Passing a complex lockdep condition to __list_check_rcu results
in false positive lockdep splat due to incorrect expression
evaluation.
For example, a lockdep check condition `cond1 || cond2` is
evaluated as `!cond1 || cond2 && !rcu_read_lock_any_held()`
which, according to operator precedence, evaluates to
`!cond1 || (cond2 && !rcu_read_lock_any_held())`.
This would result in a lockdep splat when cond1 is false
and cond2 is true which is logically incorrect.
Signed-off-by: Amol Grover <frextrite@xxxxxxxxx>
---
include/linux/rculist.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 4158b7212936..dce491f0b354 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -50,9 +50,9 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list)
#define __list_check_rcu(dummy, cond, extra...) \
({ \
check_arg_count_one(extra); \
- RCU_LOCKDEP_WARN(!cond && !rcu_read_lock_any_held(), \
+ RCU_LOCKDEP_WARN(!(cond) && !rcu_read_lock_any_held(), \
"RCU-list traversed in non-reader section!"); \
- })
+ })
#else
#define __list_check_rcu(dummy, cond, extra...) \
({ check_arg_count_one(extra); })
--
2.24.1
