On Thu, Apr 01, 2021 at 12:00:39PM +0300, Dan Carpenter wrote:
> Hi Keith,
>
> I've been trying to figure out ways Smatch can check for device managed
> resources. Like adding rules that if we call dev_set_name(&foo->bar)
> then it's device managaged and if there is a kfree(foo) without calling
> device_put(&foo->bar) then that's a resource leak.
It seems to be working from what I can see
Also I wasn't able to convince myself that any locking around
node->cache_attrs exist..
> Of course one of the rules is that if you call device_register(dev) then
> you can't kfree(dev), it has to released with device_put(dev) and that's
> true even if the register fails. But this code here feels very
> intentional so maybe there is an exception to the rule?
There is no exception. Open coding this:
> 282 free_name:
> 283 kfree_const(dev->kobj.name);
To avoid leaking memory from dev_set_name is a straight up layering
violation, WTF?
node_cacheinfo_release() is just kfree(), so there is no need.
Instead (please feel free to send this Dan):
diff --git a/drivers/base/node.c b/drivers/base/node.c
index f449dbb2c74666..89c28952863977 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -319,25 +319,24 @@ void node_add_cache(unsigned int nid, struct node_cache_attrs *cache_attrs)
return;
dev = &info->dev;
+ device_initialize(dev)
dev->parent = node->cache_dev;
dev->release = node_cacheinfo_release;
dev->groups = cache_groups;
if (dev_set_name(dev, "index%d", cache_attrs->level))
- goto free_cache;
+ goto put_device;
info->cache_attrs = *cache_attrs;
- if (device_register(dev)) {
+ if (device_add(dev)) {
dev_warn(&node->dev, "failed to add cache level:%d\n",
cache_attrs->level);
- goto free_name;
+ goto put_device
}
pm_runtime_no_callbacks(dev);
list_add_tail(&info->node, &node->cache_attrs);
return;
-free_name:
- kfree_const(dev->kobj.name);
-free_cache:
- kfree(info);
+put_device:
+ put_device(dev);
}
static void node_remove_caches(struct node *node)
