commit addc9d62d61eea790a35328cbfce53333a07bd3e

Author: Florian Weimer <fweimer@redhat.com>

Date:   Mon Aug 30 13:43:56 2021 +0200

    support: Add support_wait_for_thread_exit

    (cherry picked from commit 032d74eaf6179100048a5bf0ce942e97dc8b9a60)

diff --git a/support/Makefile b/support/Makefile

index a462781718426d35..ef2b1a980a407f8f 100644

--- a/support/Makefile

+++ b/support/Makefile

@@ -82,9 +82,10 @@ libsupport-routines = \

   support_test_compare_blob \

   support_test_compare_failure \

   support_test_compare_string \

-  support_write_file_string \

   support_test_main \

   support_test_verify_impl \

+  support_wait_for_thread_exit \

+  support_write_file_string \

   temp_file \

   timespec \

   timespec-time64 \

diff --git a/support/support.h b/support/support.h

index 834dba909770a992..a5978b939af2fb41 100644

--- a/support/support.h

+++ b/support/support.h

@@ -174,6 +174,10 @@ timer_t support_create_timer (uint64_t sec, long int nsec, bool repeat,

 /* Disable the timer TIMER.  */

 void support_delete_timer (timer_t timer);

+/* Wait until all threads except the current thread have exited (as

+   far as the kernel is concerned).  */

+void support_wait_for_thread_exit (void);

+

 struct support_stack

 {

   void *stack;

diff --git a/support/support_wait_for_thread_exit.c b/support/support_wait_for_thread_exit.c

new file mode 100644

index 0000000000000000..658a81381006ea62

--- /dev/null

+++ b/support/support_wait_for_thread_exit.c

@@ -0,0 +1,72 @@

+/* Wait until all threads except the current thread has exited.

+   Copyright (C) 2021 Free Software Foundation, Inc.

+   This file is part of the GNU C Library.

+

+   The GNU C Library is free software; you can redistribute it and/or

+   modify it under the terms of the GNU Lesser General Public

+   License as published by the Free Software Foundation; either

+   version 2.1 of the License, or (at your option) any later version.

+

+   The GNU C Library is distributed in the hope that it will be useful,

+   but WITHOUT ANY WARRANTY; without even the implied warranty of

+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

+   Lesser General Public License for more details.

+

+   You should have received a copy of the GNU Lesser General Public

+   License along with the GNU C Library; if not, see

+   <https://www.gnu.org/licenses/>.  */

+

+#include <dirent.h>

+#include <errno.h>

+#include <string.h>

+#include <support/check.h>

+#include <support/support.h>

+#include <unistd.h>

+

+void

+support_wait_for_thread_exit (void)

+{

+#ifdef __linux__

+  DIR *proc_self_task = opendir ("/proc/self/task");

+  TEST_VERIFY_EXIT (proc_self_task != NULL);

+

+  while (true)

+    {

+      errno = 0;

+      struct dirent *e = readdir (proc_self_task);

+      if (e == NULL && errno != 0)

+        FAIL_EXIT1 ("readdir: %m");

+      if (e == NULL)

+        {

+          /* Only the main thread remains.  Testing may continue.  */

+          closedir (proc_self_task);

+          return;

+        }

+

+      if (strcmp (e->d_name, ".") == 0 || strcmp (e->d_name, "..") == 0)

+        continue;

+

+      int task_tid = atoi (e->d_name);

+      if (task_tid <= 0)

+        FAIL_EXIT1 ("Invalid /proc/self/task entry: %s", e->d_name);

+

+      if (task_tid == gettid ())

+        /* The current thread.  Keep scanning for other

+           threads.  */

+        continue;

+

+      /* task_tid does not refer to this thread here, i.e., there is

+         another running thread.  */

+

+      /* Small timeout to give the thread a chance to exit.  */

+      usleep (50 * 1000);

+

+      /* Start scanning the directory from the start.  */

+      rewinddir (proc_self_task);

+    }

+#else

+  /* Use a large timeout because we cannot verify that the thread has

+     exited.  */

+  usleep (5 * 1000 * 1000);

+#endif

+}