linux-kernel - Re: [PATCH] net/mlx5: stop waiting for PCI link if reset is required

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Date:   Mon, 3 Apr 2023 21:21:05 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Niklas Schnelle <schnelle@...ux.ibm.com>
Cc:     Saeed Mahameed <saeedm@...dia.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Gerd Bayer <gbayer@...ux.ibm.com>,
        Alexander Schmidt <alexs@...ux.ibm.com>,
        netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net/mlx5: stop waiting for PCI link if reset is required

On Mon, Apr 03, 2023 at 09:56:56AM +0200, Niklas Schnelle wrote:
> after an error on the PCI link, the driver does not need to wait
> for the link to become functional again as a reset is required. Stop
> the wait loop in this case to accelerate the recovery flow.
> 
> Co-developed-by: Alexander Schmidt <alexs@...ux.ibm.com>
> Signed-off-by: Alexander Schmidt <alexs@...ux.ibm.com>
> Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/health.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/health.c b/drivers/net/ethernet/mellanox/mlx5/core/health.c
> index f9438d4e43ca..81ca44e0705a 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/health.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/health.c
> @@ -325,6 +325,8 @@ int mlx5_health_wait_pci_up(struct mlx5_core_dev *dev)
>  	while (sensor_pci_not_working(dev)) {

According to the comment in sensor_pci_not_working(), this loop is
supposed to wait till PCI will be ready again. Otherwise, already in
first iteration, we will bail out with pci_channel_offline() error.

Thanks

>  		if (time_after(jiffies, end))
>  			return -ETIMEDOUT;
> +		if (pci_channel_offline(dev->pdev))
> +			return -EIO;
>  		msleep(100);
>  	}
>  	return 0;
> @@ -332,10 +334,16 @@ int mlx5_health_wait_pci_up(struct mlx5_core_dev *dev)
>  
>  static int mlx5_health_try_recover(struct mlx5_core_dev *dev)
>  {
> +	int rc;
> +
>  	mlx5_core_warn(dev, "handling bad device here\n");
>  	mlx5_handle_bad_state(dev);
> -	if (mlx5_health_wait_pci_up(dev)) {
> -		mlx5_core_err(dev, "health recovery flow aborted, PCI reads still not working\n");
> +	rc = mlx5_health_wait_pci_up(dev);
> +	if (rc) {
> +		if (rc == -ETIMEDOUT)
> +			mlx5_core_err(dev, "health recovery flow aborted, PCI reads still not working\n");
> +		else
> +			mlx5_core_err(dev, "health recovery flow aborted, PCI channel offline\n");
>  		return -EIO;
>  	}
>  	mlx5_core_err(dev, "starting health recovery flow\n");
> 
> base-commit: 7e364e56293bb98cae1b55fd835f5991c4e96e7d
> -- 
> 2.37.2
>