Re: [PATCH net 2/6] net/mlx5: Fix misidentification of write combining CQE during poll loop

[Jacob Keller]

On 2/12/2026 2:32 AM, Tariq Toukan wrote:
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/wc.c b/drivers/net/ethernet/mellanox/mlx5/core/wc.c
> index 815a7c97d6b0..29db15c4b978 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/wc.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/wc.c
> @@ -390,12 +390,10 @@ static void mlx5_core_test_wc(struct mlx5_core_dev *mdev)
>   	mlx5_wc_post_nop(sq, &offset, true);
>   
>   	expires = jiffies + TEST_WC_POLLING_MAX_TIME_JIFFIES;
> -	do {
> -		err = mlx5_wc_poll_cq(sq);
> -		if (err)
> -			usleep_range(2, 10);
> -	} while (mdev->wc_state == MLX5_WC_STATE_UNINITIALIZED &&
> -		 time_is_after_jiffies(expires));
> +	while ((mlx5_wc_poll_cq(sq),
> +		mdev->wc_state == MLX5_WC_STATE_UNINITIALIZED) &&
> +	       time_is_after_jiffies(expires))
> +		usleep_range(2, 10);
>   

This could be written with poll_timeout_us(), but I don't know if it 
warrants holding up the fix.

Something line the following:

diff --git i/drivers/net/ethernet/mellanox/mlx5/core/wc.c 
w/drivers/net/ethernet/mellanox/mlx5/core/wc.c
index 29db15c4b978..6ec9c1a2da78 100644
--- i/drivers/net/ethernet/mellanox/mlx5/core/wc.c
+++ w/drivers/net/ethernet/mellanox/mlx5/core/wc.c
@@ -15,7 +15,7 @@
 #define TEST_WC_NUM_WQES 255
 #define TEST_WC_LOG_CQ_SZ (order_base_2(TEST_WC_NUM_WQES))
 #define TEST_WC_SQ_LOG_WQ_SZ TEST_WC_LOG_CQ_SZ
-#define TEST_WC_POLLING_MAX_TIME_JIFFIES msecs_to_jiffies(100)
+#define TEST_WC_POLLING_MAX_TIME_USEC (100 * USEC_PER_MSEC)

 struct mlx5_wc_cq {
        /* data path - accessed per cqe */
@@ -359,7 +359,6 @@ static int mlx5_wc_poll_cq(struct mlx5_wc_sq *sq)
 static void mlx5_core_test_wc(struct mlx5_core_dev *mdev)
 {
        unsigned int offset = 0;
-       unsigned long expires;
        struct mlx5_wc_sq *sq;
        int i, err;

@@ -389,11 +388,9 @@ static void mlx5_core_test_wc(struct mlx5_core_dev 
*mdev)

        mlx5_wc_post_nop(sq, &offset, true);

-       expires = jiffies + TEST_WC_POLLING_MAX_TIME_JIFFIES;
-       while ((mlx5_wc_poll_cq(sq),
-               mdev->wc_state == MLX5_WC_STATE_UNINITIALIZED) &&
-              time_is_after_jiffies(expires))
-               usleep_range(2, 10);
+       poll_timeout_us(mlx5_wc_poll_cq(sq),
+                       mdev->wc_state != MLX5_WC_STATE_UNINITIALIZED,
+                       10, TEST_WC_POLLING_MAX_TIME_USEC, false);

        mlx5_wc_destroy_sq(sq);