From 59981e4057bb0384712f2c34c3c36f7fb9cbeb6d Mon Sep 17 00:00:00 2001
From: Ian Douglas Scott <ian@iandouglasscott.com>
Date: Wed, 5 Jul 2017 12:00:46 -0700
Subject: [PATCH] Redox: Fix Condvar.wait(); do not lock mutex twice

The atomic_xchg() loop locks the mutex, so the call to mutex_lock is
incorrect, and blocks.
---
 src/libstd/sys/redox/condvar.rs | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/libstd/sys/redox/condvar.rs b/src/libstd/sys/redox/condvar.rs
index 0ca0987b245..fe4a89c6f3e 100644
--- a/src/libstd/sys/redox/condvar.rs
+++ b/src/libstd/sys/redox/condvar.rs
@@ -13,7 +13,7 @@ use intrinsics::{atomic_cxchg, atomic_xadd, atomic_xchg};
 use ptr;
 use time::Duration;
 
-use sys::mutex::{mutex_lock, mutex_unlock, Mutex};
+use sys::mutex::{mutex_unlock, Mutex};
 use sys::syscall::{futex, FUTEX_WAIT, FUTEX_WAKE, FUTEX_REQUEUE};
 
 pub struct Condvar {
@@ -83,8 +83,6 @@ impl Condvar {
             while atomic_xchg(*lock, 2) != 0 {
                 let _ = futex(*lock, FUTEX_WAIT, 2, 0, ptr::null_mut());
             }
-
-            mutex_lock(*lock);
         }
     }