Re: [PATCH 1/6] examples/l3fwd: fix lcore ID restriction

[David Marchand <david.marchand@redhat.com>]

On Mon, Dec 18, 2023 at 8:49 AM Sivaprasad Tummala
<sivaprasad.tummala@amd.com> wrote:
>
> Currently the config option allows lcore IDs up to 255,
> irrespective of RTE_MAX_LCORES and needs to be fixed.

"needs to be fixed" ?
I disagree on the principle.
The examples were written with limitations, this is not a bug.

>
> The patch allows config options based on DPDK config.
>
> Fixes: af75078fece3 ("first public release")
> Cc: stable@dpdk.org

Please remove this request for backport in the next revision.

>
> Signed-off-by: Sivaprasad Tummala <sivaprasad.tummala@amd.com>
> ---
>  examples/l3fwd/main.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/examples/l3fwd/main.c b/examples/l3fwd/main.c
> index 3bf28aec0c..847ded0ad2 100644
> --- a/examples/l3fwd/main.c
> +++ b/examples/l3fwd/main.c
> @@ -99,7 +99,7 @@ struct parm_cfg parm_config;
>  struct lcore_params {
>         uint16_t port_id;
>         uint8_t queue_id;
> -       uint8_t lcore_id;
> +       uint16_t lcore_id;

lcore_id are stored as an unsigned int (so potentially 32bits) in EAL.
Moving to uint16_t seems not enough.


>  } __rte_cache_aligned;
>
>  static struct lcore_params lcore_params_array[MAX_LCORE_PARAMS];
> @@ -292,8 +292,8 @@ setup_l3fwd_lookup_tables(void)
>  static int
>  check_lcore_params(void)
>  {
> -       uint8_t queue, lcore;
> -       uint16_t i;
> +       uint8_t queue;
> +       uint16_t i, lcore;
>         int socketid;
>
>         for (i = 0; i < nb_lcore_params; ++i) {
> @@ -359,7 +359,7 @@ static int
>  init_lcore_rx_queues(void)
>  {
>         uint16_t i, nb_rx_queue;
> -       uint8_t lcore;
> +       uint16_t lcore;
>
>         for (i = 0; i < nb_lcore_params; ++i) {
>                 lcore = lcore_params[i].lcore_id;
> @@ -500,6 +500,8 @@ parse_config(const char *q_arg)
>         char *str_fld[_NUM_FLD];
>         int i;
>         unsigned size;
> +       unsigned int max_fld[_NUM_FLD] = {RTE_MAX_ETHPORTS,

This change here is not described in the commitlog and introduces a bug.

In this example, queue_id is stored as a uint8_t.
queue_id are stored as uint16_t in ethdev.
Yet RTE_MAX_ETHPORTS can be larger than 255.


> +                                       255, RTE_MAX_LCORE};
>
>         nb_lcore_params = 0;
>
> @@ -518,7 +520,8 @@ parse_config(const char *q_arg)
>                 for (i = 0; i < _NUM_FLD; i++){
>                         errno = 0;
>                         int_fld[i] = strtoul(str_fld[i], &end, 0);
> -                       if (errno != 0 || end == str_fld[i] || int_fld[i] > 255)
> +                       if (errno != 0 || end == str_fld[i] || int_fld[i] >
> +                                                                       max_fld[i])
>                                 return -1;
>                 }
>                 if (nb_lcore_params >= MAX_LCORE_PARAMS) {
> @@ -531,7 +534,7 @@ parse_config(const char *q_arg)
>                 lcore_params_array[nb_lcore_params].queue_id =
>                         (uint8_t)int_fld[FLD_QUEUE];
>                 lcore_params_array[nb_lcore_params].lcore_id =
> -                       (uint8_t)int_fld[FLD_LCORE];
> +                       (uint16_t)int_fld[FLD_LCORE];
>                 ++nb_lcore_params;
>         }
>         lcore_params = lcore_params_array;
> --
> 2.25.1
>

I did not check other patches in the series, but I suggest you revisit
them in the light of those comments.


-- 
David Marchand