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sched_ext: Add scx_cgroup_enabled to gate cgroup operations and fix scx_tg_online()

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If the BPF scheduler does not implement ops.cgroup_init(), scx_tg_online()
didn't set SCX_TG_INITED which meant that ops.cgroup_exit(), even if
implemented, won't be called from scx_tg_offline(). This is because
SCX_HAS_OP(cgroupt_init) is used to test both whether SCX cgroup operations
are enabled and ops.cgroup_init() exists.

Fix it by introducing a separate bool scx_cgroup_enabled to gate cgroup
operations and use SCX_HAS_OP(cgroup_init) only to test whether
ops.cgroup_init() exists. Make all cgroup operations consistently use
scx_cgroup_enabled to test whether cgroup operations are enabled.
scx_cgroup_enabled is added instead of using scx_enabled() to ease planned
locking updates.

Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2024-09-27 10:02:40 -10:00
parent 4269c603cc
commit 568894edbe
1 changed files with 22 additions and 13 deletions
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35
kernel/sched/ext.c
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@ -3706,6 +3706,7 @@ bool scx_can_stop_tick(struct rq *rq)
#ifdef CONFIG_EXT_GROUP_SCHED
DEFINE_STATIC_PERCPU_RWSEM(scx_cgroup_rwsem);
static bool scx_cgroup_enabled;
static bool cgroup_warned_missing_weight;
static bool cgroup_warned_missing_idle;
@ -3725,8 +3726,7 @@ static void scx_cgroup_warn_missing_weight(struct task_group *tg)
static void scx_cgroup_warn_missing_idle(struct task_group *tg)
{
if (scx_ops_enable_state() == SCX_OPS_DISABLED ||
cgroup_warned_missing_idle)
if (!scx_cgroup_enabled || cgroup_warned_missing_idle)
return;
if (!tg->idle)
@ -3747,15 +3747,18 @@ int scx_tg_online(struct task_group *tg)
scx_cgroup_warn_missing_weight(tg);
if (SCX_HAS_OP(cgroup_init)) {
struct scx_cgroup_init_args args = { .weight = tg->scx_weight };
if (scx_cgroup_enabled) {
if (SCX_HAS_OP(cgroup_init)) {
struct scx_cgroup_init_args args =
{ .weight = tg->scx_weight };
ret = SCX_CALL_OP_RET(SCX_KF_UNLOCKED, cgroup_init,
tg->css.cgroup, &args);
if (!ret)
ret = SCX_CALL_OP_RET(SCX_KF_UNLOCKED, cgroup_init,
tg->css.cgroup, &args);
if (ret)
ret = ops_sanitize_err("cgroup_init", ret);
}
if (ret == 0)
tg->scx_flags |= SCX_TG_ONLINE | SCX_TG_INITED;
else
ret = ops_sanitize_err("cgroup_init", ret);
} else {
tg->scx_flags |= SCX_TG_ONLINE;
}
@ -3786,7 +3789,7 @@ int scx_cgroup_can_attach(struct cgroup_taskset *tset)
/* released in scx_finish/cancel_attach() */
percpu_down_read(&scx_cgroup_rwsem);
if (!scx_enabled())
if (!scx_cgroup_enabled)
return 0;
cgroup_taskset_for_each(p, css, tset) {
@ -3829,7 +3832,7 @@ err:
void scx_move_task(struct task_struct *p)
{
if (!scx_enabled())
if (!scx_cgroup_enabled)
return;
/*
@ -3865,7 +3868,7 @@ void scx_cgroup_cancel_attach(struct cgroup_taskset *tset)
struct cgroup_subsys_state *css;
struct task_struct *p;
if (!scx_enabled())
if (!scx_cgroup_enabled)
goto out_unlock;
cgroup_taskset_for_each(p, css, tset) {
@ -3882,7 +3885,7 @@ void scx_group_set_weight(struct task_group *tg, unsigned long weight)
{
percpu_down_read(&scx_cgroup_rwsem);
if (tg->scx_weight != weight) {
if (scx_cgroup_enabled && tg->scx_weight != weight) {
if (SCX_HAS_OP(cgroup_set_weight))
SCX_CALL_OP(SCX_KF_UNLOCKED, cgroup_set_weight,
tg_cgrp(tg), weight);
@ -4054,6 +4057,9 @@ static void scx_cgroup_exit(void)
percpu_rwsem_assert_held(&scx_cgroup_rwsem);
WARN_ON_ONCE(!scx_cgroup_enabled);
scx_cgroup_enabled = false;
/*
* scx_tg_on/offline() are excluded through scx_cgroup_rwsem. If we walk
* cgroups and exit all the inited ones, all online cgroups are exited.
@ -4129,6 +4135,9 @@ static int scx_cgroup_init(void)
}
rcu_read_unlock();
WARN_ON_ONCE(scx_cgroup_enabled);
scx_cgroup_enabled = true;
return 0;
}