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=-5.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 3B92DC433DF for ; Fri, 16 Oct 2020 10:54:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D4F1F2084C for ; Fri, 16 Oct 2020 10:54:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="J86GaWMX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395539AbgJPKyY (ORCPT ); Fri, 16 Oct 2020 06:54:24 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:29328 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2395537AbgJPKyX (ORCPT ); Fri, 16 Oct 2020 06:54:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602845662; 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=Z9HCeHX+Y5YHXx5lFh8SFKBrNHGin0lf0jgV0vHxv1s=; b=J86GaWMX0kXkSTt+LP0pdm1zO5PyUMUSwXeMwwkm2z1v9Dad0hh8hxPs47zTpBLjmaHzqh ieNqB9XCCbW79HSw9wPZcnU3W4r5w2aqECOkzpDgbtzsUi3C2xTq/JGryqjYazEPop2OC6 o6RIGD2JGlw4T3Xj24qxk3ONPX+rdWY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-257-tpYhCG20MMOEkAV_4Slg5g-1; Fri, 16 Oct 2020 06:54:20 -0400 X-MC-Unique: tpYhCG20MMOEkAV_4Slg5g-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DCCF16409B; Fri, 16 Oct 2020 10:54:18 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.192.149]) by smtp.corp.redhat.com (Postfix) with SMTP id 7F7A21972B; Fri, 16 Oct 2020 10:54:17 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 16 Oct 2020 12:54:18 +0200 (CEST) Date: Fri, 16 Oct 2020 12:54:16 +0200 From: Oleg Nesterov To: Thomas Gleixner Cc: Jens Axboe , linux-kernel@vger.kernel.org, io-uring@vger.kernel.org, peterz@infradead.org Subject: Re: [PATCH 4/5] x86: wire up TIF_NOTIFY_SIGNAL Message-ID: <20201016105415.GA21989@redhat.com> References: <20201015131701.511523-1-axboe@kernel.dk> <20201015131701.511523-5-axboe@kernel.dk> <87o8l3a8af.fsf@nanos.tec.linutronix.de> <20201015143409.GC24156@redhat.com> <87y2k6trzr.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87y2k6trzr.fsf@nanos.tec.linutronix.de> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 10/16, Thomas Gleixner wrote: > > On Thu, Oct 15 2020 at 16:34, Oleg Nesterov wrote: > > On 10/15, Thomas Gleixner wrote: > >> Instead of adding this to every architectures signal magic, we can > >> handle TIF_NOTIFY_SIGNAL in the core code: > >> > >> static void handle_singal_work(ti_work, regs) > >> { > >> if (ti_work & _TIF_NOTIFY_SIGNAL) > >> tracehook_notify_signal(); > >> > >> arch_do_signal(ti_work, regs); > >> } > >> > >> loop { > >> if (ti_work & (SIGPENDING | NOTIFY_SIGNAL)) > >> handle_signal_work(ti_work, regs); > >> } > > > > To me this looks like unnecessary complication. We need to change > > every architecture anyway, how can this helper help? > > This is about the generic entry code. For the users of that it makes > absolutely no sense to have that in architecture code. > > Something which every architecture needs to do in the exactly same way > goes into the common code. If not, you can spare the exercise of having > common code in the first place. > > Also arch_do_signal() becomes a misnomer with this new magic. Well, to me arch_do_signal() paths should handle the signal_pending() == T case. But I won't argue, this is subjective. > static void handle_signal_work(ti_work, regs) > { > if (ti_work & _TIF_NOTIFY_SIGNAL) > tracehook_notify_signal(); > > arch_do_signal_or_restart(ti_work, regs); > } > > which makes it entirely clear what this is about. In this case I'd prefer to pass the "(ti_work & _TIF_SIGPENDING)" boolen to arch_do_signal_or_restart(). But again, I won't argue. And to remind, we do not really need to touch arch_do_signal() at all. We can just add if (test_thread_flag(TIF_NOTIFY_SIGNAL)) tracehook_notify_signal(); if (!task_sigpending(current)) return 0; at the start of get_signal() and avoid the code duplication automatically. Oleg.