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Commit 7edc3e3b authored by Eric Anholt's avatar Eric Anholt
Browse files

drm: Add helpers for locking an array of BO reservations. 



Now that we have the reservation object in the GEM object, it's easy
to provide a helper for this common case.  Noticed while reviewing
panfrost and lima drivers.  This particular version came out of v3d,
which in turn was a copy from vc4.

v2: Fix kerneldoc warnings.

Signed-off-by: default avatarEric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20190308161716.2466-2-eric@anholt.net
Acked-by: Rob Herring <robh@kernel.org> (v1)
parent f435fe83

drivers/gpu/drm/drm_gem.c

+78 −0
Original line number Diff line number Diff line
@@ -1233,3 +1233,81 @@ void drm_gem_vunmap(struct drm_gem_object *obj, void *vaddr) 
		obj->dev->driver->gem_prime_vunmap(obj, vaddr);

}

EXPORT_SYMBOL(drm_gem_vunmap);



/**

 * drm_gem_lock_reservations - Sets up the ww context and acquires

 * the lock on an array of GEM objects.

 *

 * Once you've locked your reservations, you'll want to set up space

 * for your shared fences (if applicable), submit your job, then

 * drm_gem_unlock_reservations().

 *

 * @objs: drm_gem_objects to lock

 * @count: Number of objects in @objs

 * @acquire_ctx: struct ww_acquire_ctx that will be initialized as

 * part of tracking this set of locked reservations.

 */

int

drm_gem_lock_reservations(struct drm_gem_object **objs, int count,

			  struct ww_acquire_ctx *acquire_ctx)

{

	int contended = -1;

	int i, ret;



	ww_acquire_init(acquire_ctx, &reservation_ww_class);



retry:

	if (contended != -1) {

		struct drm_gem_object *obj = objs[contended];



		ret = ww_mutex_lock_slow_interruptible(&obj->resv->lock,

						       acquire_ctx);

		if (ret) {

			ww_acquire_done(acquire_ctx);

			return ret;

		}

	}



	for (i = 0; i < count; i++) {

		if (i == contended)

			continue;



		ret = ww_mutex_lock_interruptible(&objs[i]->resv->lock,

						  acquire_ctx);

		if (ret) {

			int j;



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

				ww_mutex_unlock(&objs[j]->resv->lock);



			if (contended != -1 && contended >= i)

				ww_mutex_unlock(&objs[contended]->resv->lock);



			if (ret == -EDEADLK) {

				contended = i;

				goto retry;

			}



			ww_acquire_done(acquire_ctx);

			return ret;

		}

	}



	ww_acquire_done(acquire_ctx);



	return 0;

}

EXPORT_SYMBOL(drm_gem_lock_reservations);



void

drm_gem_unlock_reservations(struct drm_gem_object **objs, int count,

			    struct ww_acquire_ctx *acquire_ctx)

{

	int i;



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

		ww_mutex_unlock(&objs[i]->resv->lock);



	ww_acquire_fini(acquire_ctx);

}

EXPORT_SYMBOL(drm_gem_unlock_reservations);

include/drm/drm_gem.h

+4 −0
Original line number Diff line number Diff line
@@ -384,6 +384,10 @@ void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages, 
struct drm_gem_object *drm_gem_object_lookup(struct drm_file *filp, u32 handle);

long drm_gem_reservation_object_wait(struct drm_file *filep, u32 handle,

				    bool wait_all, unsigned long timeout);

int drm_gem_lock_reservations(struct drm_gem_object **objs, int count,

			      struct ww_acquire_ctx *acquire_ctx);

void drm_gem_unlock_reservations(struct drm_gem_object **objs, int count,

				 struct ww_acquire_ctx *acquire_ctx);

int drm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,

			    u32 handle, u64 *offset);

int drm_gem_dumb_destroy(struct drm_file *file,