drm/amdgpu: fix race in GEM VA map IOCTL v2

Somebody could try to free the bo_va between mapping and updating it.

v2: fix typos in comment

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 15 insertions, 32 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 9bd1b4eae32e..4acb9c5e8b64 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -487,67 +487,50 @@ static int amdgpu_gem_va_check(void *param, struct amdgpu_bo *bo)
  *
  * @adev: amdgpu_device pointer
  * @bo_va: bo_va to update
+ * @list: validation list
+ * @operation: map or unmap
  *
- * Update the bo_va directly after setting it's address. Errors are not
+ * Update the bo_va directly after setting its address. Errors are not
  * vital here, so they are not reported back to userspace.
  */
 static void amdgpu_gem_va_update_vm(struct amdgpu_device *adev,
                                     struct amdgpu_bo_va *bo_va,
+                                    struct list_head *list,
                                     uint32_t operation)
 {
-        struct ttm_validate_buffer tv, *entry;
-        struct amdgpu_bo_list_entry vm_pd;
-        struct ww_acquire_ctx ticket;
-        struct list_head list, duplicates;
-        int r;
-
-        INIT_LIST_HEAD(&list);
-        INIT_LIST_HEAD(&duplicates);
-
-        tv.bo = &bo_va->bo->tbo;
-        tv.shared = true;
-        list_add(&tv.head, &list);
-
-        amdgpu_vm_get_pd_bo(bo_va->vm, &list, &vm_pd);
-
-        /* Provide duplicates to avoid -EALREADY */
-        r = ttm_eu_reserve_buffers(&ticket, &list, true, &duplicates);
-        if (r)
-                goto error_print;
+        struct ttm_validate_buffer *entry;
+        int r = -ERESTARTSYS;
 
-        list_for_each_entry(entry, &list, head) {
+        list_for_each_entry(entry, list, head) {
                 struct amdgpu_bo *bo =
                         container_of(entry->bo, struct amdgpu_bo, tbo);
 
                 /* if anything is swapped out don't swap it in here,
                    just abort and wait for the next CS */
                 if (!amdgpu_bo_gpu_accessible(bo))
-                        goto error_unreserve;
+                        goto error;
 
                 if (bo->shadow && !amdgpu_bo_gpu_accessible(bo->shadow))
-                        goto error_unreserve;
+                        goto error;
         }
 
         r = amdgpu_vm_validate_pt_bos(adev, bo_va->vm, amdgpu_gem_va_check,
                                       NULL);
         if (r)
-                goto error_unreserve;
+                goto error;
 
         r = amdgpu_vm_update_page_directory(adev, bo_va->vm);
         if (r)
-                goto error_unreserve;
+                goto error;
 
         r = amdgpu_vm_clear_freed(adev, bo_va->vm);
         if (r)
-                goto error_unreserve;
+                goto error;
 
         if (operation == AMDGPU_VA_OP_MAP)
                 r = amdgpu_vm_bo_update(adev, bo_va, false);
 
-error_unreserve:
-        ttm_eu_backoff_reservation(&ticket, &list);
-
-error_print:
+error:
         if (r && r != -ERESTARTSYS)
                 DRM_ERROR("Couldn't update BO_VA (%d)\n", r);
 }
@@ -640,10 +623,10 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
         default:
                 break;
         }
-        ttm_eu_backoff_reservation(&ticket, &list);
         if (!r && !(args->flags & AMDGPU_VM_DELAY_UPDATE) &&
             !amdgpu_vm_debug)
-                amdgpu_gem_va_update_vm(adev, bo_va, args->operation);
+                amdgpu_gem_va_update_vm(adev, bo_va, &list, args->operation);
+        ttm_eu_backoff_reservation(&ticket, &list);
 
         drm_gem_object_unreference_unlocked(gobj);
         return r;