Re: [dpdk-stable] [PATCH v2 2/2] eal/freebsd: add config reattach

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

On Thu, Jun 27, 2019 at 1:33 PM Anatoly Burakov <anatoly.burakov@intel.com>
wrote:

> Linux EAL will attach the shared config at an arbitrary address,
> find out where the shared config is mapped in the primary, and
> then will reattach it at that exact address.
>
> FreeBSD version doesn't seem to go for that extra reattach step,
> which makes one wonder how did it ever work in the first place.
>
> Fix the FreeBSD init to also reattach shared config to the exact
> same place the primary process has it.
>
> Fixes: 764bf26873b9 ("add FreeBSD support")
> Cc: bruce.richardson@intel.com
> Cc: stable@dpdk.org
>
> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
> ---
>
> Notes:
>     v2:
>     - Rebase on top of latest master
>     - Fix fd handling
>     - Fix mmap PROT flags on first map
>
>  lib/librte_eal/freebsd/eal/eal.c | 49 ++++++++++++++++++++++++++++++--
>  1 file changed, 46 insertions(+), 3 deletions(-)
>
> diff --git a/lib/librte_eal/freebsd/eal/eal.c
> b/lib/librte_eal/freebsd/eal/eal.c
> index 3e15af792..fac43b017 100644
> --- a/lib/librte_eal/freebsd/eal/eal.c
> +++ b/lib/librte_eal/freebsd/eal/eal.c
> @@ -288,10 +288,11 @@ rte_eal_config_attach(void)
>         }
>
>         rte_mem_cfg_addr = mmap(NULL, sizeof(*rte_config.mem_config),
> -                               PROT_READ | PROT_WRITE, MAP_SHARED,
> mem_cfg_fd, 0);
> -       close(mem_cfg_fd);
> -       mem_cfg_fd = -1;
> +                               PROT_READ, MAP_SHARED, mem_cfg_fd, 0);
> +       /* don't close the fd here, it will be closed on reattach */
>         if (rte_mem_cfg_addr == MAP_FAILED) {
> +               close(mem_cfg_fd);
> +               mem_cfg_fd = -1;
>                 RTE_LOG(ERR, EAL, "Cannot mmap memory for rte_config!
> error %i (%s)\n",
>                         errno, strerror(errno));
>                 return -1;
> @@ -302,6 +303,46 @@ rte_eal_config_attach(void)
>         return 0;
>  }
>
> +/* reattach the shared config at exact memory location primary process
> has it */
> +static int
> +rte_eal_config_reattach(void)
> +{
> +       struct rte_mem_config *mem_config;
> +       void *rte_mem_cfg_addr;
> +
> +       if (internal_config.no_shconf)
> +               return 0;
> +
> +       /* save the address primary process has mapped shared config to */
> +       rte_mem_cfg_addr =
> +                       (void
> *)(uintptr_t)rte_config.mem_config->mem_cfg_addr;
> +
> +       /* unmap original config */
> +       munmap(rte_config.mem_config, sizeof(struct rte_mem_config));
> +
> +       /* remap the config at proper address */
> +       mem_config = (struct rte_mem_config *) mmap(rte_mem_cfg_addr,
> +                       sizeof(*mem_config), PROT_READ | PROT_WRITE,
> MAP_SHARED,
> +                       mem_cfg_fd, 0);
> +       close(mem_cfg_fd);
> +       mem_cfg_fd = -1;
> +
> +       if (mem_config == MAP_FAILED) {
> +               RTE_LOG(ERR, EAL, "Cannot mmap memory for rte_config!
> error %i (%s)\n",
> +                               errno, strerror(errno));
> +               return -1;
> +       } else if (mem_config != rte_mem_cfg_addr) {
> +               /* errno is stale, don't use */
> +               RTE_LOG(ERR, EAL, "Cannot mmap memory for rte_config at
> [%p], got [%p]\n",
> +                         rte_mem_cfg_addr, mem_config);
> +               return -1;
> +       }
>

Ah, it looks better than this double if we have in linux eal.c :-)
+1

+
> +       rte_config.mem_config = mem_config;
> +
> +       return 0;
> +}
> +
>  /* Detect if we are a primary or a secondary process */
>  enum rte_proc_type_t
>  eal_proc_type_detect(void)
> @@ -342,6 +383,8 @@ rte_config_init(void)
>                 if (rte_eal_config_attach() < 0)
>                         return -1;
>                 rte_eal_mcfg_wait_complete(rte_config.mem_config);
> +               if (rte_eal_config_reattach() < 0)
> +                       return -1;
>                 break;
>         case RTE_PROC_AUTO:
>         case RTE_PROC_INVALID:
> --
> 2.17.1
>

Reviewed-by: David Marchand <david.marchand@redhat.com>

Thanks!

-- 
David Marchand