[FFmpeg-devel] [PATCH 2/2] avutil/executor: Fix stack overflow due to recursive call

[Timo Rothenpieler]

On 08.07.2024 17:32, Zhao Zhili wrote:
> 
> 
>> On Jul 8, 2024, at 22:07, Timo Rothenpieler <timo at rothenpieler.org> wrote:
>>
>> On 08.07.2024 09:43, Zhao Zhili wrote:
>>> From: Zhao Zhili <zhilizhao at tencent.com>
>>> av_executor_execute run the task directly when thread is disabled.
>>> The task can schedule a new task by call av_executor_execute. This
>>> forms an implicit recursive call. This patch removed the recursive
>>> call.
>>> ---
>>>   libavutil/executor.c | 5 +++++
>>>   1 file changed, 5 insertions(+)
>>> diff --git a/libavutil/executor.c b/libavutil/executor.c
>>> index 89058fab2f..c145c51be9 100644
>>> --- a/libavutil/executor.c
>>> +++ b/libavutil/executor.c
>>> @@ -58,6 +58,7 @@ struct AVExecutor {
>>>       int die;
>>>         AVTask *tasks;
>>> +    int stack_depth;
>>>   };
>>>     static AVTask* remove_task(AVTask **prev, AVTask *t)
>>> @@ -207,8 +208,12 @@ void av_executor_execute(AVExecutor *e, AVTask *t)
>>>       }
>>>         if (!e->thread_count || !HAVE_THREADS) {
>>> +        if (e->stack_depth > 0)
>>> +            return;
>>> +        e->stack_depth++;
>>>           // We are running in a single-threaded environment, so we must handle all tasks ourselves
>>>           while (run_one_task(e, e->local_contexts))
>>>               /* nothing */;
>>> +        e->stack_depth--;
>>
>> Won't this put the above line into the "nothing" while-loop?
>> Is that intended? If so, the indentation should be adjusted accordingly.
>> If not, the while-loop should gain empty {}.
> 
> The comment specify it’s a while loop with empty body. Maybe it’s not obvious
> in the email client.

Oh, there is a ; behind the comment.
Completely missed that. Can't say I like it, but yeah, that works.