Re: [PATCH] eal/windows: fix data race when creating threads

[Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>]

Hi Tyler,

2022-03-09 23:35 (UTC-0800), Tyler Retzlaff:
> create lcore worker threads suspended and then subsequently resume to
> allow &lcore_config[i].thread_id be stored before eal_thread_loop
> execution.
> 
> Fixes: 53ffd9f080fc ("eal/windows: add minimum viable code")
> Cc: anand.rawat@intel.com
> Cc: stable@dpdk.org
> 
> Signed-off-by: Tyler Retzlaff <roretzla@linux.microsoft.com>

Acked-by: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>

It takes some effort to correlate &lcore_config[i].thread_id
with the code in the patch and knowledge of CreateThread()
to understand the root cause.
I suggest prepending an explanation to your commit message:

	eal_thread_loop() uses lcore_config[i].thread_id,
	which is stored upon the return from CreateThread().
	Per documentation, eal_thread_loop() can start
	before CreateThread() returns and the ID is stored.

> ---
>  lib/eal/windows/eal_thread.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/eal/windows/eal_thread.c b/lib/eal/windows/eal_thread.c
> index 54fa93f..ff84cb4 100644
> --- a/lib/eal/windows/eal_thread.c
> +++ b/lib/eal/windows/eal_thread.c
> @@ -150,13 +150,18 @@
>  
>  	th = CreateThread(NULL, 0,
>  		(LPTHREAD_START_ROUTINE)(ULONG_PTR)eal_thread_loop,
> -						NULL, 0, (LPDWORD)thread);
> +						NULL, CREATE_SUSPENDED, (LPDWORD)thread);
>  	if (!th)
>  		return -1;
>  
>  	SetPriorityClass(GetCurrentProcess(), NORMAL_PRIORITY_CLASS);
>  	SetThreadPriority(th, THREAD_PRIORITY_NORMAL);
>  
> +	if (ResumeThread(th) == (DWORD)-1) {
> +		(void)CloseHandle(th);
> +		return -1;
> +	}
> +
>  	return 0;
>  }
>