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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 26F2EC43142 for ; Tue, 26 Jun 2018 07:24:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CBD10241A6 for ; Tue, 26 Jun 2018 07:24:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CBD10241A6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752458AbeFZHYR convert rfc822-to-8bit (ORCPT ); Tue, 26 Jun 2018 03:24:17 -0400 Received: from mail.bootlin.com ([62.4.15.54]:48948 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752007AbeFZHYQ (ORCPT ); Tue, 26 Jun 2018 03:24:16 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id 3D66E206ED; Tue, 26 Jun 2018 09:24:14 +0200 (CEST) Received: from bbrezillon (AAubervilliers-681-1-87-188.w90-88.abo.wanadoo.fr [90.88.29.188]) by mail.bootlin.com (Postfix) with ESMTPSA id E44A6203D9; Tue, 26 Jun 2018 09:24:13 +0200 (CEST) Date: Tue, 26 Jun 2018 09:24:13 +0200 From: Boris Brezillon To: Miquel Raynal Cc: Martin Kaiser , David Woodhouse , Sascha Hauer , Fabio Estevam , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt Message-ID: <20180626092413.703249c8@bbrezillon> In-Reply-To: <20180626091005.08d56b2a@xps13> References: <1529679025-5735-1-git-send-email-martin@kaiser.cx> <20180626091005.08d56b2a@xps13> X-Mailer: Claws Mail 3.15.0-dirty (GTK+ 2.24.31; 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 On Tue, 26 Jun 2018 09:10:05 +0200 Miquel Raynal wrote: > Hi Martin, Boris, > > On Fri, 22 Jun 2018 16:50:25 +0200, Martin Kaiser > wrote: > > > mxcnd_probe_dt is called from mxcnd_probe, which is not marked as __init. > > > > I think this line is just a side note and should be at the end of the > commit log. > > > Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can > > potentially be called at any time. After the __init functions are cleaned, > > mxcnd_probe_dt is no longer available. Calling it anyway causes a crash. > > The above paragraph explains the problem and the solution, you can just > add something like "mcvnd_probe is untouched because it is already not > marked as __init" instead of the first line. > > > > > Signed-off-by: Martin Kaiser > > Boris, do you think this patch is a good candidate for stable? > > If yes, Martin, could you please add a couple of stable/fixes tags above > your SoB? We should at least have a Fixes tag. For the stable one, I'm not so sure because the bug does not exist in practice (the compiler always inline mxcnd_probe_dt()). > > Thanks, > Miquèl > > > --- > > I hope that my understanding is correct. > > > > In practice, I could not get the kernel to crash, my compiler would > > inline mxcnd_probe_dt into mxcnd_probe and ignore the __init. > > > > If I marked mxcnd_probe_dt as noinline, I could trigger a crash as > > follows > > > > [root@host ]# echo bb000000.nand > /sys/bus/platform/drivers/mxc_nand/unbind > > [root@host ]# echo bb000000.nand > /sys/bus/platform/drivers/mxc_nand/bind > > Internal error: Oops - undefined instruction: 0 [#1] ARM > > ... > > > > drivers/mtd/nand/raw/mxc_nand.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/mtd/nand/raw/mxc_nand.c b/drivers/mtd/nand/raw/mxc_nand.c > > index 26cef21..90cfb5e 100644 > > --- a/drivers/mtd/nand/raw/mxc_nand.c > > +++ b/drivers/mtd/nand/raw/mxc_nand.c > > @@ -1686,7 +1686,7 @@ static const struct of_device_id mxcnd_dt_ids[] = { > > }; > > MODULE_DEVICE_TABLE(of, mxcnd_dt_ids); > > > > -static int __init mxcnd_probe_dt(struct mxc_nand_host *host) > > +static int mxcnd_probe_dt(struct mxc_nand_host *host) > > { > > struct device_node *np = host->dev->of_node; > > const struct of_device_id *of_id = > > @@ -1700,7 +1700,7 @@ static int __init mxcnd_probe_dt(struct mxc_nand_host *host) > > return 0; > > } > > #else > > -static int __init mxcnd_probe_dt(struct mxc_nand_host *host) > > +static int mxcnd_probe_dt(struct mxc_nand_host *host) > > { > > return 1; > > }