Re: [dpdk-dev] [PATCH] net/mlx4: fix rx not working after mbuf alloc failure

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

Hi Charles,

On Thu, Apr 13, 2017 at 07:52:34AM +0000, Myers, Charles wrote:
> I ran into an issue where the mlx4 driver stops receiving packets when mbuf allocation fails in mlx4_rx_burst().
> 
> This issue appears to be caused because the code doesn't recycle the existing mbuf to the sges array
> when mbuf allocation fails as is done in the code right above it which handles the
> (wc.status != IBV_WC_SUCCESS) case.
> 
> Copying the code from the above case before jumping to repost fixes the issue for me.
> 
> Signed-off-by: Charles Myers <Charles.Myers@spirent.com>

Thanks, this addresses a very old bug present since v2.1.0. As a fix, the
subject line should contain the word "fix", something like:

 net/mlx4: fix Rx after mbuf allocation failure

And since it's a fix:

 Fixes: acac55f16412 ("mlx4: use MOFED 3.0 fast verbs interface for Rx operations")
 Cc: stable@dpdk.org

Please also make sure the commit log is formatted according to the
submission guidelines (50 chars max for subject line, 75 chars for the rest
(except for the Fixes line), yada yada - see check-git-log.sh).

> ---
>  drivers/net/mlx4/mlx4.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c index aff9155..59d26fe 100644
> --- a/drivers/net/mlx4/mlx4.c
> +++ b/drivers/net/mlx4/mlx4.c
> @@ -3169,6 +3169,9 @@ struct txq_mp2mr_mbuf_check_data {
>  			/* Increase out of memory counters. */
>  			++rxq->stats.rx_nombuf;
>  			++rxq->priv->dev->data->rx_mbuf_alloc_failed;
> +

Another nit here, the above blank line is unnecessary.

> +			/* Add SGE to array for repost. */
> +			sges[i] = elt->sge;
>  			goto repost;
>  		}
>  
> --
> 1.7.9.5
> 

Otherwise,

Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

-- 
Adrien Mazarguil
6WIND