qla2xxx: added sess generations to detect RSCN update races

RSCN processing in qla2xxx driver can run in parallel with ELS/IO
processing. As such the decision to remove disappeared fc port's
session could be stale, because a new login sequence has occurred
since and created a brand new session.

Previous mechanism of dealing with this by delaying deletion request
was prone to erroneous deletions if the event that was supposed to
cancel the deletion never arrived or has been delayed in processing.

New mechanism relies on a time-like generation counter to serialize
RSCN updates relative to ELS/IO updates.

Cc: <stable@vger.kernel.org> # v3.18+
Signed-off-by: Alexei Potashnik <alexei@purestorage.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@qlogic.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 20 insertions, 12 deletions

diff --git a/drivers/scsi/qla2xxx/qla_init.c b/drivers/scsi/qla2xxx/qla_init.c
index bda7a0d..506621d 100644
--- a/drivers/scsi/qla2xxx/qla_init.c
+++ b/drivers/scsi/qla2xxx/qla_init.c
@@ -2927,24 +2927,14 @@ qla2x00_rport_del(void *data)
 {
 	fc_port_t *fcport = data;
 	struct fc_rport *rport;
-	scsi_qla_host_t *vha = fcport->vha;
 	unsigned long flags;
-	unsigned long vha_flags;
 
 	spin_lock_irqsave(fcport->vha->host->host_lock, flags);
 	rport = fcport->drport ? fcport->drport: fcport->rport;
 	fcport->drport = NULL;
 	spin_unlock_irqrestore(fcport->vha->host->host_lock, flags);
-	if (rport) {
+	if (rport)
 		fc_remote_port_delete(rport);
-		/*
-		 * Release the target mode FC NEXUS in qla_target.c code
-		 * if target mod is enabled.
-		 */
-		spin_lock_irqsave(&vha->hw->hardware_lock, vha_flags);
-		qlt_fc_port_deleted(vha, fcport);
-		spin_unlock_irqrestore(&vha->hw->hardware_lock, vha_flags);
-	}
 }
 
 /**
@@ -3384,6 +3374,7 @@ qla2x00_configure_fabric(scsi_qla_host_t *vha)
 	LIST_HEAD(new_fcports);
 	struct qla_hw_data *ha = vha->hw;
 	struct scsi_qla_host *base_vha = pci_get_drvdata(ha->pdev);
+	int		discovery_gen;
 
 	/* If FL port exists, then SNS is present */
 	if (IS_FWI2_CAPABLE(ha))
@@ -3454,6 +3445,14 @@ qla2x00_configure_fabric(scsi_qla_host_t *vha)
 			fcport->scan_state = QLA_FCPORT_SCAN;
 		}
 
+		/* Mark the time right before querying FW for connected ports.
+		 * This process is long, asynchronous and by the time it's done,
+		 * collected information might not be accurate anymore. E.g.
+		 * disconnected port might have re-connected and a brand new
+		 * session has been created. In this case session's generation
+		 * will be newer than discovery_gen. */
+		qlt_do_generation_tick(vha, &discovery_gen);
+
 		rval = qla2x00_find_all_fabric_devs(vha, &new_fcports);
 		if (rval != QLA_SUCCESS)
 			break;
@@ -3505,7 +3504,8 @@ qla2x00_configure_fabric(scsi_qla_host_t *vha)
 					    atomic_read(&fcport->state),
 					    fcport->flags, fcport->fc4_type,
 					    fcport->scan_state);
-					qlt_fc_port_deleted(vha, fcport);
+					qlt_fc_port_deleted(vha, fcport,
+					    discovery_gen);
 				}
 			}
 		}
@@ -4282,6 +4282,14 @@ qla2x00_update_fcports(scsi_qla_host_t *base_vha)
 			    atomic_read(&fcport->state) != FCS_UNCONFIGURED) {
 				spin_unlock_irqrestore(&ha->vport_slock, flags);
 				qla2x00_rport_del(fcport);
+
+				/*
+				 * Release the target mode FC NEXUS in
+				 * qla_target.c, if target mod is enabled.
+				 */
+				qlt_fc_port_deleted(vha, fcport,
+				    base_vha->total_fcport_update_gen);
+
 				spin_lock_irqsave(&ha->vport_slock, flags);
 			}
 		}