RE: [PATCH net] net/mlx5: Fix setting of irq->map.index for static IRQ case

[Eli Cohen]

> From: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
> Sent: Tuesday, 30 May 2023 17:13
> To: Shay Drory <shayd@xxxxxxxxxx>; Saeed Mahameed
> <saeedm@xxxxxxxxxx>; Eli Cohen <elic@xxxxxxxxxx>; Leon Romanovsky
> <leon@xxxxxxxxxx>; David S. Miller <davem@xxxxxxxxxxxxx>; Eric Dumazet
> <edumazet@xxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni
> <pabeni@xxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-
> s390@xxxxxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx
> Subject: [PATCH net] net/mlx5: Fix setting of irq->map.index for static IRQ case
> 
> When dynamic IRQ allocation is not supported all IRQs are allocated up
> front in mlx5_irq_table_create() instead of dynamically as part of
> mlx5_irq_alloc(). In the latter dynamic case irq->map.index is set
> via the mapping returned by pci_msix_alloc_irq_at(). In the static case
> and prior to commit 1da438c0ae02 ("net/mlx5: Fix indexing of mlx5_irq")
> irq->map.index was set in mlx4_irq_alloc() twice once initially to 0 and
> then to the requested index before storing in the xarray. After this
> commit it is only set to 0 which breaks all other IRQ mappins.
> 

s/mlx4_irq_alloc/mlx5_irq_alloc/
Reviewed-by: Eli Cohen <elic@xxxxxxxxxx>

> Fix this by setting irq->map.index to the requested index together with
> irq->map.virq and improve the related comment to make it clearer which
> cases it deals with.
> 
> Fixes: 1da438c0ae02 ("net/mlx5: Fix indexing of mlx5_irq")
> Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
> b/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
> index db5687d9fec9..fd5b43e8f3bb 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
> @@ -232,12 +232,13 @@ struct mlx5_irq *mlx5_irq_alloc(struct
> mlx5_irq_pool *pool, int i,
>  	if (!irq)
>  		return ERR_PTR(-ENOMEM);
>  	if (!i || !pci_msix_can_alloc_dyn(dev->pdev)) {
> -		/* The vector at index 0 was already allocated.
> -		 * Just get the irq number. If dynamic irq is not supported
> -		 * vectors have also been allocated.
> +		/* The vector at index 0 is always statically allocated. If
> +		 * dynamic irq is not supported all vectors are statically
> +		 * allocated. In both cases just get the irq number and set
> +		 * the index.
>  		 */
>  		irq->map.virq = pci_irq_vector(dev->pdev, i);
> -		irq->map.index = 0;
> +		irq->map.index = i;
>  	} else {
>  		irq->map = pci_msix_alloc_irq_at(dev->pdev,
> MSI_ANY_INDEX, af_desc);
>  		if (!irq->map.virq) {
> --
> 2.39.2