Re: [PATCH] net: renesas: sh_eth: Fix freeing wrong tx descriptor

On 9/7/21 2:29 PM, Yoshihiro Shimoda wrote:

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++.

   Not dma_wmb()? :-)

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>

Reviewed-by: Sergey Shtylyov <redacted>

[...]

MBR, Sergey