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List:       linux-scsi
Subject:    Re: [PATCH 23/25] lpfc: Correct upcalling nvmet_fc transport during io done downcall
From:       Hannes Reinecke <hare () suse ! de>
Date:       2018-12-28 12:35:15
Message-ID: 3cc86ef8-9b42-ab72-4953-51b7db83dbe7 () suse ! de
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On 12/27/18 12:33 AM, James Smart wrote:
> When the transport calls into the lpfc target to release an io job
> structure, which corresponds to an exchange, and if the driver was
> waiting for an exchange in order to post a previously received command
> to the transport, the driver immediately takes the io job and reuses
> the context for the prior command and calls nvmet_fc_rcv_fcp_req()
> to tell the transport about a newly received command.
> 
> Problem is, the execution of the io job release may be in the context
> of the back end driver and its bio completion handlers, thus it may be
> in a irq context and protection code kicks in in the bio and request
> layers that are subsequently called.
> 
> Rework lpfc so that instead of immediately upcalling, queue it to a
> deferred work thread and have the thread make the upcall.
> 
> Took advantage of this change to remove duplicated code with the normal
> command receive path that preps the io job and upcalls nvmet_fc. Created
> a common routine both paths use.
> 
> Also corrected some errors that were found during review of the context
> freeing and reuse - basically unlocked operations and a somewhat disjoint
> set of calls to release associated job elements. Cleaned up this path and
> added locks for coherency.
> 
> Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
> Signed-off-by: James Smart <jsmart2021@gmail.com>
> ---
>   drivers/scsi/lpfc/lpfc.h       |   1 +
>   drivers/scsi/lpfc/lpfc_nvmet.c | 247 ++++++++++++++++++++++-------------------
>   drivers/scsi/lpfc/lpfc_nvmet.h |   1 +
>   3 files changed, 137 insertions(+), 112 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
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