[PATCH 6.6 031/396] sched: Simplify tg_set_cfs_bandwidth()

Greg Kroah-Hartman
2024-04-01T16:37:54Z

From: Peter Zijlstra <peterz@infradead.org>

[ Upstream commit 6fb45460615358157a6d3c990e74f9c1395247e2 ]

Use guards to reduce gotos and simplify control flow.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Stable-dep-of: 1aa09b9379a7 ("powercap: intel_rapl: Fix locking in TPMI RAPL")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/cpu.h | 2 ++
kernel/sched/core.c | 38 +++++++++++++++++++-------------------
2 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 59dd421a8e35d..e990c180282e7 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -157,6 +157,8 @@ static inline int remove_cpu(unsigned int cpu) { return -EPERM; }
static inline void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) { }
#endif /* !CONFIG_HOTPLUG_CPU */

+DEFINE_LOCK_GUARD_0(cpus_read_lock, cpus_read_lock(), cpus_read_unlock())
+
#ifdef CONFIG_PM_SLEEP_SMP
extern int freeze_secondary_cpus(int primary);
extern void thaw_secondary_cpus(void);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a854b71836dd5..1f91e2c12731e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -10868,11 +10868,12 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota,
* Prevent race between setting of cfs_rq->runtime_enabled and
* unthrottle_offline_cfs_rqs().
*/
- cpus_read_lock();
- mutex_lock(&cfs_constraints_mutex);
+ guard(cpus_read_lock)();
+ guard(mutex)(&cfs_constraints_mutex);
+
ret = __cfs_schedulable(tg, period, quota);
if (ret)
- goto out_unlock;
+ return ret;

runtime_enabled = quota != RUNTIME_INF;
runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
@@ -10882,39 +10883,38 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota,
*/
if (runtime_enabled && !runtime_was_enabled)
cfs_bandwidth_usage_inc();
- raw_spin_lock_irq(&cfs_b->lock);
- cfs_b->period = ns_to_ktime(period);
- cfs_b->quota = quota;
- cfs_b->burst = burst;

- __refill_cfs_bandwidth_runtime(cfs_b);
+ scoped_guard (raw_spinlock_irq, &cfs_b->lock) {
+ cfs_b->period = ns_to_ktime(period);
+ cfs_b->quota = quota;
+ cfs_b->burst = burst;

- /* Restart the period timer (if active) to handle new period expiry: */
- if (runtime_enabled)
- start_cfs_bandwidth(cfs_b);
+ __refill_cfs_bandwidth_runtime(cfs_b);

- raw_spin_unlock_irq(&cfs_b->lock);
+ /*
+ * Restart the period timer (if active) to handle new
+ * period expiry:
+ */
+ if (runtime_enabled)
+ start_cfs_bandwidth(cfs_b);
+ }

for_each_online_cpu(i) {
struct cfs_rq *cfs_rq = tg->cfs_rq[i];
struct rq *rq = cfs_rq->rq;
- struct rq_flags rf;

- rq_lock_irq(rq, &rf);
+ guard(rq_lock_irq)(rq);
cfs_rq->runtime_enabled = runtime_enabled;
cfs_rq->runtime_remaining = 0;

if (cfs_rq->throttled)
unthrottle_cfs_rq(cfs_rq);
- rq_unlock_irq(rq, &rf);
}
+
if (runtime_was_enabled && !runtime_enabled)
cfs_bandwidth_usage_dec();
-out_unlock:
- mutex_unlock(&cfs_constraints_mutex);
- cpus_read_unlock();

- return ret;
+ return 0;
}

static int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
--
2.43.0