Re: [dpdk-dev] [PATCH v2 4/6] eal: update rte_eal_wait_lcore definition

[Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>]

+ Techboard.

This is the API (not ABI as I mentioned) compatibility breakage that I mentioned during the last Techboard meeting.

The removal of the FINISHED state itself was announced. This is a change related to that. However, the specific API change was not called out in the deprecation notice.


> -----Original Message-----
> From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> Sent: Thursday, September 9, 2021 6:13 PM
> To: dev@dpdk.org; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>; konstantin.ananyev@intel.com;
> david.marchand@redhat.com; Feifei Wang <Feifei.Wang2@arm.com>
> Cc: Ruifeng Wang <Ruifeng.Wang@arm.com>; nd <nd@arm.com>; Feifei
> Wang (Arm Technology China) <Feifei.Wang@arm.com>
> Subject: [PATCH v2 4/6] eal: update rte_eal_wait_lcore definition
> 
> Since the FINISHED state is removed, the API rte_eal_wait_lcore is updated to
> always return the status of the last function that ran in the worker core.
> 
> Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> Reviewed-by: Feifei Wang <feifei.wang@arm.com>
> ---
>  lib/eal/common/eal_common_launch.c |  6 ++----
>  lib/eal/include/rte_launch.h       | 12 +++++-------
>  2 files changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/lib/eal/common/eal_common_launch.c
> b/lib/eal/common/eal_common_launch.c
> index 78fd940267..4bc842417a 100644
> --- a/lib/eal/common/eal_common_launch.c
> +++ b/lib/eal/common/eal_common_launch.c
> @@ -23,10 +23,8 @@
>  int
>  rte_eal_wait_lcore(unsigned worker_id)
>  {
> -	if (lcore_config[worker_id].state == WAIT)
> -		return 0;
> -
> -	while (lcore_config[worker_id].state != WAIT)
> +	while (__atomic_load_n(&lcore_config[worker_id].state,
> +					__ATOMIC_ACQUIRE) != WAIT)
>  		rte_pause();
> 
>  	rte_rmb();
> diff --git a/lib/eal/include/rte_launch.h b/lib/eal/include/rte_launch.h index
> ed0bb4762a..f2d386e6e2 100644
> --- a/lib/eal/include/rte_launch.h
> +++ b/lib/eal/include/rte_launch.h
> @@ -119,18 +119,16 @@ enum rte_lcore_state_t
> rte_eal_get_lcore_state(unsigned int worker_id);
>   *
>   * To be executed on the MAIN lcore only.
>   *
> - * If the worker lcore identified by the worker_id is in a FINISHED state,
> - * switch to the WAIT state. If the lcore is in RUNNING state, wait until
> - * the lcore finishes its job and moves to the FINISHED state.
> + * If the lcore identified by the worker_id is in RUNNING state, wait
> + until
> + * the lcore finishes its job and moves to the WAIT state.
>   *
>   * @param worker_id
>   *   The identifier of the lcore.
>   * @return
> - *   - 0: If the lcore identified by the worker_id is in a WAIT state.
> + *   - 0: If the remote launch function was never called on the lcore
> + *     identified by the worker_id.
>   *   - The value that was returned by the previous remote launch
> - *     function call if the lcore identified by the worker_id was in a
> - *     FINISHED or RUNNING state. In this case, it changes the state
> - *     of the lcore to WAIT.
> + *     function call.
>   */
>  int rte_eal_wait_lcore(unsigned worker_id);
> 
> --
> 2.25.1