• David S. Miller's avatar
    ipv4: Early TCP socket demux. · 41063e9d
    David S. Miller authored
    Input packet processing for local sockets involves two major demuxes.
    One for the route and one for the socket.
    
    But we can optimize this down to one demux for certain kinds of local
    sockets.
    
    Currently we only do this for established TCP sockets, but it could
    at least in theory be expanded to other kinds of connections.
    
    If a TCP socket is established then it's identity is fully specified.
    
    This means that whatever input route was used during the three-way
    handshake must work equally well for the rest of the connection since
    the keys will not change.
    
    Once we move to established state, we cache the receive packet's input
    route to use later.
    
    Like the existing cached route in sk->sk_dst_cache used for output
    packets, we have to check for route invalidations using dst->obsolete
    and dst->ops->check().
    
    Early demux occurs outside of a socket locked section, so when a route
    invalidation occurs we defer the fixup of sk->sk_rx_dst until we are
    actually inside of established state packet processing and thus have
    the socket locked.
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    41063e9d
protocol.h 3.87 KB