On Mon, May 18, 2020 at 09:31:42PM +0300, 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@xxxxxxxxxxx>
> Cc: Arun Easi <aeasi@xxxxxxxxxxx>
> Cc: Nilesh Javali <njavali@xxxxxxxxxxx>
> Cc: Bart Van Assche <bvanassche@xxxxxxx>
> Cc: Daniel Wagner <dwagner@xxxxxxx>
> Cc: Himanshu Madhani <himanshu.madhani@xxxxxxxxxx>
> Cc: Martin Wilck <mwilck@xxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # v5.4+
> Signed-off-by: Roman Bolshakov <r.bolshakov@xxxxxxxxx>
> ---
> 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;
> --
> 2.26.1
>
P.S. A little bit cleaner alternative would be to avoid session deletion
only if scan needed is set (that allows session deletion of initiator
ports after fabric discovery if N_Port ID change happened). Please let
me know if I should submit v2 like this:
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;
