From 772b6539fdda31462cc08368e78df60b31a58bab Mon Sep 17 00:00:00 2001
From: Dietmar Eggemann <dietmar.eggemann@arm.com>
Date: Wed, 2 Mar 2022 19:34:30 +0100
Subject: [PATCH] sched/deadline: Merge dl_task_can_attach() and dl_cpu_busy()
Git-commit: 772b6539fdda31462cc08368e78df60b31a58bab
Patch-mainline: v5.18-rc1
References: git-fixes
Both functions are doing almost the same, that is checking if admission
control is still respected.
With exclusive cpusets, dl_task_can_attach() checks if the destination
cpuset (i.e. its root domain) has enough CPU capacity to accommodate the
task.
dl_cpu_busy() checks if there is enough CPU capacity in the cpuset in
case the CPU is hot-plugged out.
dl_task_can_attach() is used to check if a task can be admitted while
dl_cpu_busy() is used to check if a CPU can be hotplugged out.
Make dl_cpu_busy() able to deal with a task and use it instead of
dl_task_can_attach() in task_can_attach().
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20220302183433.333029-4-dietmar.eggemann@arm.com
Signed-off-by: Frederic Weisbecker <fweisbecker@suse.com>
---
kernel/sched/core.c | 13 +++++++----
kernel/sched/deadline.c | 52 +++++++++++------------------------------
kernel/sched/sched.h | 3 +--
3 files changed, 24 insertions(+), 44 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d342c4c779f7..68736d1dc0f4 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8805,8 +8805,11 @@ int task_can_attach(struct task_struct *p,
}
if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
- cs_cpus_allowed))
- ret = dl_task_can_attach(p, cs_cpus_allowed);
+ cs_cpus_allowed)) {
+ int cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed);
+
+ ret = dl_cpu_busy(cpu, p);
+ }
out:
return ret;
@@ -9090,8 +9093,10 @@ static void cpuset_cpu_active(void)
static int cpuset_cpu_inactive(unsigned int cpu)
{
if (!cpuhp_tasks_frozen) {
- if (dl_cpu_busy(cpu))
- return -EBUSY;
+ int ret = dl_cpu_busy(cpu, NULL);
+
+ if (ret)
+ return ret;
cpuset_update_active_cpus();
} else {
num_cpus_frozen++;
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 81bf97648e42..de677b1e3767 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2992,41 +2992,6 @@ bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)
}
#ifdef CONFIG_SMP
-int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed)
-{
- unsigned long flags, cap;
- unsigned int dest_cpu;
- struct dl_bw *dl_b;
- bool overflow;
- int ret;
-
- dest_cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed);
-
- rcu_read_lock_sched();
- dl_b = dl_bw_of(dest_cpu);
- raw_spin_lock_irqsave(&dl_b->lock, flags);
- cap = dl_bw_capacity(dest_cpu);
- overflow = __dl_overflow(dl_b, cap, 0, p->dl.dl_bw);
- if (overflow) {
- ret = -EBUSY;
- } else {
- /*
- * We reserve space for this task in the destination
- * root_domain, as we can't fail after this point.
- * We will free resources in the source root_domain
- * later on (see set_cpus_allowed_dl()).
- */
- int cpus = dl_bw_cpus(dest_cpu);
-
- __dl_add(dl_b, p->dl.dl_bw, cpus);
- ret = 0;
- }
- raw_spin_unlock_irqrestore(&dl_b->lock, flags);
- rcu_read_unlock_sched();
-
- return ret;
-}
-
int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,
const struct cpumask *trial)
{
@@ -3048,7 +3013,7 @@ int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,
return ret;
}
-bool dl_cpu_busy(unsigned int cpu)
+int dl_cpu_busy(int cpu, struct task_struct *p)
{
unsigned long flags, cap;
struct dl_bw *dl_b;
@@ -3058,11 +3023,22 @@ bool dl_cpu_busy(unsigned int cpu)
dl_b = dl_bw_of(cpu);
raw_spin_lock_irqsave(&dl_b->lock, flags);
cap = dl_bw_capacity(cpu);
- overflow = __dl_overflow(dl_b, cap, 0, 0);
+ overflow = __dl_overflow(dl_b, cap, 0, p ? p->dl.dl_bw : 0);
+
+ if (!overflow && p) {
+ /*
+ * We reserve space for this task in the destination
+ * root_domain, as we can't fail after this point.
+ * We will free resources in the source root_domain
+ * later on (see set_cpus_allowed_dl()).
+ */
+ __dl_add(dl_b, p->dl.dl_bw, dl_bw_cpus(cpu));
+ }
+
raw_spin_unlock_irqrestore(&dl_b->lock, flags);
rcu_read_unlock_sched();
- return overflow;
+ return overflow ? -EBUSY : 0;
}
#endif
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 4dfc3b02df61..0720cf0c7df1 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -324,9 +324,8 @@ extern void __setparam_dl(struct task_struct *p, const struct sched_attr *attr);
extern void __getparam_dl(struct task_struct *p, struct sched_attr *attr);
extern bool __checkparam_dl(const struct sched_attr *attr);
extern bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr);
-extern int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed);
extern int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct cpumask *trial);
-extern bool dl_cpu_busy(unsigned int cpu);
+extern int dl_cpu_busy(int cpu, struct task_struct *p);
#ifdef CONFIG_CGROUP_SCHED
--
2.34.1