Re: [PATCH v3 7/9] dma-buf/fence-chain: Add fence deadline support

From: Christian König
Date: Thu Sep 09 2021 - 02:31:22 EST

Am 08.09.21 um 20:45 schrieb Daniel Vetter:
On Wed, Sep 08, 2021 at 11:19:15AM -0700, Rob Clark wrote:
On Wed, Sep 8, 2021 at 10:54 AM Daniel Vetter <daniel@xxxxxxxx> wrote:
On Fri, Sep 03, 2021 at 11:47:58AM -0700, Rob Clark wrote:
From: Rob Clark <robdclark@xxxxxxxxxxxx>

Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
drivers/dma-buf/dma-fence-chain.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/drivers/dma-buf/dma-fence-chain.c b/drivers/dma-buf/dma-fence-chain.c
index 1b4cb3e5cec9..736a9ad3ea6d 100644
--- a/drivers/dma-buf/dma-fence-chain.c
+++ b/drivers/dma-buf/dma-fence-chain.c
@@ -208,6 +208,18 @@ static void dma_fence_chain_release(struct dma_fence *fence)

+static void dma_fence_chain_set_deadline(struct dma_fence *fence,
+ ktime_t deadline)
+ dma_fence_chain_for_each(fence, fence) {
+ struct dma_fence_chain *chain = to_dma_fence_chain(fence);
+ struct dma_fence *f = chain ? chain->fence : fence;
Doesn't this just end up calling set_deadline on a chain, potenetially
resulting in recursion? Also I don't think this should ever happen, why
did you add that?
Tbh the fence-chain was the part I was a bit fuzzy about, and the main
reason I added igt tests. The iteration is similar to how, for ex,
dma_fence_chain_signaled() work, and according to the igt test it does
what was intended
Huh indeed. Maybe something we should fix, like why does the
dma_fence_chain_for_each not give you the upcast chain pointer ... I guess
this also needs more Christian and less me.

Yeah I was also already thinking about having a dma_fence_chain_for_each_contained() macro which directly returns the containing fence, just didn't had time to implement/clean that up.

And yes the patch is correct as it is and avoid the recursion, so Reviewed-by: Christian König <christian.koenig@xxxxxxx> for this one.





+ dma_fence_set_deadline(f, deadline);
+ }
const struct dma_fence_ops dma_fence_chain_ops = {
.use_64bit_seqno = true,
.get_driver_name = dma_fence_chain_get_driver_name,
@@ -215,6 +227,7 @@ const struct dma_fence_ops dma_fence_chain_ops = {
.enable_signaling = dma_fence_chain_enable_signaling,
.signaled = dma_fence_chain_signaled,
.release = dma_fence_chain_release,
+ .set_deadline = dma_fence_chain_set_deadline,


Daniel Vetter
Software Engineer, Intel Corporation