urcu tests: hold mutex across use of custom allocator

A thread preempted for a long period of time could race, when scheduled
again, with another thread that would have been allocating/freeing
entries (thus wrapping-around the available buffer), which would trigger
this race only when overcommitting the number of threads compared to the
number of available CPUs.

Taking the mutex across alloc and free to fix this.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/tests/test_qsbr.c b/tests/test_qsbr.c
index 12346c3cea2d0701cf6c3ab45afc30ba61fb7f32..1c5a696c03491db909c4c2a23f42df9a0fe4b4b0 100644 (file)
--- a/tests/test_qsbr.c
+++ b/tests/test_qsbr.c
@@ -185,7 +185,8 @@ void rcu_copy_mutex_unlock(void)
 /*
  * malloc/free are reusing memory areas too quickly, which does not let us
  * test races appropriately. Use a large circular array for allocations.
- * ARRAY_SIZE is larger than nr_writers, which insures we never run over our tail.
+ * ARRAY_SIZE is larger than nr_writers, and we keep the mutex across
+ * both alloc and free, which insures we never run over our tail.
  */
 #define ARRAY_SIZE (1048576 * nr_writers)
 #define ARRAY_POISON 0xDEADBEEF
@@ -197,7 +198,6 @@ static struct test_array *test_array_alloc(void)
        struct test_array *ret;
        int index;
 
-       rcu_copy_mutex_lock();
        index = array_index % ARRAY_SIZE;
        assert(test_array[index].a == ARRAY_POISON ||
                test_array[index].a == 0);
@@ -205,7 +205,6 @@ static struct test_array *test_array_alloc(void)
        array_index++;
        if (array_index == ARRAY_SIZE)
                array_index = 0;
-       rcu_copy_mutex_unlock();
        return ret;
 }
 
@@ -213,9 +212,7 @@ static void test_array_free(struct test_array *ptr)
 {
        if (!ptr)
                return;
-       rcu_copy_mutex_lock();
        ptr->a = ARRAY_POISON;
-       rcu_copy_mutex_unlock();
 }
 
 void *thr_reader(void *_count)
@@ -281,6 +278,7 @@ void *thr_writer(void *_count)
        cmm_smp_mb();
 
        for (;;) {
+               rcu_copy_mutex_lock();
                new = test_array_alloc();
                new->a = 8;
                old = rcu_xchg_pointer(&test_rcu_pointer, new);
@@ -291,6 +289,7 @@ void *thr_writer(void *_count)
                if (old)
                        old->a = 0;
                test_array_free(old);
+               rcu_copy_mutex_unlock();
                nr_writes++;
                if (unlikely(!test_duration_write()))
                        break;

diff --git a/tests/test_urcu.c b/tests/test_urcu.c
index f1b2f21b1044cf32b7bd5c0515dcd556789eefbe..884d77c472ae28b3a79059d303559932f544b41d 100644 (file)
--- a/tests/test_urcu.c
+++ b/tests/test_urcu.c
@@ -186,7 +186,8 @@ void rcu_copy_mutex_unlock(void)
 /*
  * malloc/free are reusing memory areas too quickly, which does not let us
  * test races appropriately. Use a large circular array for allocations.
- * ARRAY_SIZE is larger than nr_writers, which insures we never run over our tail.
+ * ARRAY_SIZE is larger than nr_writers, and we keep the mutex across
+ * both alloc and free, which insures we never run over our tail.
  */
 #define ARRAY_SIZE (1048576 * nr_writers)
 #define ARRAY_POISON 0xDEADBEEF
@@ -198,7 +199,6 @@ static struct test_array *test_array_alloc(void)
        struct test_array *ret;
        int index;
 
-       rcu_copy_mutex_lock();
        index = array_index % ARRAY_SIZE;
        assert(test_array[index].a == ARRAY_POISON ||
                test_array[index].a == 0);
@@ -206,7 +206,6 @@ static struct test_array *test_array_alloc(void)
        array_index++;
        if (array_index == ARRAY_SIZE)
                array_index = 0;
-       rcu_copy_mutex_unlock();
        return ret;
 }
 
@@ -214,9 +213,7 @@ static void test_array_free(struct test_array *ptr)
 {
        if (!ptr)
                return;
-       rcu_copy_mutex_lock();
        ptr->a = ARRAY_POISON;
-       rcu_copy_mutex_unlock();
 }
 
 void *thr_reader(void *_count)
@@ -279,6 +276,7 @@ void *thr_writer(void *_count)
        cmm_smp_mb();
 
        for (;;) {
+               rcu_copy_mutex_lock();
                new = test_array_alloc();
                new->a = 8;
                old = rcu_xchg_pointer(&test_rcu_pointer, new);
@@ -288,6 +286,7 @@ void *thr_writer(void *_count)
                if (old)
                        old->a = 0;
                test_array_free(old);
+               rcu_copy_mutex_unlock();
                nr_writes++;
                if (unlikely(!test_duration_write()))
                        break;

diff --git a/tests/test_urcu_assign.c b/tests/test_urcu_assign.c
index 851b8506b9bc85791b77fb5fad12fdc88ea8508c..0d9ef853db8eb88b7b0fbe1650c6fc09201fec50 100644 (file)
--- a/tests/test_urcu_assign.c
+++ b/tests/test_urcu_assign.c
@@ -186,7 +186,8 @@ void rcu_copy_mutex_unlock(void)
 /*
  * malloc/free are reusing memory areas too quickly, which does not let us
  * test races appropriately. Use a large circular array for allocations.
- * ARRAY_SIZE is larger than nr_writers, which insures we never run over our tail.
+ * ARRAY_SIZE is larger than nr_writers, and we keep the mutex across
+ * both alloc and free, which insures we never run over our tail.
  */
 #define ARRAY_SIZE (1048576 * nr_writers)
 #define ARRAY_POISON 0xDEADBEEF
@@ -198,7 +199,6 @@ static struct test_array *test_array_alloc(void)
        struct test_array *ret;
        int index;
 
-       rcu_copy_mutex_lock();
        index = array_index % ARRAY_SIZE;
        assert(test_array[index].a == ARRAY_POISON ||
                test_array[index].a == 0);
@@ -206,7 +206,6 @@ static struct test_array *test_array_alloc(void)
        array_index++;
        if (array_index == ARRAY_SIZE)
                array_index = 0;
-       rcu_copy_mutex_unlock();
        return ret;
 }
 
@@ -214,9 +213,7 @@ static void test_array_free(struct test_array *ptr)
 {
        if (!ptr)
                return;
-       rcu_copy_mutex_lock();
        ptr->a = ARRAY_POISON;
-       rcu_copy_mutex_unlock();
 }
 
 void *thr_reader(void *_count)
@@ -275,18 +272,18 @@ void *thr_writer(void *_count)
        cmm_smp_mb();
 
        for (;;) {
+               rcu_copy_mutex_lock();
                new = test_array_alloc();
                new->a = 8;
-               rcu_copy_mutex_lock();
                old = test_rcu_pointer;
                rcu_assign_pointer(test_rcu_pointer, new);
                if (unlikely(wduration))
                        loop_sleep(wduration);
-               rcu_copy_mutex_unlock();
                synchronize_rcu();
                if (old)
                        old->a = 0;
                test_array_free(old);
+               rcu_copy_mutex_unlock();
                nr_writes++;
                if (unlikely(!test_duration_write()))
                        break;

diff --git a/tests/test_urcu_bp.c b/tests/test_urcu_bp.c
index 52e7f457621939983cf2ca0e18e877399197029d..ba80ae60f5129bd172960007b2f019e0ce9c1b7a 100644 (file)
--- a/tests/test_urcu_bp.c
+++ b/tests/test_urcu_bp.c
@@ -186,7 +186,8 @@ void rcu_copy_mutex_unlock(void)
 /*
  * malloc/free are reusing memory areas too quickly, which does not let us
  * test races appropriately. Use a large circular array for allocations.
- * ARRAY_SIZE is larger than nr_writers, which insures we never run over our tail.
+ * ARRAY_SIZE is larger than nr_writers, and we keep the mutex across
+ * both alloc and free, which insures we never run over our tail.
  */
 #define ARRAY_SIZE (1048576 * nr_writers)
 #define ARRAY_POISON 0xDEADBEEF
@@ -198,7 +199,6 @@ static struct test_array *test_array_alloc(void)
        struct test_array *ret;
        int index;
 
-       rcu_copy_mutex_lock();
        index = array_index % ARRAY_SIZE;
        assert(test_array[index].a == ARRAY_POISON ||
                test_array[index].a == 0);
@@ -206,7 +206,6 @@ static struct test_array *test_array_alloc(void)
        array_index++;
        if (array_index == ARRAY_SIZE)
                array_index = 0;
-       rcu_copy_mutex_unlock();
        return ret;
 }
 
@@ -214,9 +213,7 @@ static void test_array_free(struct test_array *ptr)
 {
        if (!ptr)
                return;
-       rcu_copy_mutex_lock();
        ptr->a = ARRAY_POISON;
-       rcu_copy_mutex_unlock();
 }
 
 void *thr_reader(void *_count)
@@ -275,6 +272,7 @@ void *thr_writer(void *_count)
        cmm_smp_mb();
 
        for (;;) {
+               rcu_copy_mutex_lock();
                new = test_array_alloc();
                new->a = 8;
                old = rcu_xchg_pointer(&test_rcu_pointer, new);
@@ -284,6 +282,7 @@ void *thr_writer(void *_count)
                if (old)
                        old->a = 0;
                test_array_free(old);
+               rcu_copy_mutex_unlock();
                nr_writes++;
                if (unlikely(!test_duration_write()))
                        break;