From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752967AbcFVPfk (ORCPT ); Wed, 22 Jun 2016 11:35:40 -0400 Received: from mail-yw0-f194.google.com ([209.85.161.194]:35643 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752577AbcFVPfR (ORCPT ); Wed, 22 Jun 2016 11:35:17 -0400 Date: Wed, 22 Jun 2016 11:35:07 -0400 From: Tejun Heo To: Martin KaFai Lau Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , kernel-team@fb.com Subject: Re: [PATCH -next 1/4] cgroup: Add cgroup_get_from_fd Message-ID: <20160622153507.GW3262@mtj.duckdns.org> References: <1466555002-1316296-1-git-send-email-kafai@fb.com> <1466555002-1316296-2-git-send-email-kafai@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1466555002-1316296-2-git-send-email-kafai@fb.com> User-Agent: Mutt/1.6.1 (2016-04-27) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Martin. On Tue, Jun 21, 2016 at 05:23:19PM -0700, Martin KaFai Lau wrote: > @@ -6205,6 +6206,31 @@ struct cgroup *cgroup_get_from_path(const char *path) > } > EXPORT_SYMBOL_GPL(cgroup_get_from_path); Proper function comment would be nice. > +struct cgroup *cgroup_get_from_fd(int fd) > +{ > + struct cgroup_subsys_state *css; > + struct cgroup *cgrp; > + struct file *f; > + > + f = fget_raw(fd); > + if (!f) > + return NULL; It returns NULL here. > + css = css_tryget_online_from_dir(f->f_path.dentry, NULL); > + fput(f); > + if (IS_ERR(css)) > + return ERR_CAST(css); > + > + cgrp = css->cgroup; > + if (!cgroup_on_dfl(cgrp)) { > + cgroup_put(cgrp); > + return ERR_PTR(-EINVAL); But an ERR_PTR value here. Is this intentional? Also, wouldn't it make more sense to return -EBADF here, given that that's what css_tryget_online_from_dir() would return if the filesystem type is wrong? Thanks! -- tejun