[PATCH 02/32] locking/lockdep: lock_class_is_held()

Kent Overstreet
2023-05-09T16:57:26Z

From: Kent Overstreet <kent.overstreet@gmail.com>

This patch adds lock_class_is_held(), which can be used to assert that a
particular type of lock is not held.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
---
include/linux/lockdep.h | 4 ++++
kernel/locking/lockdep.c | 20 ++++++++++++++++++++
2 files changed, 24 insertions(+)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 1023f349af..e858c288c7 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -339,6 +339,8 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
#define lockdep_repin_lock(l,c) lock_repin_lock(&(l)->dep_map, (c))
#define lockdep_unpin_lock(l,c) lock_unpin_lock(&(l)->dep_map, (c))

+int lock_class_is_held(struct lock_class_key *key);
+
#else /* !CONFIG_LOCKDEP */

static inline void lockdep_init_task(struct task_struct *task)
@@ -427,6 +429,8 @@ extern int lockdep_is_held(const void *);
#define lockdep_repin_lock(l, c) do { (void)(l); (void)(c); } while (0)
#define lockdep_unpin_lock(l, c) do { (void)(l); (void)(c); } while (0)

+static inline int lock_class_is_held(struct lock_class_key *key) { return 0; }
+
#endif /* !LOCKDEP */

enum xhlock_context_t {
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 50d4863974..e631464070 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -6487,6 +6487,26 @@ void debug_check_no_locks_held(void)
}
EXPORT_SYMBOL_GPL(debug_check_no_locks_held);

+#ifdef CONFIG_LOCKDEP
+int lock_class_is_held(struct lock_class_key *key)
+{
+ struct task_struct *curr = current;
+ struct held_lock *hlock;
+
+ if (unlikely(!debug_locks))
+ return 0;
+
+ for (hlock = curr->held_locks;
+ hlock < curr->held_locks + curr->lockdep_depth;
+ hlock++)
+ if (hlock->instance->key == key)
+ return 1;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(lock_class_is_held);
+#endif
+
#ifdef __KERNEL__
void debug_show_all_locks(void)
{
--
2.40.1