It is useful in certain circumstances to know when the fence is replaced in a syncobj. Specifically, it may be useful to know when the fence goes from NULL to something valid. This does make syncobj_replace_fence a little more expensive because it has to take a lock but, in the common case where there is no callback list, it spends a very short amount of time inside the lock.
v2: - Don't lock in drm_syncobj_fence_get. We only really need to lock around fence_replace to make the callback work.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net --- drivers/gpu/drm/drm_syncobj.c | 60 +++++++++++++++++++++++++++++++++++++++++-- include/drm/drm_syncobj.h | 39 ++++++++++++++++++++++++++++ 2 files changed, 97 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c index 4e8563c..bade497 100644 --- a/drivers/gpu/drm/drm_syncobj.c +++ b/drivers/gpu/drm/drm_syncobj.c @@ -80,6 +80,46 @@ struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private, } EXPORT_SYMBOL(drm_syncobj_find);
+static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj, + struct drm_syncobj_cb *cb, + drm_syncobj_func_t func) +{ + cb->func = func; + list_add_tail(&cb->node, &syncobj->cb_list); +} + +/** + * drm_syncobj_add_callback - adds a callback to syncobj::cb_list + * @syncobj: Sync object to which to add the callback + * @cb: Callback to add + * @func: Func to use when initializing the drm_syncobj_cb struct + * + * This adds a callback to be called next time the fence is replaced + */ +void drm_syncobj_add_callback(struct drm_syncobj *syncobj, + struct drm_syncobj_cb *cb, + drm_syncobj_func_t func) +{ + spin_lock(&syncobj->lock); + drm_syncobj_add_callback_locked(syncobj, cb, func); + spin_unlock(&syncobj->lock); +} +EXPORT_SYMBOL(drm_syncobj_add_callback); + +/** + * drm_syncobj_add_callback - removes a callback to syncobj::cb_list + * @syncobj: Sync object from which to remove the callback + * @cb: Callback to remove + */ +void drm_syncobj_remove_callback(struct drm_syncobj *syncobj, + struct drm_syncobj_cb *cb) +{ + spin_lock(&syncobj->lock); + list_del_init(&cb->node); + spin_unlock(&syncobj->lock); +} +EXPORT_SYMBOL(drm_syncobj_remove_callback); + /** * drm_syncobj_replace_fence - replace fence in a sync object. * @syncobj: Sync object to replace fence in @@ -91,10 +131,24 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj, struct dma_fence *fence) { struct dma_fence *old_fence; + struct drm_syncobj_cb *cur, *tmp;
if (fence) dma_fence_get(fence); - old_fence = xchg(&syncobj->fence, fence); + + spin_lock(&syncobj->lock); + + old_fence = syncobj->fence; + syncobj->fence = fence; + + if (fence != old_fence) { + list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node) { + list_del_init(&cur->node); + cur->func(syncobj, cur); + } + } + + spin_unlock(&syncobj->lock);
dma_fence_put(old_fence); } @@ -130,7 +184,7 @@ void drm_syncobj_free(struct kref *kref) struct drm_syncobj *syncobj = container_of(kref, struct drm_syncobj, refcount); - dma_fence_put(syncobj->fence); + drm_syncobj_replace_fence(syncobj, NULL); kfree(syncobj); } EXPORT_SYMBOL(drm_syncobj_free); @@ -146,6 +200,8 @@ static int drm_syncobj_create(struct drm_file *file_private, return -ENOMEM;
kref_init(&syncobj->refcount); + INIT_LIST_HEAD(&syncobj->cb_list); + spin_lock_init(&syncobj->lock);
idr_preload(GFP_KERNEL); spin_lock(&file_private->syncobj_table_lock); diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h index ce94d14..aef7c10 100644 --- a/include/drm/drm_syncobj.h +++ b/include/drm/drm_syncobj.h @@ -28,6 +28,8 @@
#include "linux/dma-fence.h"
+struct drm_syncobj_cb; + /** * struct drm_syncobj - sync object. * @@ -43,15 +45,47 @@ struct drm_syncobj { /** * @fence: * NULL or a pointer to the fence bound to this object. + * + * This field should not be used directly. Use drm_syncobj_fence_get + * and drm_syncobj_replace_fence instead. */ struct dma_fence *fence; /** + * @list: + * List of callbacks to call when the fence gets replaced + */ + struct list_head cb_list; + /** + * @lock: + * locks cb_list and write-locks fence. + */ + spinlock_t lock; + /** * @file: * a file backing for this syncobj. */ struct file *file; };
+typedef void (*drm_syncobj_func_t)(struct drm_syncobj *syncobj, + struct drm_syncobj_cb *cb); + +/** + * struct drm_syncobj_cb - callback for drm_syncobj_add_callback + * @node: used by drm_syncob_add_callback to append this struct to + * syncobj::cb_list + * @func: drm_syncobj_func_t to call + * + * This struct will be initialized by drm_syncobj_add_callback, additional + * data can be passed along by embedding drm_syncobj_cb in another struct. + * The callback will get called the next time drm_syncobj_replace_fence is + * called. + */ +struct drm_syncobj_cb { + struct list_head node; + drm_syncobj_func_t func; +}; + void drm_syncobj_free(struct kref *kref);
/** @@ -91,6 +125,11 @@ drm_syncobj_fence_get(struct drm_syncobj *syncobj)
struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private, u32 handle); +void drm_syncobj_add_callback(struct drm_syncobj *syncobj, + struct drm_syncobj_cb *cb, + drm_syncobj_func_t func); +void drm_syncobj_remove_callback(struct drm_syncobj *syncobj, + struct drm_syncobj_cb *cb); void drm_syncobj_replace_fence(struct drm_syncobj *syncobj, struct dma_fence *fence); int drm_syncobj_find_fence(struct drm_file *file_private,