[SCSI] iscsi transport: use atomic for session_nr allocations

qla4xxx and iscsi_tcp or iser could be creating
sessions at the same time, so make session_nr id
allocation atomic.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi_transport_iscsi.c

@@ -49,7 +49,7 @@ struct iscsi_internal {
 	struct class_device_attribute *session_attrs[ISCSI_SESSION_ATTRS + 1];
 };
 
-static int iscsi_session_nr;	/* sysfs session id for next new session */
+static atomic_t iscsi_session_nr; /* sysfs session id for next new session */
 
 /*
  * list of registered transports and lock that must
@@ -300,7 +300,7 @@ int iscsi_add_session(struct iscsi_cls_session *session, unsigned int target_id)
 	int err;
 
 	ihost = shost->shost_data;
-	session->sid = iscsi_session_nr++;
+	session->sid = atomic_add_return(1, &iscsi_session_nr);
 	session->target_id = target_id;
 
 	snprintf(session->dev.bus_id, BUS_ID_SIZE, "session%u",
@@ -1419,6 +1419,8 @@ static __init int iscsi_transport_init(void)
 	printk(KERN_INFO "Loading iSCSI transport class v%s.\n",
 		ISCSI_TRANSPORT_VERSION);
 
+	atomic_set(&iscsi_session_nr, 0);
+
 	err = class_register(&iscsi_transport_class);
 	if (err)
 		return err;