[Mesa-dev] [PATCH 7/8] radv/amdgpu: Use reference counting for bos.

[Bas Nieuwenhuizen]

Per the Vulkan spec, memory objects may be deleted before the buffers
and images using them are deleted, although those resources then
cannot be used except for deletion themselves.

For the virtual buffers, we need to access them on resource destruction
to unmap the regions, so this results in a use-after-free. Implement
reference counting to avoid this.

Signed-off-by: Bas Nieuwenhuizen <basni at google.com>
---
 src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.c | 10 ++++++++++
 src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.h |  1 +
 2 files changed, 11 insertions(+)

diff --git a/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.c b/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.c
index d5bce304510..6519b096fcc 100644
--- a/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.c
+++ b/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.c
@@ -34,6 +34,11 @@
 #include <amdgpu_drm.h>
 #include <inttypes.h>
 
+#include "util/u_atomic.h"
+
+
+static void radv_amdgpu_winsys_bo_destroy(struct radeon_winsys_bo *_bo);
+
 static void
 radv_amdgpu_winsys_virtual_map(struct radv_amdgpu_winsys_bo *bo,
                                const struct radv_amdgpu_map_range *range)
@@ -43,6 +48,7 @@ radv_amdgpu_winsys_virtual_map(struct radv_amdgpu_winsys_bo *bo,
 	if (!range->bo)
 		return; /* TODO: PRT mapping */
 
+	p_atomic_inc(&range->bo->ref_count);
 	int r = amdgpu_bo_va_op(range->bo->bo, range->bo_offset, range->size,
 	                        range->offset + bo->va, 0, AMDGPU_VA_OP_MAP);
 	if (r)
@@ -62,6 +68,7 @@ radv_amdgpu_winsys_virtual_unmap(struct radv_amdgpu_winsys_bo *bo,
 	                        range->offset + bo->va, 0, AMDGPU_VA_OP_UNMAP);
 	if (r)
 		abort();
+	radv_amdgpu_winsys_bo_destroy((struct radeon_winsys_bo *)range->bo);
 }
 
 static void
@@ -193,6 +200,8 @@ static void radv_amdgpu_winsys_bo_destroy(struct radeon_winsys_bo *_bo)
 {
 	struct radv_amdgpu_winsys_bo *bo = radv_amdgpu_winsys_bo(_bo);
 
+	if (p_atomic_dec_return(&bo->ref_count))
+		return;
 	if (bo->is_virtual) {
 		for (uint32_t i = 0; i < bo->range_count; ++i) {
 			radv_amdgpu_winsys_virtual_unmap(bo, bo->ranges + i);
@@ -254,6 +263,7 @@ radv_amdgpu_winsys_bo_create(struct radeon_winsys *_ws,
 	bo->size = size;
 	bo->ws = ws;
 	bo->is_virtual = !!(flags & RADEON_FLAG_VIRTUAL);
+	bo->ref_count = 1;
 
 	if (flags & RADEON_FLAG_VIRTUAL) {
 		bo->ranges = realloc(NULL, sizeof(struct radv_amdgpu_map_range));
diff --git a/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.h b/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.h
index c7d484bc8dd..4512e76b333 100644
--- a/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.h
+++ b/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.h
@@ -45,6 +45,7 @@ struct radv_amdgpu_winsys_bo {
 	uint64_t size;
 	struct radv_amdgpu_winsys *ws;
 	bool is_virtual;
+	int ref_count;
 
 	union {
 		/* physical bo */
-- 
2.11.0