Commit 5bb76f1d authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

sched: Simplify: migrate_swap_stop() 



Use guards to reduce gotos and simplify control flow.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarValentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20230801211811.964370836@infradead.org
parent 0f92cdf3

kernel/sched/core.c

+7 −16
Original line number Diff line number Diff line
@@ -3433,7 +3433,6 @@ static int migrate_swap_stop(void *data) 
{

	struct migration_swap_arg *arg = data;

	struct rq *src_rq, *dst_rq;

	int ret = -EAGAIN;



	if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))

		return -EAGAIN;
@@ -3441,33 +3440,25 @@ static int migrate_swap_stop(void *data) 
	src_rq = cpu_rq(arg->src_cpu);

	dst_rq = cpu_rq(arg->dst_cpu);



	double_raw_lock(&arg->src_task->pi_lock,

			&arg->dst_task->pi_lock);

	double_rq_lock(src_rq, dst_rq);

	guard(double_raw_spinlock)(&arg->src_task->pi_lock, &arg->dst_task->pi_lock);

	guard(double_rq_lock)(src_rq, dst_rq);



	if (task_cpu(arg->dst_task) != arg->dst_cpu)

		goto unlock;

		return -EAGAIN;



	if (task_cpu(arg->src_task) != arg->src_cpu)

		goto unlock;

		return -EAGAIN;



	if (!cpumask_test_cpu(arg->dst_cpu, arg->src_task->cpus_ptr))

		goto unlock;

		return -EAGAIN;



	if (!cpumask_test_cpu(arg->src_cpu, arg->dst_task->cpus_ptr))

		goto unlock;

		return -EAGAIN;



	__migrate_swap_task(arg->src_task, arg->dst_cpu);

	__migrate_swap_task(arg->dst_task, arg->src_cpu);



	ret = 0;



unlock:

	double_rq_unlock(src_rq, dst_rq);

	raw_spin_unlock(&arg->dst_task->pi_lock);

	raw_spin_unlock(&arg->src_task->pi_lock);



	return ret;

	return 0;

}



/*

kernel/sched/sched.h

+20 −0
Original line number Diff line number Diff line
@@ -2614,6 +2614,12 @@ static inline void double_rq_clock_clear_update(struct rq *rq1, struct rq *rq2) 
static inline void double_rq_clock_clear_update(struct rq *rq1, struct rq *rq2) {}

#endif



#define DEFINE_LOCK_GUARD_2(name, type, _lock, _unlock, ...)		\

__DEFINE_UNLOCK_GUARD(name, type, _unlock, type *lock2; __VA_ARGS__) \

static inline class_##name##_t class_##name##_constructor(type *lock, type *lock2) \

{ class_##name##_t _t = { .lock = lock, .lock2 = lock2 }, *_T = &_t;	\

  _lock; return _t; }



#ifdef CONFIG_SMP



static inline bool rq_order_less(struct rq *rq1, struct rq *rq2)
@@ -2743,6 +2749,16 @@ static inline void double_raw_lock(raw_spinlock_t *l1, raw_spinlock_t *l2) 
	raw_spin_lock_nested(l2, SINGLE_DEPTH_NESTING);

}



static inline void double_raw_unlock(raw_spinlock_t *l1, raw_spinlock_t *l2)

{

	raw_spin_unlock(l1);

	raw_spin_unlock(l2);

}



DEFINE_LOCK_GUARD_2(double_raw_spinlock, raw_spinlock_t,

		    double_raw_lock(_T->lock, _T->lock2),

		    double_raw_unlock(_T->lock, _T->lock2))



/*

 * double_rq_unlock - safely unlock two runqueues

 *
@@ -2800,6 +2816,10 @@ static inline void double_rq_unlock(struct rq *rq1, struct rq *rq2) 


#endif



DEFINE_LOCK_GUARD_2(double_rq_lock, struct rq,

		    double_rq_lock(_T->lock, _T->lock2),

		    double_rq_unlock(_T->lock, _T->lock2))



extern struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq);

extern struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq);