Re: [PATCH] RDMA/mlx5: Use mlx5_cmd_is_down to detect PCIe Surprise Link Down

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, Oct 09, 2025 at 10:23:20PM +0800, Jian Wen wrote:
> --- a/drivers/infiniband/hw/mlx5/umr.c
> +++ b/drivers/infiniband/hw/mlx5/umr.c
> @@ -254,7 +254,7 @@ static int mlx5r_umr_post_send(struct ib_qp *ibqp, u32 mkey, struct ib_cqe *cqe,
>  	unsigned int idx;
>  	int size, err;
>  
> -	if (unlikely(mdev->state == MLX5_DEVICE_STATE_INTERNAL_ERROR))
> +	if (unlikely(mlx5_cmd_is_down(mdev)))
>  		return -EIO;

I feel like this is just changing the race around..

The removal flow for the device is different if the HW is working than
if it isn't.

If it isn't working then the removal should disable and cancel all the
UMRs, using the umrc->lock. Otherwise there will be dead threads
floating around. It should also be setting
MLX5_DEVICE_STATE_INTERNAL_ERROR way at the start of removal.

So IDK, maybe check mlx5_cmd_is_down() and trigger the flow to
activate INTERNAL_ERROR befor doing anything else?

Jason