stmmac: reset last TSO segment size after device open

The mss variable tracks the last max segment size sent to the TSO
engine. We do not update the hardware as long as we receive skb:s with
the same value in gso_size.

During a network device down/up cycle (mapped to stmmac_release() and
stmmac_open() callbacks) we issue a reset to the hardware and it
forgets the setting for mss. However we did not zero out our mss
variable so the next transmission of a gso packet happens with an
undefined hardware setting.

This triggers a hang in the TSO engine and eventuelly the netdev
watchdog will bark.

Fixes: f748be531d70 ("stmmac: support new GMAC4")
Signed-off-by: Lars Persson <larper@axis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index f63c2ddced3c9a1e90f4425b28be95d202379a71..d7250539d0bd0c61c92fc9460c9e1197bb57ac8f 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2588,6 +2588,7 @@ static int stmmac_open(struct net_device *dev)
 
        priv->dma_buf_sz = STMMAC_ALIGN(buf_sz);
        priv->rx_copybreak = STMMAC_RX_COPYBREAK;
+       priv->mss = 0;
 
        ret = alloc_dma_desc_resources(priv);
        if (ret < 0) {