Commit 599089c6 authored by Rob Clark's avatar Rob Clark
Browse files

drm/msm/gem: Move locking in shrinker path 



Move grabbing the bo lock into shrinker, with a msm_gem_trylock() to
skip over bo's that are already locked.  This gets rid of the nested
lock classes.

Signed-off-by: default avatarRob Clark <robdclark@chromium.org>
Reviewed-by: default avatarKristian H. Kristensen <hoegsberg@google.com>
Signed-off-by: default avatarRob Clark <robdclark@chromium.org>
parent e4b87d22

drivers/gpu/drm/msm/msm_gem.c

+5 −19
Original line number Diff line number Diff line
@@ -18,8 +18,6 @@ 
#include "msm_gpu.h"

#include "msm_mmu.h"



static void msm_gem_vunmap_locked(struct drm_gem_object *obj);





static dma_addr_t physaddr(struct drm_gem_object *obj)

{
@@ -692,20 +690,19 @@ int msm_gem_madvise(struct drm_gem_object *obj, unsigned madv) 
	return (madv != __MSM_MADV_PURGED);

}



void msm_gem_purge(struct drm_gem_object *obj, enum msm_gem_lock subclass)

void msm_gem_purge(struct drm_gem_object *obj)

{

	struct drm_device *dev = obj->dev;

	struct msm_gem_object *msm_obj = to_msm_bo(obj);



	WARN_ON(!mutex_is_locked(&dev->struct_mutex));

	WARN_ON(!msm_gem_is_locked(obj));

	WARN_ON(!is_purgeable(msm_obj));

	WARN_ON(obj->import_attach);



	mutex_lock_nested(&msm_obj->lock, subclass);



	put_iova(obj);



	msm_gem_vunmap_locked(obj);

	msm_gem_vunmap(obj);



	put_pages(obj);
@@ -723,11 +720,9 @@ void msm_gem_purge(struct drm_gem_object *obj, enum msm_gem_lock subclass) 


	invalidate_mapping_pages(file_inode(obj->filp)->i_mapping,

			0, (loff_t)-1);



	msm_gem_unlock(obj);

}



static void msm_gem_vunmap_locked(struct drm_gem_object *obj)

void msm_gem_vunmap(struct drm_gem_object *obj)

{

	struct msm_gem_object *msm_obj = to_msm_bo(obj);
@@ -740,15 +735,6 @@ static void msm_gem_vunmap_locked(struct drm_gem_object *obj) 
	msm_obj->vaddr = NULL;

}



void msm_gem_vunmap(struct drm_gem_object *obj, enum msm_gem_lock subclass)

{

	struct msm_gem_object *msm_obj = to_msm_bo(obj);



	mutex_lock_nested(&msm_obj->lock, subclass);

	msm_gem_vunmap_locked(obj);

	msm_gem_unlock(obj);

}



/* must be called before _move_to_active().. */

int msm_gem_sync_object(struct drm_gem_object *obj,

		struct msm_fence_context *fctx, bool exclusive)
@@ -985,7 +971,7 @@ static void free_object(struct msm_gem_object *msm_obj) 


		drm_prime_gem_destroy(obj, msm_obj->sgt);

	} else {

		msm_gem_vunmap_locked(obj);

		msm_gem_vunmap(obj);

		put_pages(obj);

	}

drivers/gpu/drm/msm/msm_gem.h

+11 −18
Original line number Diff line number Diff line
@@ -162,6 +162,13 @@ msm_gem_lock(struct drm_gem_object *obj) 
	mutex_lock(&msm_obj->lock);

}



static inline bool __must_check

msm_gem_trylock(struct drm_gem_object *obj)

{

	struct msm_gem_object *msm_obj = to_msm_bo(obj);

	return mutex_trylock(&msm_obj->lock) == 1;

}



static inline int

msm_gem_lock_interruptible(struct drm_gem_object *obj)

{
@@ -190,6 +197,7 @@ static inline bool is_active(struct msm_gem_object *msm_obj) 


static inline bool is_purgeable(struct msm_gem_object *msm_obj)

{

	WARN_ON(!msm_gem_is_locked(&msm_obj->base));

	WARN_ON(!mutex_is_locked(&msm_obj->base.dev->struct_mutex));

	return (msm_obj->madv == MSM_MADV_DONTNEED) && msm_obj->sgt &&

			!msm_obj->base.dma_buf && !msm_obj->base.import_attach;
@@ -197,27 +205,12 @@ static inline bool is_purgeable(struct msm_gem_object *msm_obj) 


static inline bool is_vunmapable(struct msm_gem_object *msm_obj)

{

	WARN_ON(!msm_gem_is_locked(&msm_obj->base));

	return (msm_obj->vmap_count == 0) && msm_obj->vaddr;

}



/* The shrinker can be triggered while we hold objA->lock, and need

 * to grab objB->lock to purge it.  Lockdep just sees these as a single

 * class of lock, so we use subclasses to teach it the difference.

 *

 * OBJ_LOCK_NORMAL is implicit (ie. normal mutex_lock() call), and

 * OBJ_LOCK_SHRINKER is used by shrinker.

 *

 * It is *essential* that we never go down paths that could trigger the

 * shrinker for a purgable object.  This is ensured by checking that

 * msm_obj->madv == MSM_MADV_WILLNEED.

 */

enum msm_gem_lock {

	OBJ_LOCK_NORMAL,

	OBJ_LOCK_SHRINKER,

};



void msm_gem_purge(struct drm_gem_object *obj, enum msm_gem_lock subclass);

void msm_gem_vunmap(struct drm_gem_object *obj, enum msm_gem_lock subclass);

void msm_gem_purge(struct drm_gem_object *obj);

void msm_gem_vunmap(struct drm_gem_object *obj);

void msm_gem_free_work(struct work_struct *work);



/* Created per submit-ioctl, to track bo's and cmdstream bufs, etc,

drivers/gpu/drm/msm/msm_gem_shrinker.c

+19 −8
Original line number Diff line number Diff line
@@ -52,8 +52,11 @@ msm_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc) 
		return 0;



	list_for_each_entry(msm_obj, &priv->inactive_list, mm_list) {

		if (!msm_gem_trylock(&msm_obj->base))

			continue;

		if (is_purgeable(msm_obj))

			count += msm_obj->base.size >> PAGE_SHIFT;

		msm_gem_unlock(&msm_obj->base);

	}



	if (unlock)
@@ -78,10 +81,13 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) 
	list_for_each_entry(msm_obj, &priv->inactive_list, mm_list) {

		if (freed >= sc->nr_to_scan)

			break;

		if (!msm_gem_trylock(&msm_obj->base))

			continue;

		if (is_purgeable(msm_obj)) {

			msm_gem_purge(&msm_obj->base, OBJ_LOCK_SHRINKER);

			msm_gem_purge(&msm_obj->base);

			freed += msm_obj->base.size >> PAGE_SHIFT;

		}

		msm_gem_unlock(&msm_obj->base);

	}



	if (unlock)
@@ -107,8 +113,14 @@ msm_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr) 
		return NOTIFY_DONE;



	list_for_each_entry(msm_obj, &priv->inactive_list, mm_list) {

		if (!msm_gem_trylock(&msm_obj->base))

			continue;

		if (is_vunmapable(msm_obj)) {

			msm_gem_vunmap(&msm_obj->base, OBJ_LOCK_SHRINKER);

			msm_gem_vunmap(&msm_obj->base);

			unmapped++;

		}

		msm_gem_unlock(&msm_obj->base);



		/* since we don't know any better, lets bail after a few

		 * and if necessary the shrinker will be invoked again.

		 * Seems better than unmapping *everything*
@@ -116,7 +128,6 @@ msm_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr) 
		if (++unmapped >= 15)

			break;

	}

	}



	if (unlock)

		mutex_unlock(&dev->struct_mutex);