[PATCH 8/9] jrcu: fix broken rcu_barrier
From: Joe Korty
Date: Sun Mar 13 2011 - 23:52:42 EST
jrcu: fix bug in rcu_barrier.
It is not equivalent to synchronize_rcu. But it
can be implemented by a pair of synchronize_rcu's,
so do so.
Thanks go to Paul E McKenney for finding this.
Signed-off-by: Joe Korty <joe.korty@xxxxxxxx>
Index: b/kernel/jrcu.c
===================================================================
--- a/kernel/jrcu.c
+++ b/kernel/jrcu.c
@@ -183,7 +183,7 @@ void rcu_note_might_resched(void)
}
EXPORT_SYMBOL(rcu_note_might_resched);
-void rcu_barrier(void)
+void synchronize_sched(void)
{
struct rcu_synchronize rcu;
@@ -196,6 +196,13 @@ void rcu_barrier(void)
atomic_inc(&rcu_stats.nbarriers);
}
+EXPORT_SYMBOL_GPL(synchronize_sched);
+
+void rcu_barrier(void)
+{
+ synchronize_sched();
+ synchronize_sched();
+}
EXPORT_SYMBOL_GPL(rcu_barrier);
void rcu_force_quiescent_state(void)
Index: b/include/linux/jrcu.h
===================================================================
--- a/include/linux/jrcu.h
+++ b/include/linux/jrcu.h
@@ -39,12 +39,13 @@ extern void rcu_barrier(void);
#define rcu_barrier_sched rcu_barrier
#define rcu_barrier_bh rcu_barrier
-#define synchronize_rcu rcu_barrier
-#define synchronize_sched rcu_barrier
-#define synchronize_sched_expedited rcu_barrier
-#define synchronize_rcu_bh rcu_barrier
-#define synchronize_rcu_expedited rcu_barrier
-#define synchronize_rcu_bh_expedited rcu_barrier
+extern void synchronize_sched(void);
+
+#define synchronize_rcu synchronize_sched
+#define synchronize_sched_expedited synchronize_sched
+#define synchronize_rcu_bh synchronize_sched
+#define synchronize_rcu_expedited synchronize_sched
+#define synchronize_rcu_bh_expedited synchronize_sched
#define rcu_init(cpu) do { } while (0)
#define rcu_init_sched() do { } while (0)
--
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