rcu-list: Fix the data-race

Instead of using the old implementation of thread-rcu [1], let's use
the newest and correct one, thread-rcu/rcu.h. And, to avoid the data
race while we traverse the linked list, introduce the for loop API,
list_for_each_entry_rcu.

After we changed the implementation and used the new for loop API, it
doesn't report the data race:

$ make
cc -o test test.c -g -Wall -std=c99 -fsanitize=thread -D'READER_NUM=10' -D'UPDATER_NUM=1' -D'TRACE_LOOP=1000' -D'CONFIG_TRACE_TIME' -lpthread
$ ./test
[tracer] loop 1000 : 2367069575.000000 ns

[1] https://github.com/linD026/parallel-programs/blob/main/rcu/thrd-based-rcu/thrd_rcu.h

Author: linD026

rcu-list/Makefile

@@ -3,7 +3,7 @@ CFLAGS = -g
 CFLAGS += -Wall
 LDFLAGS += -lpthread
 CFLAGS += -std=c99
-# CFLAGS += -fsanitize=thread
+CFLAGS += -fsanitize=thread
 
 READER_NUM = 10
 UPDATER_NUM = 1

rcu-list/rculist.h

@@ -4,7 +4,10 @@
 
 #include <stddef.h>
 
-#include "thread-rcu.h"
+/* Reuse the RCU from thread-rcu */
+#include "../thread-rcu/rcu.h"
+
+#define __allow_unused __attribute__((unused))
 
 #define container_of(ptr, type, member)                         \
     __extension__({                                             \
@@ -63,10 +66,22 @@ static inline void list_del_rcu(struct list_head *node)
     list_init_rcu(node);
 }
 
+/*
+ * For the write side only (i.e., it should hold the lock when we use the
+ * non-rcu postfix for loop API).
+ */
+
 #define list_for_each(n, head) for (n = (head)->next; n != (head); n = n->next)
 
 #define list_for_each_from(pos, head) for (; pos != (head); pos = pos->next)
 
 #define list_for_each_safe(pos, n, head)                   \
     for (pos = (head)->next, n = pos->next; pos != (head); \
          pos = n, n = pos->next)
+
+/* The read side should only use the following API. */
+
+#define list_for_each_entry_rcu(pos, head, member)                     \
+    for (pos = list_entry_rcu((head)->next, __typeof__(*pos), member); \
+         &pos->member != (head);                                       \
+         pos = list_entry_rcu(pos->member.next, __typeof__(*pos), member))

rcu-list/test.c

@@ -33,15 +33,12 @@ static struct test *test_alloc(int val)
 static void *reader_side(void *argv)
 {
     struct test __allow_unused *tmp;
-    struct list_head *node;
 
     rcu_init();
 
     rcu_read_lock();
 
-    list_for_each (node, &head) {
-        tmp = list_entry_rcu(node, struct test, node);
-    }
+    list_for_each_entry_rcu(tmp, &head, node) {}
 
     rcu_read_unlock();