Re: [PATCH 1/3] perf: convert perf_event_context.refcount to refcount_t

[Peter Zijlstra]

On Mon, Jan 28, 2019 at 02:27:26PM +0200, Elena Reshetova wrote:
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 3cd13a3..a1e87d2 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -1171,7 +1171,7 @@ static void perf_event_ctx_deactivate(struct perf_event_context *ctx)
>  
>  static void get_ctx(struct perf_event_context *ctx)
>  {
> -	WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
> +	WARN_ON(!refcount_inc_not_zero(&ctx->refcount));

This could be refcount_inc(), remember how that already produces a WARN
when we try and increment 0.