@@ -68,6 +68,8 @@ struct bucket_table {
struct bucket_table __rcu *future_tbl;
+ struct lockdep_map dep_map;
+
struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp;
};
@@ -88,20 +90,32 @@ struct bucket_table {
* will have provided that.
*/
-static inline void rht_lock(struct rhash_head **bucket)
+static inline void rht_lock(struct bucket_table *tbl, struct rhash_head **bucket)
+{
+ local_bh_disable();
+ bit_spin_lock(1, (unsigned long *)bucket);
+ lock_map_acquire(&tbl->dep_map);
+}
+
+static inline void rht_lock_nested(struct bucket_table *tbl,
+ struct rhash_head **bucket,
+ unsigned int subclass)
{
local_bh_disable();
bit_spin_lock(1, (unsigned long *)bucket);
+ lock_acquire_exclusive(&tbl->dep_map, subclass, 0, NULL, _THIS_IP_);
}
-static inline void rht_unlock(struct rhash_head **bucket)
+static inline void rht_unlock(struct bucket_table *tbl, struct rhash_head **bucket)
{
+ lock_map_release(&tbl->dep_map);
bit_spin_unlock(1, (unsigned long *)bucket);
local_bh_enable();
}
-static inline void rht_unlocked(void)
+static inline void rht_unlocked(struct bucket_table *tbl)
{
+ lock_map_release(&tbl->dep_map);
preempt_enable();
__release(bitlock);
local_bh_enable();
@@ -654,11 +668,11 @@ static inline void *__rhashtable_insert_fast(
if (!pprev)
goto out;
lock = pprev;
- rht_lock(lock);
+ rht_lock(tbl, lock);
if (unlikely(rcu_access_pointer(tbl->future_tbl))) {
slow_path:
- rht_unlock(lock);
+ rht_unlock(tbl, lock);
rcu_read_unlock();
return rhashtable_insert_slow(ht, key, obj);
}
@@ -728,10 +742,10 @@ static inline void *__rhashtable_insert_fast(
/* Assigning to *headp unlocked the chain, so we
* mustn't do it again.
*/
- rht_unlocked();
+ rht_unlocked(tbl);
} else {
out_unlock:
- rht_unlock(lock);
+ rht_unlock(tbl, lock);
}
out:
rcu_read_unlock();
@@ -937,7 +951,7 @@ static inline int __rhashtable_remove_fast_one(
if (!pprev)
return -ENOENT;
lock = pprev;
- rht_lock(lock);
+ rht_lock(tbl, lock);
rht_for_each_from(he, rht_ptr(*pprev), tbl, hash) {
struct rhlist_head *list;
@@ -982,13 +996,13 @@ static inline int __rhashtable_remove_fast_one(
rcu_assign_pointer(*pprev, obj);
if (lock == pprev) {
/* That rcu_assign_pointer() unlocked the chain */
- rht_unlocked();
+ rht_unlocked(tbl);
goto unlocked;
}
break;
}
- rht_unlock(lock);
+ rht_unlock(tbl, lock);
unlocked:
if (err > 0) {
atomic_dec(&ht->nelems);
@@ -1096,7 +1110,7 @@ static inline int __rhashtable_replace_fast(
return -ENOENT;
lock = pprev;
- rht_lock(lock);
+ rht_lock(tbl, lock);
rht_for_each_from(he, rht_ptr(*pprev), tbl, hash) {
if (he != obj_old) {
@@ -1109,13 +1123,13 @@ static inline int __rhashtable_replace_fast(
err = 0;
if (pprev == lock) {
/* We just unlocked the chain by assigning to *pprev */
- rht_unlocked();
+ rht_unlocked(tbl);
goto unlocked;
}
break;
}
- rht_unlock(lock);
+ rht_unlock(tbl, lock);
unlocked:
return err;
@@ -173,6 +173,7 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
struct bucket_table *tbl = NULL;
size_t size;
int i;
+ static struct lock_class_key __key;
size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]);
tbl = kvzalloc(size, gfp);
@@ -187,6 +188,8 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
if (tbl == NULL)
return NULL;
+ lockdep_init_map(&tbl->dep_map, "rhashtable_bucket", &__key, 0);
+
tbl->size = size;
rcu_head_init(&tbl->rcu);
@@ -243,7 +246,7 @@ static int rhashtable_rehash_one(struct rhashtable *ht,
new_hash = head_hashfn(ht, new_tbl, entry);
- rht_lock(&new_tbl->buckets[new_hash]);
+ rht_lock_nested(new_tbl, &new_tbl->buckets[new_hash], SINGLE_DEPTH_NESTING);
head = rht_ptr(rht_dereference_bucket(new_tbl->buckets[new_hash],
new_tbl, new_hash));
@@ -251,7 +254,7 @@ static int rhashtable_rehash_one(struct rhashtable *ht,
RCU_INIT_POINTER(entry->next, head);
rcu_assign_pointer(new_tbl->buckets[new_hash], entry);
- rht_unlocked();
+ rht_unlocked(new_tbl);
/* Need to preserved the bit lock. */
if (rht_is_locked(*pprev))
@@ -272,14 +275,14 @@ static int rhashtable_rehash_chain(struct rhashtable *ht,
if (!pprev)
return 0;
- rht_lock(pprev);
+ rht_lock(old_tbl, pprev);
while (!(err = rhashtable_rehash_one(ht, pprev, old_hash)))
;
if (err == -ENOENT)
err = 0;
- rht_unlock(pprev);
+ rht_unlock(old_tbl, pprev);
return err;
}
@@ -596,7 +599,7 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key,
new_tbl = rht_dereference_rcu(tbl->future_tbl, ht);
data = ERR_PTR(-EAGAIN);
} else {
- rht_lock(pprev);
+ rht_lock(tbl, pprev);
data = rhashtable_lookup_one(ht, pprev, tbl,
hash, key, obj);
new_tbl = rhashtable_insert_one(ht, pprev, tbl,
@@ -604,7 +607,7 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key,
if (PTR_ERR(new_tbl) != -EEXIST)
data = ERR_CAST(new_tbl);
- rht_unlock(pprev);
+ rht_unlock(tbl, pprev);
}
} while (!IS_ERR_OR_NULL(new_tbl));
Native bit_spin_locks are not tracked by lockdep. The bit_spin_locks used for rhashtable buckets are local to the rhashtable implementation, so there is little opportunity for the sort of misuse that lockdep might detect. However locks are held while a hash function or compare function is called, and if one of these took a lock, a misbehaviour is possible. As it is quite easy to add lockdep support this unlikely possibility seems to be enough justification. So create a lockdep class for bucket bit_spin_lock and attach through a lockdep_map in each bucket_table. Without the 'nested' annotation in rhashtable_rehash_one(), lockdep correctly reports a possible problem as this lock is taken while another bucket lock (in another table) is held. This confirms that the added support works. With the correct nested annotation in place, lockdep reports no problems. Signed-off-by: NeilBrown <neilb@suse.com> --- include/linux/rhashtable.h | 40 +++++++++++++++++++++++++++------------- lib/rhashtable.c | 15 +++++++++------ 2 files changed, 36 insertions(+), 19 deletions(-)