On 12/14/2017 09:05 AM, Jason Yan wrote:
>
> On 2017/12/14 6:23, Bart Van Assche wrote:
>> On Wed, 2017-12-13 at 14:21 +0100, Hannes Reinecke wrote:
>>> As it turned out device_get() doesn't use kref_get_unless_zero(),
>>> so we will be always getting a device pointer.
>>> So we need to check for the device state in __scsi_remove_target()
>>> to avoid tripping over deleted objects.
>>>
>>> Fixes: fbce4d9 ("scsi: fixup kernel warning during rmmod()")
>>
>> How about adding Reported-by: Jason Yan? See also
>> https://www.spinics.net/lists/linux-scsi/msg115295.html
>>
>> Anyway:
>>
>> Reviewed-by: Bart Van Assche <bart.vanassche@xxxxxxx>
>>
>
> Seems the same as my patch.So how do we plan to fix this issue,
> pick this approach up or the approach James Bottomley suggested?
> I have sent a patch to change get_device() but Greg seems do not
> like this way.
>
This is actually a real regression, which can be trivially exercised by
eg logging out from two connections to an iSCSI target.
(Our QA tripped across that one).
So I'd rather have to have it fixed reasonably soon.
While 'get_device' is IMO the 'correct' solution it surely warrants a
broader discussion, plus one would need to audit all callers to check
the return value. If we were going down that route we should probably
add a __must_check to get_device(), too.
But again, this will probably drag out for quite some time, and I'd
prefer to have the fix in the meantime.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
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SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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