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From: Tejun Heo <htejun@gmail.com>
To: James Bottomley <James.Bottomley@SteelEye.com>
Cc: 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 07/08] scsi: remove bogus	{get|put}_device() calls
Date: Wed, 23 Mar 2005 18:13:26 +0900	[thread overview]
Message-ID: <42413336.2010004@gmail.com> (raw)
In-Reply-To: <1111551355.5520.100.camel@mulgrave>

  Hi,

James Bottomley wrote:
> On Wed, 2005-03-23 at 11:14 +0900, Tejun Heo wrote:
> 
>>	So, basically, SCSI high-level object (scsi_disk) and
>>	mid-level object (scsi_device) are reference counted by users,
>>	not the requests they submit.  Reference count cannot go zero
>>	with active users and users cannot access the object once the
>>	reference count reaches zero.
> 
> 
> Actually, no.  Unfortunately we still have some fire and forget APIs, so
> the contention that we always have an open refcounted descriptor isn't
> always true.

  Yeap, you're right.  So, what we have is

  * All high-level users have open access to the scsi high-level
    object on issueing requests, but may close it before its requests
    complete.
  * All mid-layer users do get_device() before submitting requests,
    but may put_device() before its requests complete.

  Thanks for pointing that out.  :-)

-- 
tejun


  reply	other threads:[~2005-03-23  9:13 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
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 [this message]
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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