linux-kernel - [PATCH tip/core/rcu 54/55] rcu: Make srcu_read_lock_held() call common lockdep-enabled function

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Date:	Tue,  6 Sep 2011 11:00:48 -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, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 54/55] rcu: Make srcu_read_lock_held() call common lockdep-enabled function

A common debug_lockdep_rcu_enabled() function is used to check whether
RCU lockdep splats should be reported, but srcu_read_lock() does not
use it.  This commit therefore brings srcu_read_lock_held() up to date.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 include/linux/srcu.h |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index fcbaee7..54a70b7 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -84,6 +84,9 @@ long srcu_batches_completed(struct srcu_struct *sp);
  * this assumes we are in an SRCU read-side critical section unless it can
  * prove otherwise.
  *
+ * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
+ * and while lockdep is disabled.
+ *
  * Note that if the CPU is in an extended quiescent state, for example,
  * if the CPU is in dyntick-idle mode, then rcu_read_lock_held() returns
  * false even if the CPU did an rcu_read_lock().  The reason for this is
@@ -96,7 +99,7 @@ long srcu_batches_completed(struct srcu_struct *sp);
  */
 static inline int srcu_read_lock_held(struct srcu_struct *sp)
 {
-	if (debug_locks)
+	if (!debug_lockdep_rcu_enabled())
 		return lock_is_held(&sp->dep_map);
 	if (rcu_check_extended_qs())
 		return 0;
-- 
1.7.3.2

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