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dma-buf/fence: add fence_is_later() 

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@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Christian König 2015-10-21 12:58:17 +02:00 committed by Alex Deucher
parent a519435a96
commit 6c455ac17b
1 changed files with 19 additions and 3 deletions
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22
include/linux/fence.h
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@ -279,6 +279,22 @@ fence_is_signaled(struct fence *fence)
return false;
}
/**
* 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
@ -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);