On 09/26/2018 06:35 PM, Christian König wrote:
Am 26.09.2018 um 18:18 schrieb Thomas Hellstrom:
Export ttm_bo_reference_unless_doomed() to be used when looking up buffer objects that are removed from the lookup structure in the destructor.
Cc: Christian König christian.koenig@amd.com Signed-off-by: Thomas Hellstrom thellstrom@vmware.com Reviewed-by: Sinclair Yeh syeh@vmware.com
drivers/gpu/drm/ttm/ttm_bo_vm.c | 3 +-- include/drm/ttm/ttm_bo_api.h | 18 ++++++++++++++++++ 2 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index 6fe91c1b692d..ec4b09366213 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -409,8 +409,7 @@ static struct ttm_buffer_object *ttm_bo_vm_lookup(struct ttm_bo_device *bdev, node = drm_vma_offset_lookup_locked(&bdev->vma_manager, offset, pages); if (likely(node)) { bo = container_of(node, struct ttm_buffer_object, vma_node); - if (!kref_get_unless_zero(&bo->kref)) - bo = NULL; + bo = ttm_bo_reference_unless_doomed(bo); } drm_vma_offset_unlock_lookup(&bdev->vma_manager); diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h index 8c19470785e2..b6bf6b086576 100644 --- a/include/drm/ttm/ttm_bo_api.h +++ b/include/drm/ttm/ttm_bo_api.h @@ -312,6 +312,24 @@ ttm_bo_reference(struct ttm_buffer_object *bo) return bo; } +/**
- ttm_bo_reference_unless_doomed - reference a struct
ttm_buffer_object unless
- its refcount has already reached zero.
- @bo: The buffer object.
- Used to reference a TTM buffer object in lookups where the object
is removed
- from the lookup structure during the destructor and for RCU lookups.
- Returns: @bo if the referencing was successful, NULL otherwise.
- */
+static inline __must_check struct ttm_buffer_object * +ttm_bo_reference_unless_doomed(struct ttm_buffer_object *bo)
Please name that ttm_bo_get_rcu(), we are in the process of renaming ttm_bo_reference into ttm_bo_get as well.
Could we call it ttm_bo_get_unless_doomed() or ttm_bo_get_unless_zero() to be even more consistent. (It's not restricted to rcu as the VM usage shows). Also "doomed" is more relevant for objects, "zero" is more relevant for the refcount itself?
/Thomas
Christian.
+{ + if (!kref_get_unless_zero(&bo->kref)) + return NULL; + return bo; +}
/** * ttm_bo_wait - wait for buffer idle. *