Re: [PATCH net] net: sunhme: Return an error when we are out of slots

From: Simon Horman
Date: Wed Feb 22 2023 - 16:19:23 EST


On Wed, Feb 22, 2023 at 04:07:15PM -0500, Sean Anderson wrote:
> On 2/22/23 15:59, Simon Horman wrote:
> > On Wed, Feb 22, 2023 at 12:09:35PM -0500, Sean Anderson wrote:
> > > We only allocate enough space for four devices when the parent is a QFE. If
> > > we couldn't find a spot (because five devices were created for whatever
> > > reason), we would not return an error from probe(). Return ENODEV, which
> > > was what we did before.
> > >
> > > Fixes: 96c6e9faecf1 ("sunhme: forward the error code from pci_enable_device()")
> >
> > I think the hash for that commit is acb3f35f920b.
>
> Ah, sorry that's my local copy. The upstream commit is as you noted.
>
> >
> > However, I also think this problem was introduced by the first hunk of
> > 5b3dc6dda6b1 ("sunhme: Regularize probe errors").
> >
> > Which is:
> >
> > --- a/drivers/net/ethernet/sun/sunhme.c
> > +++ b/drivers/net/ethernet/sun/sunhme.c
> > @@ -2945,7 +2945,6 @@ static int happy_meal_pci_probe(struct pci_dev *pdev,
> > if (err)
> > goto err_out;
> > pci_set_master(pdev);
> > - err = -ENODEV;
> > if (!strcmp(prom_name, "SUNW,qfe") || !strcmp(prom_name, "qfe")) {
> > qp = quattro_pci_find(pdev);
> >
>
> Yes. That's the one I should have blamed.
>
> > Which leads me to wonder if simpler fixes would be either:
> >
> > 1) Reverting the hunk above
> > 2) Or, more in keeping with the rest of that patch,
> > explicitly setting err before branching to err_out,
> > as you your patch does, but without other logic changes.
>
> > Something like this (*compile tested only!*:
> >
> > diff --git a/drivers/net/ethernet/sun/sunhme.c b/drivers/net/ethernet/sun/sunhme.c
> > index 1c16548415cd..2409e7d6c29e 100644
> > --- a/drivers/net/ethernet/sun/sunhme.c
> > +++ b/drivers/net/ethernet/sun/sunhme.c
> > @@ -2863,8 +2863,10 @@ static int happy_meal_pci_probe(struct pci_dev *pdev,
> > if (!qp->happy_meals[qfe_slot])
> > break;
> > - if (qfe_slot == 4)
> > + if (qfe_slot == 4) {
> > + err = -ENOMEM;
> > goto err_out;
> > + }
> > }
> > dev = devm_alloc_etherdev(&pdev->dev, sizeof(struct happy_meal));
>
> That's of course simpler, but this also does some cleanup to make it more
> obvious what's going on.

Sure. I do think there is merit in a minimal change as a fix.
But I don't feel strongly about it.

> > Also, I am curious why happy_meal_pci_probe() doesn't just return instaed
> > of branching to err_out. As err_out only returns err. I guess there is a
> > reason for it. But simply returning would probably simplify error handling.
> > (I'm not suggesting that approach for this fix.)
>
> I think it's because there used to be cleanup in err_out. But you're right,
> we can just return directly and avoid a goto.

Makes sense, thanks.

> --Sean
>
> > > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > > Reported-by: Dan Carpenter <error27@xxxxxxxxx>
> > > Signed-off-by: Sean Anderson <seanga2@xxxxxxxxx>
> > > ---
> > >
> > > drivers/net/ethernet/sun/sunhme.c | 7 ++++---
> > > 1 file changed, 4 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/net/ethernet/sun/sunhme.c b/drivers/net/ethernet/sun/sunhme.c
> > > index 1c16548415cd..523e26653ec8 100644
> > > --- a/drivers/net/ethernet/sun/sunhme.c
> > > +++ b/drivers/net/ethernet/sun/sunhme.c
> > > @@ -2861,12 +2861,13 @@ static int happy_meal_pci_probe(struct pci_dev *pdev,
> > > for (qfe_slot = 0; qfe_slot < 4; qfe_slot++)
> > > if (!qp->happy_meals[qfe_slot])
> > > - break;
> > > + goto found_slot;
> > > - if (qfe_slot == 4)
> > > - goto err_out;
> > > + err = -ENODEV;
> > > + goto err_out;
> > > }
> > > +found_slot:
> > > dev = devm_alloc_etherdev(&pdev->dev, sizeof(struct happy_meal));
> > > if (!dev) {
> > > err = -ENOMEM;
> > > --
> > > 2.37.1
> > >
>