From 14f19592ae7c819855052bcebc79de87069c2954 Mon Sep 17 00:00:00 2001
From: Elliott Hughes <enh@google.com>
Date: Mon, 29 Oct 2012 10:19:44 -0700
Subject: [PATCH] Fix the pthread_join on self error case.

We should return EDEADLK, not deadlock the calling thread.

Change-Id: I1243483f709c11b2a60e41142725c54c7dbfcbc9
---
 libc/bionic/pthread.c  | 12 ++++++++----
 tests/pthread_test.cpp |  5 +++++
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/libc/bionic/pthread.c b/libc/bionic/pthread.c
index ac7c64e34..c7612f75a 100644
--- a/libc/bionic/pthread.c
+++ b/libc/bionic/pthread.c
@@ -633,14 +633,18 @@ void pthread_exit(void * retval)
 int pthread_join(pthread_t thid, void ** ret_val)
 {
     pthread_internal_t*  thread = (pthread_internal_t*)thid;
-    int                  count;
+    if (thid == pthread_self()) {
+        return EDEADLK;
+    }
 
     // check that the thread still exists and is not detached
     pthread_mutex_lock(&gThreadListLock);
 
-    for (thread = gThreadList; thread != NULL; thread = thread->next)
-        if (thread == (pthread_internal_t*)thid)
+    for (thread = gThreadList; thread != NULL; thread = thread->next) {
+        if (thread == (pthread_internal_t*)thid) {
             goto FoundIt;
+        }
+    }
 
     pthread_mutex_unlock(&gThreadListLock);
     return ESRCH;
@@ -658,7 +662,7 @@ FoundIt:
     *
     * otherwise, we need to increment 'join-count' and wait to be signaled
     */
-   count = thread->join_count;
+    int count = thread->join_count;
     if (count >= 0) {
         thread->join_count += 1;
         pthread_cond_wait( &thread->join_cond, &gThreadListLock );
diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index 9a474c0a5..479c4622f 100644
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -80,3 +80,8 @@ TEST(pthread, pthread_no_op_detach_after_join) {
   ASSERT_EQ(0, pthread_join(t2, &join_result));
   ASSERT_EQ(EINVAL, reinterpret_cast<int>(join_result));
 }
+
+TEST(pthread, pthread_join_self) {
+  void* result;
+  ASSERT_EQ(EDEADLK, pthread_join(pthread_self(), &result));
+}