netdev - Re: [PATCH net 2/2] mlx5: fix skb leak while fifo resync

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Date:   Mon, 23 Jan 2023 16:52:30 +0000
From:   Vadim Fedorenko <vadfed@...a.com>
To:     Gal Pressman <gal@...dia.com>, Aya Levin <ayal@...dia.com>,
        Saeed Mahameed <saeedm@...dia.com>,
        Jakub Kicinski <kuba@...nel.org>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net 2/2] mlx5: fix skb leak while fifo resync

On 23/01/2023 12:38, Gal Pressman wrote:
> On 22/01/2023 18:16, Vadim Fedorenko wrote:
>> During ptp resync operation SKBs were poped from the fifo but were never
>> freed neither by napi_consume nor by dev_kfree_skb_any. Add call to
>> napi_consume_skb to properly free SKBs.
>>
>> Fixes: 19b43a432e3e ("net/mlx5e: Extend SKB room check to include PTP-SQ")
> 
> Same comment as previous patch?

Yeah, and it's correct for this patch too. Commit mentioned in Fixes 
introduced several bugs apart from architectural problem. The first bug 
of wrong checks and possible overflow/underflow of FIFO is fixed by 
previous patch. This patch fixes another issue of leaking SKBs from FIFO 
during synchronisation process.

> 
>> Signed-off-by: Vadim Fedorenko <vadfed@...a.com>
>> ---
>>   drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c
>> index 11a99e0f00c6..d60bb997c53b 100644
>> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c
>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c
>> @@ -102,6 +102,7 @@ static bool mlx5e_ptp_skb_fifo_ts_cqe_resync(struct mlx5e_ptpsq *ptpsq, u16 skb_
>>   		hwts.hwtstamp = mlx5e_skb_cb_get_hwts(skb)->cqe_hwtstamp;
>>   		skb_tstamp_tx(skb, &hwts);
>>   		ptpsq->cq_stats->resync_cqe++;
>> +		napi_consume_skb(skb, 1);
> 
> Was wondering whether we should pass the actual budget here instead of
> 1, but looking at napi_consume_skb() it doesn't really matter..
> 
> Anyway:
> Reviewed-by: Gal Pressman <gal@...dia.com>
> 
>>   		skb_cc = PTP_WQE_CTR2IDX(ptpsq->skb_fifo_cc);
>>   	}
>>