Signed-off-by: Rob Clark robdclark@gmail.com --- drivers/dma-buf/reservation.c | 72 ++++++++++++++++++++++++++++++++++++++++--- include/linux/reservation.h | 53 +++++++++++++++++++++++++++++++ 2 files changed, 121 insertions(+), 4 deletions(-)
diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c index 0de3ea6..0d18952 100644 --- a/drivers/dma-buf/reservation.c +++ b/drivers/dma-buf/reservation.c @@ -35,6 +35,17 @@ #include <linux/reservation.h> #include <linux/export.h>
+/** + * DOC: Reservation Object Overview + * + * The reservation object provides a mechanism to manage shared and + * exclusive fences associated with a buffer. A reservation object + * can have attached one exclusive fence (normally associated with + * write operations) or N shared fences (read operations). The RCU + * mechanism is used to protect read access to fences from locked + * write-side updates. + */ + DEFINE_WW_CLASS(reservation_ww_class); EXPORT_SYMBOL(reservation_ww_class);
@@ -43,9 +54,17 @@ EXPORT_SYMBOL(reservation_seqcount_class);
const char reservation_seqcount_string[] = "reservation_seqcount"; EXPORT_SYMBOL(reservation_seqcount_string); -/* - * Reserve space to add a shared fence to a reservation_object, - * must be called with obj->lock held. + +/** + * reservation_object_reserve_shared - Reserve space to add a shared + * fence to a reservation_object. + * @obj: reservation object + * + * Should be called before reservation_object_add_shared_fence(). Must + * be called with obj->lock held. + * + * RETURNS + * Zero for success, or -errno */ int reservation_object_reserve_shared(struct reservation_object *obj) { @@ -182,7 +201,11 @@ done: fence_put(old_fence); }
-/* +/** + * reservation_object_add_shared_fence - Add a fence to a shared slot + * @obj: the reservation object + * @fence: the shared fence to add + * * Add a fence to a shared slot, obj->lock must be held, and * reservation_object_reserve_shared_fence has been called. */ @@ -204,6 +227,13 @@ void reservation_object_add_shared_fence(struct reservation_object *obj, } EXPORT_SYMBOL(reservation_object_add_shared_fence);
+/** + * reservation_object_add_excl_fence - Add an exclusive fence. + * @obj: the reservation object + * @fence: the shared fence to add + * + * Add a fence to the exclusive slot. The obj->lock must be held. + */ void reservation_object_add_excl_fence(struct reservation_object *obj, struct fence *fence) { @@ -239,6 +269,18 @@ void reservation_object_add_excl_fence(struct reservation_object *obj, } EXPORT_SYMBOL(reservation_object_add_excl_fence);
+/** + * reservation_object_get_fences_rcu - Get an object's shared and exclusive + * fences without update side lock held + * @obj: the reservation object + * @pfence_excl: the returned exclusive fence (or NULL) + * @pshared_count: the number of shared fences returned + * @pshared: the array of shared fence ptrs returned (array is krealloc'd to + * the required size, and must be freed by caller) + * + * RETURNS + * Zero or -errno + */ int reservation_object_get_fences_rcu(struct reservation_object *obj, struct fence **pfence_excl, unsigned *pshared_count, @@ -325,6 +367,18 @@ unlock: } EXPORT_SYMBOL_GPL(reservation_object_get_fences_rcu);
+/** + * reservation_object_wait_timeout_rcu - Wait on reservation's objects + * shared and/or exclusive fences. + * @obj: the reservation object + * @wait_all: if true, wait on all fences, else wait on just exclusive fence + * @intr: if true, do interruptible wait + * @timeout: timeout value in jiffies or zero to return immediately + * + * RETURNS + * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or + * greater than zer on success. + */ long reservation_object_wait_timeout_rcu(struct reservation_object *obj, bool wait_all, bool intr, unsigned long timeout) @@ -422,6 +476,16 @@ reservation_object_test_signaled_single(struct fence *passed_fence) return ret; }
+/** + * reservation_object_test_signaled_rcu - Test if a reservation object's + * fences have been signaled. + * @obj: the reservation object + * @test_all: if true, test all fences, otherwise only test the exclusive + * fence + * + * RETURNS + * true if all fences signaled, else false + */ bool reservation_object_test_signaled_rcu(struct reservation_object *obj, bool test_all) { diff --git a/include/linux/reservation.h b/include/linux/reservation.h index 49d0576..b0f305e 100644 --- a/include/linux/reservation.h +++ b/include/linux/reservation.h @@ -49,12 +49,27 @@ extern struct ww_class reservation_ww_class; extern struct lock_class_key reservation_seqcount_class; extern const char reservation_seqcount_string[];
+/** + * struct reservation_object_list - a list of shared fences + * @rcu: for internal use + * @shared_count: table of shared fences + * @shared_max: for growing shared fence table + * @shared: shared fence table + */ struct reservation_object_list { struct rcu_head rcu; u32 shared_count, shared_max; struct fence __rcu *shared[]; };
+/** + * struct reservation_object - a reservation object manages fences for a buffer + * @lock: update side lock + * @seq: sequence count for managing RCU read-side synchronization + * @fence_excl: the exclusive fence, if there is one currently + * @fence: list of current shared fences + * @staged: staged copy of shared fences for RCU updates + */ struct reservation_object { struct ww_mutex lock; seqcount_t seq; @@ -68,6 +83,10 @@ struct reservation_object { #define reservation_object_assert_held(obj) \ lockdep_assert_held(&(obj)->lock.base)
+/** + * reservation_object_init - initialize a reservation object + * @obj: the reservation object + */ static inline void reservation_object_init(struct reservation_object *obj) { @@ -79,6 +98,10 @@ reservation_object_init(struct reservation_object *obj) obj->staged = NULL; }
+/** + * reservation_object_fini - destroys a reservation object + * @obj: the reservation object + */ static inline void reservation_object_fini(struct reservation_object *obj) { @@ -106,6 +129,14 @@ reservation_object_fini(struct reservation_object *obj) ww_mutex_destroy(&obj->lock); }
+/** + * reservation_object_get_list - get the reservation object's + * shared fence list, with update-side lock held + * @obj: the reservation object + * + * Returns the shared fence list. Does NOT take references to + * the fence. The obj->lock must be held. + */ static inline struct reservation_object_list * reservation_object_get_list(struct reservation_object *obj) { @@ -113,6 +144,17 @@ reservation_object_get_list(struct reservation_object *obj) reservation_object_held(obj)); }
+/** + * 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. The obj->lock must be held. + * + * RETURNS + * The exclusive fence or NULL + */ static inline struct fence * reservation_object_get_excl(struct reservation_object *obj) { @@ -120,6 +162,17 @@ reservation_object_get_excl(struct reservation_object *obj) 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 fence * reservation_object_get_excl_rcu(struct reservation_object *obj) {