From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2062) id 6CE1E3858C3A; Thu, 10 Feb 2022 18:22:05 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6CE1E3858C3A 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 r11-9553] libstdc++: Strengthen memory order for atomic::wait/notify X-Act-Checkin: gcc X-Git-Author: Thomas Rodgers X-Git-Refname: refs/heads/releases/gcc-11 X-Git-Oldrev: 3c9a9ce0c1d5fe3d0ac93ff32d7a57e12a5fefb6 X-Git-Newrev: 0c30241b331e11b7d3bf0ba15747b878d5e9c578 Message-Id: <20220210182205.6CE1E3858C3A@sourceware.org> Date: Thu, 10 Feb 2022 18:22:05 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Feb 2022 18:22:05 -0000 https://gcc.gnu.org/g:0c30241b331e11b7d3bf0ba15747b878d5e9c578 commit r11-9553-g0c30241b331e11b7d3bf0ba15747b878d5e9c578 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. (cherry picked from commit b25a7c05f120e46a60430dcefe529c72303b7022) 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 d7ded906360..394f666d02e 100644 --- a/libstdc++-v3/include/bits/atomic_wait.h +++ b/libstdc++-v3/include/bits/atomic_wait.h @@ -334,7 +334,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } else { - __atomic_load(__addr, &__val, __ATOMIC_RELAXED); + __atomic_load(__addr, &__val, __ATOMIC_ACQUIRE); } return __atomic_spin(__pred, __spin); } @@ -355,7 +355,7 @@ _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); }