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 C0B46C433F5 for ; Mon, 11 Oct 2021 13:27:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8C31603E9 for ; Mon, 11 Oct 2021 13:27:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235291AbhJKN3K (ORCPT ); Mon, 11 Oct 2021 09:29:10 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:48814 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235197AbhJKN3I (ORCPT ); Mon, 11 Oct 2021 09:29:08 -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 1803D1F42741; Mon, 11 Oct 2021 14:27:07 +0100 (BST) Date: Mon, 11 Oct 2021 15:27:03 +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 3/3] mtd: mtdconcat: add suspend lock handling Message-ID: <20211011152703.0086d990@collabora.com> In-Reply-To: <20211011151501.48cc9289@collabora.com> References: <20211011115253.38497-1-sean@geanix.com> <20211011115253.38497-4-sean@geanix.com> <20211011151501.48cc9289@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 Mon, 11 Oct 2021 15:15:01 +0200 Boris Brezillon wrote: > On Mon, 11 Oct 2021 13:52:53 +0200 > Sean Nyekjaer wrote: > > > Use new suspend lock handling for this special case for concatenated > > MTD devices. > > > > Fixes: 013e6292aaf5 ("mtd: rawnand: Simplify the locking") > > Signed-off-by: Sean Nyekjaer > > --- > > drivers/mtd/mtdconcat.c | 11 +++++++++-- > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c > > index f685a581df48..c497c851481f 100644 > > --- a/drivers/mtd/mtdconcat.c > > +++ b/drivers/mtd/mtdconcat.c > > @@ -561,25 +561,32 @@ static void concat_sync(struct mtd_info *mtd) > > > > static int concat_suspend(struct mtd_info *mtd) > > { > > + struct mtd_info *master = mtd_get_master(mtd); > > struct mtd_concat *concat = CONCAT(mtd); > > int i, rc = 0; > > > > for (i = 0; i < concat->num_subdev; i++) { > > struct mtd_info *subdev = concat->subdev[i]; > > - if ((rc = mtd_suspend(subdev)) < 0) > > + > > + down_write(&master->master.suspend_lock); > > + if ((rc = __mtd_suspend(subdev)) < 0) > > return rc; > > + up_write(&master->master.suspend_lock); > > } > > return rc; > > } > > > > static void concat_resume(struct mtd_info *mtd) > > { > > + struct mtd_info *master = mtd_get_master(mtd); > > struct mtd_concat *concat = CONCAT(mtd); > > int i; > > > > for (i = 0; i < concat->num_subdev; i++) { > > struct mtd_info *subdev = concat->subdev[i]; > > - mtd_resume(subdev); > > + down_write(&master->master.suspend_lock); > > + __mtd_resume(subdev); > > + up_write(&master->master.suspend_lock); > > } > > } > > > > Why do we need to implement the _suspend/_resume() hooks here? The > underlying MTD devices should be suspended at some point (when the > class ->suspend() method is called on those device), and there's > nothing mtdconcat-specific to do here. Looks like implementing this > suspend-all-subdevs loop results in calling mtd->_suspend()/_resume() > twice, which is useless. The only issue I see is if the subdevices > haven't been registered to the device model, but that happens, I > believe we have bigger issues (those devices won't be suspended when > mtdconcat is not used). Uh, just had a look at mtd_concat_create() callers, and they indeed don't register the subdevices, so I guess the suspend-all-subdevs loop is needed. I really thought mtdconcat was something more generic aggregating already registered devices...