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Subject[PATCH tip/core/rcu 45/55] rcu: check for entering dyntick-idle mode while in read-side critical section
Date
CONFIG_RCU_FAST_NO_HZ assumes that all calls to rcu_needs_cpu() are
outside of all RCU read-side critical sections. This patch adds diagnostic
checks to verify this assumption.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/rcupdate.h | 3 +++
kernel/rcutree.c | 3 +++
2 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index e86bc28..8d7efc8 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -233,6 +233,8 @@ static inline void destroy_rcu_head_on_stack(struct rcu_head *head)

#ifdef CONFIG_DEBUG_LOCK_ALLOC

+#define PROVE_RCU(a) a
+
extern struct lockdep_map rcu_lock_map;
# define rcu_read_acquire() \
lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
@@ -311,6 +313,7 @@ static inline int rcu_read_lock_sched_held(void)

#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */

+# define PROVE_RCU(a) do { } while (0)
# define rcu_read_acquire() do { } while (0)
# define rcu_read_release() do { } while (0)
# define rcu_read_acquire_bh() do { } while (0)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 8455043..743a658 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1786,6 +1786,9 @@ static int rcu_pending(int cpu)
*/
static int rcu_needs_cpu_quick_check(int cpu)
{
+ PROVE_RCU(WARN_ON_ONCE(lock_is_held(&rcu_lock_map)));
+ PROVE_RCU(WARN_ON_ONCE(lock_is_held(&rcu_bh_lock_map)));
+ PROVE_RCU(WARN_ON_ONCE(lock_is_held(&rcu_sched_lock_map)));
/* RCU callbacks either ready or pending? */
return per_cpu(rcu_sched_data, cpu).nxtlist ||
per_cpu(rcu_bh_data, cpu).nxtlist ||
--
1.7.3.2


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