Re: [net 7/9] net/mlx5e: kTLS, Call WARN_ONCE on netdev mismatch

[Jakub Kicinski]

On Thu, 25 Jul 2019 20:36:48 +0000, Saeed Mahameed wrote:
> From: Tariq Toukan <tar...@mellanox.com>
> 
> A netdev mismatch in the processed TLS SKB should not occur,
> and indicates a kernel bug.
> Add WARN_ONCE to spot such cases.
> 
> Fixes: d2ead1f360e8 ("net/mlx5e: Add kTLS TX HW offload support")
> Suggested-by: Jakub Kicinski <jakub.kicin...@netronome.com>
> Signed-off-by: Tariq Toukan <tar...@mellanox.com>
> Signed-off-by: Saeed Mahameed <sae...@mellanox.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c 
> b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c
> index ea032f54197e..3766545ce259 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c
> @@ -412,7 +412,7 @@ struct sk_buff *mlx5e_ktls_handle_tx_skb(struct 
> net_device *netdev,
>               goto out;
>  
>       tls_ctx = tls_get_ctx(skb->sk);
> -     if (unlikely(tls_ctx->netdev != netdev))
> +     if (unlikely(WARN_ON_ONCE(tls_ctx->netdev != netdev)))

Ah, nit: the unlikely is probably unnecessary but that's no big deal.

#define WARN_ON_ONCE(condition) ({                      \
        static int __warned;                            \
        int __ret_warn_once = !!(condition);            \
                                                        \
        if (unlikely(__ret_warn_once && !__warned)) {   \
                __warned = true;                        \
                WARN_ON(1);                             \
        }                                               \
        unlikely(__ret_warn_once);                      \
})

>               goto err_out;
>  
>       priv_tx = mlx5e_get_ktls_tx_priv_ctx(tls_ctx);