[PATCH 10/34] sched: Add normal_policy()

Tejun Heo
2023-07-11T01:15:17Z

A new BPF extensible sched_class will need to dynamically change how a task
picks its sched_class. For example, if the loaded BPF scheduler progs fail,
the tasks will be forced back on CFS even if the task's policy is set to the
new sched_class. To support such mapping, add normal_policy() which wraps
testing for %SCHED_NORMAL. This doesn't cause any behavior changes.

v2: Update the description with more details on the expected use.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Vernet <dvernet@meta.com>
Acked-by: Josh Don <joshdon@google.com>
Acked-by: Hao Luo <haoluo@google.com>
Acked-by: Barret Rhoden <brho@google.com>
---
kernel/sched/fair.c | 2 +-
kernel/sched/sched.h | 8 +++++++-
2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9838c82230e1..5ba7e1f2e7c7 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7900,7 +7900,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
* Batch and idle tasks do not preempt non-idle tasks (their preemption
* is driven by the tick):
*/
- if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
+ if (unlikely(!normal_policy(p->policy)) || !sched_feat(WAKEUP_PREEMPTION))
return;

find_matching_se(&se, &pse);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index cd11bf9de7f9..7eee863942f4 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -182,9 +182,15 @@ static inline int idle_policy(int policy)
{
return policy == SCHED_IDLE;
}
+
+static inline int normal_policy(int policy)
+{
+ return policy == SCHED_NORMAL;
+}
+
static inline int fair_policy(int policy)
{
- return policy == SCHED_NORMAL || policy == SCHED_BATCH;
+ return normal_policy(policy) || policy == SCHED_BATCH;
}

static inline int rt_policy(int policy)
--
2.41.0