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net: renesas: sh_eth: Fix freeing wrong tx descriptor

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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: 86a74ff21a ("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>
This commit is contained in:
Yoshihiro Shimoda 2021-09-07 20:29:40 +09:00 committed by David S. Miller
parent bbef56d861
commit 0341d5e3d1
1 changed files with 1 additions and 0 deletions
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drivers/net/ethernet/renesas/sh_eth.c
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@ -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))