From dff62c19cef2eb12fac3d15552a98886edcaba44 Mon Sep 17 00:00:00 2001
From: Amanieu d'Antras <amanieu@gmail.com>
Date: Fri, 5 Aug 2016 19:26:23 +0100
Subject: [PATCH] Handle RwLock reader count overflow

---
 src/libstd/sys/unix/rwlock.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/libstd/sys/unix/rwlock.rs b/src/libstd/sys/unix/rwlock.rs
index fbd4e1d120817..08aeb5fb8ccde 100644
--- a/src/libstd/sys/unix/rwlock.rs
+++ b/src/libstd/sys/unix/rwlock.rs
@@ -50,7 +50,9 @@ impl RWLock {
         // the implementation allows recursive locking. The POSIX standard
         // doesn't require recursivly locking a rwlock to deadlock, but we can't
         // allow that because it could lead to aliasing issues.
-        if r == libc::EDEADLK || *self.write_locked.get() {
+        if r == libc::EAGAIN {
+            panic!("rwlock maximum reader count exceeded");
+        } else if r == libc::EDEADLK || *self.write_locked.get() {
             if r == 0 {
                 self.raw_unlock();
             }