From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Serge E. Hallyn" Subject: Re: [PATCH v4] signal: add taskfd_send_signal() syscall Date: Thu, 6 Dec 2018 18:31:24 -0600 Message-ID: <20181207003124.GA11160@mail.hallyn.com> References: <20181206121858.12215-1-christian@brauner.io> <87sgzahf7k.fsf@xmission.com> <875zw6bh2z.fsf@xmission.com> <20181206193017.wpxls5p3zgjd6rv2@brauner.io> <871s6u9z6u.fsf@xmission.com> <20181206213152.gvci7ijr3dokew7w@brauner.io> <87o99y72gi.fsf@xmission.com> <20181206223948.gyfdtkgbhtozmpsp@brauner.io> <20181206231742.xxi4ghn24z4h2qki@brauner.io> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20181206231742.xxi4ghn24z4h2qki@brauner.io> Sender: linux-kernel-owner@vger.kernel.org To: Christian Brauner Cc: "Eric W. Biederman" , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, luto@kernel.org, arnd@arndb.de, serge@hallyn.com, jannh@google.com, akpm@linux-foundation.org, oleg@redhat.com, cyphar@cyphar.com, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, dancol@google.com, timmurray@google.com, linux-man@vger.kernel.org, keescook@chromium.org, fweimer@redhat.com, tglx@linutronix.de, x86@kernel.org List-Id: linux-api@vger.kernel.org On Fri, Dec 07, 2018 at 12:17:45AM +0100, Christian Brauner wrote: > On Thu, Dec 06, 2018 at 11:39:48PM +0100, Christian Brauner wrote: > > On Thu, Dec 06, 2018 at 03:46:53PM -0600, Eric W. Biederman wrote: > > > Christian Brauner writes: > > > > > > >> Your intention is to add the thread case to support pthreads once the > > > >> process case is sorted out. So this is something that needs to be made > > > >> clear. Did I miss how you plan to handle threads? > > > > > > > > Yeah, maybe you missed it in the commit message [2] which is based on a > > > > discussion with Andy [3] and Arnd [4]: > > > > > > Looking at your references I haven't missed it. You are not deciding > > > anything as of yet to keep it simple. Except you are returning > > > EOPNOTSUPP. You are very much intending to do something. > > > > That was clear all along and was pointed at every occassion in the > > threads. I even went through the hazzle to give you all of the > > references when there's lore.kernel.org. > > > > > > > > Decide. Do you use the flags parameter or is the width of the > > > target depending on the flags. > > Ok, let's try to be constructive. I understand the general concern for > the future so let's put a contract into the commit message stating that > the width of the target aka *what is signaled* will be based on a flag > parameter if we ever extend it: > > taskfd_send_signal(fd, SIGSTOP, NULL, TASKFD_PGID); > taskfd_send_signal(fd, SIGSTOP, NULL, TASKFD_TID); > > with the current default being > > taskfd_send_signal(fd, SIGSTOP, NULL, TASKFD_PID); > > This seems to me the cleanest solution as we only use one type of file > descriptor. Can everyone be on board with this? If so I'm going to send > out a new version of the patch. > > Christian I'm on board with this, but I think you need to also clarify what exactly the fd stands for. I think that (a) userspace should not have to care about the struct pid implementation, and so (b) the procfd should stand for all the pids. So when taskfd_send_signal(fd, SIGSTOP, NULL, TASKFD_PGID) becomes implemented, then open(/proc/5) will pin all three pids, as will open(/proc/5/task/6). -serge