[SCSI] zfcp: Fix oops when port disappears

The zfcp_port might have been removed, while the FC fast_io_fail timer
is still running and could trigger the terminate_rport_io callback.
Set the pointer to the zfcp_port to NULL and check accordingly
before using it.

Reviewed-by: Martin Petermann <martin@linux.vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

Author: Christof Schmitt

drivers/s390/scsi/zfcp_aux.c

@@ -671,8 +671,7 @@ void zfcp_port_dequeue(struct zfcp_port *port)
 	list_del(&port->list);
 	write_unlock_irq(&zfcp_data.config_lock);
 	if (port->rport)
-		fc_remote_port_delete(port->rport);
-	port->rport = NULL;
+		port->rport->dd_data = NULL;
 	zfcp_adapter_put(port->adapter);
 	sysfs_remove_group(&port->sysfs_device.kobj, &zfcp_sysfs_port_attrs);
 	device_unregister(&port->sysfs_device);

drivers/s390/scsi/zfcp_fsf.c

@@ -172,12 +172,16 @@ static void zfcp_fsf_link_down_info_eval(struct zfcp_fsf_req *req, char *id,
 					 struct fsf_link_down_info *link_down)
 {
 	struct zfcp_adapter *adapter = req->adapter;
+	unsigned long flags;
 
 	if (atomic_read(&adapter->status) & ZFCP_STATUS_ADAPTER_LINK_UNPLUGGED)
 		return;
 
 	atomic_set_mask(ZFCP_STATUS_ADAPTER_LINK_UNPLUGGED, &adapter->status);
+
+	read_lock_irqsave(&zfcp_data.config_lock, flags);
 	zfcp_scsi_schedule_rports_block(adapter);
+	read_unlock_irqrestore(&zfcp_data.config_lock, flags);
 
 	if (!link_down)
 		goto out;

drivers/s390/scsi/zfcp_scsi.c

@@ -486,10 +486,12 @@ static void zfcp_set_rport_dev_loss_tmo(struct fc_rport *rport, u32 timeout)
  */
 static void zfcp_scsi_dev_loss_tmo_callbk(struct fc_rport *rport)
 {
-	struct zfcp_port *port = rport->dd_data;
+	struct zfcp_port *port;
 
 	write_lock_irq(&zfcp_data.config_lock);
-	port->rport = NULL;
+	port = rport->dd_data;
+	if (port)
+		port->rport = NULL;
 	write_unlock_irq(&zfcp_data.config_lock);
 }
 
@@ -503,9 +505,18 @@ static void zfcp_scsi_dev_loss_tmo_callbk(struct fc_rport *rport)
  */
 static void zfcp_scsi_terminate_rport_io(struct fc_rport *rport)
 {
-	struct zfcp_port *port = rport->dd_data;
+	struct zfcp_port *port;
+
+	write_lock_irq(&zfcp_data.config_lock);
+	port = rport->dd_data;
+	if (port)
+		zfcp_port_get(port);
+	write_unlock_irq(&zfcp_data.config_lock);
 
-	zfcp_erp_port_reopen(port, 0, "sctrpi1", NULL);
+	if (port) {
+		zfcp_erp_port_reopen(port, 0, "sctrpi1", NULL);
+		zfcp_port_put(port);
+	}
 }
 
 static void zfcp_scsi_rport_register(struct zfcp_port *port)
@@ -534,8 +545,10 @@ static void zfcp_scsi_rport_register(struct zfcp_port *port)
 
 static void zfcp_scsi_rport_block(struct zfcp_port *port)
 {
-	if (port->rport)
-		fc_remote_port_delete(port->rport);
+	struct fc_rport *rport = port->rport;
+
+	if (rport)
+		fc_remote_port_delete(rport);
 }
 
 void zfcp_scsi_schedule_rport_register(struct zfcp_port *port)