Hello,
On Mon, Apr 14, 2014 at 03:47:29PM +0800, Li Zhong wrote:
> @@ -439,6 +439,7 @@ static ssize_t online_store(struct device *dev, struct
> device_attribute *attr,
> {
> bool val;
> int ret;
> + struct kernfs_node *kn;
>
> ret = strtobool(buf, &val);
> if (ret < 0)
> @@ -448,7 +449,19 @@ static ssize_t online_store(struct device *dev, struct
> device_attribute *attr,
> if (ret)
> return ret;
>
> + kn = kernfs_find_and_get(dev->kobj.sd, attr->attr.name);
> + if (WARN_ON_ONCE(!kn))
> + goto out;
> +
> + get_device(dev);
> + kernfs_break_active_protection(kn);
> ret = val ? device_online(dev) : device_offline(dev);
> + kernfs_unbreak_active_protection(kn);
> + put_device(dev);
> +
> + kernfs_put(kn);
> +
> +out:
> unlock_device_hotplug();
> return ret < 0 ? ret : count;
> }
Can you please add comment explainin why this is being down? As it
currently stands, it's quite a bit of complexity without any
indication what's going on why. Also, if device_hotplug is locked, is
it really necessary to get @dev? Can it go away inbetween? The code
snippet looks weird because getting @dev indicates that the device
might go away without doing it but then it proceeds to invoke
device_{on|off}line() which probably isn't safe to invoke on a removed
device.
Thanks.
--
tejun
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