The rq_of() function is used everywhere. With the introduction of hierarchical runqueues, we could modify rq_of() to return the corresponding queue. In fact, no change would be necessary for that.
However, many code paths do not handle a hierarchical runqueue adequately. Thus, we introduce variants of rq_of() to catch and handle these code paths on a case by case basis. The normal rq_of() will complain loudly if used with a hierarchical runqueue. If a code path was audited for hierarchical use, it can be switched to hrq_of(), which returns the proper hierarchical runqueue, or to cpu_rq_of(), which returns the leader's CPU runqueue. Signed-off-by: Jan H. Schönherr <jscho...@amazon.de> --- kernel/sched/fair.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8cba7b8fb6bd..24d01bf8f796 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -249,9 +249,44 @@ const struct sched_class fair_sched_class; #ifdef CONFIG_FAIR_GROUP_SCHED +/* Variant of rq_of() that always returns a per-CPU runqueue */ +static inline struct rq *cpu_rq_of(struct cfs_rq *cfs_rq) +{ +#ifdef CONFIG_COSCHEDULING + if (cfs_rq->sdrq.data->level) { + struct rq *rq = cpu_rq(cfs_rq->sdrq.data->leader); + + /* We should have this lock already. */ + lockdep_assert_held(&rq->lock); + return rq; + } +#endif + return cfs_rq->rq; +} + /* cpu runqueue to which this cfs_rq is attached */ static inline struct rq *rq_of(struct cfs_rq *cfs_rq) { +#ifdef CONFIG_COSCHEDULING + if (SCHED_WARN_ON(cfs_rq->sdrq.data->level)) { + /* + * This should be only called for the bottom level. + * If not, then it's an indicator of a not yet adjusted + * code path. Return the CPU runqueue as this is more likely + * to work than the proper hierarchical runqueue. + * + * Note, that we don't necessarily have the lock for + * this bottom level, which may lead to weird issues. + */ + return cpu_rq_of(cfs_rq); + } +#endif + return cfs_rq->rq; +} + +/* Hierarchical variant of rq_of() */ +static inline struct rq *hrq_of(struct cfs_rq *cfs_rq) +{ return cfs_rq->rq; } -- 2.9.3.1.gcba166c.dirty