From nobody Sun Aug 28 21:30:39 2022 X-Original-To: bugs@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 4MG6Dv4vYGz4ZQfh for ; Sun, 28 Aug 2022 21:30:39 +0000 (UTC) (envelope-from bugzilla-noreply@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 4MG6Dv3ZyHz3ss9 for ; Sun, 28 Aug 2022 21:30:39 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (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 4MG6Dv2Y7Fz1CMT for ; Sun, 28 Aug 2022 21:30:39 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id 27SLUdlj005093 for ; Sun, 28 Aug 2022 21:30:39 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 27SLUdmc005092 for bugs@FreeBSD.org; Sun, 28 Aug 2022 21:30:39 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 265974] SMR has several missing barriers Date: Sun, 28 Aug 2022 21:30:39 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: pierre@habouzit.net X-Bugzilla-Status: Open X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated List-Id: Bug reports List-Archive: https://lists.freebsd.org/archives/freebsd-bugs List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-bugs@freebsd.org MIME-Version: 1.0 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1661722239; 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: in-reply-to:in-reply-to:references:references; bh=ZRAoox1M5hwJhuZkjolZjjtxERiJIhsW1JYtmTf5qTg=; b=bLj01FZLIK8XtD82lxvbataSFETy2jC1XNV3NaqtKbenB9d60txEaDK+ARdMRqx97I9BfD SZT5DhK+dHgOpxxyaEgmiXycj6lVPORTK8WobakXsqhS5ZL5m9ehgWIIoxPwU04QNO8Ouw FSUO1AO1h8oLg/OZsmX6PW4lxdj8HaqVbREY3bypOXtct5bkCALleYtDEtAeKqDqprJbqQ lUVog7yJmQvEkp9zdUKl6acDFHrFjFNwSnFBsO3lL3IqGbRG/GRXbwjIVL5KbkmMj8wlZ4 Jl33NFsbZtfDgAgdaiD+6Xm+PprURLJdQFZzRpho0Q6/I18kK8RWssofELXaig== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1661722239; a=rsa-sha256; cv=none; b=pAI7ayXJmLr4VQ4x/fYOLupbwrZmU43igU71Diee5vu6tWVd94HYE3303YBsCpRRy0VqBe y8iP9OeDAaIRdJghhOeEtCFpeBSmfR98PZASE12vcc0n470WKWOjywFxAVr6cONX8rq08c A6Mb6JX3+jvzl8LQ4zXWaUsuAoFxaxm5e/s8RsyztBhVJMFdn4tuZZ4UoQcMs071AkP3ir M5ecUDWdGV2+NfAUbQRKp6l9fTj2JfQTCtINRjZrJi+849b033Ggo/Ok58oBzMVG2fBl/7 0jKL4uUlc1Se4hN8UqqdMwI2MEfxMzHMTnl2fN7wjtRVeiVbbr8rHdyeLv1OWA== ARC-Authentication-Results: i=1; mx1.freebsd.org; none X-ThisMailContainsUnwantedMimeParts: N https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D265974 --- Comment #9 from Pierre Habouzit --- `atomic_thread_fence_rel()` is a `dmb sy` ? I would have expected that to b= e a `dmb st` .. but indeed it shows I'm not familiar with with FreeBSD: ```C static __inline void atomic_thread_fence_rel(void) { dmb(sy); } ``` and indeed it makes the deferred advance correct then. It also means smr_synchronize() has a stronger semantics than I expected already and makes the smr_poll barrier on entry useless because the `atomic_load_acq_int()` in smr_poll() already give the semantics I was afte= r on entry. I think you might be right that the one on exit of smr_poll() isn't quite needed. I think I just didn't think it through and just took `ck_epoch_synchronize_wait` as an example and just was like "it needs one so smr_scan does too" but trying to come up with a reason why it breaks yields nothing.. --=20 You are receiving this mail because: You are the assignee for the bug.=