From cb1c72d36be42356a99285befde6e769dba599f5 Mon Sep 17 00:00:00 2001
From: Samy Al Bahra <sbahra@repnop.org>
Date: Wed, 26 Sep 2012 12:34:51 -0400
Subject: [PATCH] ck_queue: Add CK_?LIST_MOVE operation.

This operation is of format:
CK_S*LIST_MOVE(a, b, linkage) and is equivalent to intializing
a with the contents of b. This is done in a manner that is atomic
with respect to readers. Read-only operations are still valid in
b, but behavior is undefined for write-side operations on b after
a MOVE operation.
---
 include/ck_queue.h                       | 11 +++++++++++
 regressions/ck_queue/validate/ck_list.c  |  7 +++++--
 regressions/ck_queue/validate/ck_slist.c | 13 ++++++++-----
 3 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/include/ck_queue.h b/include/ck_queue.h
index 911d5e1..4b2f91b 100644
--- a/include/ck_queue.h
+++ b/include/ck_queue.h
@@ -105,6 +105,7 @@
  * _REMOVE_HEAD			+		-
  * _REMOVE			+		+
  * _SWAP			+		+
+ * _MOVE			+		+
  */
 
 /*
@@ -188,6 +189,10 @@ struct {									\
 		(head)->slh_first->field.sle_next);				\
 } while (0)
 
+#define CK_SLIST_MOVE(head1, head2, field) do {					\
+	ck_pr_store_ptr(&(head1)->slh_first, (head2)->slh_first);		\
+} while (0)
+
 /*
  * This operation is not applied atomically.
  */
@@ -265,6 +270,12 @@ struct {									\
 		(elm)->field.le_next->field.le_prev = (elm)->field.le_prev;	\
 } while (0)
 
+#define CK_LIST_MOVE(head1, head2, field) do {				\
+	ck_pr_store_ptr(&(head1)->lh_first, (head2)->lh_first);		\
+	if ((head1)->lh_first != NULL)					\
+		(head1)->lh_first->field.le_prev = &(head1)->lh_first;	\
+} while (0)
+
 /*
  * This operation is not applied atomically.
  */
diff --git a/regressions/ck_queue/validate/ck_list.c b/regressions/ck_queue/validate/ck_list.c
index 3ee762c..bbf45c9 100644
--- a/regressions/ck_queue/validate/ck_list.c
+++ b/regressions/ck_queue/validate/ck_list.c
@@ -122,6 +122,7 @@ main(int argc, char *argv[])
 {
 	pthread_t *thread;
 	struct test *n;
+	struct test_list target;
 	int n_threads, i;
 
 	if (argc != 3) {
@@ -199,11 +200,13 @@ main(int argc, char *argv[])
 		assert(r == 0);
 	}
 
+	CK_LIST_MOVE(&target, &head, list_entry);
+
 	for (i = 1; i <= goal; i++) {
 		volatile int j;
 
-		if (CK_LIST_EMPTY(&head) == false) {
-			struct test *r = CK_LIST_FIRST(&head);
+		if (CK_LIST_EMPTY(&target) == false) {
+			struct test *r = CK_LIST_FIRST(&target);
 			CK_LIST_REMOVE(r, list_entry);
 		}
 
diff --git a/regressions/ck_queue/validate/ck_slist.c b/regressions/ck_queue/validate/ck_slist.c
index 6d167ca..6391ae3 100644
--- a/regressions/ck_queue/validate/ck_slist.c
+++ b/regressions/ck_queue/validate/ck_slist.c
@@ -122,6 +122,7 @@ main(int argc, char *argv[])
 {
 	pthread_t *thread;
 	struct test *n;
+	struct test_list target;
 	int n_threads, i;
 
 	if (argc != 3) {
@@ -199,17 +200,19 @@ main(int argc, char *argv[])
 		assert(r == 0);
 	}
 
+	CK_SLIST_MOVE(&target, &head, list_entry);
+
 	for (i = 1; i <= goal; i++) {
 		volatile int j;
 
-		if (CK_SLIST_EMPTY(&head) == false)
-			CK_SLIST_REMOVE_HEAD(&head, list_entry);
+		if (CK_SLIST_EMPTY(&target) == false)
+			CK_SLIST_REMOVE_HEAD(&target, list_entry);
 
 		for (j = 0; j <= 1000; j++);
 
-		if (CK_SLIST_EMPTY(&head) == false) {
-			struct test *r = CK_SLIST_FIRST(&head);
-			CK_SLIST_REMOVE(&head, r, test, list_entry);
+		if (CK_SLIST_EMPTY(&target) == false) {
+			struct test *r = CK_SLIST_FIRST(&target);
+			CK_SLIST_REMOVE(&target, r, test, list_entry);
 		}
 	}