4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Lars Persson <lars.persson@xxxxxxxx>
[ Upstream commit 45ab4b13e46325d00f4acdb365d406e941a15f81 ]
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@xxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1795,6 +1795,7 @@ static int stmmac_open(struct net_device
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) {