Commit 82fe50bc authored by Thomas Hellstrom's avatar Thomas Hellstrom Committed by Dave Airlie
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drm/ttm: Optimize vm locking using kref_get_unless_zero v3 



Removes the need for a write lock each time we call ttm_bo_unref().

v2: Remove an unused variable.
v3: Really remove the unused variable.

Signed-off-by: default avatarThomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent 5293908a

drivers/gpu/drm/ttm/ttm_bo.c

+1 −4
Original line number Diff line number Diff line
@@ -696,6 +696,7 @@ static void ttm_bo_release(struct kref *kref) 
	struct ttm_bo_device *bdev = bo->bdev;

	struct ttm_mem_type_manager *man = &bdev->man[bo->mem.mem_type];



	write_lock(&bdev->vm_lock);

	if (likely(bo->vm_node != NULL)) {

		rb_erase(&bo->vm_rb, &bdev->addr_space_rb);

		drm_mm_put_block(bo->vm_node);
@@ -707,18 +708,14 @@ static void ttm_bo_release(struct kref *kref) 
	ttm_mem_io_unlock(man);

	ttm_bo_cleanup_refs_or_queue(bo);

	kref_put(&bo->list_kref, ttm_bo_release_list);

	write_lock(&bdev->vm_lock);

}



void ttm_bo_unref(struct ttm_buffer_object **p_bo)

{

	struct ttm_buffer_object *bo = *p_bo;

	struct ttm_bo_device *bdev = bo->bdev;



	*p_bo = NULL;

	write_lock(&bdev->vm_lock);

	kref_put(&bo->kref, ttm_bo_release);

	write_unlock(&bdev->vm_lock);

}

EXPORT_SYMBOL(ttm_bo_unref);

drivers/gpu/drm/ttm/ttm_bo_vm.c

+2 −2
Original line number Diff line number Diff line
@@ -259,8 +259,8 @@ int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma, 
	read_lock(&bdev->vm_lock);

	bo = ttm_bo_vm_lookup_rb(bdev, vma->vm_pgoff,

				 (vma->vm_end - vma->vm_start) >> PAGE_SHIFT);

	if (likely(bo != NULL))

		ttm_bo_reference(bo);

	if (likely(bo != NULL) && !kref_get_unless_zero(&bo->kref))

		bo = NULL;

	read_unlock(&bdev->vm_lock);



	if (unlikely(bo == NULL)) {