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

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Date:   Tue, 20 Sep 2022 09:15:35 -0700
From:   Li Zhong <floridsleeves@...il.com>
To:     Steffen Klassert <steffen.klassert@...unet.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 Tue, Sep 20, 2022 at 3:02 AM Steffen Klassert
<steffen.klassert@...unet.com> wrote:
>
> 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?
>

Since the bug is an unchecked error, we detect it with static analysis and
validate it's a bug by the comment we see above the code. So we fix this bug
following the guide of this comment.