linux-kernel - Re: [PATCH net-next v6 1/3] net/mlx4: Track RX allocation failures in a stat

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Date: Thu, 30 May 2024 14:12:13 -0700
From: Jacob Keller <jacob.e.keller@...el.com>
To: Joe Damato <jdamato@...tly.com>, <linux-kernel@...r.kernel.org>,
	<netdev@...r.kernel.org>
CC: <nalramli@...tly.com>, <mkarsten@...terloo.ca>, Tariq Toukan
	<tariqt@...dia.com>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, "open list:MELLANOX MLX4 core VPI driver"
	<linux-rdma@...r.kernel.org>
Subject: Re: [PATCH net-next v6 1/3] net/mlx4: Track RX allocation failures in
 a stat



On 5/30/2024 2:08 PM, Jacob Keller wrote:
> 
> 
> On 5/28/2024 11:11 AM, Joe Damato wrote:
>> mlx4_en_alloc_frags currently returns -ENOMEM when mlx4_alloc_page
>> fails but does not increment a stat field when this occurs.
>>
>> A new field called alloc_fail has been added to struct mlx4_en_rx_ring
>> which is now incremented in mlx4_en_rx_ring when -ENOMEM occurs.
>>
>> Signed-off-by: Joe Damato <jdamato@...tly.com>
>> Tested-by: Martin Karsten <mkarsten@...terloo.ca>
>> Reviewed-by: Tariq Toukan <tariqt@...dia.com>
>> ---
>>  drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 1 +
>>  drivers/net/ethernet/mellanox/mlx4/en_rx.c     | 4 +++-
>>  drivers/net/ethernet/mellanox/mlx4/mlx4_en.h   | 1 +
>>  3 files changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
>> index 4c089cfa027a..4d2f8c458346 100644
>> --- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
>> +++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
>> @@ -2073,6 +2073,7 @@ static void mlx4_en_clear_stats(struct net_device *dev)
>>  		priv->rx_ring[i]->csum_ok = 0;
>>  		priv->rx_ring[i]->csum_none = 0;
>>  		priv->rx_ring[i]->csum_complete = 0;
>> +		priv->rx_ring[i]->alloc_fail = 0;
>>  	}
>>  }
>>  
>> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
>> index 8328df8645d5..15c57e9517e9 100644
>> --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
>> +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
>> @@ -82,8 +82,10 @@ static int mlx4_en_alloc_frags(struct mlx4_en_priv *priv,
>>  
>>  	for (i = 0; i < priv->num_frags; i++, frags++) {
>>  		if (!frags->page) {
>> -			if (mlx4_alloc_page(priv, frags, gfp))
>> +			if (mlx4_alloc_page(priv, frags, gfp)) {
>> +				ring->alloc_fail++;
>>  				return -ENOMEM;
>> +			}
>>  			ring->rx_alloc_pages++;
>>  		}
>>  		rx_desc->data[i].addr = cpu_to_be64(frags->dma +
>> diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
>> index efe3f97b874f..cd70df22724b 100644
>> --- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
>> +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
>> @@ -355,6 +355,7 @@ struct mlx4_en_rx_ring {
>>  	unsigned long xdp_tx;
>>  	unsigned long xdp_tx_full;
>>  	unsigned long dropped;
>> +	unsigned long alloc_fail;
>>  	int hwtstamp_rx_filter;
>>  	cpumask_var_t affinity_mask;
>>  	struct xdp_rxq_info xdp_rxq;
> 
> This patch does not appear to extend either a netdev, ethtool, devlink,
> or any other interface to report this new counter.
> 
> How is a user supposed to obtain this information from the driver?

Ah. Its used in the 3rd patch.

Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>