Re: [PATCH][next] net: dsa: sja1105: Use struct_size() in kzalloc()

[Vladimir Oltean]

Hi Gustavo,

On Fri, 19 Jun 2020 at 21:04, Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> wrote:
>
> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes.
>
> This code was detected with the help of Coccinelle and, audited and
> fixed manually.
>
> Addresses-KSPP-ID: https://github.com/KSPP/linux/issues/83
> Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
> ---
>  drivers/net/dsa/sja1105/sja1105_tas.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/net/dsa/sja1105/sja1105_tas.c b/drivers/net/dsa/sja1105/sja1105_tas.c
> index 3aa1a8b5f766..31d8acff1f01 100644
> --- a/drivers/net/dsa/sja1105/sja1105_tas.c
> +++ b/drivers/net/dsa/sja1105/sja1105_tas.c
> @@ -475,8 +475,7 @@ bool sja1105_gating_check_conflicts(struct sja1105_private *priv, int port,
>         if (list_empty(&gating_cfg->entries))
>                 return false;
>
> -       dummy = kzalloc(sizeof(struct tc_taprio_sched_entry) * num_entries +
> -                       sizeof(struct tc_taprio_qopt_offload), GFP_KERNEL);
> +       dummy = kzalloc(struct_size(dummy, entries, num_entries), GFP_KERNEL);

Before, I could read this line and I knew what it did. Now, I have to
look it up.
But if it's in the interest of kernel coding style, what can I say.

Acked-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>

>         if (!dummy) {
>                 NL_SET_ERR_MSG_MOD(extack, "Failed to allocate memory");
>                 return true;
> --
> 2.27.0
>