scsi: ibmvfc: Fix invalid sub-CRQ handles after hard reset

A hard reset results in a complete transport disconnect such that the CRQ
connection with the partner VIOS is broken. This has the side effect of
also invalidating the associated sub-CRQs. The current code assumes that
the sub-CRQs are perserved resulting in a protocol violation after trying
to reconnect them with the VIOS. This introduces an infinite loop such that
the VIOS forces a disconnect after each subsequent attempt to re-register
with invalid handles.

Avoid the aforementioned issue by releasing the sub-CRQs prior to CRQ
disconnect, and driving a reinitialization of the sub-CRQs once a new CRQ
is registered with the hypervisor.

Link: https://lore.kernel.org/r/20210302230543.9905-3-tyreld@linux.ibm.com
Fixes: 3034ebe2 ("scsi: ibmvfc: Add alloc/dealloc routines for SCSI Sub-CRQ Channels")
Reviewed-by: Brian King <brking@linux.ibm.com>
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ibmvscsi/ibmvfc.c

@@ -158,6 +158,9 @@ static void ibmvfc_npiv_logout(struct ibmvfc_host *);
 static void ibmvfc_tgt_implicit_logout_and_del(struct ibmvfc_target *);
 static void ibmvfc_tgt_move_login(struct ibmvfc_target *);
 
+static void ibmvfc_release_sub_crqs(struct ibmvfc_host *);
+static void ibmvfc_init_sub_crqs(struct ibmvfc_host *);
+
 static const char *unknown_error = "unknown error";
 
 static long h_reg_sub_crq(unsigned long unit_address, unsigned long ioba,
@@ -926,8 +929,8 @@ static int ibmvfc_reset_crq(struct ibmvfc_host *vhost)
 	unsigned long flags;
 	struct vio_dev *vdev = to_vio_dev(vhost->dev);
 	struct ibmvfc_queue *crq = &vhost->crq;
-	struct ibmvfc_queue *scrq;
-	int i;
+
+	ibmvfc_release_sub_crqs(vhost);
 
 	/* Close the CRQ */
 	do {
@@ -947,16 +950,6 @@ static int ibmvfc_reset_crq(struct ibmvfc_host *vhost)
 	memset(crq->msgs.crq, 0, PAGE_SIZE);
 	crq->cur = 0;
 
-	if (vhost->scsi_scrqs.scrqs) {
-		for (i = 0; i < nr_scsi_hw_queues; i++) {
-			scrq = &vhost->scsi_scrqs.scrqs[i];
-			spin_lock(scrq->q_lock);
-			memset(scrq->msgs.scrq, 0, PAGE_SIZE);
-			scrq->cur = 0;
-			spin_unlock(scrq->q_lock);
-		}
-	}
-
 	/* And re-open it again */
 	rc = plpar_hcall_norets(H_REG_CRQ, vdev->unit_address,
 				crq->msg_token, PAGE_SIZE);
@@ -966,9 +959,12 @@ static int ibmvfc_reset_crq(struct ibmvfc_host *vhost)
 		dev_warn(vhost->dev, "Partner adapter not ready\n");
 	else if (rc != 0)
 		dev_warn(vhost->dev, "Couldn't register crq (rc=%d)\n", rc);
+
 	spin_unlock(vhost->crq.q_lock);
 	spin_unlock_irqrestore(vhost->host->host_lock, flags);
 
+	ibmvfc_init_sub_crqs(vhost);
+
 	return rc;
 }
 
@@ -5694,6 +5690,7 @@ static void ibmvfc_deregister_scsi_channel(struct ibmvfc_host *vhost, int index)
 
 	free_irq(scrq->irq, scrq);
 	irq_dispose_mapping(scrq->irq);
+	scrq->irq = 0;
 
 	do {
 		rc = plpar_hcall_norets(H_FREE_SUB_CRQ, vdev->unit_address,