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Commit 15689c3c authored by Ben Skeggs's avatar Ben Skeggs
Browse files

drm/nouveau/core: split lock into list+exec and enable refcount locks 



This fixes a reported locking inversion when interacting with the DRM
core's vblank routines.

Reviewed-by: default avatarMaarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: default avatarBen Skeggs <bskeggs@redhat.com>
parent 51cb4b39

drivers/gpu/drm/nouveau/core/core/event.c

+32 −29
Original line number Diff line number Diff line
@@ -23,27 +23,19 @@ 
#include <core/os.h>

#include <core/event.h>



static void

nouveau_event_put_locked(struct nouveau_event *event, int index,

			 struct nouveau_eventh *handler)

{

	if (__test_and_clear_bit(NVKM_EVENT_ENABLE, &handler->flags)) {

		if (!--event->index[index].refs) {

			if (event->disable)

				event->disable(event, index);

		}

		list_del(&handler->head);

	}

}



void

nouveau_event_put(struct nouveau_eventh *handler)

{

	struct nouveau_event *event = handler->event;

	unsigned long flags;

	spin_lock_irqsave(&event->lock, flags);

	nouveau_event_put_locked(handler->event, handler->index, handler);

	spin_unlock_irqrestore(&event->lock, flags);

	if (__test_and_clear_bit(NVKM_EVENT_ENABLE, &handler->flags)) {

		spin_lock_irqsave(&event->refs_lock, flags);

		if (!--event->index[handler->index].refs) {

			if (event->disable)

				event->disable(event, handler->index);

		}

		spin_unlock_irqrestore(&event->refs_lock, flags);

	}

}



void
@@ -51,22 +43,25 @@ nouveau_event_get(struct nouveau_eventh *handler) 
{

	struct nouveau_event *event = handler->event;

	unsigned long flags;



	spin_lock_irqsave(&event->lock, flags);

	if (!__test_and_set_bit(NVKM_EVENT_ENABLE, &handler->flags)) {

		list_add(&handler->head, &event->index[handler->index].list);

		spin_lock_irqsave(&event->refs_lock, flags);

		if (!event->index[handler->index].refs++) {

			if (event->enable)

				event->enable(event, handler->index);

		}

		spin_unlock_irqrestore(&event->refs_lock, flags);

	}

	spin_unlock_irqrestore(&event->lock, flags);

}



static void

nouveau_event_fini(struct nouveau_eventh *handler)

{

	struct nouveau_event *event = handler->event;

	unsigned long flags;

	nouveau_event_put(handler);

	spin_lock_irqsave(&event->list_lock, flags);

	list_del(&handler->head);

	spin_unlock_irqrestore(&event->list_lock, flags);

}



static int
@@ -74,13 +69,20 @@ nouveau_event_init(struct nouveau_event *event, int index, 
		   int (*func)(void *, int), void *priv,

		   struct nouveau_eventh *handler)

{

	unsigned long flags;



	if (index >= event->index_nr)

		return -EINVAL;



	handler->event = event;

	handler->flags = 0;

	handler->index = index;

	handler->func = func;

	handler->priv = priv;



	spin_lock_irqsave(&event->list_lock, flags);

	list_add_tail(&handler->head, &event->index[index].list);

	spin_unlock_irqrestore(&event->list_lock, flags);

	return 0;

}
@@ -116,19 +118,19 @@ nouveau_event_ref(struct nouveau_eventh *handler, struct nouveau_eventh **ref) 
void

nouveau_event_trigger(struct nouveau_event *event, int index)

{

	struct nouveau_eventh *handler, *temp;

	struct nouveau_eventh *handler;

	unsigned long flags;



	if (index >= event->index_nr)

	if (WARN_ON(index >= event->index_nr))

		return;



	spin_lock_irqsave(&event->lock, flags);

	list_for_each_entry_safe(handler, temp, &event->index[index].list, head) {

		if (handler->func(handler->priv, index) == NVKM_EVENT_DROP) {

			nouveau_event_put_locked(event, index, handler);

		}

	spin_lock_irqsave(&event->list_lock, flags);

	list_for_each_entry(handler, &event->index[index].list, head) {

		if (test_bit(NVKM_EVENT_ENABLE, &handler->flags) &&

		    handler->func(handler->priv, index) == NVKM_EVENT_DROP)

			nouveau_event_put(handler);

	}

	spin_unlock_irqrestore(&event->lock, flags);

	spin_unlock_irqrestore(&event->list_lock, flags);

}



void
@@ -152,7 +154,8 @@ nouveau_event_create(int index_nr, struct nouveau_event **pevent) 
	if (!event)

		return -ENOMEM;



	spin_lock_init(&event->lock);

	spin_lock_init(&event->list_lock);

	spin_lock_init(&event->refs_lock);

	for (i = 0; i < index_nr; i++)

		INIT_LIST_HEAD(&event->index[i].list);

	event->index_nr = index_nr;

drivers/gpu/drm/nouveau/core/include/core/event.h

+2 −1
Original line number Diff line number Diff line
@@ -18,7 +18,8 @@ struct nouveau_eventh { 
};



struct nouveau_event {

	spinlock_t lock;

	spinlock_t list_lock;

	spinlock_t refs_lock;



	void *priv;

	void (*enable)(struct nouveau_event *, int index);