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 31D2DC433EF for ; Wed, 20 Oct 2021 07:01:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0E86B610EA for ; Wed, 20 Oct 2021 07:01:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229952AbhJTHDU (ORCPT ); Wed, 20 Oct 2021 03:03:20 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:56544 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229789AbhJTHDR (ORCPT ); Wed, 20 Oct 2021 03:03:17 -0400 Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 681251F43E4F; Wed, 20 Oct 2021 08:01:02 +0100 (BST) Date: Wed, 20 Oct 2021 09:00:58 +0200 From: Boris Brezillon To: Sean Nyekjaer Cc: Miquel Raynal , 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: <20211020090058.58af1087@collabora.com> In-Reply-To: <20211020085250.030ef244@collabora.com> References: <20211011115253.38497-1-sean@geanix.com> <20211011160546.707b737b@collabora.com> <20211015082206.244a2316@xps13> <20211019180800.3v7emokse6lkpjvk@skn-laptop> <20211020085250.030ef244@collabora.com> Organization: Collabora X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Oct 2021 08:52:50 +0200 Boris Brezillon wrote: > On Tue, 19 Oct 2021 20:08:00 +0200 > Sean Nyekjaer wrote: > > > On Fri, Oct 15, 2021 at 08:22:06AM +0200, Miquel Raynal wrote: > > > 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 > > > > [ ... ] > > > > > > > > > > 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. > > > > > > > Hi Boris and Miquel, > > > > gpmi-nand.c sets NAND_SKIP_BBTSCAN so we won't get there and populate > > suspend resume hooks :( > > Guess there is other drivers that does the same thing... > > This should fix the issue: > > diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c > index 3d6c6e880520..c92b17f66994 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; > @@ -6262,13 +6260,21 @@ static int nand_scan_tail(struct nand_chip *chip) > > /* Check, if we should skip the bad block table scan */ > if (chip->options & NAND_SKIP_BBTSCAN) > - return 0; > + goto out; > > /* Build bad block table */ > ret = nand_create_bbt(chip); > if (ret) > goto err_free_secure_regions; > > +out: > + /* > + * 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; > > err_free_secure_regions: Actually, this version is even cleaner: diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index 3d6c6e880520..98c39b7f6279 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; @@ -6261,14 +6259,20 @@ static int nand_scan_tail(struct nand_chip *chip) goto err_free_interface_config; /* Check, if we should skip the bad block table scan */ - if (chip->options & NAND_SKIP_BBTSCAN) - return 0; - - /* Build bad block table */ - ret = nand_create_bbt(chip); - if (ret) - goto err_free_secure_regions; + if (chip->options & NAND_SKIP_BBTSCAN) { + /* Build bad block table */ + ret = nand_create_bbt(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; err_free_secure_regions: