diff options
| author | Chris Wilson | 2019-07-12 09:03:14 +0100 |
|---|---|---|
| committer | Chris Wilson | 2019-07-16 21:02:39 +0100 |
| commit | 30fe7b07f6cb7f391181eb9d2ea2687cd9bcf395 (patch) | |
| tree | 850f2f651e97b32ef9b98a5fa637b8464821dac1 | |
| parent | 45b2fda3d82d686cc014e4c485332f85e4bd64de (diff) | |
dma-buf: Relax the write-seqlock for reallocating the shared fence list
As the set of shared fences is not being changed during reallocation of
the reservation list, we can skip updating the write_seqlock.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190712080314.21018-2-chris@chris-wilson.co.uk
| -rw-r--r-- | drivers/dma-buf/reservation.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c index 80ecc1283d15..c71b85c8c159 100644 --- a/drivers/dma-buf/reservation.c +++ b/drivers/dma-buf/reservation.c @@ -157,15 +157,15 @@ int reservation_object_reserve_shared(struct reservation_object *obj, (ksize(new) - offsetof(typeof(*new), shared)) / sizeof(*new->shared); - preempt_disable(); - write_seqcount_begin(&obj->seq); /* - * RCU_INIT_POINTER can be used here, - * seqcount provides the necessary barriers + * We are not changing the effective set of fences here so can + * merely update the pointer to the new array; both existing + * readers and new readers will see exactly the same set of + * active (unsignaled) shared fences. Individual fences and the + * old array are protected by RCU and so will not vanish under + * the gaze of the rcu_read_lock() readers. */ - RCU_INIT_POINTER(obj->fence, new); - write_seqcount_end(&obj->seq); - preempt_enable(); + rcu_assign_pointer(obj->fence, new); if (!old) return 0; |