From e3818b8dce2a934cd1521dbc4827e5238d8f45d8 Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Date: Mon, 15 Mar 2010 17:03:43 -0700
Subject: rcu: Make rcu_read_lock_bh_held() allow for disabled BH
Disabling BH can stand in for rcu_read_lock_bh(), and this patch
updates rcu_read_lock_bh_held() to allow for this. In order to
avoid include-file hell, this function is moved out of line to
kernel/rcupdate.c.
This fixes a false positive RCU warning.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Lai Jiangshan <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: <20100316000343.GA25857@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/rcupdate.h | 19 ++++---------------
1 file changed, 4 insertions(+), 15 deletions(-)
(limited to 'include/linux/rcupdate.h')
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 3024050c82a..e1bdc4bfd27 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -123,22 +123,11 @@ static inline int rcu_read_lock_held(void)
return lock_is_held(&rcu_lock_map);
}
-/**
- * rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
- *
- * If CONFIG_PROVE_LOCKING is selected and enabled, returns nonzero iff in
- * an RCU-bh read-side critical section. In absence of CONFIG_PROVE_LOCKING,
- * this assumes we are in an RCU-bh read-side critical section unless it can
- * prove otherwise.
- *
- * Check rcu_scheduler_active to prevent false positives during boot.
+/*
+ * rcu_read_lock_bh_held() is defined out of line to avoid #include-file
+ * hell.
*/
-static inline int rcu_read_lock_bh_held(void)
-{
- if (!debug_lockdep_rcu_enabled())
- return 1;
- return lock_is_held(&rcu_bh_lock_map);
-}
+extern int rcu_read_lock_bh_held(void);
/**
* rcu_read_lock_sched_held - might we be in RCU-sched read-side critical section?
--
cgit v1.2.3-70-g09d2
From 0cff810f54b3b52075c27f7a7021d5b195264b6c Mon Sep 17 00:00:00 2001
From: Lai Jiangshan <laijs@cn.fujitsu.com>
Date: Thu, 18 Mar 2010 12:25:33 -0700
Subject: rcu: Fix local_irq_disable() CONFIG_PROVE_RCU=y false positives
It is documented that local_irq_disable() also delimits RCU_SCHED
read-site critical sections.
See the document of synchronize_sched() or
Documentation/RCU/whatisRCU.txt.
So we have to test irqs_disabled() in rcu_read_lock_sched_held().
Otherwise rcu-lockdep brings incorrect complaint.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.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
Cc: eric.dumazet@gmail.com
LKML-Reference: <1268940334-10892-1-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/rcupdate.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
(limited to 'include/linux/rcupdate.h')
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index e1bdc4bfd27..872a98e13d6 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -149,7 +149,7 @@ static inline int rcu_read_lock_sched_held(void)
return 1;
if (debug_locks)
lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
- return lockdep_opinion || preempt_count() != 0;
+ return lockdep_opinion || preempt_count() != 0 || irqs_disabled();
}
#else /* #ifdef CONFIG_PREEMPT */
static inline int rcu_read_lock_sched_held(void)
@@ -180,7 +180,7 @@ static inline int rcu_read_lock_bh_held(void)
#ifdef CONFIG_PREEMPT
static inline int rcu_read_lock_sched_held(void)
{
- return !rcu_scheduler_active || preempt_count() != 0;
+ return !rcu_scheduler_active || preempt_count() != 0 || irqs_disabled();
}
#else /* #ifdef CONFIG_PREEMPT */
static inline int rcu_read_lock_sched_held(void)
--
cgit v1.2.3-70-g09d2