From: Yoshihiro Shimoda Date: Tue, 7 Sep 2021 11:29:40 +0000 (+0900) Subject: net: renesas: sh_eth: Fix freeing wrong tx descriptor X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=0341d5e3d1ee2a36dd5a49b5bef2ce4ad1cfa6b4;p=linux.git net: renesas: sh_eth: Fix freeing wrong tx descriptor 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 Signed-off-by: David S. Miller --- diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c index 6c8ba916d1a6c..1374faa229a27 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))