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sched: Pass correct scheduling policy to __setscheduler_class

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Commit 98442f0ccd ("sched: Fix delayed_dequeue vs
switched_from_fair()") overlooked that __setscheduler_prio(), now
__setscheduler_class() relies on p->policy for task_should_scx(), and
moved the call before __setscheduler_params() updates it, causing it
to be using the old p->policy value.

Resolve this by changing task_should_scx() to take the policy itself
instead of a task pointer, such that __sched_setscheduler() can pass
in the updated policy.

Fixes: 98442f0ccd ("sched: Fix delayed_dequeue vs switched_from_fair()")
Signed-off-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Aboorva Devarajan 2024-10-26 00:20:20 +05:30 committed by Peter Zijlstra
parent 9c70b2a33c
commit 5db91545ef
5 changed files with 11 additions and 11 deletions
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8
kernel/sched/core.c
View File

@ -4711,7 +4711,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
if (rt_prio(p->prio)) {
p->sched_class = &rt_sched_class;
#ifdef CONFIG_SCHED_CLASS_EXT
} else if (task_should_scx(p)) {
} else if (task_should_scx(p->policy)) {
p->sched_class = &ext_sched_class;
#endif
} else {
@ -7025,7 +7025,7 @@ int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flag
}
EXPORT_SYMBOL(default_wake_function);
const struct sched_class *__setscheduler_class(struct task_struct *p, int prio)
const struct sched_class *__setscheduler_class(int policy, int prio)
{
if (dl_prio(prio))
return &dl_sched_class;
@ -7034,7 +7034,7 @@ const struct sched_class *__setscheduler_class(struct task_struct *p, int prio)
return &rt_sched_class;
#ifdef CONFIG_SCHED_CLASS_EXT
if (task_should_scx(p))
if (task_should_scx(policy))
return &ext_sched_class;
#endif
@ -7142,7 +7142,7 @@ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
queue_flag &= ~DEQUEUE_MOVE;
prev_class = p->sched_class;
next_class = __setscheduler_class(p, prio);
next_class = __setscheduler_class(p->policy, prio);
if (prev_class != next_class && p->se.sched_delayed)
dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK);

8
kernel/sched/ext.c
View File

@ -4256,14 +4256,14 @@ static const struct kset_uevent_ops scx_uevent_ops = {
* Used by sched_fork() and __setscheduler_prio() to pick the matching
* sched_class. dl/rt are already handled.
*/
bool task_should_scx(struct task_struct *p)
bool task_should_scx(int policy)
{
if (!scx_enabled() ||
unlikely(scx_ops_enable_state() == SCX_OPS_DISABLING))
return false;
if (READ_ONCE(scx_switching_all))
return true;
return p->policy == SCHED_EXT;
return policy == SCHED_EXT;
}
/**
@ -4493,7 +4493,7 @@ static void scx_ops_disable_workfn(struct kthread_work *work)
sched_deq_and_put_task(p, DEQUEUE_SAVE | DEQUEUE_MOVE, &ctx);
p->sched_class = __setscheduler_class(p, p->prio);
p->sched_class = __setscheduler_class(p->policy, p->prio);
check_class_changing(task_rq(p), p, old_class);
sched_enq_and_set_task(&ctx);
@ -5204,7 +5204,7 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link)
sched_deq_and_put_task(p, DEQUEUE_SAVE | DEQUEUE_MOVE, &ctx);
p->scx.slice = SCX_SLICE_DFL;
p->sched_class = __setscheduler_class(p, p->prio);
p->sched_class = __setscheduler_class(p->policy, p->prio);
check_class_changing(task_rq(p), p, old_class);
sched_enq_and_set_task(&ctx);

2
kernel/sched/ext.h
View File

@ -18,7 +18,7 @@ bool scx_can_stop_tick(struct rq *rq);
void scx_rq_activate(struct rq *rq);
void scx_rq_deactivate(struct rq *rq);
int scx_check_setscheduler(struct task_struct *p, int policy);
bool task_should_scx(struct task_struct *p);
bool task_should_scx(int policy);
void init_sched_ext_class(void);
static inline u32 scx_cpuperf_target(s32 cpu)

2
kernel/sched/sched.h
View File

@ -3830,7 +3830,7 @@ static inline int rt_effective_prio(struct task_struct *p, int prio)
extern int __sched_setscheduler(struct task_struct *p, const struct sched_attr *attr, bool user, bool pi);
extern int __sched_setaffinity(struct task_struct *p, struct affinity_context *ctx);
extern const struct sched_class *__setscheduler_class(struct task_struct *p, int prio);
extern const struct sched_class *__setscheduler_class(int policy, int prio);
extern void set_load_weight(struct task_struct *p, bool update_load);
extern void enqueue_task(struct rq *rq, struct task_struct *p, int flags);
extern bool dequeue_task(struct rq *rq, struct task_struct *p, int flags);

2
kernel/sched/syscalls.c
View File

@ -707,7 +707,7 @@ change:
}
prev_class = p->sched_class;
next_class = __setscheduler_class(p, newprio);
next_class = __setscheduler_class(policy, newprio);
if (prev_class != next_class && p->se.sched_delayed)
dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK);