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@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;-- 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;