On Tue, Apr 02, 2013 at 12:27:18AM +0100, Al Viro wrote:
> On Mon, Apr 01, 2013 at 02:44:36PM -0700, Greg Kroah-Hartman wrote:
> > > > I guess you are right, it will not. I guess we need to do what
> > > > character devices do and have an "intermediate" fops in order to protect
> > > > this. Would that work?
> > >
> > > You mean, with reassigning ->f_op in ->open()? That'll work, as long as
> > > we have exclusion between removal and fetching the sucker in primary
> > > ->open()... Where would you prefer to stash fops?
> >
> > Ick, that's not going to work as the current api just uses a fops and
> > debugfs doesn't keep anything else hanging around that referes to
> > something "before" that, like 'struct cdev' does.
>
> Er? How about just sticking it into dentry->d_fsdata and letting
> debugfs_remove() zero that out? What am I missing here?
Hrm... For what it's worth, how do debugfs entries associated with
dynamic objects deal with debugfs_remove() vs. method calls? I don't
see _anything_ in {,__}debugfs_remove() that would looks like "wait
for ongoing write(2) attempts to complete". IOW, forget rmmod - WTF
protects us from access-after-free for any kind of data that isn't
permanently allocated?
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