From: Bjørn Mork <bjorn@xxxxxxx> Date: Wed, 23 Dec 2015 13:42:43 +0100 > NCM buffer sizes are negotiated with the device independently of > the network device MTU. The RX buffers are allocated by the > usbnet framework based on the rx_urb_size value set by cdc_ncm. A > single RX buffer can hold a number of MTU sized packets. > > The default usbnet change_mtu ndo only modifies rx_urb_size if it > is equal to hard_mtu. And the cdc_ncm driver will set rx_urb_size > and hard_mtu independently of each other, based on dwNtbInMaxSize > and dwNtbOutMaxSize respectively. It was therefore assumed that > usbnet_change_mtu() would never touch rx_urb_size. This failed to > consider the case where dwNtbInMaxSize and dwNtbOutMaxSize happens > to be equal. > > Fix by implementing an NCM specific change_mtu ndo, modifying the > netdev MTU without touching the buffer size settings. > > Signed-off-by: Bjørn Mork <bjorn@xxxxxxx> Applied and queued up for -stable, thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
