From: 'Christoph Hellwig' <hch@infradead.org>
To: "Salyzyn, Mark" <mark_salyzyn@adaptec.com>
Cc: Mark Haverkamp <markh@osdl.org>, linux-scsi <linux-scsi@vger.kernel.org>
Subject: Re: dpt_i2o driver
Date: Tue, 2 Sep 2003 18:14:57 +0100 [thread overview]
Message-ID: <20030902181457.A13499@infradead.org> (raw)
In-Reply-To: <0998F43EAD645A47B3F6507196DD70EA256915@OTCEXC01>; from mark_salyzyn@adaptec.com on Tue, Sep 02, 2003 at 01:10:04PM -0400
On Tue, Sep 02, 2003 at 01:10:04PM -0400, Salyzyn, Mark wrote:
> When the device is mounted, should we not have a usage count in the kernel,
> or are the hotplug events clearing this? Sorry for showing my ignorance of
> the hotplug needs ...
Wach scsi_device has a reference count (actually two currently, but one
will go away). this is not a traditional usage count because everytime
we do something with the device without holding the protecting lock
we should have one of this references, often temporary. (We don't do
yet but we will before 2.6.0 is finished). If the device is marked for
unregistration and the last reference vanishes the device is freed.
So you only have a chance to see a zero refcount if the device isn't
unregistered yet - which is completly useless for monitoring when
it's deleted.
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On Tue, Sep 02, 2003 at 01:10:04PM -0400, Salyzyn, Mark wrote:
> When the device is mounted, should we not have a usage count in the kernel,
> or are the hotplug events clearing this? Sorry for showing my ignorance of
> the hotplug needs ...
Wach scsi_device has a reference count (actually two currently, but one
will go away). this is not a traditional usage count because everytime
we do something with the device without holding the protecting lock
we should have one of this references, often temporary. (We don't do
yet but we will before 2.6.0 is finished). If the device is marked for
unregistration and the last reference vanishes the device is freed.
So you only have a chance to see a zero refcount if the device isn't
unregistered yet - which is completly useless for monitoring when
it's deleted.
next prev parent reply other threads:[~2003-09-02 17:15 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-02 17:10 dpt_i2o driver Salyzyn, Mark
2003-09-02 17:14 ` 'Christoph Hellwig' [this message]
-- strict thread matches above, loose matches on Subject: below --
2003-09-02 17:39 Salyzyn, Mark
2003-09-02 17:26 Salyzyn, Mark
2003-09-02 17:34 ` 'Christoph Hellwig'
2003-09-02 16:41 Salyzyn, Mark
2003-09-02 17:00 ` 'Christoph Hellwig'
2003-09-02 13:51 Salyzyn, Mark
2003-09-02 14:00 ` 'Christoph Hellwig'
2003-08-26 17:17 Salyzyn, Mark
2003-08-28 10:11 ` 'Christoph Hellwig'
2003-08-26 15:02 Salyzyn, Mark
2003-08-26 16:51 ` 'Christoph Hellwig'
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