Am 04.05.22 um 09:53 schrieb Tvrtko Ursulin:
On 02/05/2022 17:37, Christian König wrote:
[SNIP]
@@ -398,6 +408,8 @@ void dma_fence_enable_sw_signaling(struct
dma_fence *fence);
static inline bool
dma_fence_is_signaled_locked(struct dma_fence *fence)
{
+ WARN_ON(test_bit(DMA_FENCE_FLAG_USER, &fence->flags));
+
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
return true;
@@ -428,6 +440,9 @@ dma_fence_is_signaled_locked(struct dma_fence
*fence)
static inline bool
dma_fence_is_signaled(struct dma_fence *fence)
{
+ if (test_bit(DMA_FENCE_FLAG_USER, &fence->flags))
+ might_fault();
Why this one can fault and the dma_fence_signal_locked cannot? I mean
obviosuly it must not in the locked section, but how do signalling
callbacks know the context of the caller?
Well, dma_fence_is_signaled_locked() shouldn't exists in the first place.
The locking can only be done by either the framework itself or the
driver exporting the fence. And if you take at the actual users than you
indeed see that the only two cases where this is used the driver knows
what fence it has and should probably call it's internal function itself.
This maybe ties back to the issue I don't think I ever found an
explanation to - why "is signal" helpers actually need (or want?) to
do the signalling itself, and are therefore hit also with the
signalling annotations?
Yeah, exactly that's what I could never figure out as well. And I think
that it isn't good design to do this, because it results in the
dma_fence being signaled from different sources.
Without it it would just be consistently signaled from the interrupt (or
whatever context) the exporter uses to signal it.
Thanks,
Christian.
Regards,
Tvrtko
+
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
return true;
@@ -583,7 +598,7 @@ static inline signed long dma_fence_wait(struct
dma_fence *fence, bool intr)
return ret < 0 ? ret : 0;
}
-struct dma_fence *dma_fence_get_stub(void);
+struct dma_fence *dma_fence_get_stub(bool user);
struct dma_fence *dma_fence_allocate_private_stub(void);
u64 dma_fence_context_alloc(unsigned num);
