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net: renesas: sh_eth: Fix freeing wrong tx descriptor

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[ Upstream commit 0341d5e3d1ee2a36dd5a49b5bef2ce4ad1cfa6b4 ]

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@renesas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Yoshihiro Shimoda 2021-09-07 20:29:40 +09:00 committed by Greg Kroah-Hartman
parent 3d32ce5472
commit f7f1bac898
1 changed files with 1 additions and 0 deletions
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drivers/net/ethernet/renesas/sh_eth.c
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@ -2567,6 +2567,7 @@ static int sh_eth_start_xmit(struct sk_buff *skb, struct net_device *ndev)
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))