usbnet: add a mutex around phy register access

When working on the mcs7830, I noticed the need for a mutex in its
mdio_read/mdio_write functions. A related problem seems to be present
in the asix driver in the respective functions.

This introduces a mutex in the common usbnet driver and uses it
from the two hardware specific drivers.

Acked-by: David Hollis <dhollis@davehollis.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/usb/net/usbnet.h b/drivers/usb/net/usbnet.h
index 743947c3fb83..07c70abbe0ec 100644
--- a/drivers/usb/net/usbnet.h
+++ b/drivers/usb/net/usbnet.h
@@ -30,6 +30,7 @@ struct usbnet {
         struct usb_device       *udev;
         struct driver_info      *driver_info;
         wait_queue_head_t       *wait;
+        struct mutex            phy_mutex;
 
         /* i/o info: pipes etc */
         unsigned                in, out;