From owner-svn-src-head@freebsd.org Tue Sep 3 14:07:43 2019 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 9887DDDA92; Tue, 3 Sep 2019 14:07:25 +0000 (UTC) (envelope-from yuripv@freebsd.org) Received: from freefall.freebsd.org (freefall.freebsd.org [IPv6:2610:1c1:1:6074::16:84]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "freefall.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 46N80X4DWpz4QZg; Tue, 3 Sep 2019 14:07:24 +0000 (UTC) (envelope-from yuripv@freebsd.org) Received: by freefall.freebsd.org (Postfix, from userid 1452) id 5BEEC1B5B7; Tue, 3 Sep 2019 14:06:38 +0000 (UTC) X-Original-To: yuripv@localmail.freebsd.org Delivered-To: yuripv@localmail.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [96.47.72.80]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (Client CN "mx1.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by freefall.freebsd.org (Postfix) with ESMTPS id 45F3F1E430; Tue, 23 Apr 2019 06:36:37 +0000 (UTC) (envelope-from owner-src-committers@freebsd.org) Received: from freefall.freebsd.org (freefall.freebsd.org [96.47.72.132]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "freefall.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4D9F191C25; Tue, 23 Apr 2019 06:36:36 +0000 (UTC) (envelope-from owner-src-committers@freebsd.org) Received: by freefall.freebsd.org (Postfix, from userid 538) id 175F01E3F3; Tue, 23 Apr 2019 06:36:36 +0000 (UTC) Delivered-To: src-committers@localmail.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (Client CN "mx1.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by freefall.freebsd.org (Postfix) with ESMTPS id A2C5D1E3F1 for ; Tue, 23 Apr 2019 06:36:33 +0000 (UTC) (envelope-from wma@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) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 54AE691C1F; Tue, 23 Apr 2019 06:36:33 +0000 (UTC) (envelope-from wma@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 2910420A97; Tue, 23 Apr 2019 06:36:33 +0000 (UTC) (envelope-from wma@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x3N6aWxE057864; Tue, 23 Apr 2019 06:36:32 GMT (envelope-from wma@FreeBSD.org) Received: (from wma@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x3N6aWQK057863; Tue, 23 Apr 2019 06:36:32 GMT (envelope-from wma@FreeBSD.org) Message-Id: <201904230636.x3N6aWQK057863@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: wma set sender to wma@FreeBSD.org using -f From: Wojciech Macek To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r346593 - head/sys/sys X-SVN-Group: head X-SVN-Commit-Author: wma X-SVN-Commit-Paths: head/sys/sys X-SVN-Commit-Revision: 346593 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk X-Loop: FreeBSD.org Sender: owner-src-committers@freebsd.org X-Rspamd-Queue-Id: 4D9F191C25 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.94 / 15.00]; local_wl_from(0.00)[freebsd.org]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; NEURAL_HAM_SHORT(-0.94)[-0.937,0]; ASN(0.00)[asn:11403, ipnet:96.47.64.0/20, country:US]; NEURAL_HAM_LONG(-1.00)[-1.000,0] Status: O X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.29 List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Date: Tue, 03 Sep 2019 14:07:44 -0000 X-Original-Date: Tue, 23 Apr 2019 06:36:32 +0000 (UTC) X-List-Received-Date: Tue, 03 Sep 2019 14:07:44 -0000 Author: wma Date: Tue Apr 23 06:36:32 2019 New Revision: 346593 URL: https://svnweb.freebsd.org/changeset/base/346593 Log: This patch offers a workaround to buf_ring reordering visible on armv7 and armv8. Similar issue to rS302292. Obtained from: Semihalf Authored by: Michal Krawczyk Approved by: wma Differential Revision: https://reviews.freebsd.org/D19932 Modified: head/sys/sys/buf_ring.h Modified: head/sys/sys/buf_ring.h ============================================================================== --- head/sys/sys/buf_ring.h Tue Apr 23 04:06:26 2019 (r346592) +++ head/sys/sys/buf_ring.h Tue Apr 23 06:36:32 2019 (r346593) @@ -310,14 +310,23 @@ buf_ring_peek_clear_sc(struct buf_ring *br) if (!mtx_owned(br->br_lock)) panic("lock not held on single consumer dequeue"); #endif - /* - * I believe it is safe to not have a memory barrier - * here because we control cons and tail is worst case - * a lagging indicator so we worst case we might - * return NULL immediately after a buffer has been enqueued - */ + if (br->br_cons_head == br->br_prod_tail) return (NULL); + +#if defined(__arm__) || defined(__aarch64__) + /* + * The barrier is required there on ARM and ARM64 to ensure, that + * br->br_ring[br->br_cons_head] will not be fetched before the above + * condition is checked. + * Without the barrier, it is possible, that buffer will be fetched + * before the enqueue will put mbuf into br, then, in the meantime, the + * enqueue will update the array and the br_prod_tail, and the + * conditional check will be true, so we will return previously fetched + * (and invalid) buffer. + */ + atomic_thread_fence_acq(); +#endif #ifdef DEBUG_BUFRING /*