Re: [PATCH] scsi: qla2xxx: Keep initiator ports after RSCN

[Himanshu Madhani <himanshu.madhani@oracle.com>]

On 5/18/20 1:31 PM, Roman Bolshakov wrote:
> The driver performs SCR (state change registration) in all modes
> including pure target mode.
> 
> For each RSCN, scan_needed flag is set in qla2x00_handle_rscn() for the
> port mentioned in the RSCN and fabric rescan is scheduled. During the
> rescan, GNN_FT handler, qla24xx_async_gnnft_done() deletes session of
> the port that caused the RSCN.
> 
> In target mode, the session deletion has an impact on ATIO handler,
> qlt_24xx_atio_pkt(). Target responds with SAM STATUS BUSY to I/O
> incoming from the deleted session. qlt_handle_cmd_for_atio() and
> qlt_handle_task_mgmt() return -EFAULT if they are not able to find
> session of the command/TMF, and that results in invocation of
> qlt_send_busy():
> 
>    qlt_24xx_atio_pkt_all_vps: qla_target(0): type 6 ox_id 0014
>    qla_target(0): Unable to send command to target, sending BUSY status
> 
> Such response causes command timeout on the initiator. Error handler
> thread on the initiator will be spawned to abort the commands:
> 
>    scsi 23:0:0:0: tag#0 abort scheduled
>    scsi 23:0:0:0: tag#0 aborting command
>    qla2xxx [0000:af:00.0]-188c:23: Entered qla24xx_abort_command.
>    qla2xxx [0000:af:00.0]-801c:23: Abort command issued nexus=23:0:0 -- 0 2003.
> 
> Command abort is rejected by target and fails (2003), error handler then
> tries to perform DEVICE RESET and TARGET RESET but they're also doomed
> to fail because TMFs are ignored for the deleted sessions.
> 
> Then initiator makes BUS RESET that resets the link via
> qla2x00_full_login_lip(). BUS RESET succeeds and brings initiator port
> up, SAN switch detects that and sends RSCN to the target port and it
> fails again the same way as described above. It never goes out of the
> loop.
> 
> The change breaks the RSCN loop by keeping initiator sessions mentioned
> in RSCN payload in all modes, including dual and pure target mode.
> 
> Fixes: 2037ce49d30a ("scsi: qla2xxx: Fix stale session")
> Cc: Quinn Tran <qutran@marvell.com>
> Cc: Arun Easi <aeasi@marvell.com>
> Cc: Nilesh Javali <njavali@marvell.com>
> Cc: Bart Van Assche <bvanassche@acm.org>
> Cc: Daniel Wagner <dwagner@suse.de>
> Cc: Himanshu Madhani <himanshu.madhani@oracle.com>
> Cc: Martin Wilck <mwilck@suse.com>
> Cc: stable@vger.kernel.org # v5.4+
> Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
> ---
>   drivers/scsi/qla2xxx/qla_gs.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> Hi Martin,
> 
> Please apply the patch to scsi-fixes/5.7 at your earliest convenience.
> 
> qla2xxx in target and, likely, dual mode is unusable in some SAN fabrics
> due to the bug.
> 
> Thanks,
> Roman
> 
> diff --git a/drivers/scsi/qla2xxx/qla_gs.c b/drivers/scsi/qla2xxx/qla_gs.c
> index 42c3ad27f1cb..b9955af5cffe 100644
> --- a/drivers/scsi/qla2xxx/qla_gs.c
> +++ b/drivers/scsi/qla2xxx/qla_gs.c
> @@ -3495,8 +3495,10 @@ void qla24xx_async_gnnft_done(scsi_qla_host_t *vha, srb_t *sp)
>   			if ((fcport->flags & FCF_FABRIC_DEVICE) == 0) {
>   				qla2x00_clear_loop_id(fcport);
>   				fcport->flags |= FCF_FABRIC_DEVICE;
> -			} else if (fcport->d_id.b24 != rp->id.b24 ||
> -				fcport->scan_needed) {
> +			} else if ((fcport->d_id.b24 != rp->id.b24 ||
> +				    fcport->scan_needed) &&
> +				   (fcport->port_type != FCT_INITIATOR &&
> +				    fcport->port_type != FCT_NVME_INITIATOR)) {
>   				qlt_schedule_sess_for_deletion(fcport);
>   			}
>   			fcport->d_id.b24 = rp->id.b24;
> 
Looks okay.

Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>

-- 
Himanshu Madhani                     Oracle Linux Engineering