firewire: fix memory leak of fw_request instances

Found and debugged by Jay Fenlason <fenlason@redhat.com>.
The bug was especially noticeable with direct I/O over fw-sbp2.

Same as commit 9c9bdf4d.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/firewire/fw-transaction.c

@@ -605,8 +605,10 @@ fw_send_response(struct fw_card *card, struct fw_request *request, int rcode)
 	 * check is sufficient to ensure we don't send response to
 	 * broadcast packets or posted writes.
 	 */
-	if (request->ack != ACK_PENDING)
+	if (request->ack != ACK_PENDING) {
+		kfree(request);
 		return;
+	}
 
 	if (rcode == RCODE_COMPLETE)
 		fw_fill_response(&request->response, request->request_header,

drivers/firewire/fw-transaction.h

@@ -124,6 +124,10 @@ typedef void (*fw_transaction_callback_t)(struct fw_card *card, int rcode,
 					  size_t length,
 					  void *callback_data);
 
+/*
+ * Important note:  The callback must guarantee that either fw_send_response()
+ * or kfree() is called on the @request.
+ */
 typedef void (*fw_address_callback_t)(struct fw_card *card,
 				      struct fw_request *request,
 				      int tcode, int destination, int source,