Re: [PATCH 1/3] random: defer seeding to EAL init

["Mattias Rönnblom" <hofors@lysator.liu.se>]

On 2024-12-05 18:57, David Marchand wrote:
> The RNG is documented as being seeded as part of EAL init.
> 
> /**
>   * Seed the pseudo-random generator.
>   *
>   * The generator is automatically seeded by the EAL init with a timer
>   * value. It may need to be re-seeded by the user with a real random
>   * value.
>   *
> ...
> 

Remove the superfluous quote.

> Move the initialisation (seeding) helper out of a constructor and
> call it explicitly from rte_eal_init() as it was done before commit
> 3f002f069612 ("eal: replace libc-based random generation with LFSR").
> 
> This also moves the unconditional lcore variable allocation out of a
> constructor.
> 
> While at it, mark local symbol rand_state as static.
> 

Reviewed-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>

> Fixes: 29c39cd3d54d ("random: keep PRNG state in lcore variable")
> Cc: stable@dpdk.org
> 
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> ---
>   lib/eal/common/eal_private.h | 6 ++++++
>   lib/eal/common/rte_random.c  | 7 +++++--
>   lib/eal/freebsd/eal.c        | 2 ++
>   lib/eal/linux/eal.c          | 2 ++
>   lib/eal/windows/eal.c        | 2 ++
>   5 files changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/eal/common/eal_private.h b/lib/eal/common/eal_private.h
> index bb315dab04..a10db6a399 100644
> --- a/lib/eal/common/eal_private.h
> +++ b/lib/eal/common/eal_private.h
> @@ -702,6 +702,12 @@ eal_get_internal_configuration(void);
>   rte_usage_hook_t
>   eal_get_application_usage_hook(void);
>   
> +/**
> + * Initialise random subsystem.
> + */
> +void
> +eal_rand_init(void);
> +
>   /**
>    * Instruct primary process that a secondary process wants to attach.
>    */
> diff --git a/lib/eal/common/rte_random.c b/lib/eal/common/rte_random.c
> index cf0756f26a..307c26bb7c 100644
> --- a/lib/eal/common/rte_random.c
> +++ b/lib/eal/common/rte_random.c
> @@ -14,6 +14,8 @@
>   #include <rte_lcore_var.h>
>   #include <rte_random.h>
>   
> +#include "eal_private.h"
> +
>   struct __rte_cache_aligned rte_rand_state {
>   	uint64_t z1;
>   	uint64_t z2;
> @@ -22,7 +24,7 @@ struct __rte_cache_aligned rte_rand_state {
>   	uint64_t z5;
>   };
>   
> -RTE_LCORE_VAR_HANDLE(struct rte_rand_state, rand_state);
> +static RTE_LCORE_VAR_HANDLE(struct rte_rand_state, rand_state);
>   
>   /* instance to be shared by all unregistered non-EAL threads */
>   static struct rte_rand_state unregistered_rand_state;
> @@ -228,7 +230,8 @@ __rte_random_initial_seed(void)
>   	return rte_get_tsc_cycles();
>   }
>   
> -RTE_INIT(rte_rand_init)
> +void
> +eal_rand_init(void)
>   {
>   	uint64_t seed;
>   
> diff --git a/lib/eal/freebsd/eal.c b/lib/eal/freebsd/eal.c
> index a96bbf5836..d07cff8651 100644
> --- a/lib/eal/freebsd/eal.c
> +++ b/lib/eal/freebsd/eal.c
> @@ -777,6 +777,8 @@ rte_eal_init(int argc, char **argv)
>   		return -1;
>   	}
>   
> +	eal_rand_init();
> +
>   	eal_check_mem_on_local_socket();
>   
>   	if (rte_thread_set_affinity_by_id(rte_thread_self(),
> diff --git a/lib/eal/linux/eal.c b/lib/eal/linux/eal.c
> index a6220524a4..b1e63e37fc 100644
> --- a/lib/eal/linux/eal.c
> +++ b/lib/eal/linux/eal.c
> @@ -1173,6 +1173,8 @@ rte_eal_init(int argc, char **argv)
>   		return -1;
>   	}
>   
> +	eal_rand_init();
> +
>   	eal_check_mem_on_local_socket();
>   
>   	if (rte_thread_set_affinity_by_id(rte_thread_self(),
> diff --git a/lib/eal/windows/eal.c b/lib/eal/windows/eal.c
> index 5cdc053a02..5c7526f922 100644
> --- a/lib/eal/windows/eal.c
> +++ b/lib/eal/windows/eal.c
> @@ -410,6 +410,8 @@ rte_eal_init(int argc, char **argv)
>   		return -1;
>   	}
>   
> +	eal_rand_init();
> +
>   	if (rte_thread_set_affinity_by_id(rte_thread_self(),
>   			&lcore_config[config->main_lcore].cpuset) != 0) {
>   		rte_eal_init_alert("Cannot set affinity");