From 82fe50bcc87e508e85250c87b745296a36a07897 Mon Sep 17 00:00:00 2001 From: Thomas Hellstrom Date: Wed, 21 Nov 2012 14:53:21 +0000 Subject: [PATCH] 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: Thomas Hellstrom Signed-off-by: Dave Airlie --- drivers/gpu/drm/ttm/ttm_bo.c | 5 +---- drivers/gpu/drm/ttm/ttm_bo_vm.c | 4 ++-- 2 files changed, 3 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index 7426fe59108..2c54c3d414b 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -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); diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index 3ba72dbdc4b..74705f329d9 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -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)) { -- 2.43.2