From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f182.google.com (mail-qk0-f182.google.com [209.85.220.182]) by kanga.kvack.org (Postfix) with ESMTP id 3DABD9003C7 for ; Wed, 1 Jul 2015 22:22:31 -0400 (EDT) Received: by qkeo142 with SMTP id o142so43180668qke.1 for ; Wed, 01 Jul 2015 19:22:31 -0700 (PDT) Received: from mail-qg0-x234.google.com (mail-qg0-x234.google.com. [2607:f8b0:400d:c04::234]) by mx.google.com with ESMTPS id m77si4717778qgm.53.2015.07.01.19.22.29 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 01 Jul 2015 19:22:29 -0700 (PDT) Received: by qgat90 with SMTP id t90so8459525qga.0 for ; Wed, 01 Jul 2015 19:22:29 -0700 (PDT) Date: Wed, 1 Jul 2015 22:22:26 -0400 From: Tejun Heo Subject: Re: [PATCH 36/51] writeback: implement bdi_for_each_wb() Message-ID: <20150702022226.GH26440@mtj.duckdns.org> References: <1432329245-5844-1-git-send-email-tj@kernel.org> <1432329245-5844-37-git-send-email-tj@kernel.org> <20150701072757.GW7252@quack.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150701072757.GW7252@quack.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Jan Kara Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org, hch@infradead.org, hannes@cmpxchg.org, linux-fsdevel@vger.kernel.org, vgoyal@redhat.com, lizefan@huawei.com, cgroups@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.cz, clm@fb.com, fengguang.wu@intel.com, david@fromorbit.com, gthelen@google.com, khlebnikov@yandex-team.ru On Wed, Jul 01, 2015 at 09:27:57AM +0200, Jan Kara wrote: > > +#define bdi_for_each_wb(wb_cur, bdi, iter, start_blkcg_id) \ > > + for ((iter)->next_id = (start_blkcg_id); \ > > + ({ (wb_cur) = !(iter)->next_id++ ? &(bdi)->wb : NULL; }); ) > > + > > This looks quite confusing. Won't it be easier to understand as: > > struct wb_iter { > } __attribute__ ((unused)); > > #define bdi_for_each_wb(wb_cur, bdi, iter, start_blkcg_id) \ > if (((wb_cur) = (!start_blkcg_id ? &(bdi)->wb : NULL))) But then break or continue wouldn't work as expected. It can get really confusing when it's wrapped by an outer loop. Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org