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Message-ID: <20250920005931.2753828-11-tj@kernel.org>
Date: Fri, 19 Sep 2025 14:58:33 -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 10/46] sched_ext: Add the @sch parameter to ext_idle helpers
In preparation for multiple scheduler support, add the @sch parameter to
validate_node(), check_builtin_idle_enabled() and select_cpu_from_kfunc(),
and update their callers to read $scx_root, verify that it's not NULL and
pass it in. The passed in @sch parameter is not used yet.
Signed-off-by: Tejun Heo <tj@...nel.org>
---
kernel/sched/ext_idle.c | 109 ++++++++++++++++++++++++++++++++++------
1 file changed, 94 insertions(+), 15 deletions(-)
diff --git a/kernel/sched/ext_idle.c b/kernel/sched/ext_idle.c
index 7174e1c1a392..6e2504ae7357 100644
--- a/kernel/sched/ext_idle.c
+++ b/kernel/sched/ext_idle.c
@@ -819,7 +819,7 @@ void scx_idle_disable(void)
* Helpers that can be called from the BPF scheduler.
*/
-static int validate_node(int node)
+static int validate_node(struct scx_sched *sch, int node)
{
if (!static_branch_likely(&scx_builtin_idle_per_node)) {
scx_kf_error("per-node idle tracking is disabled");
@@ -847,7 +847,7 @@ static int validate_node(int node)
__bpf_kfunc_start_defs();
-static bool check_builtin_idle_enabled(void)
+static bool check_builtin_idle_enabled(struct scx_sched *sch)
{
if (static_branch_likely(&scx_builtin_idle_enabled))
return true;
@@ -856,7 +856,8 @@ static bool check_builtin_idle_enabled(void)
return false;
}
-static s32 select_cpu_from_kfunc(struct task_struct *p, s32 prev_cpu, u64 wake_flags,
+static s32 select_cpu_from_kfunc(struct scx_sched *sch, struct task_struct *p,
+ s32 prev_cpu, u64 wake_flags,
const struct cpumask *allowed, u64 flags)
{
struct rq *rq;
@@ -866,7 +867,7 @@ static s32 select_cpu_from_kfunc(struct task_struct *p, s32 prev_cpu, u64 wake_f
if (!kf_cpu_valid(prev_cpu, NULL))
return -EINVAL;
- if (!check_builtin_idle_enabled())
+ if (!check_builtin_idle_enabled(sch))
return -EBUSY;
/*
@@ -946,15 +947,21 @@ __bpf_kfunc int scx_bpf_cpu_node(s32 cpu)
__bpf_kfunc s32 scx_bpf_select_cpu_dfl(struct task_struct *p, s32 prev_cpu,
u64 wake_flags, bool *is_idle)
{
+ struct scx_sched *sch;
s32 cpu;
- cpu = select_cpu_from_kfunc(p, prev_cpu, wake_flags, NULL, 0);
+ guard(rcu)();
+
+ sch = rcu_dereference(scx_root);
+ if (unlikely(!sch))
+ return -ENODEV;
+
+ cpu = select_cpu_from_kfunc(sch, p, prev_cpu, wake_flags, NULL, 0);
if (cpu >= 0) {
*is_idle = true;
return cpu;
}
*is_idle = false;
-
return prev_cpu;
}
@@ -981,7 +988,16 @@ __bpf_kfunc s32 scx_bpf_select_cpu_dfl(struct task_struct *p, s32 prev_cpu,
__bpf_kfunc s32 scx_bpf_select_cpu_and(struct task_struct *p, s32 prev_cpu, u64 wake_flags,
const struct cpumask *cpus_allowed, u64 flags)
{
- return select_cpu_from_kfunc(p, prev_cpu, wake_flags, cpus_allowed, flags);
+ struct scx_sched *sch;
+
+ guard(rcu)();
+
+ sch = rcu_dereference(scx_root);
+ if (unlikely(!sch))
+ return -ENODEV;
+
+ return select_cpu_from_kfunc(sch, p, prev_cpu, wake_flags,
+ cpus_allowed, flags);
}
/**
@@ -995,7 +1011,15 @@ __bpf_kfunc s32 scx_bpf_select_cpu_and(struct task_struct *p, s32 prev_cpu, u64
*/
__bpf_kfunc const struct cpumask *scx_bpf_get_idle_cpumask_node(int node)
{
- node = validate_node(node);
+ struct scx_sched *sch;
+
+ guard(rcu)();
+
+ sch = rcu_dereference(scx_root);
+ if (unlikely(!sch))
+ return cpu_none_mask;
+
+ node = validate_node(sch, node);
if (node < 0)
return cpu_none_mask;
@@ -1011,12 +1035,20 @@ __bpf_kfunc const struct cpumask *scx_bpf_get_idle_cpumask_node(int node)
*/
__bpf_kfunc const struct cpumask *scx_bpf_get_idle_cpumask(void)
{
+ struct scx_sched *sch;
+
+ guard(rcu)();
+
+ sch = rcu_dereference(scx_root);
+ if (unlikely(!sch))
+ return cpu_none_mask;
+
if (static_branch_unlikely(&scx_builtin_idle_per_node)) {
scx_kf_error("SCX_OPS_BUILTIN_IDLE_PER_NODE enabled");
return cpu_none_mask;
}
- if (!check_builtin_idle_enabled())
+ if (!check_builtin_idle_enabled(sch))
return cpu_none_mask;
return idle_cpumask(NUMA_NO_NODE)->cpu;
@@ -1034,7 +1066,15 @@ __bpf_kfunc const struct cpumask *scx_bpf_get_idle_cpumask(void)
*/
__bpf_kfunc const struct cpumask *scx_bpf_get_idle_smtmask_node(int node)
{
- node = validate_node(node);
+ struct scx_sched *sch;
+
+ guard(rcu)();
+
+ sch = rcu_dereference(scx_root);
+ if (unlikely(!sch))
+ return cpu_none_mask;
+
+ node = validate_node(sch, node);
if (node < 0)
return cpu_none_mask;
@@ -1054,12 +1094,20 @@ __bpf_kfunc const struct cpumask *scx_bpf_get_idle_smtmask_node(int node)
*/
__bpf_kfunc const struct cpumask *scx_bpf_get_idle_smtmask(void)
{
+ struct scx_sched *sch;
+
+ guard(rcu)();
+
+ sch = rcu_dereference(scx_root);
+ if (unlikely(!sch))
+ return cpu_none_mask;
+
if (static_branch_unlikely(&scx_builtin_idle_per_node)) {
scx_kf_error("SCX_OPS_BUILTIN_IDLE_PER_NODE enabled");
return cpu_none_mask;
}
- if (!check_builtin_idle_enabled())
+ if (!check_builtin_idle_enabled(sch))
return cpu_none_mask;
if (sched_smt_active())
@@ -1095,7 +1143,15 @@ __bpf_kfunc void scx_bpf_put_idle_cpumask(const struct cpumask *idle_mask)
*/
__bpf_kfunc bool scx_bpf_test_and_clear_cpu_idle(s32 cpu)
{
- if (!check_builtin_idle_enabled())
+ struct scx_sched *sch;
+
+ guard(rcu)();
+
+ sch = rcu_dereference(scx_root);
+ if (unlikely(!sch))
+ return false;
+
+ if (!check_builtin_idle_enabled(sch))
return false;
if (!kf_cpu_valid(cpu, NULL))
@@ -1126,7 +1182,15 @@ __bpf_kfunc bool scx_bpf_test_and_clear_cpu_idle(s32 cpu)
__bpf_kfunc s32 scx_bpf_pick_idle_cpu_node(const struct cpumask *cpus_allowed,
int node, u64 flags)
{
- node = validate_node(node);
+ struct scx_sched *sch;
+
+ guard(rcu)();
+
+ sch = rcu_dereference(scx_root);
+ if (unlikely(!sch))
+ return -ENODEV;
+
+ node = validate_node(sch, node);
if (node < 0)
return node;
@@ -1158,12 +1222,20 @@ __bpf_kfunc s32 scx_bpf_pick_idle_cpu_node(const struct cpumask *cpus_allowed,
__bpf_kfunc s32 scx_bpf_pick_idle_cpu(const struct cpumask *cpus_allowed,
u64 flags)
{
+ struct scx_sched *sch;
+
+ guard(rcu)();
+
+ sch = rcu_dereference(scx_root);
+ if (unlikely(!sch))
+ return -ENODEV;
+
if (static_branch_maybe(CONFIG_NUMA, &scx_builtin_idle_per_node)) {
scx_kf_error("per-node idle tracking is enabled");
return -EBUSY;
}
- if (!check_builtin_idle_enabled())
+ if (!check_builtin_idle_enabled(sch))
return -EBUSY;
return scx_pick_idle_cpu(cpus_allowed, NUMA_NO_NODE, flags);
@@ -1193,9 +1265,16 @@ __bpf_kfunc s32 scx_bpf_pick_idle_cpu(const struct cpumask *cpus_allowed,
__bpf_kfunc s32 scx_bpf_pick_any_cpu_node(const struct cpumask *cpus_allowed,
int node, u64 flags)
{
+ struct scx_sched *sch;
s32 cpu;
- node = validate_node(node);
+ guard(rcu)();
+
+ sch = rcu_dereference(scx_root);
+ if (unlikely(!sch))
+ return -ENODEV;
+
+ node = validate_node(sch, node);
if (node < 0)
return node;
--
2.51.0
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