From 64f798492c5d7abfef8be9837ae0703cda43b48e Mon Sep 17 00:00:00 2001
From: Alan Somers <asomers@gmail.com>
Date: Fri, 30 Jun 2017 10:49:18 -0600
Subject: Fix thread safety issues in aio, chdir, and wait tests

They have four problems:

* The chdir tests change the process's cwd, which is global.  Protect them
  all with a mutex.

* The wait tests will reap any subprocess, and several tests create
  subprocesses.  Protect them all with a mutex so only one
  subprocess-creating test will run at a time.

* When a multithreaded test forks, the child process can sometimes block in
  the stack unwinding code.  It blocks on a mutex that was held by a
  different thread in the parent, but that thread doesn't exist in the
  child, so a deadlock results.  Fix this by immediately calling
  std::process:exit in the child processes.

* My previous attempt at thread safety in the aio tests didn't work, because
  anonymous MutexGuards drop immediately.  Fix this by naming the
  SIGUSR2_MTX MutexGuards.

Fixes #251
---
 test/sys/test_aio.rs | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

(limited to 'test/sys/test_aio.rs')

diff --git a/test/sys/test_aio.rs b/test/sys/test_aio.rs
index 7945aaf8..7e2bef63 100644
--- a/test/sys/test_aio.rs
+++ b/test/sys/test_aio.rs
@@ -8,7 +8,6 @@ use std::io::{Write, Read, Seek, SeekFrom};
 use std::ops::Deref;
 use std::os::unix::io::AsRawFd;
 use std::rc::Rc;
-use std::sync::Mutex;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::{thread, time};
 use tempfile::tempfile;
@@ -233,8 +232,6 @@ fn test_write() {
 
 lazy_static! {
     pub static ref SIGNALED: AtomicBool = AtomicBool::new(false);
-    // protects access to SIGUSR2 handlers, not just SIGNALED
-    pub static ref SIGUSR2_MTX: Mutex<()> = Mutex::new(());
 }
 
 extern fn sigfunc(_: c_int) {
@@ -246,7 +243,8 @@ extern fn sigfunc(_: c_int) {
 #[test]
 #[cfg_attr(any(all(target_env = "musl", target_arch = "x86_64"), target_arch = "mips"), ignore)]
 fn test_write_sigev_signal() {
-    let _ = SIGUSR2_MTX.lock().expect("Mutex got poisoned by another test");
+    #[allow(unused_variables)]
+    let m = ::SIGUSR2_MTX.lock().expect("Mutex got poisoned by another test");
     let sa = SigAction::new(SigHandler::Handler(sigfunc),
                             SA_RESETHAND,
                             SigSet::empty());
@@ -376,7 +374,8 @@ fn test_lio_listio_nowait() {
 #[cfg(not(any(target_os = "ios", target_os = "macos")))]
 #[cfg_attr(any(target_arch = "mips", target_env = "musl"), ignore)]
 fn test_lio_listio_signal() {
-    let _ = SIGUSR2_MTX.lock().expect("Mutex got poisoned by another test");
+    #[allow(unused_variables)]
+    let m = ::SIGUSR2_MTX.lock().expect("Mutex got poisoned by another test");
     const INITIAL: &'static [u8] = b"abcdef123456";
     const WBUF: &'static [u8] = b"CDEF";
     let rbuf = Rc::new(vec![0; 4].into_boxed_slice());
-- 
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