From 5cf28b21521b496f04e94dfb250419570f17f019 Mon Sep 17 00:00:00 2001
From: Samy Al Bahra <sbahra@repnop.org>
Date: Wed, 17 Jul 2013 23:31:32 -0400
Subject: [PATCH] ck_rwcohort: Missing fences on fast path.

When spinning on global counters, it cannot be assumed that is_locked
functions will guarantee atomic to load ordering, an explicit fence
is necessary. is_locked will only guarantee load ordering.
---
 include/ck_rwcohort.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/ck_rwcohort.h b/include/ck_rwcohort.h
index 7ddc5ff..c4d8713 100644
--- a/include/ck_rwcohort.h
+++ b/include/ck_rwcohort.h
@@ -105,6 +105,7 @@
 											\
 		for (;;) {								\
 			ck_pr_inc_uint(&rw_cohort->read_counter);			\
+			ck_pr_fence_atomic_load();					\
 			if (CK_COHORT_LOCKED(N, cohort, global_context,			\
 			    local_context) == false)					\
 				break;							\
@@ -130,6 +131,7 @@
 	ck_rwcohort_wp_##N##_read_unlock(CK_RWCOHORT_WP_INSTANCE(N) *cohort)		\
 	{										\
 											\
+		ck_pr_fence_memory();							\
 		ck_pr_dec_uint(&cohort->read_counter);					\
 		return;									\
 	}
@@ -216,7 +218,9 @@
 											\
 		while (ck_pr_load_uint(&rw_cohort->read_barrier) > 0)			\
 			ck_pr_stall();							\
+											\
 		ck_pr_inc_uint(&rw_cohort->read_counter);				\
+		ck_pr_fence_atomic_load();						\
 											\
 		while (CK_COHORT_LOCKED(N, cohort, global_context,			\
 		    local_context) == true)						\
@@ -228,6 +232,7 @@
 	ck_rwcohort_rp_##N##_read_unlock(CK_RWCOHORT_RP_INSTANCE(N) *cohort)		\
 	{										\
 											\
+		ck_pr_fence_memory();							\
 		ck_pr_dec_uint(&cohort->read_counter);					\
 		return;									\
 	}
@@ -299,6 +304,7 @@
 	ck_rwcohort_neutral_##N##_read_unlock(CK_RWCOHORT_NEUTRAL_INSTANCE(N) *cohort)	\
 	{										\
 											\
+		ck_pr_fence_memory();							\
 		ck_pr_dec_uint(&cohort->read_counter);					\
 		return;									\
 	}