Messages in this thread | | | Date | Fri, 11 Apr 2014 06:26:49 -0400 | From | Tejun Heo <> | Subject | Re: [RFC PATCH v2] Use kernfs_break_active_protection() for device online store callbacks |
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Hello,
On Fri, Apr 11, 2014 at 12:10:45PM +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 +449,15 @@ 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);
Wouldn't find_and_get need to be paired with put?
> + if (WARN_ON_ONCE(!kn)) > + goto out; > + > + kernfs_break_active_protection(kn); > + > ret = val ? device_online(dev) : device_offline(dev);
With active protection protection @dev may go away at any time. There should be some protection / synchronization to prevent that, no?
> + kernfs_unbreak_active_protection(kn); > +out: > unlock_device_hotplug(); > return ret < 0 ? ret : count; > }
Thanks.
-- tejun
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