From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7722DC6786F for ; Thu, 1 Nov 2018 17:00:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 418C620820 for ; Thu, 1 Nov 2018 17:00:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 418C620820 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727465AbeKBCDx (ORCPT ); Thu, 1 Nov 2018 22:03:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56548 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726042AbeKBCDx (ORCPT ); Thu, 1 Nov 2018 22:03:53 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5DCC05CC; Thu, 1 Nov 2018 17:00:04 +0000 (UTC) Received: from krava.brq.redhat.com (unknown [10.43.17.150]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0D189612BF; Thu, 1 Nov 2018 17:00:01 +0000 (UTC) From: Jiri Olsa To: Arnaldo Carvalho de Melo Cc: Krister Johansen , lkml , Ingo Molnar , Namhyung Kim , Alexander Shishkin , Peter Zijlstra Subject: [PATCH] perf tools: Restore proper cwd on return from mnt ns Date: Thu, 1 Nov 2018 18:00:01 +0100 Message-Id: <20181101170001.30019-1-jolsa@kernel.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 01 Nov 2018 17:00:04 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When reporting on 'record' server we try to retrieve/use the mnt namespace of the profiled tasks. We use following API with cookie to hold the return namespace, roughly: nsinfo__mountns_enter(struct nsinfo *nsi, struct nscookie *nc) setns(newns, 0); ... new ns related open.. ... nsinfo__mountns_exit(struct nscookie *nc) setns(nc->oldns) Once finished we setns to old namespace, which also sets the current working directory (cwd) to "/", trashing the cwd we had. This is mostly fine, because we use absolute paths almost everywhere, but it screws up perf diff: # perf diff failed to open perf.data: No such file or directory (try 'perf record' first) ... Adding the current working directory to be part of the cookie and restoring it in the nsinfo__mountns_exit call. Cc: Krister Johansen Fixes: 843ff37bb59e ("perf symbols: Find symbols in different mount namespace") Link: http://lkml.kernel.org/n/tip-zg3vz7kjr86cco7lo91v8yhj@git.kernel.org Signed-off-by: Jiri Olsa --- tools/perf/util/namespaces.c | 18 ++++++++++++++++-- tools/perf/util/namespaces.h | 1 + 2 files changed, 17 insertions(+), 2 deletions(-) diff --git a/tools/perf/util/namespaces.c b/tools/perf/util/namespaces.c index cf8bd123cf73..fb0458b7e6aa 100644 --- a/tools/perf/util/namespaces.c +++ b/tools/perf/util/namespaces.c @@ -18,6 +18,7 @@ #include #include #include +#include struct namespaces *namespaces__new(struct namespaces_event *event) { @@ -186,6 +187,7 @@ void nsinfo__mountns_enter(struct nsinfo *nsi, char curpath[PATH_MAX]; int oldns = -1; int newns = -1; + char *oldcwd = NULL; if (nc == NULL) return; @@ -199,9 +201,13 @@ void nsinfo__mountns_enter(struct nsinfo *nsi, if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX) return; + oldcwd = get_current_dir_name(); + if (!oldcwd) + return; + oldns = open(curpath, O_RDONLY); if (oldns < 0) - return; + goto errout; newns = open(nsi->mntns_path, O_RDONLY); if (newns < 0) @@ -210,11 +216,14 @@ void nsinfo__mountns_enter(struct nsinfo *nsi, if (setns(newns, CLONE_NEWNS) < 0) goto errout; + nc->oldcwd = oldcwd; nc->oldns = oldns; nc->newns = newns; return; errout: + if (oldcwd) + free(oldcwd); if (oldns > -1) close(oldns); if (newns > -1) @@ -223,11 +232,16 @@ void nsinfo__mountns_enter(struct nsinfo *nsi, void nsinfo__mountns_exit(struct nscookie *nc) { - if (nc == NULL || nc->oldns == -1 || nc->newns == -1) + if (nc == NULL || nc->oldns == -1 || nc->newns == -1 || !nc->oldcwd) return; setns(nc->oldns, CLONE_NEWNS); + if (nc->oldcwd) { + WARN_ON_ONCE(chdir(nc->oldcwd)); + free(nc->oldcwd); + } + if (nc->oldns > -1) { close(nc->oldns); nc->oldns = -1; diff --git a/tools/perf/util/namespaces.h b/tools/perf/util/namespaces.h index cae1a9a39722..d5f46c09ea31 100644 --- a/tools/perf/util/namespaces.h +++ b/tools/perf/util/namespaces.h @@ -38,6 +38,7 @@ struct nsinfo { struct nscookie { int oldns; int newns; + char *oldcwd; }; int nsinfo__init(struct nsinfo *nsi); -- 2.17.2