Re: [PATCH tip/sched/core] Add comments to aid in safer usage of swake_up.

[Peter Zijlstra]

On Thu, Jun 08, 2017 at 08:25:46PM -0700, Krister Johansen wrote:
> The behavior of swake_up() differs from that of wake_up(), and from the
> swake_up() that came from RT linux. A memory barrier, or some other
> synchronization, is needed prior to a swake_up so that the waiter sees
> the condition set by the waker, and so that the waker does not see an
> empty wait list.

Urgh.. let me stare at that. But it sounds like the wrong solution since
we wanted to keep the wait and swait APIs as close as possible.