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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 19905C43387 for ; Tue, 8 Jan 2019 18:17:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED3FF20645 for ; Tue, 8 Jan 2019 18:17:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729451AbfAHSRp (ORCPT ); Tue, 8 Jan 2019 13:17:45 -0500 Received: from mail.hallyn.com ([178.63.66.53]:40998 "EHLO mail.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727484AbfAHSRo (ORCPT ); Tue, 8 Jan 2019 13:17:44 -0500 Received: by mail.hallyn.com (Postfix, from userid 1001) id AEDB0107D; Tue, 8 Jan 2019 12:17:42 -0600 (CST) Date: Tue, 8 Jan 2019 12:17:42 -0600 From: "Serge E. Hallyn" To: Tycho Andersen Cc: "Serge E. Hallyn" , Christian Brauner , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, luto@kernel.org, arnd@arndb.de, keescook@chromium.org, akpm@linux-foundation.org, jannh@google.com, oleg@redhat.com, cyphar@cyphar.com, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, dancol@google.com, timmurray@google.com, fweimer@redhat.com, tglx@linutronix.de, x86@kernel.org, ebiederm@xmission.com Subject: Re: [PATCH v7 2/2] selftests: add tests for pidfd_send_signal() Message-ID: <20190108181742.GA22614@mail.hallyn.com> References: <20190102161654.9093-1-christian@brauner.io> <20190102161654.9093-2-christian@brauner.io> <20190108175306.GF29009@cisco> <20190108175415.GA22353@mail.hallyn.com> <20190108175843.GA26016@cisco> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190108175843.GA26016@cisco> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 08, 2019 at 10:58:43AM -0700, Tycho Andersen wrote: > On Tue, Jan 08, 2019 at 11:54:15AM -0600, Serge E. Hallyn wrote: > > On Tue, Jan 08, 2019 at 10:53:06AM -0700, Tycho Andersen wrote: > > > On Wed, Jan 02, 2019 at 05:16:54PM +0100, Christian Brauner wrote: > > > > + /* > > > > + * Stop the child so we can inspect whether we have > > > > + * recycled pid PID_RECYCLE. > > > > + */ > > > > + close(pipe_fds[0]); > > > > + ret = kill(recycled_pid, SIGSTOP); > > > > + close(pipe_fds[1]); > > > > + if (ret) { > > > > + (void)wait_for_pid(recycled_pid); > > > > + _exit(PIDFD_ERROR); > > > > + } > > > > > > Sorry for being late to the party, but I wonder if this whole thing > > > couldn't be simplified with /proc/sys/kenrel/ns_last_pid? > > > > no, bc it's not namespaced :) > > Huh? It looks like it is... > > static int pid_ns_ctl_handler(struct ctl_table *table, int write, > void __user *buffer, size_t *lenp, loff_t *ppos) > { > struct pid_namespace *pid_ns = task_active_pid_ns(current); > struct ctl_table tmp = *table; > int ret, next; > > if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN)) > return -EPERM; > > ... Oh - hah, but that's ns_last_pid. You'd want pid_max. And that one is not namespaced.