Re: [PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()

[Alexander Lobakin]

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Date: Wed, 12 Feb 2025 18:27:09 +0300

> [PATCH next] ice: Fix signedness bug in ice_init_interrupt_scheme()

I believe it should be "PATCH net" with

> If pci_alloc_irq_vectors() can't allocate the minimum number of vectors
> then it returns -ENOSPC so there is no need to check for that in the
> caller.  In fact, because pf->msix.min is an unsigned int, it means that
> any negative error codes are type promoted to high positive values and
> treated as success.  So here the "return -ENOMEM;" is unreachable code.
> Check for negatives instead.
> 
> Fixes: 79d97b8cf9a8 ("ice: remove splitting MSI-X between features")

a 'Stable:' tag here.

> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
>  drivers/net/ethernet/intel/ice/ice_irq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_irq.c b/drivers/net/ethernet/intel/ice/ice_irq.c
> index cbae3d81f0f1..b1fdad154203 100644
> --- a/drivers/net/ethernet/intel/ice/ice_irq.c
> +++ b/drivers/net/ethernet/intel/ice/ice_irq.c
> @@ -149,7 +149,7 @@ int ice_init_interrupt_scheme(struct ice_pf *pf)
>  
>  	vectors = pci_alloc_irq_vectors(pf->pdev, pf->msix.min, vectors,
>  					PCI_IRQ_MSIX);
> -	if (vectors < pf->msix.min)
> +	if (vectors < 0)
>  		return -ENOMEM;

This pattern most likely repeats in other Intel drivers >_<

BTW it's a bit weird that we return -ENOMEM here, although we have a
precise errno in case of error. Shouldn't we do `return vectors` here?

(but this is more of an improvement, not a fix, so out of this patch's
 scope)

>  
>  	ice_init_irq_tracker(pf, pf->msix.max, vectors);

Thanks,
Olek