From c7c91ac03d3c6651b8fbe1d61afcc022f1ec3e18 Mon Sep 17 00:00:00 2001
From: Brian Norris <banorris@uci.edu>
Date: Fri, 8 Mar 2013 16:01:02 -0800
Subject: [PATCH] ms-queue: add extra POISON_IDX assertion
---
ms-queue/my_queue.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/ms-queue/my_queue.c b/ms-queue/my_queue.c
index 18ce29f..ef35552 100644
--- a/ms-queue/my_queue.c
+++ b/ms-queue/my_queue.c
@@ -12,6 +12,8 @@
#define MAX_FREELIST 4 /* Each thread can own up to MAX_FREELIST free nodes */
#define INITIAL_FREE 2 /* Each thread starts with INITIAL_FREE free nodes */
+#define POISON_IDX 0x666
+
static unsigned int (*free_lists)[MAX_FREELIST];
/* Search this thread's free list for a "new" node */
@@ -58,12 +60,13 @@ void init_queue(queue_t *q, int num_threads)
{
int i, j;
- /* Initialize each thread's free list with INITIAL_FREE NULL "pointers" */
+ /* Initialize each thread's free list with INITIAL_FREE pointers */
+ /* The actual nodes are initialized with poison indexes */
free_lists = malloc(num_threads * sizeof(*free_lists));
for (i = 0; i < num_threads; i++) {
for (j = 0; j < INITIAL_FREE; j++) {
free_lists[i][j] = 2 + i * MAX_FREELIST + j;
- atomic_init(&q->nodes[free_lists[i][j]].next, MAKE_POINTER(0, 0));
+ atomic_init(&q->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
}
}
@@ -91,6 +94,10 @@ void enqueue(queue_t *q, unsigned int val)
tail = atomic_load_explicit(&q->tail, acquire);
next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
if (tail == atomic_load_explicit(&q->tail, relaxed)) {
+
+ /* Check for uninitialized 'next' */
+ MODEL_ASSERT(get_ptr(next) != POISON_IDX);
+
if (get_ptr(next) == 0) { // == NULL
pointer value = MAKE_POINTER(node, get_count(next) + 1);
success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
@@ -127,6 +134,10 @@ unsigned int dequeue(queue_t *q)
next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
if (atomic_load_explicit(&q->head, relaxed) == head) {
if (get_ptr(head) == get_ptr(tail)) {
+
+ /* Check for uninitialized 'next' */
+ MODEL_ASSERT(get_ptr(next) != POISON_IDX);
+
if (get_ptr(next) == 0) { // NULL
return 0; // NULL
}
--
2.34.1