workqueue: fix potential ABBA deadlock in stats summing

[fio.git] / workqueue.c

diff --git a/workqueue.c b/workqueue.c
index 27d1060c6e6f2b1cd6710d540e63e9b0c621691c..7cd83bfd6216bdf9cc69c70d59d9760fc31a7b9b 100644 (file)
--- a/workqueue.c
+++ b/workqueue.c
@@ -217,13 +217,32 @@ static void sum_val(uint64_t *dst, uint64_t *src)
 }
 #endif
 
-static void sum_ddir(struct thread_data *dst, struct thread_data *src,
-                    enum fio_ddir ddir)
+static void pthread_double_unlock(pthread_mutex_t *lock1,
+                                 pthread_mutex_t *lock2)
 {
 #ifndef CONFIG_SFAA
-       pthread_mutex_lock(&dst->io_wq.stat_lock);
-       pthread_mutex_lock(&src->io_wq.stat_lock);
+       pthread_mutex_unlock(lock1);
+       pthread_mutex_unlock(lock2);
 #endif
+}
+
+static void pthread_double_lock(pthread_mutex_t *lock1, pthread_mutex_t *lock2)
+{
+#ifndef CONFIG_SFAA
+       if (lock1 < lock2) {
+               pthread_mutex_lock(lock1);
+               pthread_mutex_lock(lock2);
+       } else {
+               pthread_mutex_lock(lock2);
+               pthread_mutex_lock(lock1);
+       }
+#endif
+}
+
+static void sum_ddir(struct thread_data *dst, struct thread_data *src,
+                    enum fio_ddir ddir)
+{
+       pthread_double_lock(&dst->io_wq.stat_lock, &src->io_wq.stat_lock);
 
        sum_val(&dst->io_bytes[ddir], &src->io_bytes[ddir]);
        sum_val(&dst->io_blocks[ddir], &src->io_blocks[ddir]);
@@ -231,10 +250,7 @@ static void sum_ddir(struct thread_data *dst, struct thread_data *src,
        sum_val(&dst->this_io_bytes[ddir], &src->this_io_bytes[ddir]);
        sum_val(&dst->bytes_done[ddir], &src->bytes_done[ddir]);
 
-#ifndef CONFIG_SFAA
-       pthread_mutex_unlock(&src->io_wq.stat_lock);
-       pthread_mutex_unlock(&dst->io_wq.stat_lock);
-#endif
+       pthread_double_unlock(&dst->io_wq.stat_lock, &src->io_wq.stat_lock);
 }
 
 static void update_accounting(struct submit_worker *sw)