Messages in this thread Patch in this message | | | From | paulmck@kernel ... | Subject | [PATCH tip/core/rcu 7/7] rcu: Prevent RCU_LOCKDEP_WARN() from swallowing the condition | Date | Thu, 5 Nov 2020 15:24:54 -0800 |
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From: Jakub Kicinski <kuba@kernel.org>
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> --- include/linux/rcupdate.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index f9533bb..de08264 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -328,7 +328,7 @@ static inline void rcu_preempt_sleep_check(void) { } #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) #endif /* #else #ifdef CONFIG_PROVE_RCU */ -- 2.9.5
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