libstdc++: Do not use pthread_mutex_clocklock with ThreadSanitizer

As noted in https://github.com/llvm/llvm-project/issues/62623 there are
no tsan interceptors for some of the new POSIX-1:202x APIs added by
https://austingroupbugs.net/view.php?id=1216 so tsan gives false
positive warnings for try_lock_for on timed mutexes.

Disable the uses of the new pthread_mutex_clocklock API when tsan is
active. This changes the semantics of the try_lock_for functions,
because it can change which clock is used for the wait. This means those
functions might be affected by system clock adjustments when tsan is
used, when they would not be affected otherwise.

Reviewed-by: Thomas Rodgers <trodgers@redhat.com>
Reviewed-by: Mike Crowe <mac@mcrowe.com>
libstdc++-v3/ChangeLog:

	* acinclude.m4 (GLIBCXX_CHECK_PTHREAD_MUTEX_CLOCKLOCK): Define
	_GLIBCXX_USE_PTHREAD_MUTEX_CLOCKLOCK in terms of _GLIBCXX_TSAN.
	* configure: Regenerate.

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 42a8e7a775e1f83a8e1e01b13cecb7fe15dd397d..0ce3b8b5b31d8aa2aacabed691ea382bc98d0793 100644 (file)
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -4314,7 +4314,7 @@ AC_DEFUN([GLIBCXX_CHECK_PTHREAD_MUTEX_CLOCKLOCK], [
       [glibcxx_cv_PTHREAD_MUTEX_CLOCKLOCK=no])
   ])
   if test $glibcxx_cv_PTHREAD_MUTEX_CLOCKLOCK = yes; then
-    AC_DEFINE(_GLIBCXX_USE_PTHREAD_MUTEX_CLOCKLOCK, 1, [Define if pthread_mutex_clocklock is available in <pthread.h>.])
+    AC_DEFINE(_GLIBCXX_USE_PTHREAD_MUTEX_CLOCKLOCK, (_GLIBCXX_TSAN==0), [Define if pthread_mutex_clocklock is available in <pthread.h>.])
   fi
 
   CXXFLAGS="$ac_save_CXXFLAGS"

diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index d4286b67a73662dda55b3624cbf794a0aeebe741..c1faebd54f2f648bd707dfc5ddeee2783d83be1c 100755 (executable)
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -21364,7 +21364,7 @@ fi
 $as_echo "$glibcxx_cv_PTHREAD_MUTEX_CLOCKLOCK" >&6; }
   if test $glibcxx_cv_PTHREAD_MUTEX_CLOCKLOCK = yes; then
 
-$as_echo "#define _GLIBCXX_USE_PTHREAD_MUTEX_CLOCKLOCK 1" >>confdefs.h
+$as_echo "#define _GLIBCXX_USE_PTHREAD_MUTEX_CLOCKLOCK (_GLIBCXX_TSAN==0)" >>confdefs.h
 
   fi