rculist: Add build check for single optional list argument
diff mbox series

Message ID 20190716040743.78343-1-joel@joelfernandes.org
State New, archived
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  • rculist: Add build check for single optional list argument
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Commit Message

Joel Fernandes July 16, 2019, 4:07 a.m. UTC
In a previous patch series [1], we added an optional lockdep expression
argument to list_for_each_entry_rcu() and the hlist equivalent. This
also meant more than one optional argument can be passed to them with
that error going unnoticed. To fix this, let us force a compiler error
more than one optional argument is passed.

[1] https://lore.kernel.org/patchwork/project/lkml/list/?series=402150

Suggested-by: Paul McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
 include/linux/rculist.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff mbox series

diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 1048160625bb..86659f6d72dc 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -44,14 +44,18 @@  static inline void INIT_LIST_HEAD_RCU(struct list_head *list)
  * Check during list traversal that we are within an RCU reader
+#define check_arg_count_one(dummy)
-#define __list_check_rcu(dummy, cond, ...)				\
+#define __list_check_rcu(dummy, cond, extra...)				\
 	({								\
+	check_arg_count_one(extra);					\
 	RCU_LOCKDEP_WARN(!cond && !rcu_read_lock_any_held(),		\
 			 "RCU-list traversed in non-reader section!");	\
-#define __list_check_rcu(dummy, cond, ...) ({})
+#define __list_check_rcu(dummy, cond, extra...)				\
+	({ check_arg_count_one(extra); })