On 8/14/19 4:34 PM, Maxim Mikityanskiy wrote:
Don't uninstall an XDP program when none is installed, and don't install an XDP program that has the same ID as the one already installed. dev_change_xdp_fd doesn't perform any checks in case it uninstalls an XDP program. It means that the driver's ndo_bpf can be called with XDP_SETUP_PROG asking to set it to NULL even if it's already NULL. This case happens if the user runs `ip link set eth0 xdp off` when there is no XDP program attached. The symmetrical case is possible when the user tries to set the program that is already set. The drivers typically perform some heavy operations on XDP_SETUP_PROG, so they all have to handle these cases internally to return early if they happen. This patch puts this check into the kernel code, so that all drivers will benefit from it. Signed-off-by: Maxim Mikityanskiy <maximmi@xxxxxxxxxxxx>
Applied, thanks!
