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Subject[PATCH v3 21/24] locking/lockdep: Verify whether lock objects are small enough to be used as class keys
Date
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 8c69516b1283..a47357d3dca7 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))
--
2.20.0.rc2.403.gdbc3b29805-goog
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