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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_HIGH,URIBL_BLOCKED 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 C6D54C433F5 for ; Wed, 29 Aug 2018 16:13:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 67A05205C9 for ; Wed, 29 Aug 2018 16:13:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b="Na/n+GF0" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 67A05205C9 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=arista.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729238AbeH2ULK (ORCPT ); Wed, 29 Aug 2018 16:11:10 -0400 Received: from mail-ed1-f66.google.com ([209.85.208.66]:37001 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727484AbeH2ULK (ORCPT ); Wed, 29 Aug 2018 16:11:10 -0400 Received: by mail-ed1-f66.google.com with SMTP id a20-v6so1677279edd.4 for ; Wed, 29 Aug 2018 09:13:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=googlenew; h=message-id:subject:from:to:cc:date:in-reply-to:references :mime-version:content-transfer-encoding; bh=TW9QhLN1YOcmGH6k8eOSn2nxDQIdVy0iid+XvYemJL0=; b=Na/n+GF0rsIQemSZyTS/WfAq4e+rVyWlib7V32lqu+NOF2Cr2/VwsMOeuPGtjhJgg0 ocpNxDuyF/1hipE7taKF1oXl1yzIXJPHeniSzgM/p24k3H2pVE4fYVnuQme84c9BpWAn qNO1J+a2HbjrPymc0jAIDQ5NcwFhx6Z4PZl0ZDhNVSSnX4TYOOnRt8dE5uTym6v/NeE3 7QDr4Y7Tr12BmePZ1uJGDtt4jAalt7iB5MuL326BvswqCuc9W/iA8Vj2IUza4hwIVcIS E5Fd/5u522QEM1UFg3+ZCFmo40kXGtJuG56JKlCnHKrS6KxZBW7hdmOOTTFt1uJymnwX C6mw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:mime-version:content-transfer-encoding; bh=TW9QhLN1YOcmGH6k8eOSn2nxDQIdVy0iid+XvYemJL0=; b=brrPGVIJoRWfGUeNzmP1TuzWSarwaQXcoJ4Iznzu9mBk3dTOC3JmRVfOafEnvmaiwa 2zSJY3CEHUDUjv39t3UpUpcv/w29eG7sBS82RBiVVAYaDUVTRRXoYO0TCFwZnu2atClZ PTOSottlY96DLKigf5noYsWroMwW5W8IxAc3wwUSbCKJ0XBarHBmwJ16bWauuygK1STu sDo7//FCimZjk5rVoM01BbxrzJR9BMUVKWY4rkGtdXpcR7gP/MWtZDQiYjKdIA3AXG/c O7fbR8l1qOeK4qTK/gbjHmxO6IBztKC1pVQtJB3kaFeA/T7mqS6eIkSOyvkAnWcX7Cbb S9uA== X-Gm-Message-State: APzg51DiciXuvFbDT2NJ4t4wXMxo8+UurEZ7ZhclHsh1UufNBdNE58rp pbQT2hA1kaHiGSaDVNTDOjZtYfx/kM0= X-Google-Smtp-Source: ANB0VdY0tOUYyZXYBT8HvroT6306hMHJYLGuXJDweUdjhCssxlP1g/Z4GvXtOBWR2Jybf7AFwbLtFw== X-Received: by 2002:aa7:c881:: with SMTP id p1-v6mr8565440eds.295.1535559210717; Wed, 29 Aug 2018 09:13:30 -0700 (PDT) Received: from dhcp.ire.aristanetworks.com ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id a41-v6sm1914814edc.57.2018.08.29.09.13.29 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 29 Aug 2018 09:13:29 -0700 (PDT) Message-ID: <1535559207.23560.55.camel@arista.com> Subject: Re: [PATCH 1/4] tty: Drop tty->count on tty_reopen() failure From: Dmitry Safonov To: Jiri Slaby , linux-kernel@vger.kernel.org Cc: Daniel Axtens , Dmitry Safonov <0x7f454c46@gmail.com>, Sergey Senozhatsky , Dmitry Vyukov , Tan Xiaojun , Peter Hurley , Pasi =?ISO-8859-1?Q?K=E4rkk=E4inen?= , Greg Kroah-Hartman , Michael Neuling , Mikulas Patocka , stable@vger.kernel.org Date: Wed, 29 Aug 2018 17:13:27 +0100 In-Reply-To: References: <20180829022353.23568-1-dima@arista.com> <20180829022353.23568-2-dima@arista.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.24.6 (3.24.6-1.fc26) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2018-08-29 at 16:38 +0200, Jiri Slaby wrote: > On 08/29/2018, 04:23 AM, Dmitry Safonov wrote: > > In case of tty_ldisc_reinit() failure, tty->count should be > > decremented > > back, otherwise we will never release_tty(). > > Never seen it in the real life, but it seems not really hard to > > hit. > > I did see it. And this fixes it. Thanks, I'll add your tested-by, if I'll have to resend. > > > Cc: Greg Kroah-Hartman > > Cc: Jiri Slaby > > Cc: stable@vger.kernel.org > > Signed-off-by: Dmitry Safonov > > --- > > drivers/tty/tty_io.c | 11 ++++++++--- > > 1 file changed, 8 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c > > index 32bc3e3fe4d3..5e5da9acaf0a 100644 > > --- a/drivers/tty/tty_io.c > > +++ b/drivers/tty/tty_io.c > > @@ -1255,6 +1255,7 @@ static void tty_driver_remove_tty(struct > > tty_driver *driver, struct tty_struct * > > static int tty_reopen(struct tty_struct *tty) > > { > > struct tty_driver *driver = tty->driver; > > + int retval; > > > > if (driver->type == TTY_DRIVER_TYPE_PTY && > > driver->subtype == PTY_TYPE_MASTER) > > @@ -1268,10 +1269,14 @@ static int tty_reopen(struct tty_struct > > *tty) > > > > tty->count++; > > > > - if (!tty->ldisc) > > - return tty_ldisc_reinit(tty, tty->termios.c_line); > > + if (tty->ldisc) > > + return 0; > > > > - return 0; > > + retval = tty_ldisc_reinit(tty, tty->termios.c_line); > > + if (retval) > > + tty->count--; > > I would just do: > if (!retval) > tty->count++; > here. Nobody from ldiscs should rely on tty->count. I thought about that and probably should have described in commit message why I haven't done that: I prefer to keep it as was as I did Cc stable tree - to keep the chance of regression to minimum. I agree that your way is cleaner, but probably it may be done as cleanup on top for linux-next.. -- Thanks, Dmitry