diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/drm_gem.c | 40 | ||||
| -rw-r--r-- | drivers/gpu/drm/drm_vma_manager.c | 40 |
2 files changed, 40 insertions, 40 deletions
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index ab8ea42264f4..64353d40db53 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -862,30 +862,46 @@ int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma) { struct drm_file *priv = filp->private_data; struct drm_device *dev = priv->minor->dev; - struct drm_gem_object *obj; + struct drm_gem_object *obj = NULL; struct drm_vma_offset_node *node; int ret; if (drm_device_is_unplugged(dev)) return -ENODEV; - mutex_lock(&dev->struct_mutex); + drm_vma_offset_lock_lookup(dev->vma_offset_manager); + node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager, + vma->vm_pgoff, + vma_pages(vma)); + if (likely(node)) { + obj = container_of(node, struct drm_gem_object, vma_node); + /* + * When the object is being freed, after it hits 0-refcnt it + * proceeds to tear down the object. In the process it will + * attempt to remove the VMA offset and so acquire this + * mgr->vm_lock. Therefore if we find an object with a 0-refcnt + * that matches our range, we know it is in the process of being + * destroyed and will be freed as soon as we release the lock - + * so we have to check for the 0-refcnted object and treat it as + * invalid. + */ + if (!kref_get_unless_zero(&obj->refcount)) + obj = NULL; + } + drm_vma_offset_unlock_lookup(dev->vma_offset_manager); - node = drm_vma_offset_exact_lookup(dev->vma_offset_manager, - vma->vm_pgoff, - vma_pages(vma)); - if (!node) { - mutex_unlock(&dev->struct_mutex); + if (!obj) return -EINVAL; - } else if (!drm_vma_node_is_allowed(node, filp)) { - mutex_unlock(&dev->struct_mutex); + + if (!drm_vma_node_is_allowed(node, filp)) { + drm_gem_object_unreference_unlocked(obj); return -EACCES; } - obj = container_of(node, struct drm_gem_object, vma_node); - ret = drm_gem_mmap_obj(obj, drm_vma_node_size(node) << PAGE_SHIFT, vma); + ret = drm_gem_mmap_obj(obj, drm_vma_node_size(node) << PAGE_SHIFT, + vma); - mutex_unlock(&dev->struct_mutex); + drm_gem_object_unreference_unlocked(obj); return ret; } diff --git a/drivers/gpu/drm/drm_vma_manager.c b/drivers/gpu/drm/drm_vma_manager.c index 68c1f32fb086..2f2ecde8285b 100644 --- a/drivers/gpu/drm/drm_vma_manager.c +++ b/drivers/gpu/drm/drm_vma_manager.c @@ -112,7 +112,7 @@ void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr) EXPORT_SYMBOL(drm_vma_offset_manager_destroy); /** - * drm_vma_offset_lookup() - Find node in offset space + * drm_vma_offset_lookup_locked() - Find node in offset space * @mgr: Manager object * @start: Start address for object (page-based) * @pages: Size of object (page-based) @@ -122,37 +122,21 @@ EXPORT_SYMBOL(drm_vma_offset_manager_destroy); * region and the given node will be returned, as long as the node spans the * whole requested area (given the size in number of pages as @pages). * - * RETURNS: - * Returns NULL if no suitable node can be found. Otherwise, the best match - * is returned. It's the caller's responsibility to make sure the node doesn't - * get destroyed before the caller can access it. - */ -struct drm_vma_offset_node *drm_vma_offset_lookup(struct drm_vma_offset_manager *mgr, - unsigned long start, - unsigned long pages) -{ - struct drm_vma_offset_node *node; - - read_lock(&mgr->vm_lock); - node = drm_vma_offset_lookup_locked(mgr, start, pages); - read_unlock(&mgr->vm_lock); - - return node; -} -EXPORT_SYMBOL(drm_vma_offset_lookup); - -/** - * drm_vma_offset_lookup_locked() - Find node in offset space - * @mgr: Manager object - * @start: Start address for object (page-based) - * @pages: Size of object (page-based) + * Note that before lookup the vma offset manager lookup lock must be acquired + * with drm_vma_offset_lock_lookup(). See there for an example. This can then be + * used to implement weakly referenced lookups using kref_get_unless_zero(). * - * Same as drm_vma_offset_lookup() but requires the caller to lock offset lookup - * manually. See drm_vma_offset_lock_lookup() for an example. + * Example: + * drm_vma_offset_lock_lookup(mgr); + * node = drm_vma_offset_lookup_locked(mgr); + * if (node) + * kref_get_unless_zero(container_of(node, sth, entr)); + * drm_vma_offset_unlock_lookup(mgr); * * RETURNS: * Returns NULL if no suitable node can be found. Otherwise, the best match - * is returned. + * is returned. It's the caller's responsibility to make sure the node doesn't + * get destroyed before the caller can access it. */ struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr, unsigned long start, |