From 7edc3e3b975b5b3b1de313f43670738acbcc8e1d Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Fri, 8 Mar 2019 08:17:13 -0800 Subject: [PATCH] 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: Eric Anholt Link: https://patchwork.freedesktop.org/patch/msgid/20190308161716.2466-2-eric@anholt.net Acked-by: Rob Herring (v1) --- drivers/gpu/drm/drm_gem.c | 78 +++++++++++++++++++++++++++++++++++++++ include/drm/drm_gem.h | 4 ++ 2 files changed, 82 insertions(+) diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index ad124f5a6f4d..388b3742e562 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -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); diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index 25f1ff2df464..2955aaab3dca 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -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, -- 2.39.5