• Lendacky, Thomas's avatar
    amd-xgbe: Use wmb before updating current descriptor count · 20a41fba
    Lendacky, Thomas authored
    The code currently uses the lightweight dma_wmb barrier before updating
    the current descriptor count. Under heavy load, the Tx cleanup routine
    was seeing the updated current descriptor count before the updated
    descriptor information. As a result, the Tx descriptor was being cleaned
    up before it was used because it was not "owned" by the hardware yet,
    resulting in a Tx queue hang.
    
    Using the wmb barrier insures that the descriptor is updated before the
    descriptor counter preventing the Tx queue hang. For extra insurance,
    the Tx cleanup routine is changed to grab the current decriptor count on
    entry and uses that initial value in the processing loop rather than
    trying to chase the current value.
    Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
    Tested-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    20a41fba
xgbe-dev.c 80.3 KB