[PATCH net-next 0/3] net/mlx5: Steering misc enhancements

[PATCH net-next 0/3] net/mlx5: Steering misc enhancements

[Tariq Toukan]

Hi,

This small series by Yevgeny contains a few steering enhancements /
cleanups.

Regards,
Tariq

Yevgeny Kliteynik (3):
  net/mlx5: HWS, Check if device is down while polling for completion
  net/mlx5: HWS, Handle destroying table that has a miss table
  net/mlx5: DR, Remove unused field of struct mlx5dr_matcher_rx_tx

 .../ethernet/mellanox/mlx5/core/steering/hws/bwc.c   | 12 ++++++++++++
 .../ethernet/mellanox/mlx5/core/steering/hws/table.c |  3 +++
 .../mellanox/mlx5/core/steering/sws/dr_types.h       |  1 -
 3 files changed, 15 insertions(+), 1 deletion(-)


base-commit: dacf281771a9aed1a723b196120a0de8637910b9
-- 
2.44.0

[PATCH net-next 1/3] net/mlx5: HWS, Check if device is down while polling for completion

[Tariq Toukan]

From: Yevgeny Kliteynik <kliteyn@nvidia.com>

In case the device is down for any reason (e.g. FLR),
the HW will no longer generate completions - no point
polling and waiting for timeout.

Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Erez Shitrit <erezsh@nvidia.com>
Reviewed-by: Shay Drori <shayd@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 .../ethernet/mellanox/mlx5/core/steering/hws/bwc.c   | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
index 6dcd9c2a78aa..eae02bc74221 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
@@ -422,6 +422,18 @@ int mlx5hws_bwc_queue_poll(struct mlx5hws_context *ctx,
 	if (!got_comp && !drain)
 		return 0;
 
+	if (unlikely(ctx->mdev->state == MLX5_DEVICE_STATE_INTERNAL_ERROR)) {
+		/* If the device is down for any reason (e.g. FLR), the HW will
+		 * no longer generate completions.
+		 * Note that ETIMEDOUT is returned here because the BWC layer
+		 * already has a special handling for timeouts - it breaks the
+		 * rehash / resize / shrink loops to avoid chain of timeouts.
+		 */
+		mlx5_core_warn_once(ctx->mdev,
+				    "BWC poll: device is down, polling for completion aborted\n");
+		return -ETIMEDOUT;
+	}
+
 	queue_full = mlx5hws_send_engine_full(&ctx->send_queue[queue_id]);
 	while (queue_full || ((got_comp || drain) && *pending_rules)) {
 		ret = mlx5hws_send_queue_poll(ctx, queue_id, comp, burst_th);
-- 
2.44.0

Re: [PATCH net-next 1/3] net/mlx5: HWS, Check if device is down while polling for completion

[Simon Horman]

From: 'Simon Horman' <horms@kernel.org>

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.
Full review at: https://sashiko.dev
---
net/mlx5: HWS, Check if device is down while polling for completion

This commit adds a check to abort polling for hardware completions if the
device state indicates an internal error. This returns -ETIMEDOUT early to
avoid long timeouts when the hardware stops generating completions.

> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
> index 6dcd9c2a78aa8..eae02bc742218 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
> @@ -422,6 +422,18 @@ int mlx5hws_bwc_queue_poll(struct mlx5hws_context *ctx,
>  	if (!got_comp && !drain)
>  		return 0;
>  
> +	if (unlikely(ctx->mdev->state == MLX5_DEVICE_STATE_INTERNAL_ERROR)) {
> +		/* If the device is down for any reason (e.g. FLR), the HW will
> +		 * no longer generate completions.
> +		 * Note that ETIMEDOUT is returned here because the BWC layer
> +		 * already has a special handling for timeouts - it breaks the
> +		 * rehash / resize / shrink loops to avoid chain of timeouts.
> +		 */
> +		mlx5_core_warn_once(ctx->mdev,
> +				    "BWC poll: device is down, polling for completion aborted\n");
> +		return -ETIMEDOUT;
> +	}
> +
>  	queue_full = mlx5hws_send_engine_full(&ctx->send_queue[queue_id]);
>  	while (queue_full || ((got_comp || drain) && *pending_rules)) {

Could this lead to a CPU stall if the device goes down during the polling loop?

The hardware state check is placed outside the while loop. The loop has a
60-second timeout (MLX5HWS_BWC_POLLING_TIMEOUT) and lacks cond_resched(),
meaning it can peg the CPU while spinning.

If the hardware fails and stops generating completions while we are already
inside the loop, the driver's health thread on another CPU might detect the
failure and set ctx->mdev->state to MLX5_DEVICE_STATE_INTERNAL_ERROR.

Since the check is outside the loop, we would fail to detect the state change
and continue to spin uselessly for the remainder of the 60 seconds, which
could trigger a soft lockup panic.

Should the state check be moved inside the polling loop, perhaps using
READ_ONCE() on ctx->mdev->state to ensure the compiler does not hoist the
lockless read?

>  		ret = mlx5hws_send_queue_poll(ctx, queue_id, comp, burst_th);

Re: [PATCH net-next 1/3] net/mlx5: HWS, Check if device is down while polling for completion

[Yevgeny Kliteynik]

On 10-May-26 22:03, Simon Horman wrote:
> From: 'Simon Horman' <horms@kernel.org>
> 
> This is an AI-generated review of your patch. The human sending this
> email has considered the AI review valid, or at least plausible.
> Full review at: https://sashiko.dev
> ---
> net/mlx5: HWS, Check if device is down while polling for completion
> 
> This commit adds a check to abort polling for hardware completions if the
> device state indicates an internal error. This returns -ETIMEDOUT early to
> avoid long timeouts when the hardware stops generating completions.
> 
>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
>> index 6dcd9c2a78aa8..eae02bc742218 100644
>> --- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
>> @@ -422,6 +422,18 @@ int mlx5hws_bwc_queue_poll(struct mlx5hws_context *ctx,
>>   	if (!got_comp && !drain)
>>   		return 0;
>>   
>> +	if (unlikely(ctx->mdev->state == MLX5_DEVICE_STATE_INTERNAL_ERROR)) {
>> +		/* If the device is down for any reason (e.g. FLR), the HW will
>> +		 * no longer generate completions.
>> +		 * Note that ETIMEDOUT is returned here because the BWC layer
>> +		 * already has a special handling for timeouts - it breaks the
>> +		 * rehash / resize / shrink loops to avoid chain of timeouts.
>> +		 */
>> +		mlx5_core_warn_once(ctx->mdev,
>> +				    "BWC poll: device is down, polling for completion aborted\n");
>> +		return -ETIMEDOUT;
>> +	}
>> +
>>   	queue_full = mlx5hws_send_engine_full(&ctx->send_queue[queue_id]);
>>   	while (queue_full || ((got_comp || drain) && *pending_rules)) {
> 
> Could this lead to a CPU stall if the device goes down during the polling loop?

That is correct.
There is the possibility that the device goes down while we're already inside
the polling loop, in which case the looping will continue till it reaches the
timeout.
But what we're trying to optimize is the "normal" flow. We prefer not to
add additional 'if' into the polling loop, which should be as efficient
as possible - it affects rules insertion/deletion rate.
So this patch aims to prevent chain of timeouts when device is in error
state, which is happening during deletion of all the flows, and during
shrinking of the matchers, while it still leaves some probability to see
a single initial timeout.


> The hardware state check is placed outside the while loop. The loop has a
> 60-second timeout (MLX5HWS_BWC_POLLING_TIMEOUT) and lacks cond_resched(),
> meaning it can peg the CPU while spinning.
> 
> If the hardware fails and stops generating completions while we are already
> inside the loop, the driver's health thread on another CPU might detect the
> failure and set ctx->mdev->state to MLX5_DEVICE_STATE_INTERNAL_ERROR.
> 
> Since the check is outside the loop, we would fail to detect the state change
> and continue to spin uselessly for the remainder of the 60 seconds, which
> could trigger a soft lockup panic.
> 
> Should the state check be moved inside the polling loop, perhaps using
> READ_ONCE() on ctx->mdev->state to ensure the compiler does not hoist the
> lockless read?
> 
>>   		ret = mlx5hws_send_queue_poll(ctx, queue_id, comp, burst_th);

[PATCH net-next 2/3] net/mlx5: HWS, Handle destroying table that has a miss table

[Tariq Toukan]

From: Yevgeny Kliteynik <kliteyn@nvidia.com>

If a table has a miss table that was created by
'mlx5hws_table_set_default_miss' API function, its miss_tbl
keeps the table that points to it in a list.
If such table is deleted, we need to also remove it from the
miss_tbl list, otherwise the node in miss_tbl list will contain
garbage.

Signed-off-by: Erez Shitrit <erezsh@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/steering/hws/table.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/table.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/table.c
index bd292485a25b..dd7927983ab2 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/table.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/table.c
@@ -282,6 +282,9 @@ int mlx5hws_table_destroy(struct mlx5hws_table *tbl)
 		goto unlock_err;
 	}
 
+	if (tbl->default_miss.miss_tbl)
+		list_del_init(&tbl->default_miss.next);
+
 	list_del_init(&tbl->tbl_list_node);
 	mutex_unlock(&ctx->ctrl_lock);
 
-- 
2.44.0

Re: [PATCH net-next 2/3] net/mlx5: HWS, Handle destroying table that has a miss table

[Simon Horman]

On Thu, May 07, 2026 at 08:34:42PM +0300, Tariq Toukan wrote:
> From: Yevgeny Kliteynik <kliteyn@nvidia.com>
> 
> If a table has a miss table that was created by
> 'mlx5hws_table_set_default_miss' API function, its miss_tbl
> keeps the table that points to it in a list.
> If such table is deleted, we need to also remove it from the
> miss_tbl list, otherwise the node in miss_tbl list will contain
> garbage.
> 
> Signed-off-by: Erez Shitrit <erezsh@nvidia.com>
> Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
> Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
> Signed-off-by: Tariq Toukan <tariqt@nvidia.com>

Reviewed-by: Simon Horman <horms@kernel.org>

[PATCH net-next 3/3] net/mlx5: DR, Remove unused field of struct mlx5dr_matcher_rx_tx

[Tariq Toukan]

From: Yevgeny Kliteynik <kliteyn@nvidia.com>

Remove a field that was never used.

Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Erez Shitrit <erezsh@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/steering/sws/dr_types.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/sws/dr_types.h b/drivers/net/ethernet/mellanox/mlx5/core/steering/sws/dr_types.h
index cc328292bf84..e0344707f522 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/sws/dr_types.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/sws/dr_types.h
@@ -986,7 +986,6 @@ struct mlx5dr_matcher_rx_tx {
 					       [DR_RULE_MAX_STES];
 	u8 num_of_builders;
 	u8 num_of_builders_arr[DR_RULE_IPV_MAX][DR_RULE_IPV_MAX];
-	u64 default_icm_addr;
 	struct mlx5dr_table_rx_tx *nic_tbl;
 	u32 prio;
 	struct list_head list_node;
-- 
2.44.0

Re: [PATCH net-next 3/3] net/mlx5: DR, Remove unused field of struct mlx5dr_matcher_rx_tx

[Simon Horman]

On Thu, May 07, 2026 at 08:34:43PM +0300, Tariq Toukan wrote:
> From: Yevgeny Kliteynik <kliteyn@nvidia.com>
> 
> Remove a field that was never used.
> 
> Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
> Reviewed-by: Erez Shitrit <erezsh@nvidia.com>
> Signed-off-by: Tariq Toukan <tariqt@nvidia.com>

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH net-next 0/3] net/mlx5: Steering misc enhancements

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 7 May 2026 20:34:40 +0300 you wrote:
> Hi,
> 
> This small series by Yevgeny contains a few steering enhancements /
> cleanups.
> 
> Regards,
> Tariq
> 
> [...]

Here is the summary with links:
  - [net-next,1/3] net/mlx5: HWS, Check if device is down while polling for completion
    https://git.kernel.org/netdev/net-next/c/e3ec1570895b
  - [net-next,2/3] net/mlx5: HWS, Handle destroying table that has a miss table
    https://git.kernel.org/netdev/net-next/c/60e9e82f162a
  - [net-next,3/3] net/mlx5: DR, Remove unused field of struct mlx5dr_matcher_rx_tx
    https://git.kernel.org/netdev/net-next/c/6316d40b8509

You are awesome, thank you!
-- 
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