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Message-ID: <20250920005931.2753828-22-tj@kernel.org>
Date: Fri, 19 Sep 2025 14:58:44 -1000
From: Tejun Heo <tj@...nel.org>
To: void@...ifault.com,
arighi@...dia.com,
multics69@...il.com
Cc: linux-kernel@...r.kernel.org,
sched-ext@...ts.linux.dev,
memxor@...il.com,
bpf@...r.kernel.org,
Tejun Heo <tj@...nel.org>
Subject: [PATCH 21/46] sched_ext: Minor reorganization of enable/disable path
- Separate out scx_root_disable() from scx_disable_workfn().
- Rename scx_enable() to scx_root_enable().
- Add @sch to scx_disable(). The callers are now responsible for providing
the scx_sched to disable.
No functional changes.
Signed-off-by: Tejun Heo <tj@...nel.org>
---
kernel/sched/ext.c | 70 ++++++++++++++++++++++++++--------------------
1 file changed, 40 insertions(+), 30 deletions(-)
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 0ee716ff4dab..54f65a196d94 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -3018,8 +3018,8 @@ void sched_ext_free(struct task_struct *p)
spin_unlock_irqrestore(&scx_tasks_lock, flags);
/*
- * @p is off scx_tasks and wholly ours. scx_enable()'s READY -> ENABLED
- * transitions can't race us. Disable ops for @p.
+ * @p is off scx_tasks and wholly ours. scx_root_enable()'s READY ->
+ * ENABLED transitions can't race us. Disable ops for @p.
*/
if (scx_get_task_state(p) != SCX_TASK_NONE) {
struct rq_flags rf;
@@ -3933,24 +3933,12 @@ static const char *scx_exit_reason(enum scx_exit_kind kind)
}
}
-static void scx_disable_workfn(struct kthread_work *work)
+static void scx_root_disable(struct scx_sched *sch)
{
- struct scx_sched *sch = container_of(work, struct scx_sched, disable_work);
struct scx_exit_info *ei = sch->exit_info;
struct scx_task_iter sti;
struct task_struct *p;
- int kind, cpu;
-
- kind = atomic_read(&sch->exit_kind);
- while (true) {
- if (kind == SCX_EXIT_DONE) /* already disabled? */
- return;
- WARN_ON_ONCE(kind == SCX_EXIT_NONE);
- if (atomic_try_cmpxchg(&sch->exit_kind, &kind, SCX_EXIT_DONE))
- break;
- }
- ei->kind = kind;
- ei->reason = scx_exit_reason(ei->kind);
+ int cpu;
/* guarantee forward progress by bypassing scx_ops */
scx_bypass(true);
@@ -4078,21 +4066,35 @@ static void scx_disable_workfn(struct kthread_work *work)
scx_bypass(false);
}
-static void scx_disable(enum scx_exit_kind kind)
+static void scx_disable_workfn(struct kthread_work *work)
+{
+ struct scx_sched *sch = container_of(work, struct scx_sched, disable_work);
+ struct scx_exit_info *ei = sch->exit_info;
+ int kind;
+
+ kind = atomic_read(&sch->exit_kind);
+ while (true) {
+ if (kind == SCX_EXIT_DONE) /* already disabled? */
+ return;
+ WARN_ON_ONCE(kind == SCX_EXIT_NONE);
+ if (atomic_try_cmpxchg(&sch->exit_kind, &kind, SCX_EXIT_DONE))
+ break;
+ }
+ ei->kind = kind;
+ ei->reason = scx_exit_reason(ei->kind);
+
+ scx_root_disable(sch);
+}
+
+static void scx_disable(struct scx_sched *sch, enum scx_exit_kind kind)
{
int none = SCX_EXIT_NONE;
- struct scx_sched *sch;
if (WARN_ON_ONCE(kind == SCX_EXIT_NONE || kind == SCX_EXIT_DONE))
kind = SCX_EXIT_ERROR;
- rcu_read_lock();
- sch = rcu_dereference(scx_root);
- if (sch) {
- atomic_try_cmpxchg(&sch->exit_kind, &none, kind);
- kthread_queue_work(sch->helper, &sch->disable_work);
- }
- rcu_read_unlock();
+ atomic_try_cmpxchg(&sch->exit_kind, &none, kind);
+ kthread_queue_work(sch->helper, &sch->disable_work);
}
static void dump_newline(struct seq_buf *s)
@@ -4558,7 +4560,7 @@ static int validate_ops(struct scx_sched *sch, const struct sched_ext_ops *ops)
return 0;
}
-static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link)
+static int scx_root_enable(struct sched_ext_ops *ops, struct bpf_link *link)
{
struct scx_sched *sch;
struct scx_task_iter sti;
@@ -4808,7 +4810,7 @@ static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link)
* Flush scx_disable_work to ensure that error is reported before init
* completion. sch's base reference will be put by bpf_scx_unreg().
*/
- scx_error(sch, "scx_enable() failed (%d)", ret);
+ scx_error(sch, "scx_root_enable() failed (%d)", ret);
kthread_flush_work(&sch->disable_work);
return 0;
}
@@ -4940,7 +4942,7 @@ static int bpf_scx_check_member(const struct btf_type *t,
static int bpf_scx_reg(void *kdata, struct bpf_link *link)
{
- return scx_enable(kdata, link);
+ return scx_root_enable(kdata, link);
}
static void bpf_scx_unreg(void *kdata, struct bpf_link *link)
@@ -4948,7 +4950,7 @@ static void bpf_scx_unreg(void *kdata, struct bpf_link *link)
struct sched_ext_ops *ops = kdata;
struct scx_sched *sch = ops->priv;
- scx_disable(SCX_EXIT_UNREG);
+ scx_disable(sch, SCX_EXIT_UNREG);
kthread_flush_work(&sch->disable_work);
kobject_put(&sch->kobj);
}
@@ -5074,7 +5076,15 @@ static struct bpf_struct_ops bpf_sched_ext_ops = {
static void sysrq_handle_sched_ext_reset(u8 key)
{
- scx_disable(SCX_EXIT_SYSRQ);
+ struct scx_sched *sch;
+
+ rcu_read_lock();
+ sch = rcu_dereference(scx_root);
+ if (likely(sch))
+ scx_disable(sch, SCX_EXIT_SYSRQ);
+ else
+ pr_info("sched_ext: BPF schedulers not loaded\n");
+ rcu_read_unlock();
}
static const struct sysrq_key_op sysrq_sched_ext_reset_op = {
--
2.51.0
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