[PATCH 09/29] drm/i915: make lockdep slightly happier about execbuf.

[Maarten Lankhorst]

From: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>

As soon as we install fences, we should stop allocating memory
in order to prevent any potential deadlocks.

This is required later on, when we start adding support for
dma-fence annotations, and also required for userptr.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 18 ++++++++++++------
 drivers/gpu/drm/i915/i915_vma.c                |  8 +++++---
 drivers/gpu/drm/i915/i915_vma.h                |  3 +++
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 6e262670535f..4de5f46738d6 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -48,11 +48,12 @@ enum {
 #define DBG_FORCE_RELOC 0 /* choose one of the above! */
 };
 
-#define __EXEC_OBJECT_HAS_PIN		BIT(31)
-#define __EXEC_OBJECT_HAS_FENCE		BIT(30)
-#define __EXEC_OBJECT_NEEDS_MAP		BIT(29)
-#define __EXEC_OBJECT_NEEDS_BIAS	BIT(28)
-#define __EXEC_OBJECT_INTERNAL_FLAGS	(~0u << 28) /* all of the above */
+/* __EXEC_OBJECT_NO_RESERVE is BIT(31), defined in i915_vma.h */
+#define __EXEC_OBJECT_HAS_PIN		BIT(30)
+#define __EXEC_OBJECT_HAS_FENCE		BIT(29)
+#define __EXEC_OBJECT_NEEDS_MAP		BIT(28)
+#define __EXEC_OBJECT_NEEDS_BIAS	BIT(27)
+#define __EXEC_OBJECT_INTERNAL_FLAGS	(~0u << 27) /* all of the above + */
 #define __EXEC_OBJECT_RESERVED (__EXEC_OBJECT_HAS_PIN | __EXEC_OBJECT_HAS_FENCE)
 
 #define __EXEC_HAS_RELOC	BIT(31)
@@ -2094,7 +2095,8 @@ static int eb_move_to_gpu(struct i915_execbuffer *eb)
 		}
 
 		if (err == 0)
-			err = i915_vma_move_to_active(vma, eb->request, flags);
+			err = i915_vma_move_to_active(vma, eb->request,
+						      flags | __EXEC_OBJECT_NO_RESERVE);
 	}
 
 	if (unlikely(err))
@@ -2291,6 +2293,10 @@ static int eb_parse_pipeline(struct i915_execbuffer *eb,
 	if (err)
 		goto err_commit;
 
+	err = dma_resv_reserve_shared(shadow->resv, 1);
+	if (err)
+		goto err_commit;
+
 	/* Wait for all writes (and relocs) into the batch to complete */
 	err = i915_sw_fence_await_reservation(&pw->base.chain,
 					      pw->batch->resv, NULL, false,
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index c6bf04ca2032..8066f167d6b9 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -1227,9 +1227,11 @@ int i915_vma_move_to_active(struct i915_vma *vma,
 		obj->write_domain = I915_GEM_DOMAIN_RENDER;
 		obj->read_domains = 0;
 	} else {
-		err = dma_resv_reserve_shared(vma->resv, 1);
-		if (unlikely(err))
-			return err;
+		if (!(flags & __EXEC_OBJECT_NO_RESERVE)) {
+			err = dma_resv_reserve_shared(vma->resv, 1);
+			if (unlikely(err))
+				return err;
+		}
 
 		dma_resv_add_shared_fence(vma->resv, &rq->fence);
 		obj->write_domain = 0;
diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
index d0d01f909548..4b325a670a04 100644
--- a/drivers/gpu/drm/i915/i915_vma.h
+++ b/drivers/gpu/drm/i915/i915_vma.h
@@ -52,6 +52,9 @@ static inline bool i915_vma_is_active(const struct i915_vma *vma)
 	return !i915_active_is_idle(&vma->active);
 }
 
+/* do not reserve memory to prevent deadlocks */
+#define __EXEC_OBJECT_NO_RESERVE BIT(31)
+
 int __must_check __i915_vma_move_to_active(struct i915_vma *vma,
 					   struct i915_request *rq);
 int __must_check i915_vma_move_to_active(struct i915_vma *vma,
-- 
2.28.0