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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43AA6C433F5 for ; Fri, 15 Oct 2021 06:22:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 14C3760EE5 for ; Fri, 15 Oct 2021 06:22:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234311AbhJOGYS convert rfc822-to-8bit (ORCPT ); Fri, 15 Oct 2021 02:24:18 -0400 Received: from relay7-d.mail.gandi.net ([217.70.183.200]:41373 "EHLO relay7-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232124AbhJOGYQ (ORCPT ); Fri, 15 Oct 2021 02:24:16 -0400 Received: (Authenticated sender: miquel.raynal@bootlin.com) by relay7-d.mail.gandi.net (Postfix) with ESMTPSA id 49C9020002; Fri, 15 Oct 2021 06:22:08 +0000 (UTC) Date: Fri, 15 Oct 2021 08:22:06 +0200 From: Miquel Raynal To: Boris Brezillon Cc: Sean Nyekjaer , Richard Weinberger , Vignesh Raghavendra , Boris Brezillon , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/3] mtd: core: protect access to mtd devices while in suspend Message-ID: <20211015082206.244a2316@xps13> In-Reply-To: <20211011160546.707b737b@collabora.com> References: <20211011115253.38497-1-sean@geanix.com> <20211011160546.707b737b@collabora.com> Organization: Bootlin X-Mailer: Claws Mail 3.17.7 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sean, boris.brezillon@collabora.com wrote on Mon, 11 Oct 2021 16:05:46 +0200: > On Mon, 11 Oct 2021 13:52:50 +0200 > Sean Nyekjaer wrote: > > > Follow-up on discussion in https://lkml.org/lkml/2021/10/4/41 > > > > Changes since from rfc v1/v2: > > - added access protection for all device access hooks in mtd_info. > > - added Suggested-by to [1/3] patch. > > - removed refereces to commit ef347c0cfd61 ("mtd: rawnand: gpmi: Implement exec_op") > > from commit msg as commit 013e6292aaf5 ("mtd: rawnand: Simplify the locking") is > > to be blamed. > > - tested on a kernel with LOCKDEP enabled. > > > > @Miquel: I havn't covered every ioctl, to me it looks like they havn't > > direct device access. Yes indeed it looks like they re-use most of the mtdcore.c functions, so it should be fine. > > One (small) issue still present. gpmi_nand.c uses the rwsem before it's > > initialized. Seems cumbersome to have every mtd/nand driver to call > > init_waitqueue_head() and init_rwsem(). Could we somehow move the call > > to mtd_set_dev_defaults() before nand_create_bbt()? > > I have a nasty trick for that one, but I'm not sure Miquel will like it > (actually, I don't like it either, but it's so simple compared to the > other options we have that I'm tempted to go for this approach until > someone has time to invest in a cleaner solution :-)): > > diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c > index 3d6c6e880520..a9ac2d528a4d 100644 > --- a/drivers/mtd/nand/raw/nand_base.c > +++ b/drivers/mtd/nand/raw/nand_base.c > @@ -6222,8 +6222,6 @@ static int nand_scan_tail(struct nand_chip *chip) > mtd->_sync = nand_sync; > mtd->_lock = nand_lock; > mtd->_unlock = nand_unlock; > - mtd->_suspend = nand_suspend; > - mtd->_resume = nand_resume; > mtd->_reboot = nand_shutdown; > mtd->_block_isreserved = nand_block_isreserved; > mtd->_block_isbad = nand_block_isbad; > @@ -6269,6 +6267,13 @@ static int nand_scan_tail(struct nand_chip *chip) > if (ret) > goto err_free_secure_regions; > > + /* > + * Populate the suspend/resume hooks after the BBT has been scanned to > + * avoid using the suspend lock and resume waitqueue which are only > + * initialized when mtd_device_register() is called. > + */ > + mtd->_suspend = nand_suspend; > + mtd->_resume = nand_resume; > return 0; I'm fine with this as long as it is documented for now. Thanks, Miquèl