Re: [PATCH] scsi: avoid a permanent stop of the scsi device's request queue

[James Bottomley <jejb@linux.vnet.ibm.com>]

On Wed, 2016-12-07 at 12:40 -0500, Ewan D. Milne wrote:
> On Wed, 2016-12-07 at 08:55 -0800, Bart Van Assche wrote:
> > On 12/07/2016 08:48 AM, Bart Van Assche wrote:
> > > It's a known bug. Some time ago I posted a patch that serializes 
> > > all scsi_device_set_state() calls but I have not yet found it in 
> > > the list archives. However, that patch has not yet been merged.
> > 
> > See also https://www.spinics.net/lists/linux-scsi/msg66966.html.
> > 
> > Bart.
> > 
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> 
> Yes, however that patch does not fix Wei Fang's issue.  In fact I 
> just received a crash dump that appears to be the same thing.  It 
> looks like the rport went away right after the initial INQUIRY, so we 
> set the state to SDEV_BLOCK and stop the queue, and then the scan 
> code continues and sets the state back to SDEV_RUNNING.

So here's the violation of the state model.  the rport went CREATED
->BLOCK which is wrong: it should go CREATED->CREATED_BLOCK and then
the add code would set it to BLOCK instead of RUNNING.

The question to diagnose is why CREATED->BLOCK worked.

James