From 67c97fb79a7f8621d4514275691d75f5ff158c46 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20K=C3=B6nig?= Date: Tue, 6 Aug 2019 14:19:33 +0200 Subject: dma-buf: add reservation_object_fences helper MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add a new helper to get a consistent set of pointers from the reservation object. While at it group all access helpers together in the header file. v2: correctly return shared_count as well Signed-off-by: Christian König Reviewed-by: Chris Wilson Link: https://patchwork.freedesktop.org/patch/322378/?series=64837&rev=1 --- include/linux/reservation.h | 115 +++++++++++++++++++++++++++----------------- 1 file changed, 70 insertions(+), 45 deletions(-) (limited to 'include/linux') diff --git a/include/linux/reservation.h b/include/linux/reservation.h index 56b782fec49b..c6c8c93785c4 100644 --- a/include/linux/reservation.h +++ b/include/linux/reservation.h @@ -81,6 +81,25 @@ struct reservation_object { #define reservation_object_assert_held(obj) \ lockdep_assert_held(&(obj)->lock.base) +/** + * reservation_object_get_excl - get the reservation object's + * exclusive fence, with update-side lock held + * @obj: the reservation object + * + * Returns the exclusive fence (if any). Does NOT take a + * reference. Writers must hold obj->lock, readers may only + * hold a RCU read side lock. + * + * RETURNS + * The exclusive fence or NULL + */ +static inline struct dma_fence * +reservation_object_get_excl(struct reservation_object *obj) +{ + return rcu_dereference_protected(obj->fence_excl, + reservation_object_held(obj)); +} + /** * reservation_object_get_list - get the reservation object's * shared fence list, with update-side lock held @@ -96,6 +115,57 @@ reservation_object_get_list(struct reservation_object *obj) reservation_object_held(obj)); } +/** + * reservation_object_fences - read consistent fence pointers + * @obj: reservation object where we get the fences from + * @excl: pointer for the exclusive fence + * @list: pointer for the shared fence list + * + * Make sure we have a consisten exclusive fence and shared fence list. + * Must be called with rcu read side lock held. + */ +static inline void +reservation_object_fences(struct reservation_object *obj, + struct dma_fence **excl, + struct reservation_object_list **list, + u32 *shared_count) +{ + unsigned int seq; + + do { + seq = read_seqcount_begin(&obj->seq); + *excl = rcu_dereference(obj->fence_excl); + *list = rcu_dereference(obj->fence); + *shared_count = *list ? (*list)->shared_count : 0; + } while (read_seqcount_retry(&obj->seq, seq)); +} + +/** + * reservation_object_get_excl_rcu - get the reservation object's + * exclusive fence, without lock held. + * @obj: the reservation object + * + * If there is an exclusive fence, this atomically increments it's + * reference count and returns it. + * + * RETURNS + * The exclusive fence or NULL if none + */ +static inline struct dma_fence * +reservation_object_get_excl_rcu(struct reservation_object *obj) +{ + struct dma_fence *fence; + + if (!rcu_access_pointer(obj->fence_excl)) + return NULL; + + rcu_read_lock(); + fence = dma_fence_get_rcu_safe(&obj->fence_excl); + rcu_read_unlock(); + + return fence; +} + /** * reservation_object_lock - lock the reservation object * @obj: the reservation object @@ -239,51 +309,6 @@ reservation_object_unlock(struct reservation_object *obj) ww_mutex_unlock(&obj->lock); } -/** - * reservation_object_get_excl - get the reservation object's - * exclusive fence, with update-side lock held - * @obj: the reservation object - * - * Returns the exclusive fence (if any). Does NOT take a - * reference. Writers must hold obj->lock, readers may only - * hold a RCU read side lock. - * - * RETURNS - * The exclusive fence or NULL - */ -static inline struct dma_fence * -reservation_object_get_excl(struct reservation_object *obj) -{ - return rcu_dereference_protected(obj->fence_excl, - reservation_object_held(obj)); -} - -/** - * reservation_object_get_excl_rcu - get the reservation object's - * exclusive fence, without lock held. - * @obj: the reservation object - * - * If there is an exclusive fence, this atomically increments it's - * reference count and returns it. - * - * RETURNS - * The exclusive fence or NULL if none - */ -static inline struct dma_fence * -reservation_object_get_excl_rcu(struct reservation_object *obj) -{ - struct dma_fence *fence; - - if (!rcu_access_pointer(obj->fence_excl)) - return NULL; - - rcu_read_lock(); - fence = dma_fence_get_rcu_safe(&obj->fence_excl); - rcu_read_unlock(); - - return fence; -} - void reservation_object_init(struct reservation_object *obj); void reservation_object_fini(struct reservation_object *obj); int reservation_object_reserve_shared(struct reservation_object *obj, -- cgit v1.2.3