usb: gadgetfs: return number of bytes on ep0 read request

A read from GadgetFS endpoint 0 during the data stage of a control
request would always return 0 on success (as returned by
wait_event_interruptible) despite having written data into the user
buffer.
This patch makes it correctly set the return value to the number of
bytes read.

Signed-off-by: Thomas Faber <thfabba@gmx.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/usb/gadget/inode.c b/drivers/usb/gadget/inode.c
index ae04266dba1b..4f18a0e46070 100644
--- a/drivers/usb/gadget/inode.c
+++ b/drivers/usb/gadget/inode.c
@@ -1043,6 +1043,8 @@ ep0_read (struct file *fd, char __user *buf, size_t len, loff_t *ptr)
 // FIXME don't call this with the spinlock held ...
                                 if (copy_to_user (buf, dev->req->buf, len))
                                         retval = -EFAULT;
+                                else
+                                        retval = len;
                                 clean_req (dev->gadget->ep0, dev->req);
                                 /* NOTE userspace can't yet choose to stall */
                         }