linux-kernel - [PATCH RFC tip/core/rcu 14/28] rcu: Warn when rcu_read_lock() is used in extended quiescent state

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Date:	Wed,  2 Nov 2011 13:30:35 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...ymtl.ca,
	josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
	peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu,
	dhowells@...hat.com, eric.dumazet@...il.com, darren@...art.com,
	patches@...aro.org, Frederic Weisbecker <fweisbec@...il.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: [PATCH RFC tip/core/rcu 14/28] rcu: Warn when rcu_read_lock() is used in extended quiescent state

From: Frederic Weisbecker <fweisbec@...il.com>

We are currently able to detect uses of rcu_dereference_check() inside
extended quiescent states (such as the RCU-free window in idle).
But rcu_read_lock() and friends can be used without rcu_dereference(),
so that the earlier commit checking for use of rcu_dereference() and
friends while in RCU idle mode miss some error conditions.  This commit
therefore adds extended quiescent state checking to rcu_read_lock() and
friends.

Uses of RCU from within RCU-idle mode are totally ignored by
RCU, hence the importance of these checks.

Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Lai Jiangshan <laijs@...fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 include/linux/rcupdate.h |   52 +++++++++++++++++++++++++++++++++++++--------
 1 files changed, 42 insertions(+), 10 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index bf91fcf..d201c15 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -237,21 +237,53 @@ static inline int rcu_is_cpu_idle(void)
 }
 #endif /* else !CONFIG_PROVE_RCU */
 
+static inline void rcu_lock_acquire(struct lockdep_map *map)
+{
+	WARN_ON_ONCE(rcu_is_cpu_idle());
+	lock_acquire(map, 0, 0, 2, 1, NULL, _THIS_IP_);
+}
+
+static inline void rcu_lock_release(struct lockdep_map *map)
+{
+	WARN_ON_ONCE(rcu_is_cpu_idle());
+	lock_release(map, 1, _THIS_IP_);
+}
+
 extern struct lockdep_map rcu_lock_map;
-# define rcu_read_acquire() \
-		lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
-# define rcu_read_release()	lock_release(&rcu_lock_map, 1, _THIS_IP_)
+
+static inline void rcu_read_acquire(void)
+{
+	rcu_lock_acquire(&rcu_lock_map);
+}
+
+static inline void rcu_read_release(void)
+{
+	rcu_lock_release(&rcu_lock_map);
+}
 
 extern struct lockdep_map rcu_bh_lock_map;
-# define rcu_read_acquire_bh() \
-		lock_acquire(&rcu_bh_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
-# define rcu_read_release_bh()	lock_release(&rcu_bh_lock_map, 1, _THIS_IP_)
+
+static inline void rcu_read_acquire_bh(void)
+{
+	rcu_lock_acquire(&rcu_bh_lock_map);
+}
+
+static inline void rcu_read_release_bh(void)
+{
+	rcu_lock_release(&rcu_bh_lock_map);
+}
 
 extern struct lockdep_map rcu_sched_lock_map;
-# define rcu_read_acquire_sched() \
-		lock_acquire(&rcu_sched_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
-# define rcu_read_release_sched() \
-		lock_release(&rcu_sched_lock_map, 1, _THIS_IP_)
+
+static inline void rcu_read_acquire_sched(void)
+{
+	rcu_lock_acquire(&rcu_sched_lock_map);
+}
+
+static inline void rcu_read_release_sched(void)
+{
+	rcu_lock_release(&rcu_sched_lock_map);
+}
 
 extern int debug_lockdep_rcu_enabled(void);
 
-- 
1.7.3.2

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