On 29/07/19 18:49, Peter Zijlstra wrote: > On Fri, Jul 26, 2019 at 09:27:55AM +0100, Dietmar Eggemann wrote: > > Remove BUG_ON() in __enqueue_dl_entity() since there is already one in > > enqueue_dl_entity(). > > > > Move the check that the dl_se is not on the dl_rq from > > __dequeue_dl_entity() to dequeue_dl_entity() to align with the enqueue > > side and use the on_dl_rq() helper function. > > > > Signed-off-by: Dietmar Eggemann <[email protected]> > > --- > > kernel/sched/deadline.c | 8 +++----- > > 1 file changed, 3 insertions(+), 5 deletions(-) > > > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > > index 1fa005f79307..a9cb52ceb761 100644 > > --- a/kernel/sched/deadline.c > > +++ b/kernel/sched/deadline.c > > @@ -1407,8 +1407,6 @@ static void __enqueue_dl_entity(struct > > sched_dl_entity *dl_se) > > struct sched_dl_entity *entry; > > int leftmost = 1; > > > > - BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node)); > > - > > while (*link) { > > parent = *link; > > entry = rb_entry(parent, struct sched_dl_entity, rb_node); > > @@ -1430,9 +1428,6 @@ static void __dequeue_dl_entity(struct > > sched_dl_entity *dl_se) > > { > > struct dl_rq *dl_rq = dl_rq_of_se(dl_se); > > > > - if (RB_EMPTY_NODE(&dl_se->rb_node)) > > - return; > > - > > rb_erase_cached(&dl_se->rb_node, &dl_rq->root); > > RB_CLEAR_NODE(&dl_se->rb_node); > > > > @@ -1466,6 +1461,9 @@ enqueue_dl_entity(struct sched_dl_entity *dl_se, > > > > static void dequeue_dl_entity(struct sched_dl_entity *dl_se) > > { > > + if (!on_dl_rq(dl_se)) > > + return; > > Why allow double dequeue instead of WARN?
As I was saying to Valentin, it can currently happen that a task could have already been dequeued by update_curr_dl()->throttle called by dequeue_task_dl() before calling __dequeue_task_dl(). Do you think we should check for this condition before calling into dequeue_dl_entity()?
