Untested: Remove duplicate Mutex efforts in pte.rs

See #151

src/mutex.rs

 use core::cell::UnsafeCell;
-use core::intrinsics;
 use core::ops::{Deref, DerefMut};
+use core::sync::atomic::AtomicI32 as AtomicInt;
+use core::sync::atomic::Ordering::SeqCst;
 use core::sync::atomic;
 use platform::types::*;
 use platform::{Pal, Sys};
@@ -9,30 +10,43 @@ pub const FUTEX_WAIT: c_int = 0;
 pub const FUTEX_WAKE: c_int = 1;
 
 pub struct Mutex<T> {
-    lock: UnsafeCell<c_int>,
+    lock: UnsafeCell<AtomicInt>,
     content: UnsafeCell<T>,
 }
 unsafe impl<T: Send> Send for Mutex<T> {}
 unsafe impl<T: Send> Sync for Mutex<T> {}
 impl<T> Mutex<T> {
     /// Create a new mutex
-    pub fn new(content: T) -> Self {
+    pub const fn new(content: T) -> Self {
         Self {
-            lock: UnsafeCell::new(0),
+            lock: UnsafeCell::new(AtomicInt::new(0)),
+            content: UnsafeCell::new(content),
+        }
+    }
+    /// Create a new mutex that is already locked. This is a more
+    /// efficient way to do the following:
+    /// ```rust
+    /// let mut mutex = Mutex::new(());
+    /// mutex.manual_lock();
+    /// ```
+    pub unsafe fn locked(content: T) -> Self {
+        Self {
+            lock: UnsafeCell::new(AtomicInt::new(1)),
             content: UnsafeCell::new(content),
         }
     }
 
+    unsafe fn atomic(&self) -> &mut AtomicInt {
+        &mut *self.lock.get()
+    }
+
     /// Tries to lock the mutex, fails if it's already locked. Manual means
     /// it's up to you to unlock it after mutex. Returns the last atomic value
     /// on failure. You should probably not worry about this, it's used for
     /// internal optimizations.
     pub unsafe fn manual_try_lock(&self) -> Result<&mut T, c_int> {
-        let value = intrinsics::atomic_cxchg(self.lock.get(), 0, 1).0;
-        if value == 0 {
-            return Ok(&mut *self.content.get());
-        }
-        Err(value)
+        self.atomic().compare_exchange(0, 1, SeqCst, SeqCst)
+            .map(|_| &mut *self.content.get())
     }
     /// Lock the mutex, returning the inner content. After doing this, it's
     /// your responsibility to unlock it after usage. Mostly useful for FFI:
@@ -56,8 +70,8 @@ impl<T> Mutex<T> {
             //
             // - Skip the atomic operation if the last value was 2, since it most likely hasn't changed.
             // - Skip the futex wait if the atomic operation says the mutex is unlocked.
-            if last == 2 || intrinsics::atomic_cxchg(self.lock.get(), 1, 2).0 != 0 {
-                Sys::futex(self.lock.get(), FUTEX_WAIT, 2);
+            if last == 2 || self.atomic().compare_exchange(1, 2, SeqCst, SeqCst).unwrap_or_else(|err| err) == 2 {
+                Sys::futex(self.atomic().get_mut(), FUTEX_WAIT, 2);
             }
 
             last = match self.manual_try_lock() {
@@ -68,9 +82,9 @@ impl<T> Mutex<T> {
     }
     /// Unlock the mutex, if it's locked.
     pub unsafe fn manual_unlock(&self) {
-        if intrinsics::atomic_xchg(self.lock.get(), 0) == 2 {
+        if self.atomic().swap(0, SeqCst) == 2 {
             // At least one futex is up, so let's notify it
-            Sys::futex(self.lock.get(), FUTEX_WAKE, 1);
+            Sys::futex(self.atomic().get_mut(), FUTEX_WAKE, 1);
         }
     }
 

src/platform/pte.rs

@@ -8,17 +8,17 @@ use core::{intrinsics, ptr};
 use header::sys_mman;
 use header::time::timespec;
 use ld_so::tcb::{Master, Tcb};
-use mutex::{FUTEX_WAIT, FUTEX_WAKE};
+use mutex::Mutex;
 use platform::types::{c_int, c_uint, c_void, pid_t, size_t};
 use platform::{Pal, Sys};
 
 pub struct Semaphore {
-    lock: i32,
+    lock: Mutex<()>,
     count: i32,
 }
 
 type pte_osThreadHandle = pid_t;
-type pte_osMutexHandle = *mut i32;
+type pte_osMutexHandle = *mut Mutex<()>;
 type pte_osSemaphoreHandle = *mut Semaphore;
 type pte_osThreadEntryPoint = unsafe extern "C" fn(params: *mut c_void) -> c_int;
 
@@ -37,10 +37,10 @@ pub enum pte_osResult {
 use self::pte_osResult::*;
 
 static mut pid_mutexes: Option<BTreeMap<pte_osThreadHandle, pte_osMutexHandle>> = None;
-static mut pid_mutexes_lock: i32 = 0;
+static mut pid_mutexes_lock: Mutex<()> = Mutex::new(());
 
 static mut pid_stacks: Option<BTreeMap<pte_osThreadHandle, (*mut c_void, size_t)>> = None;
-static mut pid_stacks_lock: i32 = 0;
+static mut pid_stacks_lock: Mutex<()> = Mutex::new(());
 
 #[thread_local]
 static mut LOCALS: *mut BTreeMap<c_uint, *mut c_void> = ptr::null_mut();
@@ -94,7 +94,7 @@ pub unsafe extern "C" fn pte_osThreadCreate(
     ppte_osThreadHandle: *mut pte_osThreadHandle,
 ) -> pte_osResult {
     // Create a locked mutex, unlocked by pte_osThreadStart
-    let mutex: pte_osMutexHandle = Box::into_raw(Box::new(2));
+    let mutex: pte_osMutexHandle = Box::into_raw(Box::new(Mutex::locked(())));
 
     let stack_size = if stackSize == 0 {
         1024 * 1024
@@ -278,7 +278,7 @@ pub unsafe extern "C" fn pte_osThreadGetDefaultPriority() -> c_int {
 
 #[no_mangle]
 pub unsafe extern "C" fn pte_osMutexCreate(pHandle: *mut pte_osMutexHandle) -> pte_osResult {
-    *pHandle = Box::into_raw(Box::new(0));
+    *pHandle = Box::into_raw(Box::new(Mutex::new(())));
     PTE_OS_OK
 }
 
@@ -290,38 +290,13 @@ pub unsafe extern "C" fn pte_osMutexDelete(handle: pte_osMutexHandle) -> pte_osR
 
 #[no_mangle]
 pub unsafe extern "C" fn pte_osMutexLock(handle: pte_osMutexHandle) -> pte_osResult {
-    let mut c = 0;
-    for _i in 0..100 {
-        c = intrinsics::atomic_cxchg(handle, 0, 1).0;
-        if c == 0 {
-            break;
-        }
-    }
-    if c == 1 {
-        c = intrinsics::atomic_xchg(handle, 2);
-    }
-    while c != 0 {
-        Sys::futex(handle, FUTEX_WAIT, 2);
-        c = intrinsics::atomic_xchg(handle, 2);
-    }
-
+    (*handle).manual_lock();
     PTE_OS_OK
 }
 
 #[no_mangle]
 pub unsafe extern "C" fn pte_osMutexUnlock(handle: pte_osMutexHandle) -> pte_osResult {
-    if *handle == 2 {
-        *handle = 0;
-    } else if intrinsics::atomic_xchg(handle, 0) == 1 {
-        return PTE_OS_OK;
-    }
-    for _i in 0..100 {
-        if *handle != 0 && intrinsics::atomic_cxchg(handle, 1, 2).0 != 0 {
-            return PTE_OS_OK;
-        }
-    }
-    Sys::futex(handle, FUTEX_WAKE, 1);
-
+    (*handle).manual_unlock();
     PTE_OS_OK
 }
 
@@ -331,7 +306,7 @@ pub unsafe extern "C" fn pte_osSemaphoreCreate(
     pHandle: *mut pte_osSemaphoreHandle,
 ) -> pte_osResult {
     *pHandle = Box::into_raw(Box::new(Semaphore {
-        lock: 0,
+        lock: Mutex::new(()),
         count: initialValue,
     }));
     PTE_OS_OK
@@ -349,9 +324,8 @@ pub unsafe extern "C" fn pte_osSemaphorePost(
     count: c_int,
 ) -> pte_osResult {
     let semaphore = &mut *handle;
-    pte_osMutexLock(&mut semaphore.lock);
+    let _guard = semaphore.lock.lock();
     intrinsics::atomic_xadd(&mut semaphore.count, 1);
-    pte_osMutexUnlock(&mut semaphore.lock);
     PTE_OS_OK
 }
 
@@ -364,12 +338,11 @@ pub unsafe extern "C" fn pte_osSemaphorePend(
     let semaphore = &mut *handle;
     let mut acquired = false;
     while !acquired {
-        pte_osMutexLock(&mut semaphore.lock);
+        let _guard = semaphore.lock.lock();
         if intrinsics::atomic_load(&semaphore.count) > 0 {
             intrinsics::atomic_xsub(&mut semaphore.count, 1);
             acquired = true;
         }
-        pte_osMutexUnlock(&mut semaphore.lock);
         Sys::sched_yield();
     }
     PTE_OS_OK