On Fri, 19 Oct 2012 14:46:35 +0800
wency@xxxxxxxxxxxxxx wrote:
> From: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
>
> When calling unregister_node(), the function shows following message at
> device_release().
>
> "Device 'node2' does not have a release() function, it is broken and must
> be fixed."
>
> The reason is node's device struct does not have a release() function.
>
> So the patch registers node_device_release() to the device's release()
> function for suppressing the warning message. Additionally, the patch adds
> memset() to initialize a node struct into register_node(). Because the node
> struct is part of node_devices[] array and it cannot be freed by
> node_device_release(). So if system reuses the node struct, it has a garbage.
>
> ...
>
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -252,6 +252,9 @@ static inline void hugetlb_register_node(struct node *node) {}
> static inline void hugetlb_unregister_node(struct node *node) {}
> #endif
>
> +static void node_device_release(struct device *dev)
> +{
> +}
>
> /*
> * register_node - Setup a sysfs device for a node.
> @@ -263,8 +266,11 @@ int register_node(struct node *node, int num, struct node *parent)
> {
> int error;
>
> + memset(node, 0, sizeof(*node));
> +
> node->dev.id = num;
> node->dev.bus = &node_subsys;
> + node->dev.release = node_device_release;
> error = device_register(&node->dev);
>
> if (!error){
Greg won't like that empty ->release function ;)
As you say, this device item does not reside in per-device dynamically
allocated memory - it is part of an externally managed array.
So a proper fix here would be to convert this storage so that it *is*
dynamically allocated on a per-device basis.
Or perhaps we should recognize that the whole kobject
get/put/release-on-last-put model is inappropriate for these objects,
and stop using it entirely.
>From Kosaki's comment, it does sound that we plan to take the first
option: convert to per-device dynamically allocated memory? If so, I
suggest that we just leave the warning as-is for now, until we fix
things proprely.
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