Commit 02070f04 authored by Rob Clark's avatar Rob Clark
Browse files

drm/gem: Add ww_acquire_ctx support to drm_gem_lru_scan() 



If the callback is going to have to attempt to grab more locks, it is
useful to have an ww_acquire_ctx to avoid locking order problems.

Why not use the drm_exec helper instead?  Mainly because (a) where
ww_acquire_init() is called is awkward, and (b) we don't really
need to retry after backoff, we can just move on to the next object.

Signed-off-by: default avatarRob Clark <robdclark@chromium.org>
Signed-off-by: default avatarRob Clark <robin.clark@oss.qualcomm.com>
Tested-by: default avatarAntonino Maniscalco <antomani103@gmail.com>
Reviewed-by: default avatarAntonino Maniscalco <antomani103@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/661463/
parent 471920ce

drivers/gpu/drm/drm_gem.c

+11 −3
Original line number Diff line number Diff line
@@ -1429,12 +1429,14 @@ EXPORT_SYMBOL(drm_gem_lru_move_tail); 
 * @nr_to_scan: The number of pages to try to reclaim

 * @remaining: The number of pages left to reclaim, should be initialized by caller

 * @shrink: Callback to try to shrink/reclaim the object.

 * @ticket: Optional ww_acquire_ctx context to use for locking

 */

unsigned long

drm_gem_lru_scan(struct drm_gem_lru *lru,

		 unsigned int nr_to_scan,

		 unsigned long *remaining,

		 bool (*shrink)(struct drm_gem_object *obj))

		 bool (*shrink)(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket),

		 struct ww_acquire_ctx *ticket)

{

	struct drm_gem_lru still_in_lru;

	struct drm_gem_object *obj;
@@ -1467,17 +1469,20 @@ drm_gem_lru_scan(struct drm_gem_lru *lru, 
		 */

		mutex_unlock(lru->lock);



		if (ticket)

			ww_acquire_init(ticket, &reservation_ww_class);



		/*

		 * Note that this still needs to be trylock, since we can

		 * hit shrinker in response to trying to get backing pages

		 * for this obj (ie. while it's lock is already held)

		 */

		if (!dma_resv_trylock(obj->resv)) {

		if (!ww_mutex_trylock(&obj->resv->lock, ticket)) {

			*remaining += obj->size >> PAGE_SHIFT;

			goto tail;

		}



		if (shrink(obj)) {

		if (shrink(obj, ticket)) {

			freed += obj->size >> PAGE_SHIFT;



			/*
@@ -1491,6 +1496,9 @@ drm_gem_lru_scan(struct drm_gem_lru *lru, 


		dma_resv_unlock(obj->resv);



		if (ticket)

			ww_acquire_fini(ticket);



tail:

		drm_gem_object_put(obj);

		mutex_lock(lru->lock);

drivers/gpu/drm/msm/msm_gem_shrinker.c

+13 −11
Original line number Diff line number Diff line
@@ -44,7 +44,7 @@ msm_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc) 
}



static bool

purge(struct drm_gem_object *obj)

purge(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket)

{

	if (!is_purgeable(to_msm_bo(obj)))

		return false;
@@ -58,7 +58,7 @@ purge(struct drm_gem_object *obj) 
}



static bool

evict(struct drm_gem_object *obj)

evict(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket)

{

	if (is_unevictable(to_msm_bo(obj)))

		return false;
@@ -79,21 +79,21 @@ wait_for_idle(struct drm_gem_object *obj) 
}



static bool

active_purge(struct drm_gem_object *obj)

active_purge(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket)

{

	if (!wait_for_idle(obj))

		return false;



	return purge(obj);

	return purge(obj, ticket);

}



static bool

active_evict(struct drm_gem_object *obj)

active_evict(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket)

{

	if (!wait_for_idle(obj))

		return false;



	return evict(obj);

	return evict(obj, ticket);

}



static unsigned long
@@ -102,7 +102,7 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) 
	struct msm_drm_private *priv = shrinker->private_data;

	struct {

		struct drm_gem_lru *lru;

		bool (*shrink)(struct drm_gem_object *obj);

		bool (*shrink)(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket);

		bool cond;

		unsigned long freed;

		unsigned long remaining;
@@ -123,7 +123,8 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) 
		stages[i].freed =

			drm_gem_lru_scan(stages[i].lru, nr,

					 &stages[i].remaining,

					 stages[i].shrink);

					 stages[i].shrink,

					 NULL);

		nr -= stages[i].freed;

		freed += stages[i].freed;

		remaining += stages[i].remaining;
@@ -164,7 +165,7 @@ msm_gem_shrinker_shrink(struct drm_device *dev, unsigned long nr_to_scan) 
static const int vmap_shrink_limit = 15;



static bool

vmap_shrink(struct drm_gem_object *obj)

vmap_shrink(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket)

{

	if (!is_vunmapable(to_msm_bo(obj)))

		return false;
@@ -192,7 +193,8 @@ msm_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr) 
		unmapped += drm_gem_lru_scan(lrus[idx],

					     vmap_shrink_limit - unmapped,

					     &remaining,

					     vmap_shrink);

					     vmap_shrink,

					     NULL);

	}



	*(unsigned long *)ptr += unmapped;

include/drm/drm_gem.h

+6 −4
Original line number Diff line number Diff line
@@ -560,10 +560,12 @@ void drm_gem_lru_init(struct drm_gem_lru *lru, struct mutex *lock); 
void drm_gem_lru_remove(struct drm_gem_object *obj);

void drm_gem_lru_move_tail_locked(struct drm_gem_lru *lru, struct drm_gem_object *obj);

void drm_gem_lru_move_tail(struct drm_gem_lru *lru, struct drm_gem_object *obj);

unsigned long drm_gem_lru_scan(struct drm_gem_lru *lru,

unsigned long

drm_gem_lru_scan(struct drm_gem_lru *lru,

		 unsigned int nr_to_scan,

		 unsigned long *remaining,

			       bool (*shrink)(struct drm_gem_object *obj));

		 bool (*shrink)(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket),

		 struct ww_acquire_ctx *ticket);



int drm_gem_evict_locked(struct drm_gem_object *obj);