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

tip-bot for Paul E. McKenney
2010-03-04T16:33:07Z

Commit-ID: e6033e3b307fcfae08408e0673266db38392bda4
Gitweb: http://git.kernel.org/tip/e6033e3b307fcfae08408e0673266db38392bda4
Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
AuthorDate: Wed, 3 Mar 2010 17:50:16 -0800
Committer: Ingo Molnar <mingo@elte.hu>
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@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1267667418-32233-1-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
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 */