[SCSI] zfcp: Locking for req_no and req_seq_no

There is a possible race condition while generating the unique request ids and sequence numbers. Both might be read at the same time and have the same value. Fix this by serializing the access through the queue lock of the adapter: First call zfcp_fsf_req_sbal_get that acquires the lock, then read and increment the unique ids. Signed-off-by: Christof Schmitt <[email protected]> Signed-off-by: Swen Schillig <[email protected]> Signed-off-by: James Bottomley <[email protected]>
khadas · May 8, 2007 · 801e0ce · 801e0ce
1 parent 1d589ed
commit 801e0ce
Showing 1 changed file with 8 additions and 9 deletions.
diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
@@ -4645,23 +4645,22 @@ zfcp_fsf_req_create(struct zfcp_adapter *adapter, u32 fsf_cmd, int req_flags,
 	fsf_req->adapter = adapter;
 	fsf_req->fsf_command = fsf_cmd;
 	INIT_LIST_HEAD(&fsf_req->list);
-
-	/* this is serialized (we are holding req_queue-lock of adapter */
-	if (adapter->req_no == 0)
-		adapter->req_no++;
-	fsf_req->req_id = adapter->req_no++;
-
 	init_timer(&fsf_req->timer);
-	zfcp_fsf_req_qtcb_init(fsf_req);
 
 	/* initialize waitqueue which may be used to wait on 
 	   this request completion */
 	init_waitqueue_head(&fsf_req->completion_wq);
 
         ret = zfcp_fsf_req_sbal_get(adapter, req_flags, lock_flags);
-        if(ret < 0) {
+        if (ret < 0)
                 goto failed_sbals;
-	}
+
+	/* this is serialized (we are holding req_queue-lock of adapter) */
+	if (adapter->req_no == 0)
+		adapter->req_no++;
+	fsf_req->req_id = adapter->req_no++;
+
+	zfcp_fsf_req_qtcb_init(fsf_req);
 
 	/*
 	 * We hold queue_lock here. Check if QDIOUP is set and let request fail