Fix undefined behavior when re-locking a mutex from the same thread

The only applies to pthread mutexes. We solve this by creating the
mutex with the PTHREAD_MUTEX_NORMAL type, which guarantees that
re-locking from the same thread will deadlock.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/libstd/sync/mutex.rs b/src/libstd/sync/mutex.rs
index 90cc79dad66..e53a97eccdf 100644
--- a/src/libstd/sync/mutex.rs
+++ b/src/libstd/sync/mutex.rs
@@ -190,10 +190,14 @@ impl<T> Mutex<T> {
     /// Creates a new mutex in an unlocked state ready for use.
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new(t: T) -> Mutex<T> {
-        Mutex {
+        let mut m = Mutex {
             inner: box StaticMutex::new(),
             data: UnsafeCell::new(t),
+        };
+        unsafe {
+            m.inner.lock.init();
         }
+        m
     }
 }