From mboxrd@z Thu Jan  1 00:00:00 1970
From: Bart Van Assche <bart.vanassche@sandisk.com>
Subject: Re: [PATCH v2] Separate target visibility from reaped state
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Date: Wed, 18 Nov 2015 16:37:46 -0800
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To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>, Christoph Hellwig <hch@lst.de>, Johannes Thumshirn <jthumshirn@suse.de>, Dan Williams <dan.j.williams@intel.com>, "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>

On 11/16/2015 10:22 PM, James Bottomley wrote:
> OK, could you justify this, please ... like with traces and things.
> [ ... ]
> If that isn't the case, we can fix it, but I'd like to see the evidence.

Hello James,

To my own surprise so far I have not yet been able to trigger a lockup 
without this patch. After I had inserted an msleep() call at the start 
of scsi_target_reap_ref_release() to delay the starget->state = 
STARGET_DEL assignment I rebuilt and rebooted the kernel, started 
multipathd and held a SCSI device open by creating a filesystem on it 
and by mounting it. Next I removed all SRP targets (for p in 
/sys/class/srp_remote_ports/*; do echo 1 >$p/delete & done). During this 
test no lockup was reported.

Bart.