From owner-svn-src-stable@freebsd.org Sat Nov 24 17:11:49 2018 Return-Path: Delivered-To: svn-src-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id D525B1104CAD; Sat, 24 Nov 2018 17:11:48 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 7D7EA83845; Sat, 24 Nov 2018 17:11:48 +0000 (UTC) (envelope-from markj@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 45CF810DA0; Sat, 24 Nov 2018 17:11:48 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id wAOHBmBm012642; Sat, 24 Nov 2018 17:11:48 GMT (envelope-from markj@FreeBSD.org) Received: (from markj@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id wAOHBmMD012641; Sat, 24 Nov 2018 17:11:48 GMT (envelope-from markj@FreeBSD.org) Message-Id: <201811241711.wAOHBmMD012641@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: markj set sender to markj@FreeBSD.org using -f From: Mark Johnston Date: Sat, 24 Nov 2018 17:11:48 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r340904 - stable/11/sys/kern X-SVN-Group: stable-11 X-SVN-Commit-Author: markj X-SVN-Commit-Paths: stable/11/sys/kern X-SVN-Commit-Revision: 340904 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 7D7EA83845 X-Spamd-Result: default: False [1.79 / 15.00]; local_wl_from(0.00)[FreeBSD.org]; NEURAL_SPAM_LONG(0.61)[0.611,0]; NEURAL_SPAM_MEDIUM(0.70)[0.697,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US]; NEURAL_SPAM_SHORT(0.49)[0.486,0] X-Rspamd-Server: mx1.freebsd.org X-BeenThere: svn-src-stable@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: SVN commit messages for all the -stable branches of the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 24 Nov 2018 17:11:49 -0000 Author: markj Date: Sat Nov 24 17:11:47 2018 New Revision: 340904 URL: https://svnweb.freebsd.org/changeset/base/340904 Log: MFC r340734: Avoid unsynchronized updates to kn_status. Modified: stable/11/sys/kern/kern_event.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/kern/kern_event.c ============================================================================== --- stable/11/sys/kern/kern_event.c Sat Nov 24 17:09:35 2018 (r340903) +++ stable/11/sys/kern/kern_event.c Sat Nov 24 17:11:47 2018 (r340904) @@ -1391,6 +1391,8 @@ findkn: kn->kn_kevent.flags &= ~(EV_ADD | EV_DELETE | EV_ENABLE | EV_DISABLE | EV_FORCEONESHOT); kn->kn_status = KN_INFLUX|KN_DETACHED; + if ((kev->flags & EV_DISABLE) != 0) + kn->kn_status |= KN_DISABLED; error = knote_attach(kn, kq); KQ_UNLOCK(kq); @@ -1427,6 +1429,11 @@ findkn: KNOTE_ACTIVATE(kn, 1); } + if ((kev->flags & EV_ENABLE) != 0) + kn->kn_status &= ~KN_DISABLED; + else if ((kev->flags & EV_DISABLE) != 0) + kn->kn_status |= KN_DISABLED; + /* * The user may change some filter values after the initial EV_ADD, * but doing so will not reset any filter which has already been @@ -1443,19 +1450,17 @@ findkn: kn->kn_sdata = kev->data; } +done_ev_add: /* * We can get here with kn->kn_knlist == NULL. This can happen when * the initial attach event decides that the event is "completed" - * already. i.e. filt_procattach is called on a zombie process. It - * will call filt_proc which will remove it from the list, and NULL + * already, e.g., filt_procattach() is called on a zombie process. It + * will call filt_proc() which will remove it from the list, and NULL * kn_knlist. + * + * KN_DISABLED will be stable while the knote is in flux, so the + * unlocked read will not race with an update. */ -done_ev_add: - if ((kev->flags & EV_ENABLE) != 0) - kn->kn_status &= ~KN_DISABLED; - else if ((kev->flags & EV_DISABLE) != 0) - kn->kn_status |= KN_DISABLED; - if ((kn->kn_status & KN_DISABLED) == 0) event = kn->kn_fop->f_event(kn, 0); else