1. 27 Apr, 2015 27 commits
  2. 21 Apr, 2015 11 commits
  3. 13 Apr, 2015 2 commits
    • Neal Cardwell's avatar
      tcp: fix FRTO undo on cumulative ACK of SACKed range · 39ae67b0
      Neal Cardwell authored
      commit 666b8051 upstream.
      
      On processing cumulative ACKs, the FRTO code was not checking the
      SACKed bit, meaning that there could be a spurious FRTO undo on a
      cumulative ACK of a previously SACKed skb.
      
      The FRTO code should only consider a cumulative ACK to indicate that
      an original/unretransmitted skb is newly ACKed if the skb was not yet
      SACKed.
      
      The effect of the spurious FRTO undo would typically be to make the
      connection think that all previously-sent packets were in flight when
      they really weren't, leading to a stall and an RTO.
      Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
      Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
      Fixes: e33099f9 ("tcp: implement RFC5682 F-RTO")
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      39ae67b0
    • Jonathan Davies's avatar
      xen-netfront: transmit fully GSO-sized packets · 53d556c7
      Jonathan Davies authored
      commit 0c36820e upstream.
      
      xen-netfront limits transmitted skbs to be at most 44 segments in size. However,
      GSO permits up to 65536 bytes, which means a maximum of 45 segments of 1448
      bytes each. This slight reduction in the size of packets means a slight loss in
      efficiency.
      
      Since c/s 9ecd1a75, xen-netfront sets gso_max_size to
          XEN_NETIF_MAX_TX_SIZE - MAX_TCP_HEADER,
      where XEN_NETIF_MAX_TX_SIZE is 65535 bytes.
      
      The calculation used by tcp_tso_autosize (and also tcp_xmit_size_goal since c/s
      6c09fa09) in determining when to split an skb into two is
          sk->sk_gso_max_size - 1 - MAX_TCP_HEADER.
      
      So the maximum permitted size of an skb is calculated to be
          (XEN_NETIF_MAX_TX_SIZE - MAX_TCP_HEADER) - 1 - MAX_TCP_HEADER.
      
      Intuitively, this looks like the wrong formula -- we don't need two TCP headers.
      Instead, there is no need to deviate from the default gso_max_size of 65536 as
      this already accommodates the size of the header.
      
      Currently, the largest skb transmitted by netfront is 63712 bytes (44 segments
      of 1448 bytes each), as observed via tcpdump. This patch makes netfront send
      skbs of up to 65160 bytes (45 segments of 1448 bytes each).
      
      Similarly, the maximum allowable mtu does not need to subtract MAX_TCP_HEADER as
      it relates to the size of the whole packet, including the header.
      
      Fixes: 9ecd1a75 ("xen-netfront: reduce gso_max_size to account for max TCP header")
      Signed-off-by: default avatarJonathan Davies <jonathan.davies@citrix.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      53d556c7