scsi: zfcp: Move shost modification after QDIO (re-)open into fenced function

When establishing and activating the QDIO queue pair for a FCP device for
the first time, or after an adapter recovery, we publish some of its
characteristics to the scsi host object representing that FCP device.

When moving the scsi host object allocation and registration to after the
first exchange config and exchange port data, this is not possible for the
former case - QDIO open for the first time - because that happens before
exchange config and exchange port data.

Move the scsi host object update into a fenced function that checks whether
the object already exists or not. This way we can repeat that step later,
once we are past the allocation.

Once the first recovery succeeds we don't release the scsi host object
anymore, so further recoveries do work as before.

Link: https://lore.kernel.org/r/a214ebf508f71e3690113e3e90edab1cea0e24e3.1588956679.git.bblock@linux.ibm.com
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/s390/scsi/zfcp_ext.h

@@ -153,6 +153,8 @@ extern int zfcp_qdio_sbal_get(struct zfcp_qdio *);
 extern int zfcp_qdio_send(struct zfcp_qdio *, struct zfcp_qdio_req *);
 extern int zfcp_qdio_sbals_from_sg(struct zfcp_qdio *, struct zfcp_qdio_req *,
 				   struct scatterlist *);
+extern void zfcp_qdio_shost_update(struct zfcp_adapter *const adapter,
+				   const struct zfcp_qdio *const qdio);
 extern int zfcp_qdio_open(struct zfcp_qdio *);
 extern void zfcp_qdio_close(struct zfcp_qdio *);
 extern void zfcp_qdio_siosl(struct zfcp_adapter *);

drivers/s390/scsi/zfcp_qdio.c

@@ -4,7 +4,7 @@
  *
  * Setup and helper functions to access QDIO.
  *
- * Copyright IBM Corp. 2002, 2017
+ * Copyright IBM Corp. 2002, 2020
  */
 
 #define KMSG_COMPONENT "zfcp"
@@ -342,6 +342,18 @@ void zfcp_qdio_close(struct zfcp_qdio *qdio)
 	atomic_set(&qdio->req_q_free, 0);
 }
 
+void zfcp_qdio_shost_update(struct zfcp_adapter *const adapter,
+			    const struct zfcp_qdio *const qdio)
+{
+	struct Scsi_Host *const shost = adapter->scsi_host;
+
+	if (shost == NULL)
+		return;
+
+	shost->sg_tablesize = qdio->max_sbale_per_req;
+	shost->max_sectors = qdio->max_sbale_per_req * 8;
+}
+
 /**
  * zfcp_qdio_open - prepare and initialize response queue
  * @qdio: pointer to struct zfcp_qdio
@@ -420,10 +432,7 @@ int zfcp_qdio_open(struct zfcp_qdio *qdio)
 	atomic_set(&qdio->req_q_free, QDIO_MAX_BUFFERS_PER_Q);
 	atomic_or(ZFCP_STATUS_ADAPTER_QDIOUP, &qdio->adapter->status);
 
-	if (adapter->scsi_host) {
-		adapter->scsi_host->sg_tablesize = qdio->max_sbale_per_req;
-		adapter->scsi_host->max_sectors = qdio->max_sbale_per_req * 8;
-	}
+	zfcp_qdio_shost_update(adapter, qdio);
 
 	return 0;