releases/4.9.70/stmmac-reset-last-tso-segment-size-after-device-open.patch

   1 From foo@baz Thu Dec 14 11:45:58 CET 2017
   2 From: Lars Persson <lars.persson@axis.com>
   3 Date: Fri, 1 Dec 2017 11:12:44 +0100
   4 Subject: stmmac: reset last TSO segment size after device open
   5
   6 From: Lars Persson <lars.persson@axis.com>
   7
   8
   9 [ Upstream commit 45ab4b13e46325d00f4acdb365d406e941a15f81 ]
  10
  11 The mss variable tracks the last max segment size sent to the TSO
  12 engine. We do not update the hardware as long as we receive skb:s with
  13 the same value in gso_size.
  14
  15 During a network device down/up cycle (mapped to stmmac_release() and
  16 stmmac_open() callbacks) we issue a reset to the hardware and it
  17 forgets the setting for mss. However we did not zero out our mss
  18 variable so the next transmission of a gso packet happens with an
  19 undefined hardware setting.
  20
  21 This triggers a hang in the TSO engine and eventuelly the netdev
  22 watchdog will bark.
  23
  24 Fixes: f748be531d70 ("stmmac: support new GMAC4")
  25 Signed-off-by: Lars Persson <larper@axis.com>
  26 Signed-off-by: David S. Miller <davem@davemloft.net>
  27 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  28 ---
  29  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |    1 +
  30  1 file changed, 1 insertion(+)
  31
  32 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
  33 +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
  34 @@ -1795,6 +1795,7 @@ static int stmmac_open(struct net_device
  35
  36         priv->dma_buf_sz = STMMAC_ALIGN(buf_sz);
  37         priv->rx_copybreak = STMMAC_RX_COPYBREAK;
  38 +       priv->mss = 0;
  39
  40         ret = alloc_dma_desc_resources(priv);
  41         if (ret < 0) {