Re: [dpdk-stable] [PATCH] net/mlx5: fix buffer leakage on Tx queue release

[Kevin Traynor <ktraynor@redhat.com>]

Relevant for 19.11 and 20.11 LTS

+cc Christian (19.11 LTS maintainer)

On 17/04/2021 19:38, Viacheslav Ovsiienko wrote:
> On Tx queue release the mlx5 PMD freed the mbufs stored
> in the elts array (holds buffers being transmitted) only
> for zero reference counter. The one reference is hold
> for the queue release call. Hence, on device stop call
> the reference counter was at least 2 and elts array was
> not freed. If application called the device start without
> queue release the elts array was cleaned up and the
> remaining mbufs were lost.
> 
> Fixes: 6e78005a9b30 ("net/mlx5: add reference counter on DPDK Tx queues")
> 
> Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
> 
> ---
> This patch is applicable for 19.11LTS only (and possible for
> preceeding releases), no bug in 20.11 and Upstream.
> 
>  drivers/net/mlx5/mlx5_txq.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/mlx5/mlx5_txq.c b/drivers/net/mlx5/mlx5_txq.c
> index 9c929a57ea..d9576e7a64 100644
> --- a/drivers/net/mlx5/mlx5_txq.c
> +++ b/drivers/net/mlx5/mlx5_txq.c
> @@ -1415,6 +1415,8 @@ mlx5_txq_release(struct rte_eth_dev *dev, uint16_t idx)
>  	txq = container_of((*priv->txqs)[idx], struct mlx5_txq_ctrl, txq);
>  	if (txq->obj && !mlx5_txq_obj_release(txq->obj))
>  		txq->obj = NULL;
> +	if (rte_atomic32_read(&txq->refcnt <= 2)
> +		txq_free_elts(txq);
>  	if (rte_atomic32_dec_and_test(&txq->refcnt)) {
>  		txq_free_elts(txq);
>  		mlx5_mr_btree_free(&txq->txq.mr_ctrl.cache_bh);
>