linux-kernel - Re: [PATCH 4/5] genirq: Use the common function irq_expand_nr

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Date:   Tue, 31 Jan 2023 10:43:55 -0600
From:   Shanker Donthineni <sdonthineni@...dia.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>, Michael Walle <michael@...le.cc>
Cc:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Hans de Goede <hdegoede@...hat.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] genirq: Use the common function irq_expand_nr_irqs()



On 1/31/23 03:35, Thomas Gleixner wrote:
> External email: Use caution opening links or attachments
> 
> 
> On Sun, Jan 29 2023 at 18:57, Shanker Donthineni wrote:
> 
>> Subject: genirq: Use the common function ...
> 
>    genirq: Unify irq_expand_nr_irqs()
> 
>    irq_expand_nr_irqs() is implemented as a stub function for !SPARSEIRQ
>    builds. That's not necessary as the SPARSEIRQ version returns -ENOMEM
>    correctly even for the !SPARSEIRQ case as the ....
> 
> 
> But this common function is non-obvious for the !SPARSEIRQ case. It at
> least needs a comment
> 
>> +static int irq_expand_nr_irqs(unsigned int nr)
>> +{
>> +     if (nr > MAX_SPARSE_IRQS)
>> +             return -ENOMEM;
>> +     nr_irqs = nr;
>> +     return 0;
>> +}
> 
> or preferrably something like this:
> 
>          if (!IS_ENABLED(CONFIG_SPARSEIRQ) || nr > MAX_SPARSE_IRQS)
>                  return -ENOMEM;
> 
> which makes it entirely clear and also allows the compiler to optimize
> is down to a 'return -ENOMEM'.
> 

I'll drop this patch since you're suggesting to remove !SPARSEIRQ support.