Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 2 Feb 2024 07:47:50 -0500 | From | Kent Overstreet <> | Subject | Re: [PATCH 1/4] fs/pipe: Convert to lockdep_cmp_fn |
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On Fri, Feb 02, 2024 at 01:03:57PM +0100, Jan Kara wrote: > On Fri 26-01-24 21:08:28, Kent Overstreet wrote: > > *_lock_nested() is fundamentally broken; lockdep needs to check lock > > ordering, but we cannot device a total ordering on an unbounded number > > of elements with only a few subclasses. > > > > the replacement is to define lock ordering with a proper comparison > > function. > > > > fs/pipe.c was already doing everything correctly otherwise, nothing > > much changes here. > > > > Cc: Alexander Viro <viro@zeniv.linux.org.uk> > > Cc: Christian Brauner <brauner@kernel.org> > > Cc: Jan Kara <jack@suse.cz> > > Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> > > I had to digest for a while what this new lockdep lock ordering feature is > about. I have one pending question - what is the motivation of this > conversion of pipe code? AFAIU we don't have any problems with lockdep > annotations on pipe->mutex because there are always only two subclasses?
It's one of the easier conversions to do, and ideally /all/ users of subclasses would go away.
Start with the easier ones, figure out those patterns, then the harder...
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