From: Bart Van Assche <bvanassche@acm.org>
To: James Bottomley <jbottomley@parallels.com>
Cc: linux-scsi <linux-scsi@vger.kernel.org>,
Joe Lawrence <jdl1291@gmail.com>, Tejun Heo <tj@kernel.org>,
Chanho Min <chanho.min@lge.com>,
David Milburn <dmilburn@redhat.com>,
Hannes Reinecke <hare@suse.de>,
Mike Christie <michaelc@cs.wisc.edu>
Subject: Re: [PATCH v11 2/9] Remove get_device() / put_device() pair from scsi_request_fn()
Date: Mon, 24 Jun 2013 09:13:16 +0200 [thread overview]
Message-ID: <51C7F18C.7010904@acm.org> (raw)
In-Reply-To: <1372041391.2386.20.camel@dabdike>
On 06/24/13 04:36, James Bottomley wrote:
> On Wed, 2013-06-12 at 14:51 +0200, Bart Van Assche wrote:
>> Now that all scsi_request_fn() callers hold a reference on the
>> SCSI device that function is invoked for
>
> What makes you think that this is a true statement? The usual caller is
> the block layer, which doesn't really know anything about the
> sdev->sdev_gendev.
The reasoning behind that comment is as follows:
* The block layer guarantees that the reference count of a request
queue is >= 1 as long as a request_fn() call is in progress (see also
blk_cleanup_queue(), the __blk_drain_queue() call in that function
and the loop in __blk_drain_queue() that waits until
request_fn_active == 0).
* The SCSI core guarantees that blk_cleanup_queue() is invoked before
the final put on sdev->sdev_gendev.
Bart.
next prev parent reply other threads:[~2013-06-24 7:13 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-12 12:48 [PATCH v11 0/9] More device removal fixes Bart Van Assche
2013-06-12 12:49 ` [PATCH v11 1/9] Fix race between starved list and device removal Bart Van Assche
2013-06-24 15:38 ` James Bottomley
2013-06-24 16:16 ` Bart Van Assche
2013-06-24 16:23 ` James Bottomley
2013-06-24 17:24 ` Mike Christie
2013-06-24 17:49 ` James Bottomley
2013-06-12 12:51 ` [PATCH v11 2/9] Remove get_device() / put_device() pair from scsi_request_fn() Bart Van Assche
2013-06-24 1:29 ` Mike Christie
2013-06-24 2:36 ` James Bottomley
2013-06-24 7:13 ` Bart Van Assche [this message]
2013-06-24 13:34 ` James Bottomley
2013-06-24 15:43 ` Bart Van Assche
2013-06-12 12:52 ` [PATCH v11 3/9] Avoid calling __scsi_remove_device() twice Bart Van Assche
2013-06-23 21:35 ` Mike Christie
2013-06-24 6:29 ` Bart Van Assche
2013-06-24 17:38 ` James Bottomley
2013-06-25 8:37 ` Bart Van Assche
2013-06-25 13:44 ` James Bottomley
2013-06-25 15:23 ` Bart Van Assche
2013-06-12 12:53 ` [PATCH v11 4/9] Disallow changing the device state via sysfs into "deleted" Bart Van Assche
2013-06-24 1:05 ` Mike Christie
2013-06-24 6:35 ` Bart Van Assche
2013-06-24 17:59 ` James Bottomley
2013-06-25 8:41 ` Bart Van Assche
2013-06-25 13:42 ` James Bottomley
2013-06-12 12:54 ` [PATCH v11 5/9] Avoid saving/restoring interrupt state inside scsi_remove_host() Bart Van Assche
2013-06-24 1:06 ` Mike Christie
2013-06-12 12:55 ` [PATCH v11 6/9] Make scsi_remove_host() wait until error handling finished Bart Van Assche
2013-06-24 1:15 ` Mike Christie
2013-06-24 6:49 ` Bart Van Assche
2013-06-24 19:19 ` James Bottomley
2013-06-24 20:04 ` Mike Christie
2013-06-24 22:27 ` James Bottomley
2013-06-25 2:26 ` Mike Christie
2013-06-25 2:56 ` Michael Christie
2013-06-25 9:01 ` Bart Van Assche
2013-06-25 13:45 ` James Bottomley
2013-06-25 15:31 ` Bart Van Assche
2013-06-25 16:13 ` Michael Christie
2013-06-25 17:40 ` James Bottomley
2013-06-25 17:47 ` Bart Van Assche
2014-01-30 19:46 ` Bart Van Assche
2014-01-31 5:58 ` James Bottomley
2014-01-31 7:52 ` Bart Van Assche
2013-06-25 11:13 ` Bart Van Assche
2013-06-12 12:56 ` PATCH v11 7/9] Avoid that scsi_device_set_state() triggers a race Bart Van Assche
2013-06-12 12:57 ` [PATCH v11 8/9] Save and restore host_scribble during error handling Bart Van Assche
2013-06-24 1:21 ` Mike Christie
2013-06-24 2:08 ` James Bottomley
2013-06-12 12:58 ` [PATCH v11 9/9] Avoid reenabling I/O after the transport became offline Bart Van Assche
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