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Subject[bug report] node: Add memory-side caching attributes
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.

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?

The patch acc02a109b04: "node: Add memory-side caching attributes"
from Mar 11, 2019, leads to the following static checker warning:

drivers/base/node.c:285 node_init_cache_dev()
error: kfree after device_register(): 'dev'

drivers/base/node.c
263 static void node_init_cache_dev(struct node *node)
264 {
265 struct device *dev;
266
267 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
268 if (!dev)
269 return;
270
271 dev->parent = &node->dev;
272 dev->release = node_cache_release;
273 if (dev_set_name(dev, "memory_side_cache"))
274 goto free_dev;
275
276 if (device_register(dev))
^^^^^^^^^^^^^^^^^^^
277 goto free_name;
278
279 pm_runtime_no_callbacks(dev);
280 node->cache_dev = dev;
281 return;
282 free_name:
283 kfree_const(dev->kobj.name);
284 free_dev:
285 kfree(dev);
^^^^^^^^^^
286 }

regards,
dan carpenter

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