• Alexander Sverdlin's avatar
    octeon_mgmt: Fix MIX registers configuration on MTU setup · 70cc6b67
    Alexander Sverdlin authored
    [ Upstream commit 4aac0b43
    
     ]
    
    octeon_mgmt driver doesn't drop RX frames that are 1-4 bytes bigger than
    MTU set for the corresponding interface. The problem is in the
    AGL_GMX_RX0/1_FRM_MAX register setting, which should not account for VLAN
    tagging.
    
    According to Octeon HW manual:
    "For tagged frames, MAX increases by four bytes for each VLAN found up to a
    maximum of two VLANs, or MAX + 8 bytes."
    
    OCTEON_FRAME_HEADER_LEN "define" is fine for ring buffer management, but
    should not be used for AGL_GMX_RX0/1_FRM_MAX.
    
    The problem could be easily reproduced using "ping" command. If affected
    system has default MTU 1500, other host (having MTU >= 1504) can
    successfully "ping" the affected system with payload size 1473-1476,
    resulting in IP packets of size 1501-1504 accepted by the mgmt driver.
    Fixed system still accepts IP packets of 1500 bytes even with VLAN tagging,
    because the limits are lifted in HW as expected, for every VLAN tag.
    Signed-off-by: default avatarAlexander Sverdlin <alexander.sverdlin@nokia.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: default avatarSasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    70cc6b67
octeon_mgmt.c 41.3 KB