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=-3.0 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,USER_AGENT_GIT 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 C1AA7C433F5 for ; Wed, 29 Aug 2018 02:23:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5CBDF2087C for ; Wed, 29 Aug 2018 02:23:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b="ibxkO2Oe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5CBDF2087C 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 S1727272AbeH2GS1 (ORCPT ); Wed, 29 Aug 2018 02:18:27 -0400 Received: from mail-ed1-f66.google.com ([209.85.208.66]:42965 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725882AbeH2GS1 (ORCPT ); Wed, 29 Aug 2018 02:18:27 -0400 Received: by mail-ed1-f66.google.com with SMTP id l5so139441edw.9 for ; Tue, 28 Aug 2018 19:23:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=googlenew; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=9lT82Va3OFQGc4TMQuT/0EsfvOn0U4QTm1pkVepw5e0=; b=ibxkO2OeiGfl5FnQ8R+MdJ0WZSPo7yJh2RAWWuzBtz8dieHoMgU1v8sJH8XTVtQBWg 75lPUpw4ybvGBBV0l9XTBoG3NinZfXdJ5gFBecrd1KV/qhboKuqM7RJh0i4QPR2G5o7V +SU0q3TE6KcYATjZN5jb3OmNbAOV2GEl3msOK0Fj4Bn5Yx2NAkIVDRT1r2oUpvupuWrI DYj3NqJk5Nr6yPCecWJ2CKxdrGLo8dm7H26F/gyz52OQ29g4ih/qf6McANf2wPBNOmsA ftUcrc8DMtL8Bv6aQOirgvz/UhcTqFLJxVfDuV8z8kjY1BjExv+4rLXMvpzO1B/fyt8r 0FTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=9lT82Va3OFQGc4TMQuT/0EsfvOn0U4QTm1pkVepw5e0=; b=oxHgN+KH0EyIqY8OMfxJfW+YjtSdhLotobr6Xpa2BxpLcKCSOf7NOXMaqadXaUIKd4 Tjg450wasMk1xINEON/gGKTMzd2UzMo7HqeBlh3LnBos36Wmo5PQHWkz763Hy2U4PEfF nGdNc7kYM0zCZbXUnGZcZ87FsK89ynmCyQ78c3FWrC5pqWPSKcZC6Th99/SgPAG2NmxP ajlrsmxdIJRD3RKsZ2eRP3WHjS9eOOP4irGjqjXPbULNuDy53KEdfyV0hMy/eGhe7edb hbeqqgCxyZK8kBdXufvby+w9XBpKXVjCzgxHXDLPE1+a/cCN5e3sVHdsUp753DJj8y8F nuDw== X-Gm-Message-State: APzg51Dcs049vAqFfVy7mTRFZTd2xxPvwdH90wAeoj3R3yD2SiaQAQ+4 o4G4ikdBUmCIFfGIulBu5fdC6TewxBc= X-Google-Smtp-Source: ANB0VdbChMjrF4kq5Wkhphbce00S0YWwtqQ5u47WdIYNyl8K1pPCrC7Op9bicuy7sKv5c/b/X+pu8Q== X-Received: by 2002:a50:c05a:: with SMTP id u26-v6mr5077430edd.107.1535509435005; Tue, 28 Aug 2018 19:23:55 -0700 (PDT) Received: from dhcp.ire.aristanetworks.com ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id f26-v6sm1236367edb.28.2018.08.28.19.23.53 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 28 Aug 2018 19:23:54 -0700 (PDT) From: Dmitry Safonov To: linux-kernel@vger.kernel.org Cc: Dmitry Safonov <0x7f454c46@gmail.com>, Dmitry Safonov , Daniel Axtens , Dmitry Vyukov , Michael Neuling , Mikulas Patocka , =?UTF-8?q?Pasi=20K=C3=A4rkk=C3=A4inen?= , Peter Hurley , Sergey Senozhatsky , Tan Xiaojun , Greg Kroah-Hartman , Jiri Slaby , stable@vger.kernel.org Subject: [PATCH 0/4] tty: Hold write ldisc sem in tty_reopen() Date: Wed, 29 Aug 2018 03:23:49 +0100 Message-Id: <20180829022353.23568-1-dima@arista.com> X-Mailer: git-send-email 2.13.6 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Two fixes for potential and real issues. Looks worth to have in stables as we've hit it on v4.9 stable. And for linux-next - adding lockdep asserts for line discipline changing code, verifying that write ldisc sem will be held forthwith. I couldn't verify that holding write lock fixes the issue as we've hit it only once and I've failed in reproducing it. But searching in lkml, Cc'ing here people who probably had the same crash (and in hope someone of them could give tested-by): Cc: Daniel Axtens Cc: Dmitry Vyukov Cc: Michael Neuling Cc: Mikulas Patocka Cc: Pasi Kärkkäinen Cc: Peter Hurley Cc: Sergey Senozhatsky Cc: Tan Xiaojun (please, ignore if I Cc'ed you mistakenly) Dmitry Safonov (4): tty: Drop tty->count on tty_reopen() failure tty: Hold tty_ldisc_lock() during tty_reopen() tty: Lock tty pair in tty_init_dev() tty/lockdep: Add ldisc_sem asserts drivers/tty/tty_io.c | 21 +++++++++++++++------ drivers/tty/tty_ldisc.c | 12 ++++++++---- include/linux/tty.h | 4 ++++ 3 files changed, 27 insertions(+), 10 deletions(-) -- 2.13.6