[PATCH] drm/amdgpu: Remove hidden double memset from amdgpu_vm_pt_clear()

Tvrtko Ursulin tursulin at igalia.com
Tue Aug 13 14:08:35 UTC 2024


From: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>

When CONFIG_INIT_STACK_ALL_ZERO is set and so -ftrivial-auto-var-init=zero
compiler option active, compiler fails to notice that later in
amdgpu_vm_pt_clear() there  is a second memset to clear the same on stack
struct amdgpu_vm_update_params.

If we replace this memset with an explicit automatic variable initializer,
compiler can then see it and avoid clearing this struct twice.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
---
This is perhaps a bit questionable, regardless of how annoying it is to
know there is this double memset.
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
index e39d6e7643bf..ecdc8fffe941 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
@@ -361,7 +361,7 @@ int amdgpu_vm_pt_clear(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 {
 	unsigned int level = adev->vm_manager.root_level;
 	struct ttm_operation_ctx ctx = { true, false };
-	struct amdgpu_vm_update_params params;
+	struct amdgpu_vm_update_params params = { };
 	struct amdgpu_bo *ancestor = &vmbo->bo;
 	unsigned int entries;
 	struct amdgpu_bo *bo = &vmbo->bo;
@@ -398,7 +398,6 @@ int amdgpu_vm_pt_clear(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 	if (r)
 		goto exit;
 
-	memset(&params, 0, sizeof(params));
 	params.adev = adev;
 	params.vm = vm;
 	params.immediate = immediate;
-- 
2.44.0



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