netdev - Re: [PATCH v1] drivers/net/ethernet/3com: check the return value of vortex

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Message-ID: <20220920100157.GV2950045@gauss3.secunet.de>
Date:   Tue, 20 Sep 2022 12:01:57 +0200
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Li Zhong <floridsleeves@...il.com>
CC:     <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <f.fainelli@...il.com>, <pabeni@...hat.com>, <kuba@...nel.org>,
        <edumazet@...gle.com>, <davem@...emloft.net>, <klassert@...nel.org>
Subject: Re: [PATCH v1] drivers/net/ethernet/3com: check the return value of
 vortex_up()

On Mon, Sep 19, 2022 at 12:36:31AM -0700, Li Zhong wrote:
> Check the return value of vortex_up(), which could be error code when
> the rx ring is not full.
> 
> Signed-off-by: Li Zhong <floridsleeves@...il.com>
> ---
>  drivers/net/ethernet/3com/3c59x.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/3com/3c59x.c b/drivers/net/ethernet/3com/3c59x.c
> index ccf07667aa5e..7806c5f60ac8 100644
> --- a/drivers/net/ethernet/3com/3c59x.c
> +++ b/drivers/net/ethernet/3com/3c59x.c
> @@ -1942,6 +1942,7 @@ vortex_error(struct net_device *dev, int status)
>  	void __iomem *ioaddr = vp->ioaddr;
>  	int do_tx_reset = 0, reset_mask = 0;
>  	unsigned char tx_status = 0;
> +	int err;
>  
>  	if (vortex_debug > 2) {
>  		pr_err("%s: vortex_error(), status=0x%x\n", dev->name, status);
> @@ -2016,7 +2017,9 @@ vortex_error(struct net_device *dev, int status)
>  			/* Must not enter D3 or we can't legally issue the reset! */
>  			vortex_down(dev, 0);
>  			issue_and_wait(dev, TotalReset | 0xff);
> -			vortex_up(dev);		/* AKPM: bug.  vortex_up() assumes that the rx ring is full. It may not be. */
> +			err = vortex_up(dev);
> +			if (err)
> +				return;

Why does that fix the bug mentioned in the above comment?