Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753167Ab2HZHwO (ORCPT ); Sun, 26 Aug 2012 03:52:14 -0400 Received: from mail-vc0-f174.google.com ([209.85.220.174]:46915 "EHLO mail-vc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752245Ab2HZHwM (ORCPT ); Sun, 26 Aug 2012 03:52:12 -0400 MIME-Version: 1.0 In-Reply-To: <20120825123149.3fafa4f4@halley> References: <1345925210-7500-1-git-send-email-shijie8@gmail.com> <20120825123149.3fafa4f4@halley> Date: Sun, 26 Aug 2012 03:52:12 -0400 Message-ID: Subject: Re: [PATCH v2] mtd: cmdlinepart: fix the wrong check condition From: Huang Shijie To: Shmulik Ladkani Cc: dedekind1@gmail.com, dwmw2@infradead.org, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2781 Lines: 78 On Sat, Aug 25, 2012 at 5:31 AM, Shmulik Ladkani wrote: > Hi Huang, Artem, > > On Sat, 25 Aug 2012 16:06:50 -0400 Huang Shijie wrote: >> diff --git a/drivers/mtd/cmdlinepart.c b/drivers/mtd/cmdlinepart.c >> index fc960a3..216d751 100644 >> --- a/drivers/mtd/cmdlinepart.c >> +++ b/drivers/mtd/cmdlinepart.c >> @@ -322,13 +322,16 @@ static int parse_cmdline_partitions(struct mtd_info *master, >> struct cmdline_mtd_partition *part; >> const char *mtd_id = master->name; >> >> + if (!mtd_id) >> + return 0; >> + >> /* parse command line */ >> if (!cmdline_parsed) >> mtdpart_setup_real(cmdline); >> >> for(part = partitions; part; part = part->next) >> { >> - if ((!mtd_id) || (!strcmp(part->mtd_id, mtd_id))) >> + if (!strcmp(part->mtd_id, mtd_id)) >> { >> for(i = 0, offset = 0; i < part->num_parts; i++) >> { > > This changes the behavior of cmdling parsing, which might affect users > expecting the old behavior. > > According to the remark above 'parse_cmdline_partitions': > > * It returns partitions for the requested mtd device, or > * the first one in the chain if a NULL mtd_id is passed in. > > I think the purpose of a NULL 'mtd_id' was to support simple systems > where there's a single driver and a single chip. > The driver could be dumb, not specifying its 'mtd_info->name' > (thus, a NULL mtd_id is passed). > > In this case, since the system is simply configured (one driver, one > chip), 'parse_cmdline_partitions' simply disregards the "mtd-id" name > specified in the cmdline string, allowing the user to present some > arbitrary string there. > > I quite remember seeing this pattern somewhere in the past, I don't know > if it's still used, though. > thanks for the detail explanation. > Obviously if you have many drivers (and many chips) in a system, that > won't work; the drivers must initialize 'mtd_info->name' and the user > should present a cmdline that has explicit 'mtd-id's. > > So question is, would we like to prohibit NULL mtd-id? I prefer to prohibit the NULL mtd-id. The code looks strange enough. > > If so, we must make sure all drivers are properly assigning their > 'mtd_info->name', and all users correctly specifying 'mtd-id' in their > "mtdparts" cmdline strings. yes. I agree that all the driver should set the mtd_info->name properly. Best Regards Huang Shijie > > Regards, > Shmulik -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/