From 175db95b3d98b1874b9d49a5e79a0755aed3e8fa Mon Sep 17 00:00:00 2001
From: Baoshan Pang <baoshan.pang@windriver.com>
Date: Mon, 7 Oct 2019 09:59:08 -0700
Subject: [PATCH] add checking (r == 0)

---
 src/libstd/sys/vxworks/rwlock.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstd/sys/vxworks/rwlock.rs b/src/libstd/sys/vxworks/rwlock.rs
index 718f422ed11..19b123f2b61 100644
--- a/src/libstd/sys/vxworks/rwlock.rs
+++ b/src/libstd/sys/vxworks/rwlock.rs
@@ -25,7 +25,7 @@ impl RWLock {
         let r = libc::pthread_rwlock_rdlock(self.inner.get());
         if r == libc::EAGAIN {
             panic!("rwlock maximum reader count exceeded");
-        } else if r == libc::EDEADLK || *self.write_locked.get() {
+        } else if r == libc::EDEADLK || (r == 0 && *self.write_locked.get()) {
             if r == 0 {
                 self.raw_unlock();
             }