Fixes problems on systems with opaque mutex

src/libstd/comm/mod.rs

@@ -600,20 +600,22 @@ impl<T: Send> Clone for Sender<T> {
         let (packet, sleeper) = match *unsafe { self.inner() } {
             Oneshot(ref p) => {
                 let a = Arc::new(Unsafe::new(shared::Packet::new()));
-                match unsafe {
-                    (*p.get()).upgrade(Receiver::new(Shared(a.clone())))
-                } {
-                    oneshot::UpSuccess | oneshot::UpDisconnected => (a, None),
-                    oneshot::UpWoke(task) => (a, Some(task))
+                unsafe {
+                    (*a.get()).postinit_lock();
+                    match (*p.get()).upgrade(Receiver::new(Shared(a.clone()))) {
+                        oneshot::UpSuccess | oneshot::UpDisconnected => (a, None),
+                        oneshot::UpWoke(task) => (a, Some(task))
+                    }
                 }
             }
             Stream(ref p) => {
                 let a = Arc::new(Unsafe::new(shared::Packet::new()));
-                match unsafe {
-                    (*p.get()).upgrade(Receiver::new(Shared(a.clone())))
-                } {
-                    stream::UpSuccess | stream::UpDisconnected => (a, None),
-                    stream::UpWoke(task) => (a, Some(task)),
+                unsafe {
+                    (*a.get()).postinit_lock();
+                    match (*p.get()).upgrade(Receiver::new(Shared(a.clone()))) {
+                        stream::UpSuccess | stream::UpDisconnected => (a, None),
+                        stream::UpWoke(task) => (a, Some(task)),
+                    }
                 }
             }
             Shared(ref p) => {

src/libstd/comm/shared.rs

@@ -66,7 +66,8 @@ pub enum Failure {
 }
 
 impl<T: Send> Packet<T> {
-    // Creation of a packet *must* be followed by a call to inherit_blocker
+    // Creation of a packet *must* be followed by a call to postinit_lock
+    // and later by inherit_blocker
     pub fn new() -> Packet<T> {
         let p = Packet {
             queue: mpsc::Queue::new(),
@@ -78,11 +79,18 @@ impl<T: Send> Packet<T> {
             sender_drain: atomics::AtomicInt::new(0),
             select_lock: unsafe { NativeMutex::new() },
         };
-        // see comments in inherit_blocker about why we grab this lock
-        unsafe { p.select_lock.lock_noguard() }
         return p;
     }
 
+    // This function should be used after newly created Packet
+    // was wrapped with an Arc
+    // In other case mutex data will be duplicated while clonning
+    // and that could cause problems on platforms where it is
+    // represented by opaque data structure
+    pub fn postinit_lock(&mut self) {
+        unsafe { self.select_lock.lock_noguard() }
+    }
+
     // This function is used at the creation of a shared packet to inherit a
     // previously blocked task. This is done to prevent spurious wakeups of
     // tasks in select().

src/libstd/unstable/mutex.rs

@@ -98,6 +98,7 @@ impl StaticNativeMutex {
     ///
     /// Note that a mutex created in this way needs to be explicit
     /// freed with a call to `destroy` or it will leak.
+    /// Also it is important to avoid locking until mutex has stopped moving
     pub unsafe fn new() -> StaticNativeMutex {
         StaticNativeMutex { inner: imp::Mutex::new() }
     }
@@ -172,6 +173,7 @@ impl NativeMutex {
     ///
     /// The user must be careful to ensure the mutex is not locked when its is
     /// being destroyed.
+    /// Also it is important to avoid locking until mutex has stopped moving
     pub unsafe fn new() -> NativeMutex {
         NativeMutex { inner: StaticNativeMutex::new() }
     }
@@ -262,7 +264,6 @@ mod imp {
     use libc;
     use self::os::{PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER,
                    pthread_mutex_t, pthread_cond_t};
-    use mem;
     use ty::Unsafe;
     use kinds::marker;
 
@@ -294,6 +295,7 @@ mod imp {
         static __PTHREAD_MUTEX_SIZE__: uint = 40;
         #[cfg(target_arch = "x86")]
         static __PTHREAD_COND_SIZE__: uint = 24;
+
         static _PTHREAD_MUTEX_SIG_init: libc::c_long = 0x32AAABA7;
         static _PTHREAD_COND_SIG_init: libc::c_long = 0x3CB0B1BB;
 
@@ -389,14 +391,14 @@ mod imp {
 
     impl Mutex {
         pub unsafe fn new() -> Mutex {
+            // As mutex might be moved and address is changing it
+            // is better to avoid initialization of potentially
+            // opaque OS data before it landed
             let m = Mutex {
-                lock: Unsafe::new(mem::zeroed()),
-                cond: Unsafe::new(mem::zeroed()),
+                lock: Unsafe::new(PTHREAD_MUTEX_INITIALIZER),
+                cond: Unsafe::new(PTHREAD_COND_INITIALIZER),
             };
 
-            pthread_mutex_init(m.lock.get(), 0 as *libc::c_void);
-            pthread_cond_init(m.cond.get(), 0 as *libc::c_void);
-
             return m;
         }
 
@@ -416,11 +418,7 @@ mod imp {
     }
 
     extern {
-        fn pthread_mutex_init(lock: *mut pthread_mutex_t,
-                              attr: *pthread_mutexattr_t) -> libc::c_int;
         fn pthread_mutex_destroy(lock: *mut pthread_mutex_t) -> libc::c_int;
-        fn pthread_cond_init(cond: *mut pthread_cond_t,
-                              attr: *pthread_condattr_t) -> libc::c_int;
         fn pthread_cond_destroy(cond: *mut pthread_cond_t) -> libc::c_int;
         fn pthread_mutex_lock(lock: *mut pthread_mutex_t) -> libc::c_int;
         fn pthread_mutex_trylock(lock: *mut pthread_mutex_t) -> libc::c_int;