From owner-dev-commits-src-all@freebsd.org Mon Jun 7 00:40:17 2021 Return-Path: Delivered-To: dev-commits-src-all@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 09A41643490; Mon, 7 Jun 2021 00:40:17 +0000 (UTC) (envelope-from git@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 4FyvfS6Xqdz4r61; Mon, 7 Jun 2021 00:40:16 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (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 C3369570F; Mon, 7 Jun 2021 00:40:16 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 1570eGjV064821; Mon, 7 Jun 2021 00:40:16 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 1570eGqG064815; Mon, 7 Jun 2021 00:40:16 GMT (envelope-from git) Date: Mon, 7 Jun 2021 00:40:16 GMT Message-Id: <202106070040.1570eGqG064815@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Mateusz Guzik Subject: git: a138a50c75e4 - stable/13 - vfs: use the sentinel trick in locked lookup path parsing MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: mjg X-Git-Repository: src X-Git-Refname: refs/heads/stable/13 X-Git-Reftype: branch X-Git-Commit: a138a50c75e4d4c92ca09d098a6d660551beaae0 Auto-Submitted: auto-generated X-BeenThere: dev-commits-src-all@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commit messages for all branches of the src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 07 Jun 2021 00:40:17 -0000 The branch stable/13 has been updated by mjg: URL: https://cgit.FreeBSD.org/src/commit/?id=a138a50c75e4d4c92ca09d098a6d660551beaae0 commit a138a50c75e4d4c92ca09d098a6d660551beaae0 Author: Mateusz Guzik AuthorDate: 2021-05-25 17:34:26 +0000 Commit: Mateusz Guzik CommitDate: 2021-06-07 00:34:56 +0000 vfs: use the sentinel trick in locked lookup path parsing (cherry picked from commit d81aefa8b7dd8cbeffeda541fca9962802404983) --- sys/kern/vfs_lookup.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c index 5336bf87ec68..e0b98c9f5661 100644 --- a/sys/kern/vfs_lookup.c +++ b/sys/kern/vfs_lookup.c @@ -850,6 +850,7 @@ lookup(struct nameidata *ndp) { char *cp; /* pointer into pathname argument */ char *prev_ni_next; /* saved ndp->ni_next */ + char *nulchar; /* location of '\0' in cn_pnbuf */ struct vnode *dp = NULL; /* the directory we are searching */ struct vnode *tdp; /* saved dp */ struct mount *mp; /* mount table entry */ @@ -909,9 +910,23 @@ dirloop: * cnp->cn_nameptr for callers that need the name. Callers needing * the name set the SAVENAME flag. When done, they assume * responsibility for freeing the pathname buffer. + * + * Store / as a temporary sentinel so that we only have one character + * to test for. Pathnames tend to be short so this should not be + * resulting in cache misses. */ - for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) + nulchar = &cnp->cn_nameptr[ndp->ni_pathlen - 1]; + KASSERT(*nulchar == '\0', + ("%s: expected nul at %p; string [%s]\n", __func__, nulchar, + cnp->cn_pnbuf)); + *nulchar = '/'; + for (cp = cnp->cn_nameptr; *cp != '/'; cp++) { + KASSERT(*cp != '\0', + ("%s: encountered unexpected nul; string [%s]\n", __func__, + cnp->cn_nameptr)); continue; + } + *nulchar = '\0'; cnp->cn_namelen = cp - cnp->cn_nameptr; if (cnp->cn_namelen > NAME_MAX) { error = ENAMETOOLONG;