On Mon, Jan 21, 2019 at 04:52:40PM +0100, Andrea Parri wrote: > move_queued_task() synchronizes with task_rq_lock() as follows: > > move_queued_task() task_rq_lock() > > [S] ->on_rq = MIGRATING [L] rq = task_rq() > WMB (__set_task_cpu()) ACQUIRE (rq->lock); > [S] ->cpu = new_cpu [L] ->on_rq > > where "[L] rq = task_rq()" is ordered before "ACQUIRE (rq->lock)" by an > address dependency and, in turn, "ACQUIRE (rq->lock)" is ordered before > "[L] ->on_rq" by the ACQUIRE itself. > > Use READ_ONCE() to load ->cpu in task_rq() (c.f., task_cpu()) to honor > this address dependency. Also, mark the accesses to ->cpu and ->on_rq > with READ_ONCE()/WRITE_ONCE() to comply with the LKMM. > > Signed-off-by: Andrea Parri <[email protected]>
Thanks!
