From nobody Wed Mar 23 20:04:54 2022 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id DACFF1A20C4B; Wed, 23 Mar 2022 20:04:55 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4KNzpv3XS9z4XrG; Wed, 23 Mar 2022 20:04:55 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1648065895; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=s7M/+E8915mJ6J5A1xPmhuux2qGYYHcg6j/TQPPuO/c=; b=i+Z53d2s1ZZduLGzsCcbi6vGwDOpOON8FVuKoPgPRMGxUDJSSZ0dOhqiX0N0P8syVCQq6d E5NvucIWPA5sBl+Wy83hgwQAagrsfR5CB7C0FaS2MPEJt9vJgFZQLDqizf5gWFrkdrtEH+ U4aui4t8i2yIqsZOmiTyyLAMJAxQcg7/M7Pd4kNBEiYhhlo5Y+0haY+SoDuzDyGkqbcrCx 5j/rYDaD2ArN0r/BjBh4pGTnPNRY8XzkcE48s1Fd2nQIsIzroLK+B0YD9S4ZIZQ763fvGW 9rjZirtRloqwv+FHXIF3wZtlJrmaWo5wzYITejbQrP+mfUe1y+aAn0IyIhuEgg== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 1A7ED1EC1; Wed, 23 Mar 2022 20:04:55 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 22NK4sOd035139; Wed, 23 Mar 2022 20:04:54 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 22NK4smp035138; Wed, 23 Mar 2022 20:04:54 GMT (envelope-from git) Date: Wed, 23 Mar 2022 20:04:54 GMT Message-Id: <202203232004.22NK4smp035138@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Dimitry Andric Subject: git: fba80a78193a - stable/13 - Merge libcxxrt commit f2e55091e2e878386c9f7974d4922bbdc4faed84 List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-all@freebsd.org X-BeenThere: dev-commits-src-all@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: dim X-Git-Repository: src X-Git-Refname: refs/heads/stable/13 X-Git-Reftype: branch X-Git-Commit: fba80a78193a9b54ae184ff0bdf45186dae125d4 Auto-Submitted: auto-generated ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1648065895; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=s7M/+E8915mJ6J5A1xPmhuux2qGYYHcg6j/TQPPuO/c=; b=AuEKBKmE4J77eIp5Uaj9GwtV2lfe8A1WpNxOiQ8AuqNLiAuvewu/aqUcAARaOFtx9K67Bo jY5ELqFcoXgYrta1ZNdtiBRyrFnXz0M3t74WWzzPZgTgO9aQFqj2HT4Bxxfk4JaGZruztz HyIhrIA2qKYwIvoh7fKT1qVeDtX8aDhafmwRReuhhf9G7uXOBxn79vkVI6eY9JFWnEvLyH CniSjpQbNfxTz4wO+W1P+ZIuwi/7QCRmkwb+BQ7kCeItWEPrAIHP81y1vAhuEa5yZUj/ix w4tYOAJCW0xzd4o9Twaftm00R/R/dgSEpAx+V6rWKFH1lxUYJNOI5hZ1X8n0yw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1648065895; a=rsa-sha256; cv=none; b=P0JZjhnkl1Kc37Rz9bU2DeHXStMMXy3dFI1bjedaS9CzDPEPa/LjTXnLBQz6XeffV077cb HfUmRUvH5DvdqWk2UllwUYOQtoF/WaLU+Ar0obmEHwNCRubVjH+usJ6ioBXEIxMkNPrJPT C785kUlXvYTex7Kuanj2OOfxDzYnmGJCTBM57qRI1D34vI3TSjT4XR+A0A3F6nGG+JNSTy evyraZct4nF4xdlCs/z1J2T6hZdPjuNxjnMMvbW/f3EoT3mEsiPzdh5MknCSepVjPeGRft AnZ8U9JvciBN2ndbuTAUJFMOz9/E/J7xojxaBNAGSRv7KFaDM5PyQh9UGyHFQw== ARC-Authentication-Results: i=1; mx1.freebsd.org; none X-ThisMailContainsUnwantedMimeParts: N The branch stable/13 has been updated by dim: URL: https://cgit.FreeBSD.org/src/commit/?id=fba80a78193a9b54ae184ff0bdf45186dae125d4 commit fba80a78193a9b54ae184ff0bdf45186dae125d4 Author: Dimitry Andric AuthorDate: 2022-03-20 21:21:28 +0000 Commit: Dimitry Andric CommitDate: 2022-03-23 20:03:59 +0000 Merge libcxxrt commit f2e55091e2e878386c9f7974d4922bbdc4faed84 Fix unlock in two-word version and add missing comment. Fixes #15 Fixes #16 This should fix the hangs in __cxa_guard_acquire() reported on i386 (and possibly other 32-bit platforms). Obtained from: https://github.com/libcxxrt/libcxxrt/commit/f2e5509 Fixes: 56aaed388b0a MFC after: 2 weeks (cherry picked from commit 7819a911ff5132b34996c8b09b2a024cd10fd4fb) --- contrib/libcxxrt/guard.cc | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/contrib/libcxxrt/guard.cc b/contrib/libcxxrt/guard.cc index 515992563a10..cb58aa7da28e 100644 --- a/contrib/libcxxrt/guard.cc +++ b/contrib/libcxxrt/guard.cc @@ -69,7 +69,12 @@ * progress). The bit to use depends on the byte order of the target. * * On many 32-bit platforms, 64-bit atomics are unavailable (or slow) and so we - * treat the two halves of the 64-bit word as independent values and + * treat the two halves of the 64-bit word as independent values and establish + * an ordering on them such that the guard word is never modified unless the + * lock word is in the locked state. This means that we can do double-checked + * locking by loading the guard word and, if it is not initialised, trying to + * transition the lock word from the unlocked to locked state, and then + * manipulate the guard word. */ namespace { @@ -227,7 +232,7 @@ namespace // If another thread did manage to initialise this, release // the lock and notify the caller that initialisation is // done. - lock_word.store(initialised, memory_order::release); + lock_word.store(0, memory_order::release); return GuardState::InitDone; } return GuardState::InitLockSucceeded;