Messages in this thread | | | Date | Mon, 7 Nov 2011 08:21:59 -0800 | From | Tejun Heo <> | Subject | Re: [PATCH 1/4] lockdep: lock_set_subclass() fix |
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Hello,
On Mon, Nov 07, 2011 at 05:10:29PM +0100, Peter Zijlstra wrote: > We could move the key and name pointer to the start of the structure and > memset everything after that, however wouldn't that leave kmemcheck with > the same problem? It wouldn't know those two pointers would be > initialized properly.
At that point, lockdep_map is guaranteed to have passed through lockdep_init_map(), so I think it should be fine.
> @@ -148,9 +148,9 @@ void clear_lock_stats(struct lock_class *class); > * This is embedded into specific lock instances: > */ > struct lockdep_map { > + const char *name; > struct lock_class_key *key; > struct lock_class *class_cache[NR_LOCKDEP_CACHING_CLASSES]; > - const char *name; > #ifdef CONFIG_LOCK_STAT > int cpu; > unsigned long ip;
Probably fat comment explaining the ordering requirement here w/
#define LOCKDEP_MAP_INIT_OFFSET offsetof(struct lockdep_map, class_cache)
> diff --git a/kernel/lockdep.c b/kernel/lockdep.c > index e69434b..81855cf 100644 > --- a/kernel/lockdep.c > +++ b/kernel/lockdep.c > @@ -2948,7 +2948,8 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this, > void lockdep_init_map(struct lockdep_map *lock, const char *name, > struct lock_class_key *key, int subclass) > { > - memset(lock, 0, sizeof(*lock)); > + kmemcheck_mark_initialized(lock, 2*sizeof(void *)); > + memset(&lock->class_cache[0], 0, sizeof(*lock)-2*sizeof(void *));
And something like the following?
memset((void *)lock + LOCKDEP_MAP_INIT_OFFSET, 0, sizeof(*lock) - LOCKDEP_MAP_INIT_OFFSET);
Thanks.
-- tejun
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