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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30FB4C433F5 for ; Wed, 20 Apr 2022 18:03:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1359117AbiDTSGV (ORCPT ); Wed, 20 Apr 2022 14:06:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58262 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241671AbiDTSGU (ORCPT ); Wed, 20 Apr 2022 14:06:20 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id D39E83FDA2 for ; Wed, 20 Apr 2022 11:03:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1650477813; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=CIL7ig4ne/h1LgZxz8/JxhT2oGMYZ2VjyaHLoNy0IU4=; b=DXyJd8dcWRGeQkkAfGg7swMNQaz4As6Dp9ol5LQSCDyePEH7tXMLOk1EKgD4SzPXb4pybg MT2y9Bydl6ZfSnzVsp7504h+guXx/Xf6xc1WTDZ+o2t/ADJQcVUAD499Gly+CpRUc4o516 HMzrtuGSuz6gCcmhwru18ir+keZc1Hw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-665-rjH9If2oMhOJ4NqgafTknw-1; Wed, 20 Apr 2022 14:03:29 -0400 X-MC-Unique: rjH9If2oMhOJ4NqgafTknw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B11D08002BF; Wed, 20 Apr 2022 18:03:28 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.192.37]) by smtp.corp.redhat.com (Postfix) with SMTP id 9AEC140D0166; Wed, 20 Apr 2022 18:03:25 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 20 Apr 2022 20:03:27 +0200 (CEST) Date: Wed, 20 Apr 2022 20:03:23 +0200 From: Oleg Nesterov To: Peter Zijlstra Cc: rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, ebiederm@xmission.com, bigeasy@linutronix.de, Will Deacon , linux-kernel@vger.kernel.org, tj@kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH 2/5] sched,ptrace: Fix ptrace_check_attach() vs PREEMPT_RT Message-ID: <20220420180323.GA14947@redhat.com> References: <20220413192053.GY2731@worktop.programming.kicks-ass.net> <20220413195612.GC2762@worktop.programming.kicks-ass.net> <20220414115410.GA32752@redhat.com> <20220414183433.GC32752@redhat.com> <20220415101644.GA10421@redhat.com> <20220415105755.GA15217@redhat.com> <20220418170104.GA16199@redhat.com> <20220420131731.GF2731@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220420131731.GF2731@worktop.programming.kicks-ass.net> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 04/20, Peter Zijlstra wrote: > > Does something like: > > #define JOBCTL_TRACED_BIT 25 > #define JOBCTL_TRACED_QUIESCE_BIT 26 > > work? Agreed! ;) > > } else { > > /* > > * By the time we got the lock, our tracer went away. > > - * Don't drop the lock yet, another tracer may come. > > - * > > + * Don't drop the lock yet, another tracer may come, > > + * tasklist protects us from ptrace_freeze_traced(). > > + */ > > + __set_current_state(TASK_RUNNING); > > + clear_traced_xxx(); > > + /* > > * If @gstop_done, the ptracer went away between group stop > > * completion and here. During detach, it would have set > > * JOBCTL_STOP_PENDING on us and we'll re-enter > > This is that same else clause again; perhaps make signal_wake_up_state() > also clear TRACED_XXX instead? I swear, I too thought about this after my last email. Yes, I think this makes sense. Thanks, Oleg.