fail is that the hrtimer
callback is currently executing, so current change should be fine. 
Besides cpu-clock, task-clock should need similar change as well. I would
post a complete change later. [REGRESSION] bisected: perf: hang when using async-profiler caused by perf: Fix the POLL_HUP delivery breakage"Mi, Dapeng" <dapeng1.mi@linux.intel.com> undefinedPeter Zijlstra <peterz@infradead.org> undefined undefined undefined undefined undefined undefined†"ƒŽL