James Bottomley
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