Re: [PATCH v2 net-next 11/13] net: enetc: optimize the allocation of tx_bdr

[Frank Li]

On Tue, Oct 15, 2024 at 08:58:39PM +0800, Wei Fang wrote:
> From: Clark Wang <xiaoning.wang@xxxxxxx>
>
> There is a situation where num_tx_rings cannot be divided by bdr_int_num.
> For example, num_tx_rings is 8 and bdr_int_num is 3. According to the
> previous logic, this results in two tx_bdr corresponding memories not
> being allocated, so when sending packets to tx ring 6 or 7, wild pointers
> will be accessed. Of course, this issue doesn't exist on LS1028A, because
> its num_tx_rings is 8, and bdr_int_num is either 1 or 2. However, there
> is a risk for the upcoming i.MX95. Therefore, it is necessary to ensure
> that each tx_bdr can be allocated to the corresponding memory.
>
> Signed-off-by: Clark Wang <xiaoning.wang@xxxxxxx>
> Signed-off-by: Wei Fang <wei.fang@xxxxxxx>
> ---
> v2 changes:
> This patch is separated from v1 patch 9 ("net: enetc: optimize the
> allocation of tx_bdr"). Only the optimized part is kept.
> ---
>  drivers/net/ethernet/freescale/enetc/enetc.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
> index d36af3f8ba31..72ddf8b16271 100644
> --- a/drivers/net/ethernet/freescale/enetc/enetc.c
> +++ b/drivers/net/ethernet/freescale/enetc/enetc.c
> @@ -3049,10 +3049,10 @@ static void enetc_int_vector_destroy(struct enetc_ndev_priv *priv, int i)
>  int enetc_alloc_msix(struct enetc_ndev_priv *priv)
>  {
>  	struct pci_dev *pdev = priv->si->pdev;
> +	int v_tx_rings, v_remainder;
>  	int num_stack_tx_queues;
>  	int first_xdp_tx_ring;
>  	int i, n, err, nvec;
> -	int v_tx_rings;

Nit: Needn't move v_tx_rings.

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>
>  	nvec = ENETC_BDR_INT_BASE_IDX + priv->bdr_int_num;
>  	/* allocate MSIX for both messaging and Rx/Tx interrupts */
> @@ -3066,10 +3066,14 @@ int enetc_alloc_msix(struct enetc_ndev_priv *priv)
>
>  	/* # of tx rings per int vector */
>  	v_tx_rings = priv->num_tx_rings / priv->bdr_int_num;
> +	v_remainder = priv->num_tx_rings % priv->bdr_int_num;
>
> -	for (i = 0; i < priv->bdr_int_num; i++)
> -		if (enetc_int_vector_init(priv, i, v_tx_rings))
> +	for (i = 0; i < priv->bdr_int_num; i++) {
> +		int num_tx_rings = i < v_remainder ? v_tx_rings + 1 : v_tx_rings;
> +
> +		if (enetc_int_vector_init(priv, i, num_tx_rings))
>  			goto fail;
> +	}
>
>  	num_stack_tx_queues = enetc_num_stack_tx_queues(priv);
>
> --
> 2.34.1
>