From: Christian König <christian.koenig@xxxxxxx>
Return true when fence 1 is later than fence 2 without
checking if any of them are signaled.
Useful for driver specific resource handling based on fences.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx>
---
include/linux/fence.h | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/include/linux/fence.h b/include/linux/fence.h
index a4084d6..bb52201 100644
--- a/include/linux/fence.h
+++ b/include/linux/fence.h
@@ -280,6 +280,22 @@ fence_is_signaled(struct fence *fence)
}
/**
+ * fence_is_later - return if f1 is chronologically later than f2
+ * @f1: [in] the first fence from the same context
+ * @f2: [in] the second fence from the same context
+ *
+ * Returns true if f1 is chronologically later than f2. Both fences must be
+ * from the same context, since a seqno is not re-used across contexts.
+ */
+static inline bool fence_is_later(struct fence *f1, struct fence *f2)
+{
+ if (WARN_ON(f1->context != f2->context))
+ return false;
+
+ return f1->seqno - f2->seqno < INT_MAX;
+}
+
+/**
* fence_later - return the chronologically later fence
* @f1: [in] the first fence from the same context
* @f2: [in] the second fence from the same context
@@ -298,10 +314,10 @@ static inline struct fence *fence_later(struct fence *f1, struct fence *f2)
* set if enable_signaling wasn't called, and enabling that here is
* overkill.
*/
- if (f2->seqno - f1->seqno <= INT_MAX)
- return fence_is_signaled(f2) ? NULL : f2;
- else
+ if (fence_is_later(f1, f2))
return fence_is_signaled(f1) ? NULL : f1;
+ else
+ return fence_is_signaled(f2) ? NULL : f2;
}
signed long fence_wait_timeout(struct fence *, bool intr, signed long timeout);
--
1.9.1
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