linux-kernel - Re: [PATCH] ibmvfc: fix command state accounting and stale response detection

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Date:   Wed, 28 Jul 2021 23:37:07 -0400
From:   "Martin K. Petersen" <martin.petersen@...cle.com>
To:     james.bottomley@...senpartnership.com,
        Tyrel Datwyler <tyreld@...ux.ibm.com>
Cc:     "Martin K . Petersen" <martin.petersen@...cle.com>,
        linuxppc-dev@...ts.ozlabs.org, brking@...ux.ibm.com,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux-scsi@...r.kernel.org
Subject: Re: [PATCH] ibmvfc: fix command state accounting and stale response detection

On Fri, 16 Jul 2021 14:52:20 -0600, Tyrel Datwyler wrote:

> Prior to commit 1f4a4a19508d ("scsi: ibmvfc: Complete commands outside
> the host/queue lock") responses to commands were completed sequentially
> with the host lock held such that a command had a basic binary state of
> active or free. It was therefore a simple affair of ensuring the
> assocaiated ibmvfc_event to a VIOS response was valid by testing that it
> was not already free. The lock relexation work to complete commands
> outside the lock inadverdently made it a trinary command state such that
> a command is either in flight, received and being completed, or
> completed and now free. This breaks the stale command detection logic as
> a command may be still marked active and been placed on the delayed
> completion list when a second stale response for the same command
> arrives. This can lead to double completions and list corruption. This
> issue was exposed by a recent VIOS regression were a missing memory
> barrier could occasionally result in the ibmvfc client receiveing a
> duplicate response for the same command.
> 
> [...]

Applied to 5.14/scsi-fixes, thanks!

[1/1] ibmvfc: fix command state accounting and stale response detection
      https://git.kernel.org/mkp/scsi/c/73bfdf707d01

-- 
Martin K. Petersen	Oracle Linux Engineering