From 122020af856181c24fe45903e43e3cc987c175f7 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 15 Nov 2016 15:46:42 +0000 Subject: [PATCH] dma-buf: Provide wrappers for reservation's lock Joonas complained that writing ww_mutex_lock(&resv->lock, ctx) was too intrusive compared to reservation_object_lock(resv, ctx); Signed-off-by: Chris Wilson Cc: Sumit Semwal Cc: Joonas Lahtinen Reviewed-by: Alex Deucher Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20161115154642.31850-1-chris@chris-wilson.co.uk --- include/linux/reservation.h | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/include/linux/reservation.h b/include/linux/reservation.h index d9706a6f5ae2..2b5a4679daea 100644 --- a/include/linux/reservation.h +++ b/include/linux/reservation.h @@ -144,6 +144,40 @@ reservation_object_get_list(struct reservation_object *obj) reservation_object_held(obj)); } +/** + * reservation_object_lock - lock the reservation object + * @obj: the reservation object + * @ctx: the locking context + * + * Locks the reservation object for exclusive access and modification. Note, + * that the lock is only against other writers, readers will run concurrently + * with a writer under RCU. The seqlock is used to notify readers if they + * overlap with a writer. + * + * As the reservation object may be locked by multiple parties in an + * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle + * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation + * object may be locked by itself by passing NULL as @ctx. + */ +static inline int +reservation_object_lock(struct reservation_object *obj, + struct ww_acquire_ctx *ctx) +{ + return ww_mutex_lock(&obj->lock, ctx); +} + +/** + * reservation_object_unlock - unlock the reservation object + * @obj: the reservation object + * + * Unlocks the reservation object following exclusive access. + */ +static inline void +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 -- 2.20.1