Re: [FFmpeg-devel] [PATCH] avutil/executor: Fix missing check before using mutex

[Nuo Mi <nuomi2021@gmail.com>]

On Sun, Jun 30, 2024 at 6:45 PM Zhao Zhili <quinkblack@foxmail.com> wrote:

> From: Zhao Zhili <zhilizhao@tencent.com>
>
> ---
> The code can be simplified by always creating mutex/cond. I'm not sure
> it worth the overhead. Please note !HAVE_THREADS don't have the same
> problem since it has mock implementation of ff_mutex_lock/unlock.
>
Hi Zhili,
Thank you for the patch.
Do we really need this? The lock/unlock/signal functions will return an
error if the lock and condition variables are not initialized.

>
>  libavutil/executor.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/libavutil/executor.c b/libavutil/executor.c
> index fb20104b58..89058fab2f 100644
> --- a/libavutil/executor.c
> +++ b/libavutil/executor.c
> @@ -194,14 +194,17 @@ void av_executor_execute(AVExecutor *e, AVTask *t)
>      AVTaskCallbacks *cb = &e->cb;
>      AVTask **prev;
>
> -    ff_mutex_lock(&e->lock);
> +    if (e->thread_count)
> +        ff_mutex_lock(&e->lock);
>      if (t) {
>          for (prev = &e->tasks; *prev && cb->priority_higher(*prev, t);
> prev = &(*prev)->next)
>              /* nothing */;
>          add_task(prev, t);
>      }
> -    ff_cond_signal(&e->cond);
> -    ff_mutex_unlock(&e->lock);
> +    if (e->thread_count) {
> +        ff_cond_signal(&e->cond);
> +        ff_mutex_unlock(&e->lock);
> +    }
>
>      if (!e->thread_count || !HAVE_THREADS) {
>          // We are running in a single-threaded environment, so we must
> handle all tasks ourselves
> --
> 2.42.0
>
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