From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751971AbdFNKiZ (ORCPT ); Wed, 14 Jun 2017 06:38:25 -0400 Received: from smtprelay0051.hostedemail.com ([216.40.44.51]:52820 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750728AbdFNKiY (ORCPT ); Wed, 14 Jun 2017 06:38:24 -0400 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::,RULES_HIT:41:355:379:541:599:966:988:989:1260:1277:1311:1313:1314:1345:1359:1373:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2194:2196:2199:2200:2393:2553:2559:2562:2828:3138:3139:3140:3141:3142:3353:3622:3865:3866:3867:3868:3870:3871:3872:3873:3874:4321:4385:5007:7903:8660:10004:10400:10848:11026:11232:11473:11657:11658:11914:12043:12296:12438:12740:12760:12895:13069:13148:13149:13161:13229:13230:13255:13311:13357:13439:14096:14097:14659:14721:21080:21451:21611:21627:30012:30054:30070:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:1,LUA_SUMMARY:none X-HE-Tag: ball47_663141e9a6417 X-Filterd-Recvd-Size: 2248 Message-ID: <1497436701.18751.41.camel@perches.com> Subject: Re: [PATCH 1/2] staging: rtl8723bs: Convert LIST_CONTAINOR to use kernel container_of From: Joe Perches To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, Hans de Goede , Larry Finger Date: Wed, 14 Jun 2017 03:38:21 -0700 In-Reply-To: <20170614101853.GA8107@kroah.com> References: <629c18e79e3528e03deabdd1996ceb857f34aa81.1497388055.git.joe@perches.com> <20170614101853.GA8107@kroah.com> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.22.6-1ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2017-06-14 at 12:18 +0200, Greg Kroah-Hartman wrote: > On Tue, Jun 13, 2017 at 02:12:56PM -0700, Joe Perches wrote: > > These are similar macros so use the normal kernel one. > > > > As well, there are odd games being played with casting a plist to > > a union recv_frame by using LIST_CONTAINOR. Just use a direct cast > > to union recv_frame instead. [] > > diff --git a/drivers/staging/rtl8723bs/core/rtw_recv.c b/drivers/staging/rtl8723bs/core/rtw_recv.c [] > > @@ -129,7 +129,7 @@ union recv_frame *_rtw_alloc_recvframe(struct __queue *pfree_recv_queue) > > > > plist = get_next(phead); > > > > - precvframe = LIST_CONTAINOR(plist, union recv_frame, u); > > + precvframe = (union recv_frame *)plist; > > No, you are "assuming" that the list_head is going to stay the first > object of this structure, and what if it isn't? > > Just use container_of, that way at least you get the type safeness of > the call, and if something changes in the future, you don't instantly > break the code everywhere without knowing it. It's a named union u and it's exactly at the beginning. It's unlikely to change. The container_of macro doesn't work here as there it has a BUILD_BUG_ON_MSG and there are pointer type mismatches on those uses.