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authorChristian König <christian.koenig@amd.com>2019-08-05 14:24:55 +0200
committerChristian König <christian.koenig@amd.com>2019-08-13 09:07:58 +0200
commit5d344f58da760b226562e7d5199fb73294eb93fa (patch)
treedabe9434fb720c4c0d80b7078cccf3acde6e0f9a /drivers/dma-buf
parentd3c6dd1fb30d3853c2012549affe75c930f4a2f9 (diff)
downloadlinux-5d344f58da760b226562e7d5199fb73294eb93fa.tar.bz2
dma-buf: nuke reservation_object seq number
The only remaining use for this is to protect against setting a new exclusive fence while we grab both exclusive and shared. That can also be archived by looking if the exclusive fence has changed or not after completing the operation. v2: switch setting excl fence to rcu_assign_pointer Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/322380/
Diffstat (limited to 'drivers/dma-buf')
-rw-r--r--drivers/dma-buf/reservation.c24
1 files changed, 5 insertions, 19 deletions
diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index 90bc6ef03598..f7f4a0858c2a 100644
--- a/drivers/dma-buf/reservation.c
+++ b/drivers/dma-buf/reservation.c
@@ -49,12 +49,6 @@
DEFINE_WD_CLASS(reservation_ww_class);
EXPORT_SYMBOL(reservation_ww_class);
-struct lock_class_key reservation_seqcount_class;
-EXPORT_SYMBOL(reservation_seqcount_class);
-
-const char reservation_seqcount_string[] = "reservation_seqcount";
-EXPORT_SYMBOL(reservation_seqcount_string);
-
/**
* reservation_object_list_alloc - allocate fence list
* @shared_max: number of fences we need space for
@@ -103,9 +97,6 @@ static void reservation_object_list_free(struct reservation_object_list *list)
void reservation_object_init(struct reservation_object *obj)
{
ww_mutex_init(&obj->lock, &reservation_ww_class);
-
- __seqcount_init(&obj->seq, reservation_seqcount_string,
- &reservation_seqcount_class);
RCU_INIT_POINTER(obj->fence, NULL);
RCU_INIT_POINTER(obj->fence_excl, NULL);
}
@@ -282,12 +273,10 @@ void reservation_object_add_excl_fence(struct reservation_object *obj,
dma_fence_get(fence);
preempt_disable();
- write_seqcount_begin(&obj->seq);
- /* write_seqcount_begin provides the necessary memory barrier */
- RCU_INIT_POINTER(obj->fence_excl, fence);
+ rcu_assign_pointer(obj->fence_excl, fence);
+ /* pointer update must be visible before we modify the shared_count */
if (old)
- old->shared_count = 0;
- write_seqcount_end(&obj->seq);
+ smp_store_mb(old->shared_count, 0);
preempt_enable();
/* inplace update, no shared fences */
@@ -368,11 +357,8 @@ retry:
old = reservation_object_get_excl(dst);
preempt_disable();
- write_seqcount_begin(&dst->seq);
- /* write_seqcount_begin provides the necessary memory barrier */
- RCU_INIT_POINTER(dst->fence_excl, new);
- RCU_INIT_POINTER(dst->fence, dst_list);
- write_seqcount_end(&dst->seq);
+ rcu_assign_pointer(dst->fence_excl, new);
+ rcu_assign_pointer(dst->fence, dst_list);
preempt_enable();
reservation_object_list_free(src_list);