Re: [PATCH 02/14] PCI: aardvark: Fix return value of MSI domain .alloc() method

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Tue, Oct 12, 2021 at 06:41:33PM +0200, Marek Behún wrote:
> MSI domain callback .alloc() (implemented by advk_msi_irq_domain_alloc()
> function) should return zero on success, since non-zero value indicates
> failure.

AFAICS the .alloc() method is called in:

irq_domain_alloc_irqs_hierarchy()

which in turn is called by:

__irq_domain_alloc_irqs() -> that checks (ret < 0)

irq_domain_push_irq() -> that checks for rv != 0

irq_domain_alloc_irqs_parent() called by many drivers and also
by msi_domain_alloc() (that checks ret < 0)

This patch is fine, I am just asking, given the above:

- How did you detect it (given that aardvark would not fail ret < 0) ?
- Should we consolidate the .alloc() return value handling ?

Apologies if I missed something in the IRQ domain code.

Lorenzo

> When the driver was converted to generic MSI API in commit f21a8b1b6837
> ("PCI: aardvark: Move to MSI handling using generic MSI support"), it
> was converted so that it returns hwirq number.
> 
> Fix this.
> 
> Fixes: f21a8b1b6837 ("PCI: aardvark: Move to MSI handling using generic MSI support")
> Signed-off-by: Pali Rohár <pali@kernel.org>
> Reviewed-by: Marek Behún <kabel@kernel.org>
> Signed-off-by: Marek Behún <kabel@kernel.org>
> Cc: stable@vger.kernel.org
> ---
>  drivers/pci/controller/pci-aardvark.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index 10476c00b312..b45ff2911c80 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -1138,7 +1138,7 @@ static int advk_msi_irq_domain_alloc(struct irq_domain *domain,
>  				    domain->host_data, handle_simple_irq,
>  				    NULL, NULL);
>  
> -	return hwirq;
> +	return 0;
>  }
>  
>  static void advk_msi_irq_domain_free(struct irq_domain *domain,
> -- 
> 2.32.0
>