The cur_tx counter must be incremented after TACT bit of
txdesc->status was set. However, a CPU is possible to reorder
instructions and/or memory accesses between cur_tx and
txdesc->status. And then, if TX interrupt happened at such a
timing, the sh_eth_tx_free() may free the descriptor wrongly.
So, add wmb() before cur_tx++.
Otherwise NETDEV WATCHDOG timeout is possible to happen.
Fixes: 86a74ff21a7a ("net: sh_eth: add support for Renesas SuperH Ethernet")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
---
drivers/net/ethernet/renesas/sh_eth.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 6c8ba916d1a6..1374faa229a2 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -2533,6 +2533,7 @@ static netdev_tx_t sh_eth_start_xmit(struct sk_buff *skb,
else
txdesc->status |= cpu_to_le32(TD_TACT);
+ wmb(); /* cur_tx must be incremented after TACT bit was set */
mdp->cur_tx++;
if (!(sh_eth_read(ndev, EDTRR) & mdp->cd->edtrr_trns))
--
2.25.1
