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From: Sergey Shtylyov <>
To: Yoshihiro Shimoda <>,
	<>, <>
Cc: <>, <>
Subject: Re: [PATCH] net: renesas: sh_eth: Fix freeing wrong tx descriptor
Date: Tue, 7 Sep 2021 22:29:56 +0300	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

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 <>

Reviewed-by: Sergey Shtylyov <>


MBR, Sergey

  parent reply	other threads:[~2021-09-07 19:30 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-07 11:29 Yoshihiro Shimoda
2021-09-07 13:10 ` patchwork-bot+netdevbpf
2021-09-07 19:29 ` Sergey Shtylyov [this message]
2021-09-08  5:45   ` Yoshihiro Shimoda
2021-09-08  9:46     ` Sergey Shtylyov
2021-09-08 11:43       ` Yoshihiro Shimoda

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