Re: [PATCH 3/3] can: flexcan: handle S32G2/S32G3 separate interrupt lines

[Ciprian Marian Costea]

On 11/19/2024 1:36 PM, Vincent Mailhol wrote:
> On 19/11/2024 at 20:26, Vincent Mailhol wrote:
> > On 19/11/2024 at 19:01, Ciprian Marian Costea wrote:
> > > On 11/19/2024 11:26 AM, Vincent Mailhol wrote:
> > > > On 19/11/2024 at 17:10, Ciprian Costea wrote:
> >
> > (...)
> >
> > > > >    +    if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SECONDARY_MB_IRQ) {
> > > > > +        err = request_irq(priv->irq_secondary_mb,
> > > > > +                  flexcan_irq, IRQF_SHARED, dev->name, dev);
> > > > > +        if (err)
> > > > > +            goto out_free_irq_err;
> > > > > +    }
> > > >
> > > > Is the logic here correct?
> > > >
> > > >     request_irq(priv->irq_err, flexcan_irq, IRQF_SHARED, dev->name, dev);
> > > >
> > > > is called only if the device has the FLEXCAN_QUIRK_NR_IRQ_3 quirk.
> > > >
> > > > So, if the device has the FLEXCAN_QUIRK_SECONDARY_MB_IRQ but not the
> > > > FLEXCAN_QUIRK_NR_IRQ_3, you may end up trying to free an irq which was
> > > > not initialized.
> > > >
> > > > Did you confirm if it is safe to call free_irq() on an uninitialized irq?
> > > >
> > > > (and I can see that currently there is no such device with
> > > > FLEXCAN_QUIRK_SECONDARY_MB_IRQ but without FLEXCAN_QUIRK_NR_IRQ_3, but
> > > > who knows if such device will be introduced in the future?)
> > >
> > > Hello Vincent,
> > >
> > > Thanks for your review. Indeed this seems to be an incorrect logic since
> > > I do not want to create any dependency between 'FLEXCAN_QUIRK_NR_IRQ_3'
> > > and 'FLEXCAN_QUIRK_SECONDARY_MB_IRQ'.
> > >
> > > I will change the impacted section to:
> > >      if (err) {
> > >          if (priv->devtype_data.quirks & FLEXCAN_QUIRK_NR_IRQ_3)
> > >              goto out_free_irq_err;
> > >          else
> > >              goto out_free_irq;
> > >      }
> >
> > This is better. Alternatively, you could move the check into the label:
> >
> >    out_free_irq_err:
> >    	if (priv->devtype_data.quirks & FLEXCAN_QUIRK_NR_IRQ_3)
> >    		free_irq(priv->irq_err, dev);
> >
> > But this is not a strong preference, I let you pick the one which you
> > prefer.
>
> On second thought, it is a strong preference. If you keep the
>
> 	if (priv->devtype_data.quirks & FLEXCAN_QUIRK_NR_IRQ_3)
> 		goto out_free_irq_err;
> 	else
> 		goto out_free_irq;
>
> then what if more code with a clean-up label is added to flexcan_open()?
> I am thinking of this:
>
>    out_free_foo:
>    	free(foo);
>    out_free_irq_err:
>    	free_irq(priv-irq_err, dev);
>    out_free_irq_boff:
>    	free_irq(priv->irq_boff, dev);
>
> Jumping to out_free_foo would now be incorrect because the
> out_free_irq_err label would also be visited.

Correct, moving the check under the label would be better. Thanks.
I will change accordingly in V2.


Best Regards,
Ciprian

> > > > >        flexcan_chip_interrupts_enable(dev);
> > > > >          netif_start_queue(dev);
> > > > >          return 0;
> > > > >    + out_free_irq_err:
> > > > > +    free_irq(priv->irq_err, dev);
> > > > >     out_free_irq_boff:
> > > > >        free_irq(priv->irq_boff, dev);
> > > > >     out_free_irq:
> >
> > (...)
>
> Yours sincerely,
> Vincent Mailhol