Data is traversed using hlist_for_each_entry_rcu outside an
RCU read-side critical section but under the protection
of either lockdep_lock or with irqs disabled.
Hence, add corresponding lockdep expression to silence false-positive
lockdep warnings, and harden RCU lists. Also add macro for
corresponding lockdep expression.
Two things to note:
- RCU traversals protected under both, irqs disabled and
graph lock, have both the checks in the lockdep expression.
- RCU traversals under the protection of just disabled irqs
don't have a corresponding lockdep expression as it is implicitly
checked for.
Signed-off-by: Amol Grover <[email protected]>
---
kernel/locking/lockdep.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 32282e7112d3..696ad5d4daed 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -85,6 +85,8 @@ module_param(lock_stat, int, 0644);
* code to recurse back into the lockdep code...
*/
static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+#define graph_lock_held() \
+ arch_spin_is_locked(&lockdep_lock)
static struct task_struct *lockdep_selftest_task_struct;
static int graph_lock(void)
@@ -1009,7 +1011,7 @@ static bool __check_data_structures(void)
/* Check the chain_key of all lock chains. */
for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
head = chainhash_table + i;
- hlist_for_each_entry_rcu(chain, head, entry) {
+ hlist_for_each_entry_rcu(chain, head, entry, graph_lock_held()) {
if (!check_lock_chain_key(chain))
return false;
}
@@ -1124,7 +1126,8 @@ void lockdep_register_key(struct lock_class_key *key)
raw_local_irq_save(flags);
if (!graph_lock())
goto restore_irqs;
- hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
+ hlist_for_each_entry_rcu(k, hash_head, hash_entry,
+ irqs_disabled() && graph_lock_held()) {
if (WARN_ON_ONCE(k == key))
goto out_unlock;
}
@@ -1203,7 +1206,8 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
* We have to do the hash-walk again, to avoid races
* with another CPU:
*/
- hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
+ hlist_for_each_entry_rcu(class, hash_head, hash_entry,
+ irqs_disabled() && graph_lock_held()) {
if (class->key == key)
goto out_unlock_set;
}
@@ -2858,7 +2862,7 @@ static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
struct hlist_head *hash_head = chainhashentry(chain_key);
struct lock_chain *chain;
- hlist_for_each_entry_rcu(chain, hash_head, entry) {
+ hlist_for_each_entry_rcu(chain, hash_head, entry, graph_lock_held()) {
if (READ_ONCE(chain->chain_key) == chain_key) {
debug_atomic_inc(chain_lookup_hits);
return chain;
@@ -4833,7 +4837,7 @@ static void remove_class_from_lock_chains(struct pending_free *pf,
for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
head = chainhash_table + i;
- hlist_for_each_entry_rcu(chain, head, entry) {
+ hlist_for_each_entry_rcu(chain, head, entry, graph_lock_held()) {
remove_class_from_lock_chain(pf, chain, class);
}
}
@@ -4993,7 +4997,7 @@ static void __lockdep_free_key_range(struct pending_free *pf, void *start,
/* Unhash all classes that were created by a module. */
for (i = 0; i < CLASSHASH_SIZE; i++) {
head = classhash_table + i;
- hlist_for_each_entry_rcu(class, head, hash_entry) {
+ hlist_for_each_entry_rcu(class, head, hash_entry, graph_lock_held()) {
if (!within(class->key, start, size) &&
!within(class->name, start, size))
continue;
@@ -5076,7 +5080,7 @@ static bool lock_class_cache_is_registered(struct lockdep_map *lock)
for (i = 0; i < CLASSHASH_SIZE; i++) {
head = classhash_table + i;
- hlist_for_each_entry_rcu(class, head, hash_entry) {
+ hlist_for_each_entry_rcu(class, head, hash_entry, graph_lock_held()) {
for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
if (lock->class_cache[j] == class)
return true;
@@ -5181,7 +5185,8 @@ void lockdep_unregister_key(struct lock_class_key *key)
goto out_irq;
pf = get_pending_free();
- hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
+ hlist_for_each_entry_rcu(k, hash_head, hash_entry,
+ irqs_disabled() && graph_lock_held()) {
if (k == key) {
hlist_del_rcu(&k->hash_entry);
found = true;
--
2.24.1