Commit 875feb41 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

sched: Allow sched_core_put() from atomic context 



Stuff the meat of sched_core_put() into a work such that we can use
sched_core_put() from atomic context.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarDon Hiatt <dhiatt@digitalocean.com>
Tested-by: default avatarHongyu Ning <hongyu.ning@linux.intel.com>
Tested-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20210422123308.377455632@infradead.org
parent 9ef7e7e3

kernel/sched/core.c

+27 −6
Original line number Diff line number Diff line
@@ -102,7 +102,7 @@ DEFINE_STATIC_KEY_FALSE(__sched_core_enabled); 
 */



static DEFINE_MUTEX(sched_core_mutex);

static int sched_core_count;

static atomic_t sched_core_count;

static struct cpumask sched_core_mask;



static void __sched_core_flip(bool enabled)
@@ -170,19 +170,40 @@ static void __sched_core_disable(void) 


void sched_core_get(void)

{

	if (atomic_inc_not_zero(&sched_core_count))

		return;



	mutex_lock(&sched_core_mutex);

	if (!sched_core_count++)

	if (!atomic_read(&sched_core_count))

		__sched_core_enable();



	smp_mb__before_atomic();

	atomic_inc(&sched_core_count);

	mutex_unlock(&sched_core_mutex);

}



void sched_core_put(void)

static void __sched_core_put(struct work_struct *work)

{

	mutex_lock(&sched_core_mutex);

	if (!--sched_core_count)

	if (atomic_dec_and_mutex_lock(&sched_core_count, &sched_core_mutex)) {

		__sched_core_disable();

		mutex_unlock(&sched_core_mutex);

	}

}



void sched_core_put(void)

{

	static DECLARE_WORK(_work, __sched_core_put);



	/*

	 * "There can be only one"

	 *

	 * Either this is the last one, or we don't actually need to do any

	 * 'work'. If it is the last *again*, we rely on

	 * WORK_STRUCT_PENDING_BIT.

	 */

	if (!atomic_add_unless(&sched_core_count, -1, 1))

		schedule_work(&_work);

}



#endif /* CONFIG_SCHED_CORE */