mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-01-04 22:54:56 +01:00
1dfddff5fc
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@mork.no> Signed-off-by: David S. Miller <davem@davemloft.net>