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

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Message-ID: <f84991f7-66c6-4366-9953-b230761b6b7a@wanadoo.fr>
Date: Tue, 19 Nov 2024 20:26:26 +0900
From: Vincent Mailhol <mailhol.vincent@...adoo.fr>
To: Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>,
 Marc Kleine-Budde <mkl@...gutronix.de>, Andrew Lunn <andrew+netdev@...n.ch>,
 "David S . Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Cc: linux-can@...r.kernel.org, netdev@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 imx@...ts.linux.dev, NXP Linux Team <s32@....com>,
 Christophe Lizzi <clizzi@...hat.com>, Alberto Ruiz <aruizrui@...hat.com>,
 Enric Balletbo <eballetb@...hat.com>
Subject: Re: [PATCH 3/3] can: flexcan: handle S32G2/S32G3 separate interrupt
 lines

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.

>>>       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