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

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

[Niklas Schnelle]

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.

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@linux.ibm.com>
---
 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

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

[Simon Horman]

On Tue, May 30, 2023 at 04:13:04PM +0200, Niklas Schnelle wrote:
> 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.
> 
> 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@linux.ibm.com>

Reviewed-by: Simon Horman <simon.horman@corigine.com>

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

[Mark Brown]

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On Tue, May 30, 2023 at 04:13:04PM +0200, Niklas Schnelle wrote:
> 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/mappins/mappings/

We were seeing the issue that this fixes on a Cavium ThunderX2 system
and the analysis looks good so:

Tested-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>

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

[Eli Cohen]

> From: Niklas Schnelle <schnelle@linux.ibm.com>
> Sent: Tuesday, 30 May 2023 17:13
> To: Shay Drory <shayd@nvidia.com>; Saeed Mahameed
> <saeedm@nvidia.com>; Eli Cohen <elic@nvidia.com>; Leon Romanovsky
> <leon@kernel.org>; David S. Miller <davem@davemloft.net>; Eric Dumazet
> <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni
> <pabeni@redhat.com>
> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
> s390@vger.kernel.org; linux-rdma@vger.kernel.org
> 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@nvidia.com>

> 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@linux.ibm.com>
> ---
>  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