Re: [RT] lockdep munching nr_list_entries like popcorn

Peter Zijlstra
2017-02-16T11:06:18Z

On Thu, Feb 16, 2017 at 10:01:18AM +0100, Thomas Gleixner wrote:
> On Thu, 16 Feb 2017, Mike Galbraith wrote:
>
> > On Thu, 2017-02-16 at 09:37 +0100, Thomas Gleixner wrote:
> > > On Thu, 16 Feb 2017, Mike Galbraith wrote:
> > >
> > ...
> > > > swapvec_lock? Oodles of 'em? Nope.
> > >
> > > Well, it's a per cpu lock and the lru_cache_add() variants might be called
> > > from a gazillion of different call chains, but yes, it does not make a lot
> > > of sense. We'll have a look.
> >
> > Adding explicit local_irq_lock_init() makes things heaps better, so
> > presumably we need better lockdep-foo in DEFINE_LOCAL_IRQ_LOCK().
>
> Bah.

#ifdef CONFIG_DEBUG_LOCK_ALLOC
#define PER_CPU_DEP_MAP_INIT(lockname) \
.dep_map = { \
.key = ({ static struct lock_class_key __key; &__key }), \
.name = #lockname, \
}
#else
#define PER_CPU_DEP_MAP_INIT(lockname)
#endif

#define DEFINE_LOCAL_IRQ_LOCK(lvar) \
DEFINE_PER_CPU(struct local_irq_lock, lvar) = { \
.lock = { .rlock = { \
.raw_lock = __ARCH_SPIN_LOCK_UNLOCKED, \
SPIN_DEBUG_INIT(lvar) \
PER_CPU_DEP_MAP_INIT(lvar) \
} } \
}

That's fairly horrible for poking inside all the internals, but it might
just work ;-)