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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 51464C2BA19 for ; Mon, 6 Apr 2020 12:06:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2B6E420BED for ; Mon, 6 Apr 2020 12:06:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727986AbgDFMGN convert rfc822-to-8bit (ORCPT ); Mon, 6 Apr 2020 08:06:13 -0400 Received: from coyote.holtmann.net ([212.227.132.17]:52364 "EHLO mail.holtmann.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727857AbgDFMGM (ORCPT ); Mon, 6 Apr 2020 08:06:12 -0400 Received: from marcel-macbook.fritz.box (p4FEFC5A7.dip0.t-ipconnect.de [79.239.197.167]) by mail.holtmann.org (Postfix) with ESMTPSA id 47318CECC3; Mon, 6 Apr 2020 14:15:45 +0200 (CEST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.80.23.2.2\)) Subject: Re: [PATCH] Bluetooth: Simplify / fix return values from tk_request From: Marcel Holtmann In-Reply-To: <0f0ea237-5976-e56f-cd31-96b76bb03254@roeck-us.net> Date: Mon, 6 Apr 2020 14:06:10 +0200 Cc: Alain Michaud , Johan Hedberg , "David S. Miller" , Jakub Kicinski , BlueZ , netdev , LKML , Sonny Sasaka Content-Transfer-Encoding: 8BIT Message-Id: <6456552C-5910-4D77-9607-14D9D1FA38FD@holtmann.org> References: <20200403150236.74232-1-linux@roeck-us.net> <0f0ea237-5976-e56f-cd31-96b76bb03254@roeck-us.net> To: Guenter Roeck X-Mailer: Apple Mail (2.3608.80.23.2.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Guenter, >>> Some static checker run by 0day reports a variableScope warning. >>> >>> net/bluetooth/smp.c:870:6: warning: >>> The scope of the variable 'err' can be reduced. [variableScope] >>> >>> There is no need for two separate variables holding return values. >>> Stick with the existing variable. While at it, don't pre-initialize >>> 'ret' because it is set in each code path. >>> >>> tk_request() is supposed to return a negative error code on errors, >>> not a bluetooth return code. The calling code converts the return >>> value to SMP_UNSPECIFIED if needed. >>> >>> Fixes: 92516cd97fd4 ("Bluetooth: Always request for user confirmation for Just Works") >>> Cc: Sonny Sasaka >>> Signed-off-by: Guenter Roeck >>> --- >>> net/bluetooth/smp.c | 9 ++++----- >>> 1 file changed, 4 insertions(+), 5 deletions(-) >>> >>> diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c >>> index d0b695ee49f6..30e8626dd553 100644 >>> --- a/net/bluetooth/smp.c >>> +++ b/net/bluetooth/smp.c >>> @@ -854,8 +854,7 @@ static int tk_request(struct l2cap_conn *conn, u8 remote_oob, u8 auth, >>> struct l2cap_chan *chan = conn->smp; >>> struct smp_chan *smp = chan->data; >>> u32 passkey = 0; >>> - int ret = 0; >>> - int err; >>> + int ret; >>> >>> /* Initialize key for JUST WORKS */ >>> memset(smp->tk, 0, sizeof(smp->tk)); >>> @@ -887,12 +886,12 @@ static int tk_request(struct l2cap_conn *conn, u8 remote_oob, u8 auth, >>> /* If Just Works, Continue with Zero TK and ask user-space for >>> * confirmation */ >>> if (smp->method == JUST_WORKS) { >>> - err = mgmt_user_confirm_request(hcon->hdev, &hcon->dst, >>> + ret = mgmt_user_confirm_request(hcon->hdev, &hcon->dst, >>> hcon->type, >>> hcon->dst_type, >>> passkey, 1); >>> - if (err) >>> - return SMP_UNSPECIFIED; >>> + if (ret) >>> + return ret; >> I think there may be some miss match between expected types of error >> codes here. The SMP error code type seems to be expected throughout >> this code base, so this change would propagate a potential negative >> value while the rest of the SMP protocol expects strictly positive >> error codes. >> > > Up to the patch introducing the SMP_UNSPECIFIED return value, tk_request() > returned negative error codes, and all callers convert it to SMP_UNSPECIFIED. > > If tk_request() is supposed to return SMP_UNSPECIFIED on error, it should > be returned consistently, and its callers don't have to convert it again. maybe we need to fix that initial patch then. Regards Marcel