[PATCH v6 09/11] drm/amdgpu: validate the shared bo for tracking usage size

[Prike Liang]

It requires validating the shared BO before updating its usage
size; otherwise, there is a potential NULL pointer error when the
BO released improperly.

Signed-off-by: Prike Liang <prike.li...@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index f042372d9f2e..a574effdd3ec 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -321,12 +321,26 @@ static void amdgpu_vm_bo_reset_state_machine(struct 
amdgpu_vm *vm)
  */
 static void amdgpu_vm_update_shared(struct amdgpu_vm_bo_base *base)
 {
-       struct amdgpu_vm *vm = base->vm;
-       struct amdgpu_bo *bo = base->bo;
-       uint64_t size = amdgpu_bo_size(bo);
-       uint32_t bo_memtype = amdgpu_bo_mem_stats_placement(bo);
+       struct amdgpu_vm *vm;
+       struct amdgpu_bo *bo;
+       uint64_t size = 0;
+       uint32_t bo_memtype = TTM_PL_SYSTEM;
        bool shared;
 
+       if (likely(base)) {
+               vm = base->vm;
+               bo = base->bo;
+       } else {
+               return;
+       }
+
+       if (likely(bo)) {
+               size = amdgpu_bo_size(bo);
+               bo_memtype = amdgpu_bo_mem_stats_placement(bo);
+       } else {
+               return;
+       }
+
        spin_lock(&vm->status_lock);
        shared = drm_gem_object_is_shared_for_memory_stats(&bo->tbo.base);
        if (base->shared != shared) {
@@ -353,6 +367,9 @@ void amdgpu_vm_bo_update_shared(struct amdgpu_bo *bo)
 {
        struct amdgpu_vm_bo_base *base;
 
+       if (unlikely(!bo))
+               return;
+
        for (base = bo->vm_bo; base; base = base->next)
                amdgpu_vm_update_shared(base);
 }
-- 
2.34.1