greybus: fill in destination data at send time

For ES1 we need to insert the destination CPort id before the data
to be sent over UniPro.  Currently this is done at the time the
buffer is created, but there's no need to do so until we're actually
going to send the content of the buffer.

Move the setting of that destination information into submit_gbuf().
Note that this allows us to defer initializing a few other gbuf
fields until after we know the buffer allocation has succeeded.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/es1-ap-usb.c

@@ -95,7 +95,6 @@ static void cport_out_callback(struct urb *urb);
 static int alloc_gbuf_data(struct gbuf *gbuf, unsigned int size,
 				gfp_t gfp_mask)
 {
-	u8 dest_cport_id = gbuf->dest_cport_id;
 	u8 *buffer;
 
 	if (gbuf->transfer_buffer)
@@ -122,15 +121,6 @@ static int alloc_gbuf_data(struct gbuf *gbuf, unsigned int size,
 		return -ENOMEM;
 	buffer += GB_BUFFER_ALIGN;
 
-	/* Insert the cport id for outbound buffers */
-	if (dest_cport_id != CPORT_ID_BAD && dest_cport_id > (u16)U8_MAX) {
-		pr_err("dest_cport_id (%hd) is out of range!\n",
-			gbuf->dest_cport_id);
-		kfree(buffer);
-		return -EINVAL;
-	}
-	*(buffer - 1) = gbuf->dest_cport_id;
-
 	gbuf->transfer_buffer = buffer;
 	gbuf->transfer_buffer_length = size;
 
@@ -212,6 +202,7 @@ static int submit_gbuf(struct gbuf *gbuf, gfp_t gfp_mask)
 	struct greybus_host_device *hd = gbuf->hd;
 	struct es1_ap_dev *es1 = hd_to_es1(hd);
 	struct usb_device *udev = es1->usb_dev;
+	u16 dest_cport_id = gbuf->dest_cport_id;
 	int retval;
 	u8 *transfer_buffer;
 	u8 *buffer;
@@ -222,11 +213,17 @@ static int submit_gbuf(struct gbuf *gbuf, gfp_t gfp_mask)
 		return -EINVAL;
 	buffer = &transfer_buffer[-1];	/* yes, we mean -1 */
 
-	/* Do one last check of the target CPort id */
-	if (*buffer == CPORT_ID_BAD) {
-		pr_err("request to submit inbound buffer\n");
+	/* Do one last check of the target CPort id before filling it in */
+	if (dest_cport_id == CPORT_ID_BAD) {
+		pr_err("request to send inbound data buffer\n");
+		return -EINVAL;
+	}
+	if (dest_cport_id > (u16)U8_MAX) {
+		pr_err("dest_cport_id (%hd) is out of range for ES1\n",
+			dest_cport_id);
 		return -EINVAL;
 	}
+	*buffer = dest_cport_id;
 
 	/* Find a free urb */
 	urb = next_free_urb(es1, gfp_mask);

drivers/staging/greybus/operation.c

@@ -241,12 +241,12 @@ static int gb_operation_message_init(struct gb_operation *operation,
 	else
 		dest_cport_id = CPORT_ID_BAD;
 
-	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)
 		return ret;
+	gbuf->hd = hd;
+	gbuf->dest_cport_id = dest_cport_id;
+	gbuf->status = -EBADR;	/* Initial value--means "never set" */
 
 	/* Fill in the header structure */
 	header = (struct gb_operation_msg_hdr *)gbuf->transfer_buffer;