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

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Message-ID: <ZMj7Cp3fhN7GmCZp@shell.armlinux.org.uk>
Date:   Tue, 1 Aug 2023 13:31:06 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Matti Vaittinen <mazziesaccount@...il.com>
Cc:     Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 7/8] net-next: mvpp2: relax return value check for IRQ
 get

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@...il.com>

Sorry, but I don't think you've properly considered the effects of your
patch.

> @@ -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.

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.

-- 
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