Re: [dpdk-dev] [PATCH v5 2/2] eal: add additional info if core mask too long

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

On Thu, Sep 23, 2021 at 1:03 PM David Hunt <david.hunt@intel.com> wrote:
>
> If the user requests to use an lcore above 128 using -c,
> the eal will exit with "EAL: invalid coremask syntax" and
> very little else useful information.
>
> This patch adds some extra information suggesting to use --lcores
> so that physical cores above RTE_MAX_LCORE (default 128) can be
> used. This is achieved by using the --lcores option by mapping
> the logical cores in the application to physical cores.
>
> For example, if "-c 0x300000000000000000000000000000000" is
> used, we see the following additional output on the command line:
>
> EAL: lcore 128 >= RTE_MAX_LCORE (128)
> EAL: lcore 129 >= RTE_MAX_LCORE (128)
> EAL: to use high physical core ids , please use --lcores to
> map them to lcore ids below RTE_MAX_LCORE,
> EAL:     e.g. --lcores 0@128,1@129
>
> Signed-off-by: David Hunt <david.hunt@intel.com>
> Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
> changes in v3
>    * added this patch to the set. Addresses the changes for
>      the -c option.
> changes in v4
>    * fixed buffer overrun in populating lcore array.
>    * switched from strlcpy to strdup due to a clang error.
> changes in v5
>    * replaced strdup and frees with a const char *, as we
>      just need to keep track of original pointer location.
>    * reverted err: usage to return -1, as no free() needed.
>    * other minod code cleanups.
> ---
> ---
>  lib/eal/common/eal_common_options.c | 47 ++++++++++++++++++++++++-----
>  1 file changed, 40 insertions(+), 7 deletions(-)
>
> diff --git a/lib/eal/common/eal_common_options.c b/lib/eal/common/eal_common_options.c
> index 72735e0b09..7f715e4c15 100644
> --- a/lib/eal/common/eal_common_options.c
> +++ b/lib/eal/common/eal_common_options.c
> @@ -750,10 +750,12 @@ check_core_list(int *lcores, unsigned int count)
>  static int
>  eal_parse_coremask(const char *coremask, int *cores)
>  {
> -       unsigned count = 0;
> +       unsigned int count = 0;
>         int i, j, idx;
>         int val;
>         char c;
> +       int lcores[RTE_MAX_LCORE];
> +       const char *coremask_orig = coremask;
>
>         for (idx = 0; idx < RTE_MAX_LCORE; idx++)
>                 cores[idx] = -1;
> @@ -770,29 +772,60 @@ eal_parse_coremask(const char *coremask, int *cores)
>         i = strlen(coremask);
>         while ((i > 0) && isblank(coremask[i - 1]))
>                 i--;
> -       if (i == 0)
> +       if (i == 0) {
> +               RTE_LOG(ERR, EAL, "No lcores in coremask: [%s]\n",
> +                               coremask_orig);
>                 return -1;
> +       }
>
> -       for (i = i - 1; i >= 0 && idx < RTE_MAX_LCORE; i--) {
> +       for (i = i - 1; i >= 0; i--) {

This loop exit condition changes here: this ensures that, once we
leave the loop, i == -1.
As a consequence... (see below)


>                 c = coremask[i];
>                 if (isxdigit(c) == 0) {
>                         /* invalid characters */
> +                       RTE_LOG(ERR, EAL, "invalid characters in coremask: [%s]\n",
> +                                       coremask_orig);
>                         return -1;
>                 }
>                 val = xdigit2val(c);
> -               for (j = 0; j < BITS_PER_HEX && idx < RTE_MAX_LCORE; j++, idx++)
> +               for (j = 0; j < BITS_PER_HEX; j++, idx++)
>                 {
>                         if ((1 << j) & val) {
> -                               cores[idx] = count;
> +                               if (count >= RTE_MAX_LCORE) {
> +                                       RTE_LOG(ERR, EAL, "Too many lcores provided. Cannot exceed %d\n",
> +                                                       RTE_MAX_LCORE);
> +                                       return -1;
> +                               }
> +                               lcores[count] = idx;
>                                 count++;
>                         }
>                 }
>         }

... this loop below is dead code.

>         for (; i >= 0; i--)
> -               if (coremask[i] != '0')
> +               if (coremask[i] != '0') {
> +                       RTE_LOG(ERR, EAL, "invalid characters in coremask: [%s]\n",
> +                                       coremask_orig);

Nit: capital letter.

>                         return -1;
> -       if (count == 0)
> +               }
> +       if (count == 0) {
> +               RTE_LOG(ERR, EAL, "No lcores in coremask: [%s]\n",
> +                               coremask_orig);
> +               return -1;
> +       }
> +
> +       if (check_core_list(lcores, count))
>                 return -1;
> +
> +       /*
> +        * Now that we've gto a list of cores no longer than

Same typo I commented on patch 1 for v4.



> +        * RTE_MAX_LCORE, and no lcore in that list is greater
> +        * than RTE_MAX_LCORE, populate the cores
> +        * array and return.
> +        */
> +       do {
> +               count--;
> +               cores[lcores[count]] = count;
> +       } while (count != 0);
> +
>         return 0;
>  }
>
> --
> 2.17.1
>

-- 
David Marchand