On Mon, Feb 15, 2021 at 02:12:30PM +0100, Johannes Berg wrote:
> On Mon, 2021-02-15 at 11:44 +0100, Peter Zijlstra wrote:
> >
> > I think something like so will work, but please double check.
>
> Yeah, that looks better.
>
> > +++ b/include/linux/lockdep.h
> > @@ -294,11 +294,15 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
> >
> > #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
> >
> > -#define lockdep_assert_held(l) do { \
> > - WARN_ON(debug_locks && !lockdep_is_held(l)); \
> > +#define lockdep_assert_held(l) do { \
> > + WARN_ON(debug_locks && lockdep_is_held(l) == 0)); \
> > } while (0)
>
> That doesn't really need to change? It's the same.
Correct, but I found it more symmetric vs the not implementation below.
> > -#define lockdep_assert_held_write(l) do { \
> > +#define lockdep_assert_not_held(l) do { \
> > + WARN_ON(debug_locks && lockdep_is_held(l) == 1)); \
> > + } while (0)
> > +
> > +#define lockdep_assert_held_write(l) do { \
> > WARN_ON(debug_locks && !lockdep_is_held_type(l, 0)); \
> > } while (0)
> >
> > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> > index c1418b47f625..983ba206f7b2 100644
> > --- a/kernel/locking/lockdep.
> > +++ b/kernel/locking/lockdep.c
> > @@ -5467,7 +5467,7 @@ noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
> > int ret = 0;
> >
> > if (unlikely(!lockdep_enabled()))
> > - return 1; /* avoid false negative lockdep_assert_held() */
> > + return -1; /* avoid false negative lockdep_assert_held() */
>
> Maybe add lockdep_assert_not_held() to the comment, to explain the -1
> (vs non-zero)?
Yeah, or frob a '*' in there.
