From: Tejun Heo <tj@kernel.org> mainline inclusion from mainline-v6.12-rc1 commit 18f856991d0596aa125cf63893ca08d7c74b85a2 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IDC9YK Reference: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi... -------------------------------- Now that there's nothing left after the big if block, flip the if condition and unindent the body. No functional changes intended. v2: Add BUG() to clarify control can't reach the end of dispatch_to_local_dsq() in UP kernels per David. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: David Vernet <void@manifault.com> Signed-off-by: Zicheng Qu <quzicheng@huawei.com> --- kernel/sched/ext.c | 96 ++++++++++++++++++++++------------------------ 1 file changed, 46 insertions(+), 50 deletions(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 8f4b6ba38880..18ebc0b3a468 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -2411,65 +2411,61 @@ static void dispatch_to_local_dsq(struct rq *rq, struct scx_dispatch_q *dst_dsq, } #ifdef CONFIG_SMP - if (likely(task_can_run_on_remote_rq(p, dst_rq, true))) { - /* - * @p is on a possibly remote @src_rq which we need to lock to - * move the task. If dequeue is in progress, it'd be locking - * @src_rq and waiting on DISPATCHING, so we can't grab @src_rq - * lock while holding DISPATCHING. - * - * As DISPATCHING guarantees that @p is wholly ours, we can - * pretend that we're moving from a DSQ and use the same - * mechanism - mark the task under transfer with holding_cpu, - * release DISPATCHING and then follow the same protocol. See - * unlink_dsq_and_lock_src_rq(). - */ - p->scx.holding_cpu = raw_smp_processor_id(); + if (unlikely(!task_can_run_on_remote_rq(p, dst_rq, true))) { + dispatch_enqueue(&scx_dsq_global, p, enq_flags | SCX_ENQ_CLEAR_OPSS); + return; + } - /* store_release ensures that dequeue sees the above */ - atomic_long_set_release(&p->scx.ops_state, SCX_OPSS_NONE); + /* + * @p is on a possibly remote @src_rq which we need to lock to move the + * task. If dequeue is in progress, it'd be locking @src_rq and waiting + * on DISPATCHING, so we can't grab @src_rq lock while holding + * DISPATCHING. + * + * As DISPATCHING guarantees that @p is wholly ours, we can pretend that + * we're moving from a DSQ and use the same mechanism - mark the task + * under transfer with holding_cpu, release DISPATCHING and then follow + * the same protocol. See unlink_dsq_and_lock_src_rq(). + */ + p->scx.holding_cpu = raw_smp_processor_id(); - /* switch to @src_rq lock */ - if (rq != src_rq) { - raw_spin_rq_unlock(rq); - raw_spin_rq_lock(src_rq); - } + /* store_release ensures that dequeue sees the above */ + atomic_long_set_release(&p->scx.ops_state, SCX_OPSS_NONE); - /* task_rq couldn't have changed if we're still the holding cpu */ - if (likely(p->scx.holding_cpu == raw_smp_processor_id()) && - !WARN_ON_ONCE(src_rq != task_rq(p))) { - /* - * If @p is staying on the same rq, there's no need to - * go through the full deactivate/activate cycle. - * Optimize by abbreviating the operations in - * move_task_to_local_dsq(). - */ - if (src_rq == dst_rq) { - p->scx.holding_cpu = -1; - dispatch_enqueue(&dst_rq->scx.local_dsq, - p, enq_flags); - } else { - move_task_to_local_dsq(p, enq_flags, - src_rq, dst_rq); - } + /* switch to @src_rq lock */ + if (rq != src_rq) { + raw_spin_rq_unlock(rq); + raw_spin_rq_lock(src_rq); + } - /* if the destination CPU is idle, wake it up */ - if (sched_class_above(p->sched_class, - dst_rq->curr->sched_class)) - resched_curr(dst_rq); + /* task_rq couldn't have changed if we're still the holding cpu */ + if (likely(p->scx.holding_cpu == raw_smp_processor_id()) && + !WARN_ON_ONCE(src_rq != task_rq(p))) { + /* + * If @p is staying on the same rq, there's no need to go + * through the full deactivate/activate cycle. Optimize by + * abbreviating the operations in move_task_to_local_dsq(). + */ + if (src_rq == dst_rq) { + p->scx.holding_cpu = -1; + dispatch_enqueue(&dst_rq->scx.local_dsq, p, enq_flags); + } else { + move_task_to_local_dsq(p, enq_flags, src_rq, dst_rq); } - /* switch back to @rq lock */ - if (rq != dst_rq) { - raw_spin_rq_unlock(dst_rq); - raw_spin_rq_lock(rq); - } + /* if the destination CPU is idle, wake it up */ + if (sched_class_above(p->sched_class, dst_rq->curr->sched_class)) + resched_curr(dst_rq); + } - return; + /* switch back to @rq lock */ + if (rq != dst_rq) { + raw_spin_rq_unlock(dst_rq); + raw_spin_rq_lock(rq); } +#else /* CONFIG_SMP */ + BUG(); /* control can not reach here on UP */ #endif /* CONFIG_SMP */ - - dispatch_enqueue(&scx_dsq_global, p, enq_flags | SCX_ENQ_CLEAR_OPSS); } /** -- 2.34.1