greybus: move gbuf initialization to caller

Change greybus_alloc_gbuf() so all it does is allocate the gbuf data
structure.  Move all of the initialization of the gbuf structure in
the caller.  Do the inverse in the caller prior to freeing the gbuf
structure via greybus_free_gbuf().  Use a null gbuf->transfer_buffer
pointer rather than a null gbuf pointer to indicate an unused gbuf.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/gbuf.c

@@ -38,32 +38,12 @@ struct gbuf *greybus_alloc_gbuf(struct greybus_host_device *hd,
 				unsigned int size,
 				gfp_t gfp_mask)
 {
-	struct gbuf *gbuf;
-	int retval;
-
-	gbuf = kmem_cache_zalloc(gbuf_head_cache, gfp_mask);
-	if (!gbuf)
-		return NULL;
-
-	gbuf->hd = hd;
-	gbuf->dest_cport_id = dest_cport_id;
-	gbuf->status = -EBADR;	/* Initial value--means "never set" */
-
-	/* Host controller specific allocation for the actual buffer */
-	retval = hd->driver->alloc_gbuf_data(gbuf, size, gfp_mask);
-	if (retval) {
-		kmem_cache_free(gbuf_head_cache, gbuf);
-		return NULL;
-	}
-
-	return gbuf;
+	return kmem_cache_zalloc(gbuf_head_cache, gfp_mask);
 }
 EXPORT_SYMBOL_GPL(greybus_alloc_gbuf);
 
 void greybus_free_gbuf(struct gbuf *gbuf)
 {
-	gbuf->hd->driver->free_gbuf_data(gbuf);
-
 	kmem_cache_free(gbuf_head_cache, gbuf);
 }
 EXPORT_SYMBOL_GPL(greybus_free_gbuf);

drivers/staging/greybus/greybus.h

@@ -106,7 +106,8 @@ void greybus_cport_in(struct greybus_host_device *hd, u16 cport_id,
 			u8 *data, size_t length);
 
 struct gbuf *greybus_alloc_gbuf(struct greybus_host_device *hd,
-				u16 dest_cport_id, unsigned int size,
+				u16 dest_cport_id,
+				unsigned int size,
 				gfp_t gfp_mask);
 void greybus_free_gbuf(struct gbuf *gbuf);
 

drivers/staging/greybus/operation.c

@@ -202,10 +202,13 @@ static int gb_operation_message_init(struct gb_operation *operation,
 					bool request, bool data_out)
 {
 	struct gb_connection *connection = operation->connection;
+	struct greybus_host_device *hd = connection->hd;
 	struct gb_message *message;
 	struct gb_operation_msg_hdr *header;
+	struct gbuf *gbuf;
 	gfp_t gfp_flags = data_out ? GFP_KERNEL : GFP_ATOMIC;
 	u16 dest_cport_id;
+	int ret;
 
 	if (size > GB_OPERATION_MESSAGE_SIZE_MAX)
 		return -E2BIG;
@@ -224,19 +227,27 @@ static int gb_operation_message_init(struct gb_operation *operation,
 	if (message->gbuf)
 		return -EALREADY;	/* Sanity check */
 	size += sizeof(*header);
-	message->gbuf = greybus_alloc_gbuf(connection->hd, dest_cport_id,
-					size, gfp_flags);
-	if (!message->gbuf)
+	gbuf = greybus_alloc_gbuf(hd, dest_cport_id, size, gfp_flags);
+	if (!gbuf)
 		return -ENOMEM;
+	gbuf->hd = hd;
+	gbuf->dest_cport_id = dest_cport_id;
+	gbuf->status = -EBADR;	/* Initial value--means "never set" */
+	ret = hd->driver->alloc_gbuf_data(gbuf, size, gfp_flags);
+	if (ret) {
+		greybus_free_gbuf(gbuf);
+		return ret;
+	}
 
 	/* Fill in the header structure */
-	header = (struct gb_operation_msg_hdr *)message->gbuf->transfer_buffer;
+	header = (struct gb_operation_msg_hdr *)gbuf->transfer_buffer;
 	header->size = cpu_to_le16(size);
 	header->id = 0;		/* Filled in when submitted */
 	header->type = type;
 
 	message->payload = header + 1;
 	message->operation = operation;
+	message->gbuf = gbuf;
 
 	return 0;
 }
@@ -245,6 +256,7 @@ static void gb_operation_message_exit(struct gb_message *message)
 {
 	message->operation = NULL;
 	message->payload = NULL;
+	message->gbuf->hd->driver->free_gbuf_data(message->gbuf);
 	greybus_free_gbuf(message->gbuf);
 	message->gbuf = NULL;
 }