diff mbox

[02/15] dma-fence: Make ->enable_signaling optional

Message ID 20180503142603.28513-3-daniel.vetter@ffwll.ch (mailing list archive)
State New, archived
Headers show

Commit Message

Daniel Vetter May 3, 2018, 2:25 p.m. UTC 
Many drivers have a trivial implementation for ->enable_signaling.
Let's make it optional by assuming that signalling is already
available when the callback isn't present.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
---
 drivers/dma-buf/dma-fence.c | 13 ++++++++++++-
 include/linux/dma-fence.h   |  3 ++-
 2 files changed, 14 insertions(+), 2 deletions(-)

Comments

Chris Wilson May 3, 2018, 3:51 p.m. UTC | #1 
Quoting Daniel Vetter (2018-05-03 15:25:50)
> @@ -560,7 +567,7 @@ dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
>                spinlock_t *lock, u64 context, unsigned seqno)
>  {
>         BUG_ON(!lock);
> -       BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
> +       BUG_ON(!ops || !ops->wait ||
>                !ops->get_driver_name || !ops->get_timeline_name);

One thing I was wondering about (following the discussion of rhashtable
on lwn) was inlining this function and passing dma_fence_ops by value.
And seeing if that eliminates the branch and makes smaller code
(probably not, mostly idling wondering about that technique) and kills
off the BUGs (can then be BUILD_BUG_ON).
-Chris
diff mbox

Patch

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 4edb9fd3cf47..7b5b40d6b70e 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -181,6 +181,13 @@  void dma_fence_release(struct kref *kref)
 }
 EXPORT_SYMBOL(dma_fence_release);
 
+/**
+ * dma_fence_free - default release function for &dma_fence.
+ * @fence: fence to release
+ *
+ * This is the default implementation for &dma_fence_ops.release. It calls
+ * kfree_rcu() on @fence.
+ */
 void dma_fence_free(struct dma_fence *fence)
 {
 	kfree_rcu(fence, rcu);
@@ -560,7 +567,7 @@  dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
 	       spinlock_t *lock, u64 context, unsigned seqno)
 {
 	BUG_ON(!lock);
-	BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
+	BUG_ON(!ops || !ops->wait ||
 	       !ops->get_driver_name || !ops->get_timeline_name);
 
 	kref_init(&fence->refcount);
@@ -572,6 +579,10 @@  dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
 	fence->flags = 0UL;
 	fence->error = 0;
 
+	if (!ops->enable_signaling)
+		set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
+			&fence->flags);
+
 	trace_dma_fence_init(fence);
 }
 EXPORT_SYMBOL(dma_fence_init);
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 111aefe1c956..c053d19e1e24 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -166,7 +166,8 @@  struct dma_fence_ops {
 	 * released when the fence is signalled (through e.g. the interrupt
 	 * handler).
 	 *
-	 * This callback is mandatory.
+	 * This callback is optional. If this callback is not present, then the
+	 * driver must always have signaling enabled.
 	 */
 	bool (*enable_signaling)(struct dma_fence *fence);