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=-9.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable 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 11BECC43441 for ; Mon, 12 Nov 2018 21:40:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C7935224E0 for ; Mon, 12 Nov 2018 21:40:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Bms8byNL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C7935224E0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-bluetooth-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730548AbeKMHfO (ORCPT ); Tue, 13 Nov 2018 02:35:14 -0500 Received: from mail-pg1-f193.google.com ([209.85.215.193]:39407 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725817AbeKMHfI (ORCPT ); Tue, 13 Nov 2018 02:35:08 -0500 Received: by mail-pg1-f193.google.com with SMTP id r9-v6so4638571pgv.6 for ; Mon, 12 Nov 2018 13:40:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=iHOW629F4mpFjxsqJaP1AmqGYv4DQ5FykhLL32YDDFU=; b=Bms8byNL1W3LRHNXS/m8JFW3vARD26dLgtzCXLG2aLl/MA7TIQhT0zKuwPw8ZanXnj YleB0ppvn1S5Ahr6qEbjbXqx7zD6RaYKrBhdlUzsq2CkWJKLV19P0qF5UD7kYziOKPFQ mFABzSuSNMFbag0rS+WZv53NzKqzGo8L4pIkA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=iHOW629F4mpFjxsqJaP1AmqGYv4DQ5FykhLL32YDDFU=; b=gMf+7HqwVYfJgOzCncliWauRC234A8QggEnWWru4Xzlon4vVuCylFzsXKXFfq7/ET2 jbQc9kVFIuPIp4Vfpsas1gzqKP/fPsM29UpqUtKVJUvZSzGXTfO4w+4FZj7+lFFifupg LeLcWh3NV170GcNibfvBxuFMzcTN01tcTA0Kc0Y04o+vlj3PqvMgv4TFnvOgPkaNGPkD GZYEC7KzoDSmBkQdoGHnA8yJUYJUZDq4lgIIHeM5dp/MXPYoPvK/XBJFkRIrcFdlDyfF 4ke4mWmCdOVJUgNrOThf9Mb3HU0onNKuldoOtz69DWyVcH/PKjghYn0ygb/6JFDI6A2z 1CwA== X-Gm-Message-State: AGRZ1gLGfrI5Y3IA1CyB1BS2iVL42ilHU/uRQEfY48WB3fI1Gp3Z8ThK Uxk2h1GqrHzwyj03qW15y5CowQ== X-Google-Smtp-Source: AJdET5cx7XhZ3X8NaweHwgl0hJccbOA/PDdix/DAsHbK27KfF/P2zCs//O0QvAY29yFe8Bix5fOp/g== X-Received: by 2002:a63:3858:: with SMTP id h24mr2243843pgn.300.1542058805183; Mon, 12 Nov 2018 13:40:05 -0800 (PST) Received: from localhost ([2620:15c:202:1:b6af:f85:ed6c:ac6a]) by smtp.gmail.com with ESMTPSA id r124-v6sm26751290pfr.151.2018.11.12.13.40.04 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 12 Nov 2018 13:40:04 -0800 (PST) Date: Mon, 12 Nov 2018 13:40:03 -0800 From: Matthias Kaehlcke To: Marcel Holtmann , Johan Hedberg , "David S . Miller" , Dean Jenkins Cc: linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Konstantin Khlebnikov , Balakrishna Godavarthi , Douglas Anderson , Dmitry Grinberg Subject: Re: [PATCH] Bluetooth: Fix locking in bt_accept_enqueue() for BH context Message-ID: <20181112214003.GE22824@google.com> References: <20181015223910.197729-1-mka@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181015223910.197729-1-mka@chromium.org> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-bluetooth-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org On Mon, Oct 15, 2018 at 03:39:10PM -0700, Matthias Kaehlcke wrote: > With commit e16337622016 ("Bluetooth: Handle bt_accept_enqueue() socket > atomically") lock_sock[_nested]() is used to acquire the socket lock > before manipulating the socket. lock_sock[_nested]() may block, which > is problematic since bt_accept_enqueue() can be called in bottom half > context (e.g. from rfcomm_connect_ind()). > > The socket API provides bh_lock_sock[_nested]() to acquire the socket > lock in bottom half context. Check the context in bt_accept_enqueue() > and use the appropriate locking mechanism for the context. > > Fixes: e16337622016 ("Bluetooth: Handle bt_accept_enqueue() socket atomically") > Signed-off-by: Matthias Kaehlcke > --- > Not sure if this is the correct solution, it's certainly not elegant and > checkpatch.pl complains that in_atomic() shouldn't be used outside of > core kernel code. I'm open to other suggestions :) > > net/bluetooth/af_bluetooth.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c > index deacc52d7ff1..0f0540dbb44a 100644 > --- a/net/bluetooth/af_bluetooth.c > +++ b/net/bluetooth/af_bluetooth.c > @@ -159,10 +159,20 @@ void bt_accept_enqueue(struct sock *parent, struct sock *sk) > BT_DBG("parent %p, sk %p", parent, sk); > > sock_hold(sk); > - lock_sock_nested(sk, SINGLE_DEPTH_NESTING); > + > + if (in_atomic()) > + bh_lock_sock_nested(sk); > + else > + lock_sock_nested(sk, SINGLE_DEPTH_NESTING); > + > list_add_tail(&bt_sk(sk)->accept_q, &bt_sk(parent)->accept_q); > bt_sk(sk)->parent = parent; > - release_sock(sk); > + > + if (in_atomic()) > + bh_unlock_sock(sk); > + else > + release_sock(sk); > + > parent->sk_ack_backlog++; > } > EXPORT_SYMBOL(bt_accept_enqueue); Any comments or ideas for a better solutions? Thanks Matthias