[tip:core/urgent] rcu: Make rcu_read_lock_sched_held() handle !PREEMPT

[tip-bot for Paul E. McKenney]

Commit-ID:  e6033e3b307fcfae08408e0673266db38392bda4
Gitweb:     http://git.kernel.org/tip/e6033e3b307fcfae08408e0673266db38392bda4
Author:     Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Wed, 3 Mar 2010 17:50:16 -0800
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 4 Mar 2010 12:07:33 +0100

rcu: Make rcu_read_lock_sched_held() handle !PREEMPT

The rcu_read_lock_sched_held() needs to unconditionally return
the value "1" in a !PREEMPT kernel, because under !PREEMPT,
-all- kernel code is implicitly preempt-disabled.  This patch
makes this happen.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: laijs@xxxxxxxxxxxxxx
Cc: dipankar@xxxxxxxxxx
Cc: mathieu.desnoyers@xxxxxxxxxx
Cc: josh@xxxxxxxxxxxxxxxx
Cc: dvhltc@xxxxxxxxxx
Cc: niv@xxxxxxxxxx
Cc: peterz@xxxxxxxxxxxxx
Cc: rostedt@xxxxxxxxxxx
Cc: Valdis.Kletnieks@xxxxxx
Cc: dhowells@xxxxxxxxxx
LKML-Reference: <1267667418-32233-1-git-send-email-paulmck@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 include/linux/rcupdate.h |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index c843736..e22960e 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -136,6 +136,7 @@ static inline int rcu_read_lock_bh_held(void)
  * can prove otherwise.  Note that disabling of preemption (including
  * disabling irqs) counts as an RCU-sched read-side critical section.
  */
+#ifdef CONFIG_PREEMPT
 static inline int rcu_read_lock_sched_held(void)
 {
 	int lockdep_opinion = 0;
@@ -144,6 +145,12 @@ static inline int rcu_read_lock_sched_held(void)
 		lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
 	return lockdep_opinion || preempt_count() != 0 || !rcu_scheduler_active;
 }
+#else /* #ifdef CONFIG_PREEMPT */
+static inline int rcu_read_lock_sched_held(void)
+{
+	return 1;
+}
+#endif /* #else #ifdef CONFIG_PREEMPT */
 
 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
@@ -164,10 +171,17 @@ static inline int rcu_read_lock_bh_held(void)
 	return 1;
 }
 
+#ifdef CONFIG_PREEMPT
 static inline int rcu_read_lock_sched_held(void)
 {
 	return preempt_count() != 0 || !rcu_scheduler_active;
 }
+#else /* #ifdef CONFIG_PREEMPT */
+static inline int rcu_read_lock_sched_held(void)
+{
+	return 1;
+}
+#endif /* #else #ifdef CONFIG_PREEMPT */
 
 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
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