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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 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 83EC7C5DF60 for ; Tue, 5 Nov 2019 19:03:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5756D217F4 for ; Tue, 5 Nov 2019 19:03:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390776AbfKETDu convert rfc822-to-8bit (ORCPT ); Tue, 5 Nov 2019 14:03:50 -0500 Received: from relay7-d.mail.gandi.net ([217.70.183.200]:48345 "EHLO relay7-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390514AbfKETDu (ORCPT ); Tue, 5 Nov 2019 14:03:50 -0500 X-Originating-IP: 91.224.148.103 Received: from xps13 (unknown [91.224.148.103]) (Authenticated sender: miquel.raynal@bootlin.com) by relay7-d.mail.gandi.net (Postfix) with ESMTPSA id 4E88320004; Tue, 5 Nov 2019 19:03:46 +0000 (UTC) Date: Tue, 5 Nov 2019 20:03:44 +0100 From: Miquel Raynal To: Kamal Dasu Cc: linux-mtd@lists.infradead.org, bcm-kernel-feedback-list@broadcom.com, linux-kernel@vger.kernel.org, David Woodhouse , Brian Norris , Marek Vasut , Richard Weinberger , Vignesh Raghavendra Subject: Re: [PATCH] mtd: set mtd partition panic write flag Message-ID: <20191105200344.1e8c3eab@xps13> In-Reply-To: <20191021193343.41320-1-kdasu.kdev@gmail.com> References: <20191021193343.41320-1-kdasu.kdev@gmail.com> Organization: Bootlin X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Kamal, Richard, something to look into below :) Kamal Dasu wrote on Mon, 21 Oct 2019 15:32:52 -0400: > Check mtd panic write flag and set the mtd partition panic > write flag so that low level drivers can use it to take > required action to ensure oops data gets written to assigned > mtd partition. I feel there is something wrong with the current implementation regarding partitions but I am not sure this is the right fix. Is this something you detected with some kind of static checker or did you actually experience an issue? In the commit log you say "check mtd (I suppose you mean the master) panic write flag and set the mtd partition panic write flag" which makes sense, but in reality my understanding is that you do the opposite: you check mtd->oops_panic_write which is the partitions' structure, and set part->parent->oops_panic_write which is the master's flag. Also, I am not sure if it is worth checking anything, why not just set mtd->oops_panic_write in this function? Same comment for the -already existing- condition in mtd_panic_write. As soon as we are in these functions, we know there is a panic, right? So why checking if the bit is already set before forcing it? > > Fixes: 9f897bfdd8 ("mtd: Add flag to indicate panic_write") > Signed-off-by: Kamal Dasu > --- > drivers/mtd/mtdpart.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c > index 7328c066c5ba..b4f6479abeda 100644 > --- a/drivers/mtd/mtdpart.c > +++ b/drivers/mtd/mtdpart.c > @@ -159,6 +159,10 @@ static int part_panic_write(struct mtd_info *mtd, loff_t to, size_t len, > size_t *retlen, const u_char *buf) > { > struct mtd_part *part = mtd_to_part(mtd); > + > + if (mtd->oops_panic_write) > + part->parent->oops_panic_write = true; > + > return part->parent->_panic_write(part->parent, to + part->offset, len, > retlen, buf); > } Thanks, Miquèl