From owner-svn-src-head@freebsd.org Mon Dec 19 22:18:37 2016 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A73E3C88441; Mon, 19 Dec 2016 22:18:37 +0000 (UTC) (envelope-from kib@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 mx1.freebsd.org (Postfix) with ESMTPS id 5D2341771; Mon, 19 Dec 2016 22:18:37 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id uBJMIacY001228; Mon, 19 Dec 2016 22:18:36 GMT (envelope-from kib@FreeBSD.org) Received: (from kib@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id uBJMIa1p001227; Mon, 19 Dec 2016 22:18:36 GMT (envelope-from kib@FreeBSD.org) Message-Id: <201612192218.uBJMIa1p001227@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: kib set sender to kib@FreeBSD.org using -f From: Konstantin Belousov Date: Mon, 19 Dec 2016 22:18:36 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r310302 - head/sys/kern X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Dec 2016 22:18:37 -0000 Author: kib Date: Mon Dec 19 22:18:36 2016 New Revision: 310302 URL: https://svnweb.freebsd.org/changeset/base/310302 Log: Do not clear KN_INFLUX when not owning influx state. For notes in KN_INFLUX|KN_SCAN state, the influx bit is set by a parallel scan. When knote() reports event for the vnode filters, which require kqueue unlocked, it unconditionally sets and then clears influx to keep note around kqueue unlock. There, do not clear influx flag if a scan set it, since we do not own it, instead we prevent scan from executing by holding knlist lock. The knote_fork() function has somewhat similar problem, it might set KN_INFLUX for scanned note, drop kqueue and list locks, and then clear the flag after relock. A solution there would be different enough, as well as the test program, so close the reported issue first. Reported and test case provided by: yjh0502@gmail.com PR: 214923 Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Modified: head/sys/kern/kern_event.c Modified: head/sys/kern/kern_event.c ============================================================================== --- head/sys/kern/kern_event.c Mon Dec 19 22:15:29 2016 (r310301) +++ head/sys/kern/kern_event.c Mon Dec 19 22:18:36 2016 (r310302) @@ -2006,6 +2006,7 @@ knote(struct knlist *list, long hint, in struct kqueue *kq; struct knote *kn, *tkn; int error; + bool own_influx; if (list == NULL) return; @@ -2036,11 +2037,14 @@ knote(struct knlist *list, long hint, in */ KQ_UNLOCK(kq); } else if ((lockflags & KNF_NOKQLOCK) != 0) { - kn->kn_status |= KN_INFLUX; + own_influx = (kn->kn_status & KN_INFLUX) == 0; + if (own_influx) + kn->kn_status |= KN_INFLUX; KQ_UNLOCK(kq); error = kn->kn_fop->f_event(kn, hint); KQ_LOCK(kq); - kn->kn_status &= ~KN_INFLUX; + if (own_influx) + kn->kn_status &= ~KN_INFLUX; if (error) KNOTE_ACTIVATE(kn, 1); KQ_UNLOCK_FLUX(kq);