Re: [PATCH v8 7/8] net-next: mvpp2: relax return value check for IRQ get

[Matti Vaittinen]

On 8/1/23 15:31, Russell King (Oracle) wrote:
> On Tue, Aug 01, 2023 at 03:04:24PM +0300, Matti Vaittinen wrote:
> > fwnode_irq_get[_byname]() were changed to not return 0 anymore.
> >
> > Drop check for return value 0.
> >
> > Signed-off-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
>
> Sorry, but I don't think you've properly considered the effects of your
> patch.

Don't be sorry.

> > @@ -5833,7 +5833,7 @@ static int mvpp2_multi_queue_vectors_init(struct mvpp2_port *port,
> >   			v->irq = of_irq_get_byname(port_node, irqname);
> >   		else
> >   			v->irq = fwnode_irq_get(port->fwnode, i);
> > -		if (v->irq <= 0) {
> > +		if (v->irq < 0) {
>
> You're making this change based on the assumption that fwnode_irq_get()
> has changed its return values, but I really don't think you've looked
> at the code and considered the return value behaviour of the DT function
> above. Reading it's documentation, it states that of_irq_get_byname()
> may return 0 on IRQ mapping failure.

You're correct. Thanks for spotting this! Seems like I really overlooked 
the behaviour of the of_irq_get_byname().

> So, by making this change, you are allowing IRQ mapping failure in the
> DT path to succeed rather than fail.
>
> >   			ret = -EINVAL;
> >   			goto err;
> >   		}
> > @@ -6764,7 +6764,7 @@ static int mvpp2_port_probe(struct platform_device *pdev,
> >   		err = -EPROBE_DEFER;
> >   		goto err_deinit_qvecs;
> >   	}
> > -	if (port->port_irq <= 0)
> > +	if (port->port_irq < 0)
>
> Exactly the same problem here, but...
>
> >   		/* the link irq is optional */
> >   		port->port_irq = 0;
>
> this is less critical... but still wrong.
>
> So, given that this patch is basically incorrect...
>
> NAK.

--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

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