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Message-ID: <20260121231140.832332-14-tj@kernel.org>
Date: Wed, 21 Jan 2026 13:11:19 -1000
From: Tejun Heo <tj@...nel.org>
To: linux-kernel@...r.kernel.org,
sched-ext@...ts.linux.dev
Cc: void@...ifault.com,
andrea.righi@...ux.dev,
changwoo@...lia.com,
emil@...alapatis.com,
Tejun Heo <tj@...nel.org>
Subject: [PATCH 13/34] sched_ext: Refactor task init/exit helpers
- Add the @sch parameter to scx_init_task() and drop @tg as it can be
obtained from @p. Separate out __scx_init_task() which does everything
except for the task state transition.
- Add the @sch parameter to scx_enable_task(). Separate out
__scx_enable_task() which does everything except for the task state
transition.
- Add the @sch parameter to scx_disable_task().
- Rename scx_exit_task() to scx_disable_and_exit_task() and separate out
__scx_disable_and_exit_task() which does everything except for the task
state transition.
While some task state transitions are relocated, no meaningful behavior
changes are expected.
Signed-off-by: Tejun Heo <tj@...nel.org>
---
kernel/sched/ext.c | 67 +++++++++++++++++++++++++++++++---------------
1 file changed, 45 insertions(+), 22 deletions(-)
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 07cd130f62fb..a834da7701df 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -2987,9 +2987,9 @@ static void scx_set_task_state(struct task_struct *p, enum scx_task_state state)
p->scx.flags |= state << SCX_TASK_STATE_SHIFT;
}
-static int scx_init_task(struct task_struct *p, struct task_group *tg, bool fork)
+static int __scx_init_task(struct scx_sched *sch, struct task_struct *p, bool fork)
{
- struct scx_sched *sch = scx_root;
+ struct task_group *tg = task_group(p);
int ret;
p->scx.disallow = false;
@@ -3008,8 +3008,6 @@ static int scx_init_task(struct task_struct *p, struct task_group *tg, bool fork
}
}
- scx_set_task_state(p, SCX_TASK_INIT);
-
if (p->scx.disallow) {
if (unlikely(scx_parent(sch))) {
scx_error(sch, "non-root ops.init_task() set task->scx.disallow for %s[%d]",
@@ -3039,13 +3037,27 @@ static int scx_init_task(struct task_struct *p, struct task_group *tg, bool fork
}
}
- p->scx.flags |= SCX_TASK_RESET_RUNNABLE_AT;
return 0;
}
-static void scx_enable_task(struct task_struct *p)
+static int scx_init_task(struct scx_sched *sch, struct task_struct *p, bool fork)
+{
+ int ret;
+
+ ret = __scx_init_task(sch, p, fork);
+ if (!ret) {
+ /*
+ * While @p's rq is not locked. @p is not visible to the rest of
+ * SCX yet and it's safe to update the flags and state.
+ */
+ p->scx.flags |= SCX_TASK_RESET_RUNNABLE_AT;
+ scx_set_task_state(p, SCX_TASK_INIT);
+ }
+ return ret;
+}
+
+static void __scx_enable_task(struct scx_sched *sch, struct task_struct *p)
{
- struct scx_sched *sch = scx_root;
struct rq *rq = task_rq(p);
u32 weight;
@@ -3064,16 +3076,20 @@ static void scx_enable_task(struct task_struct *p)
if (SCX_HAS_OP(sch, enable))
SCX_CALL_OP_TASK(sch, SCX_KF_REST, enable, rq, p);
- scx_set_task_state(p, SCX_TASK_ENABLED);
if (SCX_HAS_OP(sch, set_weight))
SCX_CALL_OP_TASK(sch, SCX_KF_REST, set_weight, rq,
p, p->scx.weight);
}
-static void scx_disable_task(struct task_struct *p)
+static void scx_enable_task(struct scx_sched *sch, struct task_struct *p)
+{
+ __scx_enable_task(sch, p);
+ scx_set_task_state(p, SCX_TASK_ENABLED);
+}
+
+static void scx_disable_task(struct scx_sched *sch, struct task_struct *p)
{
- struct scx_sched *sch = scx_root;
struct rq *rq = task_rq(p);
lockdep_assert_rq_held(rq);
@@ -3084,9 +3100,9 @@ static void scx_disable_task(struct task_struct *p)
scx_set_task_state(p, SCX_TASK_READY);
}
-static void scx_exit_task(struct task_struct *p)
+static void __scx_disable_and_exit_task(struct scx_sched *sch,
+ struct task_struct *p)
{
- struct scx_sched *sch = scx_task_sched(p);
struct scx_exit_task_args args = {
.cancelled = false,
};
@@ -3103,7 +3119,7 @@ static void scx_exit_task(struct task_struct *p)
case SCX_TASK_READY:
break;
case SCX_TASK_ENABLED:
- scx_disable_task(p);
+ scx_disable_task(sch, p);
break;
default:
WARN_ON_ONCE(true);
@@ -3113,6 +3129,13 @@ static void scx_exit_task(struct task_struct *p)
if (SCX_HAS_OP(sch, exit_task))
SCX_CALL_OP_TASK(sch, SCX_KF_REST, exit_task, task_rq(p),
p, &args);
+}
+
+static void scx_disable_and_exit_task(struct scx_sched *sch,
+ struct task_struct *p)
+{
+ __scx_disable_and_exit_task(sch, p);
+
scx_set_task_sched(p, NULL);
scx_set_task_state(p, SCX_TASK_NONE);
}
@@ -3148,7 +3171,7 @@ int scx_fork(struct task_struct *p, struct kernel_clone_args *kargs)
percpu_rwsem_assert_held(&scx_fork_rwsem);
if (scx_init_task_enabled) {
- ret = scx_init_task(p, task_group(p), true);
+ ret = scx_init_task(scx_root, p, true);
if (!ret)
scx_set_task_sched(p, scx_root);
return ret;
@@ -3172,7 +3195,7 @@ void scx_post_fork(struct task_struct *p)
struct rq *rq;
rq = task_rq_lock(p, &rf);
- scx_enable_task(p);
+ scx_enable_task(scx_task_sched(p), p);
task_rq_unlock(rq, p, &rf);
}
}
@@ -3192,7 +3215,7 @@ void scx_cancel_fork(struct task_struct *p)
rq = task_rq_lock(p, &rf);
WARN_ON_ONCE(scx_get_task_state(p) >= SCX_TASK_READY);
- scx_exit_task(p);
+ scx_disable_and_exit_task(scx_task_sched(p), p);
task_rq_unlock(rq, p, &rf);
}
@@ -3216,7 +3239,7 @@ void sched_ext_dead(struct task_struct *p)
struct rq *rq;
rq = task_rq_lock(p, &rf);
- scx_exit_task(p);
+ scx_disable_and_exit_task(scx_task_sched(p), p);
task_rq_unlock(rq, p, &rf);
}
}
@@ -3242,7 +3265,7 @@ static void switching_to_scx(struct rq *rq, struct task_struct *p)
{
struct scx_sched *sch = scx_task_sched(p);
- scx_enable_task(p);
+ scx_enable_task(sch, p);
/*
* set_cpus_allowed_scx() is not called while @p is associated with a
@@ -3255,7 +3278,7 @@ static void switching_to_scx(struct rq *rq, struct task_struct *p)
static void switched_from_scx(struct rq *rq, struct task_struct *p)
{
- scx_disable_task(p);
+ scx_disable_task(scx_task_sched(p), p);
}
static void wakeup_preempt_scx(struct rq *rq, struct task_struct *p,int wake_flags) {}
@@ -4485,7 +4508,7 @@ static void scx_root_disable(struct scx_sched *sch)
/*
* Shut down cgroup support before tasks so that the cgroup attach path
- * doesn't race against scx_exit_task().
+ * doesn't race against scx_disable_and_exit_task().
*/
scx_cgroup_lock();
scx_cgroup_exit(sch);
@@ -4514,7 +4537,7 @@ static void scx_root_disable(struct scx_sched *sch)
p->sched_class = new_class;
}
- scx_exit_task(p);
+ scx_disable_and_exit_task(scx_task_sched(p), p);
}
scx_task_iter_stop(&sti);
@@ -5379,7 +5402,7 @@ static s32 scx_root_enable(struct sched_ext_ops *ops, struct bpf_link *link)
scx_task_iter_unlock(&sti);
- ret = scx_init_task(p, task_group(p), false);
+ ret = scx_init_task(sch, p, false);
if (ret) {
put_task_struct(p);
scx_task_iter_stop(&sti);
--
2.52.0
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