Re: [PATCH 13/19] vfs: Add a mount-notification facility [ver #16]

[Jann Horn]

On Fri, Feb 21, 2020 at 1:24 PM David Howells <dhowells@xxxxxxxxxx> wrote:
> Jann Horn <jannh@xxxxxxxxxx> wrote:
>
> > > + * Post mount notifications to all watches going rootwards along the tree.
> > > + *
> > > + * Must be called with the mount_lock held.
> >
> > Please put such constraints into lockdep assertions instead of
> > comments; that way, violations can actually be detected.
>
> What's the best way to write a lockdep assertion?
>
>         BUG_ON(!lockdep_is_held(lock));

lockdep_assert_held(lock) is the normal way, I think - that will
WARN() if lockdep is enabled and the lock is not held.