scsi: qla2xxx: Fix kernel crash after disconnecting NVMe devices

BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<ffffffffc050d10c>] qla_nvme_unregister_remote_port+0x6c/0xf0 [qla2xxx]
PGD 800000084cf41067 PUD 84d288067 PMD 0
Oops: 0000 [#1] SMP
Call Trace:
 [<ffffffff98abcfdf>] process_one_work+0x17f/0x440
 [<ffffffff98abdca6>] worker_thread+0x126/0x3c0
 [<ffffffff98abdb80>] ? manage_workers.isra.26+0x2a0/0x2a0
 [<ffffffff98ac4f81>] kthread+0xd1/0xe0
 [<ffffffff98ac4eb0>] ? insert_kthread_work+0x40/0x40
 [<ffffffff9918ad37>] ret_from_fork_nospec_begin+0x21/0x21
 [<ffffffff98ac4eb0>] ? insert_kthread_work+0x40/0x40
RIP  [<ffffffffc050d10c>] qla_nvme_unregister_remote_port+0x6c/0xf0 [qla2xxx]

The crash is due to a bad entry in the nvme_rport_list. This list is not
protected, and when a remoteport_delete callback is called, driver
traverses the list and crashes.

Actually, the list could be removed and driver could traverse the main
fcport list instead. Fix does exactly that.
Signed-off-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_def.h

@@ -4376,7 +4376,6 @@ typedef struct scsi_qla_host {
 
 	struct		nvme_fc_local_port *nvme_local_port;
 	struct completion nvme_del_done;
-	struct list_head nvme_rport_list;
 
 	uint16_t	fcoe_vlan_id;
 	uint16_t	fcoe_fcf_idx;

drivers/scsi/qla2xxx/qla_nvme.c

@@ -74,7 +74,6 @@ int qla_nvme_register_remote(struct scsi_qla_host *vha, struct fc_port *fcport)
 
 	rport = fcport->nvme_remote_port->private;
 	rport->fcport = fcport;
-	list_add_tail(&rport->list, &vha->nvme_rport_list);
 
 	fcport->nvme_flag |= NVME_FLAG_REGISTERED;
 	return 0;
@@ -542,19 +541,12 @@ static void qla_nvme_localport_delete(struct nvme_fc_local_port *lport)
 static void qla_nvme_remoteport_delete(struct nvme_fc_remote_port *rport)
 {
 	fc_port_t *fcport;
-	struct qla_nvme_rport *qla_rport = rport->private, *trport;
+	struct qla_nvme_rport *qla_rport = rport->private;
 
 	fcport = qla_rport->fcport;
 	fcport->nvme_remote_port = NULL;
 	fcport->nvme_flag &= ~NVME_FLAG_REGISTERED;
 
-	list_for_each_entry_safe(qla_rport, trport,
-	    &fcport->vha->nvme_rport_list, list) {
-		if (qla_rport->fcport == fcport) {
-			list_del(&qla_rport->list);
-			break;
-		}
-	}
 	complete(&fcport->nvme_del_done);
 
 	if (!test_bit(UNLOADING, &fcport->vha->dpc_flags)) {
@@ -590,7 +582,7 @@ static void qla_nvme_unregister_remote_port(struct work_struct *work)
 {
 	struct fc_port *fcport = container_of(work, struct fc_port,
 	    nvme_del_work);
-	struct qla_nvme_rport *qla_rport, *trport;
+	int ret;
 
 	if (!IS_ENABLED(CONFIG_NVME_FC))
 		return;
@@ -598,23 +590,14 @@ static void qla_nvme_unregister_remote_port(struct work_struct *work)
 	ql_log(ql_log_warn, NULL, 0x2112,
 	    "%s: unregister remoteport on %p\n",__func__, fcport);
 
-	list_for_each_entry_safe(qla_rport, trport,
-	    &fcport->vha->nvme_rport_list, list) {
-		if (qla_rport->fcport == fcport) {
-			ql_log(ql_log_info, fcport->vha, 0x2113,
-			    "%s: fcport=%p\n", __func__, fcport);
-			nvme_fc_set_remoteport_devloss
-				(fcport->nvme_remote_port, 0);
+	nvme_fc_set_remoteport_devloss(fcport->nvme_remote_port, 0);
 	init_completion(&fcport->nvme_del_done);
-			if (nvme_fc_unregister_remoteport
-			    (fcport->nvme_remote_port))
+	ret = nvme_fc_unregister_remoteport(fcport->nvme_remote_port);
+	if (ret)
 		ql_log(ql_log_info, fcport->vha, 0x2114,
-				    "%s: Failed to unregister nvme_remote_port\n",
-				    __func__);
+			"%s: Failed to unregister nvme_remote_port (%d)\n",
+			    __func__, ret);
 	wait_for_completion(&fcport->nvme_del_done);
-			break;
-		}
-	}
 }
 
 void qla_nvme_delete(struct scsi_qla_host *vha)

drivers/scsi/qla2xxx/qla_nvme.h

@@ -37,7 +37,6 @@ struct nvme_private {
 };
 
 struct qla_nvme_rport {
-	struct list_head list;
 	struct fc_port *fcport;
 };
 

drivers/scsi/qla2xxx/qla_os.c

@@ -4789,7 +4789,6 @@ struct scsi_qla_host *qla2x00_create_host(struct scsi_host_template *sht,
 	INIT_LIST_HEAD(&vha->plogi_ack_list);
 	INIT_LIST_HEAD(&vha->qp_list);
 	INIT_LIST_HEAD(&vha->gnl.fcports);
-	INIT_LIST_HEAD(&vha->nvme_rport_list);
 	INIT_LIST_HEAD(&vha->gpnid_list);
 	INIT_WORK(&vha->iocb_work, qla2x00_iocb_work_fn);