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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 98743C282DE for ; Wed, 5 Jun 2019 09:05:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C0AE2075C for ; Wed, 5 Jun 2019 09:05:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726876AbfFEJFF (ORCPT ); Wed, 5 Jun 2019 05:05:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53592 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726857AbfFEJFE (ORCPT ); Wed, 5 Jun 2019 05:05:04 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 42F9630832C9; Wed, 5 Jun 2019 09:04:59 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.159]) by smtp.corp.redhat.com (Postfix) with SMTP id F089B5D6A9; Wed, 5 Jun 2019 09:04:55 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 5 Jun 2019 11:04:58 +0200 (CEST) Date: Wed, 5 Jun 2019 11:04:54 +0200 From: Oleg Nesterov To: "Eric W. Biederman" Cc: Linus Torvalds , Andrew Morton , Deepa Dinamani , Linux List Kernel Mailing , Arnd Bergmann , Davidlohr Bueso , Jens Axboe , Davidlohr Bueso , e@80x24.org, Jason Baron , linux-fsdevel , linux-aio@kvack.org, omar.kilani@gmail.com, Thomas Gleixner , stable , Al Viro , David Laight Subject: Re: [PATCH] signal: remove the wrong signal_pending() check in restore_user_sigmask() Message-ID: <20190605090453.GB32406@redhat.com> References: <20190522032144.10995-1-deepa.kernel@gmail.com> <20190529161157.GA27659@redhat.com> <20190604134117.GA29963@redhat.com> <878sugewok.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <878sugewok.fsf@xmission.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Wed, 05 Jun 2019 09:05:04 +0000 (UTC) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On 06/04, Eric W. Biederman wrote: > > >> - restore_user_sigmask(ksig.sigmask, &sigsaved); > >> - if (signal_pending(current) && !ret) > >> + > >> + interrupted = signal_pending(current); > >> + restore_user_sigmask(ksig.sigmask, &sigsaved, interrupted); > >> + if (interrupted && !ret) > >> ret = -ERESTARTNOHAND; > > > > are wrong to begin with, and we really should aim for an interface > > which says "tell me whether you completed the system call, and I'll > > give you an error return if not". > > The pattern you are pointing out is specific to io_pgetevents and it's > variations. It does look buggy to me but not for the reason you point > out, but instead because it does not appear to let a pending signal > cause io_pgetevents to return early. > > I suspect we should fix that and have do_io_getevents return > -EINTR or -ERESTARTNOHAND like everyone else. Exactly. It should not even check signal_pending(). It can rely on wait_event_interruptible_hrtimeout(). > So can we please get this fix in and then look at cleaning up and > simplifying this code. Yes ;) Oleg.