From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2062) id BF0873858D1E; Thu, 10 Feb 2022 18:14:54 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org BF0873858D1E MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Thomas Rodgers To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r12-7186] libstdc++: Strengthen memory order for atomic::wait/notify X-Act-Checkin: gcc X-Git-Author: Thomas Rodgers X-Git-Refname: refs/heads/master X-Git-Oldrev: c22f3fb780775b91548e32937a3ce1095a7c72a3 X-Git-Newrev: b25a7c05f120e46a60430dcefe529c72303b7022 Message-Id: <20220210181454.BF0873858D1E@sourceware.org> Date: Thu, 10 Feb 2022 18:14:54 +0000 (GMT) X-BeenThere: libstdc++-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libstdc++-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Feb 2022 18:14:54 -0000 https://gcc.gnu.org/g:b25a7c05f120e46a60430dcefe529c72303b7022 commit r12-7186-gb25a7c05f120e46a60430dcefe529c72303b7022 Author: Thomas Rodgers Date: Thu Feb 10 10:12:36 2022 -0800 libstdc++: Strengthen memory order for atomic::wait/notify This changes the memory order used in the spin wait code to match that of libc++. libstdc++-v3/ChangeLog: * include/bits/atomic_wait.h (__waiter_base::_S_do_spin, __waiter_base::_S_do_spin_v): Change memory order from relaxed to acquire. Diff: --- libstdc++-v3/include/bits/atomic_wait.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/include/bits/atomic_wait.h b/libstdc++-v3/include/bits/atomic_wait.h index 6ce7f9343cf..125b1cad886 100644 --- a/libstdc++-v3/include/bits/atomic_wait.h +++ b/libstdc++-v3/include/bits/atomic_wait.h @@ -332,7 +332,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } else { - __atomic_load(__addr, &__val, __ATOMIC_RELAXED); + __atomic_load(__addr, &__val, __ATOMIC_ACQUIRE); } return __atomic_spin(__pred, __spin); } @@ -353,7 +353,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION __platform_wait_t& __val, _Spin __spin = _Spin{ }) { - __atomic_load(__addr, &__val, __ATOMIC_RELAXED); + __atomic_load(__addr, &__val, __ATOMIC_ACQUIRE); return __atomic_spin(__pred, __spin); }