Re: [PATCH 0/5] lockdep: (Was: check && lockdep_no_validate)

From: Alan Stern
Date: Mon Jan 20 2014 - 16:42:52 EST

On Mon, 20 Jan 2014, Oleg Nesterov wrote:

> > > At first glance, can't __ATTR_IGNORE_LOCKDEP() use no_validate too ?
> > > (ignoring the fact won't be happy). This can simplify
> > > the code, it seems.
> >
> > Well, the macro itself doesn't specify the lockdep class. That happens
> > implicitly in sysfs_get_active(), in the call to rwsem_acquire_read().
> > However, it ought to be possible to change the code so that when
> > ignore_lockdep(sd) returns nonzero, we end up using no_validate.
> sysfs_dirent_init_lockdep() can check ->ignore_lockdep and do
> lockdep_set_novalidate_class(). This way sysfs_ignore_lockdep() can
> go away.
> I guess we could even change __ATTR_IGNORE_LOCKDEP() to initialize
> ->key = __lockdep_no_validate__ and kill ->ignore_lockdep.

It's clear that you have a more thorough understanding of how sysfs and
lockdep work than I do. :-)

This suggestion sounds quite reasonable.

Alan Stern

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