[glibc] test-dlclose-exit-race: avoid hang on pthread_create error

[glibc] test-dlclose-exit-race: avoid hang on pthread_create error

[DJ Delorie]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=ac30324c67d94696fdb0799e9d4fc51dc70d490b

commit ac30324c67d94696fdb0799e9d4fc51dc70d490b
Author: DJ Delorie <dj@redhat.com>
Date:   Tue Aug 3 16:33:29 2021 -0400

    test-dlclose-exit-race: avoid hang on pthread_create error
    
    This test depends on the "last" function being called in a
    different thread than the "first" function, as "last" posts
    a semaphore that "first" is waiting on.  However, if pthread_create
    fails - for example, if running in an older container before
    the clone3()-in-container-EPERM fixes - exit() is called in the
    same thread as everything else, the semaphore never gets posted,
    and first hangs.
    
    The fix is to pre-post that semaphore before a single-threaded
    exit.
    
    Reviewed-by: Arjun Shankar <arjun@redhat.com>

Diff:
---
 stdlib/test-dlclose-exit-race.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/stdlib/test-dlclose-exit-race.c b/stdlib/test-dlclose-exit-race.c
index b463253281..2c44efdde6 100644
--- a/stdlib/test-dlclose-exit-race.c
+++ b/stdlib/test-dlclose-exit-race.c
@@ -29,6 +29,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <errno.h>
 #include <semaphore.h>
 #include <support/check.h>
 #include <support/xdlfcn.h>
@@ -64,6 +65,7 @@ last (void)
 int
 main (void)
 {
+  int value;
   void *dso;
   pthread_t thread;
 
@@ -71,7 +73,17 @@ main (void)
 
   dso = xdlopen ("$ORIGIN/test-dlclose-exit-race-helper.so",
 		 RTLD_NOW|RTLD_GLOBAL);
-  thread = xpthread_create (NULL, exit_thread, NULL);
+  if ((value = pthread_create (&thread, NULL, exit_thread, NULL)) != 0)
+    {
+      /* If pthread_create fails, then exit() is called in the main
+	 thread instead of a second thread, so the semaphore post that
+	 would have happened in 'last' gets blocked behind the call to
+	 first() - which is waiting on the semaphore, and thus
+	 hangs.  */
+      sem_post (&order2);
+      errno = value;
+      FAIL_EXIT1 ("pthread_create: %m");
+    }
 
   xdlclose (dso);
   xpthread_join (thread);