linux-kernel - [PATCH tip/core/rcu 5/7] srcu: Use a more appropriate lockdep helper

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Message-Id: <20201105232454.19919-5-paulmck@kernel.org>
Date:   Thu,  5 Nov 2020 15:24:52 -0800
From:   paulmck@...nel.org
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com, mingo@...nel.org,
        jiangshanlai@...il.com, akpm@...ux-foundation.org,
        mathieu.desnoyers@...icios.com, josh@...htriplett.org,
        tglx@...utronix.de, peterz@...radead.org, rostedt@...dmis.org,
        dhowells@...hat.com, edumazet@...gle.com, fweisbec@...il.com,
        oleg@...hat.com, joel@...lfernandes.org,
        Jakub Kicinski <kuba@...nel.org>, paulmck@...nel.org
Subject: [PATCH tip/core/rcu 5/7] srcu: Use a more appropriate lockdep helper

From: Jakub Kicinski <kuba@...nel.org>

The lockdep_is_held() macro is defined as:

 #define lockdep_is_held(lock)		lock_is_held(&(lock)->dep_map)

This hides away the dereference, so that builds with !LOCKDEP don't break.
This works in current kernels because the RCU_LOCKDEP_WARN() eliminates
its condition at preprocessor time in !LOCKDEP kernels.  However, later
patches in this series will cause the compiler to see this condition even
in !LOCKDEP kernels.  This commit prepares for this upcoming change by
switching from lock_is_held() to lockdep_is_held().

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
--
CC: jiangshanlai@...il.com
CC: paulmck@...nel.org
CC: josh@...htriplett.org
CC: rostedt@...dmis.org
CC: mathieu.desnoyers@...icios.com
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/rcu/srcutree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index c13348e..6cd6fa2 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -906,7 +906,7 @@ static void __synchronize_srcu(struct srcu_struct *ssp, bool do_norm)
 {
 	struct rcu_synchronize rcu;
 
-	RCU_LOCKDEP_WARN(lock_is_held(&ssp->dep_map) ||
+	RCU_LOCKDEP_WARN(lockdep_is_held(ssp) ||
 			 lock_is_held(&rcu_bh_lock_map) ||
 			 lock_is_held(&rcu_lock_map) ||
 			 lock_is_held(&rcu_sched_lock_map),
-- 
2.9.5