Re: Lockdep false positive in sysfs

[Alan Stern]

On Fri, 27 Apr 2012, Tejun Heo wrote:

> > Would it be better to release just the lockdep annotation while
> > continuing to hold the actual lock, or to really drop the lock?
> 
> Just the lockdep annotation, I think.

This is turning out to be harder than it looked.

In order to release the lockdep annotation, I need the lockdep_map
which is stored in the sysfs_dirent structure.  But when the attribute
method is called, all it is given is a pointer to the attribute itself
(which contains the lockdep_class_key but not the lockdep_map) and a
pointer to the corresponding kobject.

Is there any reasonable way to get from the kobject and the attribute
to the appropriate sysfs_dirent?  Search through all the groups
attached to the kobject?  Restrict the new interface so that it can be
used only by attributes at the kobject's top level (i.e., not in a
named group)?

Any suggestions?

Alan Stern

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