linux-kernel - Re: [net-next PATCH v3 2/5] net: ethernet: stmicro: stmmac: first disable all queues in release

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Message-ID: <YtUloYvDtTxX1MQA@shell.armlinux.org.uk>
Date:   Mon, 18 Jul 2022 10:19:29 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Christian Marangi <ansuelsmth@...il.com>
Cc:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [net-next PATCH v3 2/5] net: ethernet: stmicro: stmmac: first
 disable all queues in release

On Sun, Jul 17, 2022 at 01:07:59AM +0200, Christian Marangi wrote:
> Disable all queues before tx_disable in stmmac_release to prevent a
> corner case where packet may be still queued at the same time tx_disable
> is called resulting in kernel panic if some packet still has to be
> processed.
> 
> Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 5578abb14949..1854dcdd6095 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -3758,6 +3758,11 @@ static int stmmac_release(struct net_device *dev)
>  	struct stmmac_priv *priv = netdev_priv(dev);
>  	u32 chan;
>  
> +	stmmac_disable_all_queues(priv);
> +
> +	for (chan = 0; chan < priv->plat->tx_queues_to_use; chan++)
> +		hrtimer_cancel(&priv->tx_queue[chan].txtimer);
> +
>  	netif_tx_disable(dev);

Is there a reason not to call phylink_stop() as the very first thing in
this function? That will bring the link (and therefore carrier) down
before phylink_stop() returns which should also prevent packets being
queued into the driver for transmission.

Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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