On Mon, Jun 1, 2020 at 10:04 PM Andrii Nakryiko <andriin@xxxxxx> wrote:
>
> Make sample_cnt volatile to fix possible selftests failure due to compiler
> optimization preventing latest sample_cnt value to be visible to main thread.
> sample_cnt is incremented in background thread, which is then joined into main
> thread. So in terms of visibility sample_cnt update is ok. But because it's
> not volatile, compiler might make optimizations that would prevent main thread
> to see latest updated value. Fix this by marking global variable volatile.
>
> Fixes: cb1c9ddd5525 ("selftests/bpf: Add BPF ringbuf selftests")
> Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
Acked-by: Song Liu <songliubraving@xxxxxx>
