linux-kernel - RE: [PATCH net-next 2/2] mlx5/core: deduplicate {mlx5_,}eq_update

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Message-ID:
 <CY8PR12MB71958512F168E2C172D0BE05DC502@CY8PR12MB7195.namprd12.prod.outlook.com>
Date: Sun, 3 Nov 2024 03:55:39 +0000
From: Parav Pandit <parav@...dia.com>
To: Caleb Sander Mateos <csander@...estorage.com>, Saeed Mahameed
	<saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>, Tariq Toukan
	<tariqt@...dia.com>, Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller"
	<davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
	<kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH net-next 2/2] mlx5/core: deduplicate
 {mlx5_,}eq_update_ci()



> From: Caleb Sander Mateos <csander@...estorage.com>
> Sent: Friday, November 1, 2024 9:17 AM
> 
> The logic of eq_update_ci() is duplicated in mlx5_eq_update_ci(). The only
> additional work done by mlx5_eq_update_ci() is to increment
> eq->cons_index. Call eq_update_ci() from mlx5_eq_update_ci() to avoid
> the duplication.
> 
> Signed-off-by: Caleb Sander Mateos <csander@...estorage.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/eq.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eq.c
> b/drivers/net/ethernet/mellanox/mlx5/core/eq.c
> index 859dcf09b770..078029c81935 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/eq.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/eq.c
> @@ -802,19 +802,12 @@ struct mlx5_eqe *mlx5_eq_get_eqe(struct
> mlx5_eq *eq, u32 cc)  }  EXPORT_SYMBOL(mlx5_eq_get_eqe);
> 
>  void mlx5_eq_update_ci(struct mlx5_eq *eq, u32 cc, bool arm)  {
> -	__be32 __iomem *addr = eq->doorbell + (arm ? 0 : 2);
> -	u32 val;
> -
>  	eq->cons_index += cc;
> -	val = (eq->cons_index & 0xffffff) | (eq->eqn << 24);
> -
> -	__raw_writel((__force u32)cpu_to_be32(val), addr);
> -	/* We still want ordering, just not swabbing, so add a barrier */
> -	wmb();
> +	eq_update_ci(eq, arm);
Long ago I had similar rework patches to get rid of __raw_writel(), which I never got chance to push,

Eq_update_ci() is using full memory barrier.
While mlx5_eq_update_ci() is using only write memory barrier.

So it is not 100% deduplication by this patch.
Please have a pre-patch improving eq_update_ci() to use wmb().
Followed by this patch.

>  }
>  EXPORT_SYMBOL(mlx5_eq_update_ci);
> 
>  static void comp_irq_release_pci(struct mlx5_core_dev *dev, u16 vecidx)  {
> --
> 2.45.2
>