Re: [PATCH v5 5/9] perf auxtrace: Use WRITE_ONCE() for updating aux_tail

[Arnaldo Carvalho de Melo]

Em Mon, Aug 09, 2021 at 07:14:03PM +0800, Leo Yan escreveu:
> Use WRITE_ONCE() for updating aux_tail, so can avoid unexpected memory
> behaviour.

Thanks, applied to perf/core.

- Arnaldo

 
> Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
> Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> ---
>  tools/perf/util/auxtrace.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
> index cc1c1b9cec9c..79227b8864cd 100644
> --- a/tools/perf/util/auxtrace.h
> +++ b/tools/perf/util/auxtrace.h
> @@ -480,7 +480,7 @@ static inline void auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail)
>  	/* Ensure all reads are done before we write the tail out */
>  	smp_mb();
>  #if BITS_PER_LONG == 64 || !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
> -	pc->aux_tail = tail;
> +	WRITE_ONCE(pc->aux_tail, tail);
>  #else
>  	do {
>  		old_tail = __sync_val_compare_and_swap(&pc->aux_tail, 0, 0);
> -- 
> 2.25.1
> 

-- 

- Arnaldo