From owner-svn-src-head@freebsd.org Wed Nov 20 12:07:54 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 EA6A51B529F; Wed, 20 Nov 2019 12:07:54 +0000 (UTC) (envelope-from mjg@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 47J1ff5qPhz3FXR; Wed, 20 Nov 2019 12:07:54 +0000 (UTC) (envelope-from mjg@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 AC839226F4; Wed, 20 Nov 2019 12:07:54 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id xAKC7sU9022080; Wed, 20 Nov 2019 12:07:54 GMT (envelope-from mjg@FreeBSD.org) Received: (from mjg@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id xAKC7s4J022079; Wed, 20 Nov 2019 12:07:54 GMT (envelope-from mjg@FreeBSD.org) Message-Id: <201911201207.xAKC7s4J022079@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mjg set sender to mjg@FreeBSD.org using -f From: Mateusz Guzik Date: Wed, 20 Nov 2019 12:07:54 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r354892 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: mjg X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 354892 X-SVN-Commit-Repository: base 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: 2.1.29 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: Wed, 20 Nov 2019 12:07:55 -0000 Author: mjg Date: Wed Nov 20 12:07:54 2019 New Revision: 354892 URL: https://svnweb.freebsd.org/changeset/base/354892 Log: vfs: perform a more racy check in vfs_notify_upper Locking mp does not buy anything interms of correctness and only contributes to contention. Modified: head/sys/kern/vfs_subr.c Modified: head/sys/kern/vfs_subr.c ============================================================================== --- head/sys/kern/vfs_subr.c Wed Nov 20 12:06:29 2019 (r354891) +++ head/sys/kern/vfs_subr.c Wed Nov 20 12:07:54 2019 (r354892) @@ -3526,11 +3526,9 @@ vfs_notify_upper(struct vnode *vp, int event) mp = vp->v_mount; if (mp == NULL) return; - - MNT_ILOCK(mp); if (TAILQ_EMPTY(&mp->mnt_uppers)) - goto unlock; - MNT_IUNLOCK(mp); + return; + mmp = malloc(sizeof(struct mount), M_TEMP, M_WAITOK | M_ZERO); mmp->mnt_op = &vgonel_vfsops; mmp->mnt_kern_flag |= MNTK_MARKER; @@ -3564,7 +3562,6 @@ vfs_notify_upper(struct vnode *vp, int event) mp->mnt_kern_flag &= ~MNTK_VGONE_WAITER; wakeup(&mp->mnt_uppers); } -unlock: MNT_IUNLOCK(mp); }