From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nyb79-008HIi-4E for linux-um@lists.infradead.org; Tue, 07 Jun 2022 15:27:28 +0000 Date: Tue, 7 Jun 2022 17:26:54 +0200 From: Oleg Nesterov Subject: Re: [PATCH 07/16] signal: Wake up the designated parent Message-ID: <20220607152627.GA10192@redhat.com> References: <871qwq5ucx.fsf_-_@email.froward.int.ebiederm.org> <20220518225355.784371-7-ebiederm@xmission.com> <20220524132553.GD14347@redhat.com> <20220524162808.GF14347@redhat.com> <20220525142845.GA2687@redhat.com> <87a6ap30lh.fsf@email.froward.int.ebiederm.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87a6ap30lh.fsf@email.froward.int.ebiederm.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+geert=linux-m68k.org@lists.infradead.org To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, bigeasy@linutronix.de, Will Deacon , tj@kernel.org, linux-pm@vger.kernel.org, Peter Zijlstra , Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Kees Cook , Jann Horn , linux-ia64@vger.kernel.org, Robert OCallahan , Kyle Huey , Richard Henderson , Ivan Kokshaysky , Matt Turner , Jason Wessel , Daniel Thompson , Douglas Anderson , Douglas Miller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras On 06/06, Eric W. Biederman wrote: > > Which if I have had enough sleep reduces this patch to just: > > diff --git a/kernel/exit.c b/kernel/exit.c > index f072959fcab7..c8156366b722 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -1431,8 +1431,10 @@ static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, > if (!eligible_pid(wo, p)) > return 0; > > - if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) > - return 0; > + if ((wo->wo_flags & __WNOTHREAD) && > + (wait->private != p->parent) && > + (wait->private != p->real_parent)) > + return 0; > > return default_wake_function(wait, mode, sync, key); > } > > > I think that solves the issue without missing wake-ups without adding > any more. Agreed, and looks much simpler. > For the same set of reasons it looks like the __wake_up_parent in > __ptrace_detach is just simply dead code. I don't think there is a case > where when !ptrace_reparented the thread that is the real_parent can > sleep in do_wait when the thread that was calling ptrace could not. Yes... this doesn't really differ from the case when one thread reaps a natural child and another thread sleep in do_wait(). > That needs a very close look to confirm. Yes. Oleg. _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um