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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>
This commit is contained in:
Jakub Kicinski 2020-09-16 11:45:28 -07:00 committed by Paul E. McKenney
parent cd539cff94
commit 65e9eb1ccf
1 changed files with 1 additions and 1 deletions
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2
include/linux/rcupdate.h
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@ -328,7 +328,7 @@ static inline void rcu_preempt_sleep_check(void) { }
#else /* #ifdef CONFIG_PROVE_RCU */ #else /* #ifdef CONFIG_PROVE_RCU */
#define RCU_LOCKDEP_WARN(c, s) do { } while (0) #define RCU_LOCKDEP_WARN(c, s) do { } while (0 && (c))
#define rcu_sleep_check() do { } while (0) #define rcu_sleep_check() do { } while (0)
#endif /* #else #ifdef CONFIG_PROVE_RCU */ #endif /* #else #ifdef CONFIG_PROVE_RCU */