Messages in this thread | | | Subject | Re: [PATCH v2 21/24] locking/lockdep: Verify whether lock objects are small enough to be used as class keys | From | Bart Van Assche <> | Date | Tue, 04 Dec 2018 13:39:13 -0800 |
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On Tue, 2018-12-04 at 16:08 -0500, Waiman Long wrote: > On 12/03/2018 07:28 PM, Bart Van Assche wrote: > > Cc: Peter Zijlstra <peterz@infradead.org> > > Cc: Waiman Long <longman@redhat.com> > > Cc: Johannes Berg <johannes@sipsolutions.net> > > Signed-off-by: Bart Van Assche <bvanassche@acm.org> > > --- > > kernel/locking/lockdep.c | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c > > index c936fce5b9d7..b4772e5fc176 100644 > > --- a/kernel/locking/lockdep.c > > +++ b/kernel/locking/lockdep.c > > @@ -727,6 +727,15 @@ static bool assign_lock_key(struct lockdep_map *lock) > > { > > unsigned long can_addr, addr = (unsigned long)lock; > > > > + /* > > + * lockdep_free_key_range() assumes that struct lock_class_key > > + * objects do not overlap. Since we use the address of lock > > + * objects as class key for static objects, check whether the > > + * size of lock_class_key objects does not exceed the size of > > + * the smallest lock object. > > + */ > > + BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t)); > > + > > if (__is_kernel_percpu_address(addr, &can_addr)) > > lock->key = (void *)can_addr; > > else if (__is_module_percpu_address(addr, &can_addr)) > > I don't understand what this check is for. lock_class_key and spinlock > are different objects. Their relative size shouldn't matter.
Hi Waiman,
Peter asked me to add this check.
Bart.
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