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, 6 insertions, 0 deletions

diff --git a/src/libstd/sys/common/mutex.rs b/src/libstd/sys/common/mutex.rs
index 5a6dfe7fb1a..7a2183c522f 100644
--- a/src/libstd/sys/common/mutex.rs
+++ b/src/libstd/sys/common/mutex.rs
@@ -27,6 +27,12 @@ impl Mutex {
     /// first used with any of the functions below.
     pub const fn new() -> Mutex { Mutex(imp::Mutex::new()) }
 
+    /// Prepare the mutex for use.
+    ///
+    /// This should be called once the mutex is at a stable memory address.
+    #[inline]
+    pub unsafe fn init(&mut self) { self.0.init() }
+
     /// Locks the mutex blocking the current thread until it is available.
     ///
     /// Behavior is undefined if the mutex has been moved between this and any