[PATCH v2 2/4] dma-buf: enable signaling for the stub fence on debug

[Arvind Yadav <Arvind.Yadav@amd.com>]

Here's on debug enabling software signaling for the stub fence
which is always signaled. This fence should enable software
signaling otherwise the AMD GPU scheduler will cause a GPU reset
due to a GPU scheduler cleanup activity timeout.

Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.com>
---

Changes in v1 :
1- Addressing Christian's comment to remove unnecessary callback.
2- Replacing CONFIG_DEBUG_WW_MUTEX_SLOWPATH instead of CONFIG_DEBUG_FS.
3- The version of this patch is also changed and previously
it was [PATCH 3/4]

---
 drivers/dma-buf/dma-fence.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 066400ed8841..2378b12538c4 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -27,6 +27,10 @@ EXPORT_TRACEPOINT_SYMBOL(dma_fence_signaled);
 static DEFINE_SPINLOCK(dma_fence_stub_lock);
 static struct dma_fence dma_fence_stub;
 
+#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
+static bool __dma_fence_enable_signaling(struct dma_fence *fence);
+#endif
+
 /*
  * fence context counter: each execution context should have its own
  * fence context, this allows checking if fences belong to the same
@@ -136,6 +140,9 @@ struct dma_fence *dma_fence_get_stub(void)
 			       &dma_fence_stub_ops,
 			       &dma_fence_stub_lock,
 			       0, 0);
+#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
+		__dma_fence_enable_signaling(&dma_fence_stub);
+#endif
 		dma_fence_signal_locked(&dma_fence_stub);
 	}
 	spin_unlock(&dma_fence_stub_lock);
-- 
2.25.1