rcu: Prevent RCU_LOCKDEP_WARN() from swallowing the condition
We run into a unused variable warning in bridge code when variable is
only used inside the condition of rcu_dereference_protected().
#define mlock_dereference(X, br) \
rcu_dereference_protected(X, lockdep_is_held(&br->multicast_lock))
Since on builds with CONFIG_PROVE_RCU=n rcu_dereference_protected()
compiles to nothing the compiler doesn't see the variable use.
This commit therefore prevents this warning by adding the condition as
dead code.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
--
CC: paulmck@kernel.org
CC: josh@joshtriplett.org
CC: rostedt@goodmis.org
CC: mathieu.desnoyers@efficios.com
CC: joel@joelfernandes.org
CC: jiangshanlai@gmail.com
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>