scsi: qla2xxx: Prevent PRLI in target mode

In a case when the initiator in P2P mode by some circumstances does not
send PRLI, the target, in a case when the target port's WWPN is less than
initiator's, changes the discovery state in DSC_GNL. When gnl completes it
sends PRLI to the initiator.

Usually the initiator in P2P mode always sends PRLI. We caught this issue
on Linux stable v5.4.6 https://www.spinics.net/lists/stable/msg458515.html.

Fix this particular corner case in the behaviour of the P2P mod target
login state machine.

Link: https://lore.kernel.org/r/20210422153414.4022-1-a.kovaleva@yadro.com
Fixes: a9ed06d4 ("scsi: qla2xxx: Allow PLOGI in target mode")
Reviewed-by: NRoman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: NHimanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: NAnastasia Kovaleva <a.kovaleva@yadro.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_init.c

@@ -1195,6 +1195,9 @@ static int qla24xx_post_prli_work(struct scsi_qla_host *vha, fc_port_t *fcport)
 {
 	struct qla_work_evt *e;
 
+	if (vha->host->active_mode == MODE_TARGET)
+		return QLA_FUNCTION_FAILED;
+
 	e = qla2x00_alloc_work(vha, QLA_EVT_PRLI);
 	if (!e)
 		return QLA_FUNCTION_FAILED;