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 E35A5C433E7 for ; Thu, 15 Oct 2020 15:18:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7138E2223F for ; Thu, 15 Oct 2020 15:18:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bBPbFS63" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389493AbgJOPSF (ORCPT ); Thu, 15 Oct 2020 11:18:05 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:37292 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388086AbgJOPSF (ORCPT ); Thu, 15 Oct 2020 11:18:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602775083; 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=ZmIzkd5uRDI24FvTtgkvnJd3MIzG72UtYvWuNQeQTr0=; b=bBPbFS63o5u4w2+q2kY5KV2N5ENwEpZLO96eCa7fv8GTEZCqhMkxSR7fmd74pC2FEsx3Nu U+wEfhwqVbO1FRptASg1PoyV5g2AAWDX/6AvL62+rFmKGMJdrMrfWVet4QnFXlEPfT6hK2 dJb0X1pjEE/J3/fTz9UMnzTHOwGT3dQ= 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-408-bNInItiKNX-b_VsXjfsoGg-1; Thu, 15 Oct 2020 11:18:01 -0400 X-MC-Unique: bNInItiKNX-b_VsXjfsoGg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9D57618BE161; Thu, 15 Oct 2020 15:17:59 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.193.8]) by smtp.corp.redhat.com (Postfix) with SMTP id 31C4D73661; Thu, 15 Oct 2020 15:17:57 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Thu, 15 Oct 2020 17:17:59 +0200 (CEST) Date: Thu, 15 Oct 2020 17:17:56 +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: <20201015151756.GK24156@redhat.com> References: <20201015143409.GC24156@redhat.com> <87v9fbv8te.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87v9fbv8te.fsf@nanos.tec.linutronix.de> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 10/15, 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? > > You need to change ONE architecture because nobody else uses the common > entry loop right now. so we need to change other arches to use the common entry loop. > For those who move over they have to supply > arch_do_signal() anyway, and this arch_do_signal() should be changed to check _TIF_SIGPENDING. See also my replies to 3/5. I strongly disagree with CONFIG_GENERIC_ENTRY. But even if we require CONFIG_GENERIC_ENTRY, why do we want this helper? We can just change exit_to_user_mode_loop() to do if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) { if (ti_work & _TIF_NOTIFY_SIGNAL) tracehook_notify_signal(); arch_do_signal(ti_work, regs); } but I'd prefer to handle SIGPENDING/NOTIFY_SIGNAL in one place. Oleg.