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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9BBEC43334 for ; Tue, 5 Jul 2022 16:26:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229590AbiGEQ0q (ORCPT ); Tue, 5 Jul 2022 12:26:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229554AbiGEQ0q (ORCPT ); Tue, 5 Jul 2022 12:26:46 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31AA715717; Tue, 5 Jul 2022 09:26:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id BEB2D61BF4; Tue, 5 Jul 2022 16:26:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A223FC341C7; Tue, 5 Jul 2022 16:26:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657038404; bh=xdkJ7dDI1TMRfLqibzYhOTOYetxZoqPZfydt+biEvLU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kWxNROmp9R1w+sHCDwq34HpsR/P/bYP1YyJTlrBFRbzTTg1TGK4+UACqqGtEX8q4G g8mdzVIhDrzuFPp3Qv9PHUaBpduIKfMkmybADyOSNU0uVrYi633TcgBVpf0wElooP8 G5gtLo7aYlN9if14nJafisUEhLkGNABol3TP8Kcs= Date: Tue, 5 Jul 2022 18:26:41 +0200 From: Greg Kroah-Hartman To: Hsin-Yi Wang Cc: "Rafael J . Wysocki" , Kevin Hilman , Ulf Hansson , Len Brown , Pavel Machek , Thierry Strudel , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, AngeloGioacchino Del Regno , Pin-yen Lin Subject: Re: [PATCH] PM: domains: Ensure genpd_debugfs_dir exists before remove Message-ID: References: <20220705094946.827697-1-hsinyi@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Tue, Jul 05, 2022 at 11:58:52PM +0800, Hsin-Yi Wang wrote: > On Tue, Jul 5, 2022 at 7:51 PM Greg Kroah-Hartman > wrote: > > > > On Tue, Jul 05, 2022 at 07:06:41PM +0800, Hsin-Yi Wang wrote: > > > On Tue, Jul 5, 2022 at 6:38 PM Greg Kroah-Hartman > > > wrote: > > > > > > > > On Tue, Jul 05, 2022 at 05:49:47PM +0800, Hsin-Yi Wang wrote: > > > > > genpd_debug_remove() may be indirectly called from others while > > > > > genpd_debugfs_dir is not yet set. Make sure genpd_debugfs_dir exists > > > > > before remove the sub components, otherwise components under > > > > > /sys/kernel/debug may be accidentally removed. > > > > > > > > > > Fixes: 718072ceb211 ("PM: domains: create debugfs nodes when adding power domains") > > > > > Signed-off-by: Hsin-Yi Wang > > > > > --- > > > > > An example: > > > > > scpsys_probe() in drivers/soc/mediatek/mtk-pm-domains.c indirectly calls > > > > > genpd_debug_remove() on probe fail, causing /sys/kernel/debug/usb to be > > > > > removed. > > > > > --- > > > > > drivers/base/power/domain.c | 3 +++ > > > > > 1 file changed, 3 insertions(+) > > > > > > > > > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c > > > > > index 3e86772d5fac5..5a2e0232862e0 100644 > > > > > --- a/drivers/base/power/domain.c > > > > > +++ b/drivers/base/power/domain.c > > > > > @@ -222,6 +222,9 @@ static void genpd_debug_remove(struct generic_pm_domain *genpd) > > > > > { > > > > > struct dentry *d; > > > > > > > > > > + if (!genpd_debugfs_dir) > > > > > + return; > > > > > + > > > > > d = debugfs_lookup(genpd->name, genpd_debugfs_dir); > > > > > debugfs_remove(d); > > > > > > > > Why not just change this to be: > > > > debugfs_remove(debugfs_lookup(genpd->name, debugfs_lookup("pm_genpd", NULL))); > > > If pm_genpd hasn't been created yet, debugfs_lookup("pm_genpd", NULL) > > > will return null. > > > > And how is this codepath being called if pm_genpd is not created yet? > > Surely you are not relying on the presence of a debugfs file to > > determine that? > > > > Caller didn't directly call genpd_debug_remove(). The flow is as follows: > > Normally, scpsys will create pm domain by: > scpsys_probe() > --> scpsys_add_one_domain() > --> pm_genpd_init() > --> genpd_debug_add() > > > If something fails, it will do the cleanup: > scpsys_probe() > --> scpsys_domain_cleanup() > --> scpsys_remove_one_domain() > --> pm_genpd_remove() > --> genpd_remove() > --> genpd_debug_remove() > > genpd_debug_add() checks if genpd_debugfs_dir is init by a > late_initcall genpd_debug_init(). If it's NULL, it will return > directly without creating anything. Later when genpd_debug_init() is > called, it will call genpd_debug_add() again. > > pm_genpd_remove() still needs to be called on the cleanup path to free > other stuff, but if genpd_debug_init() hasn't happened, > genpd_debug_remove() should be a no-op, or genpd_remove() shouldn't > call it. (We can move the check there, but adding in > genpd_debug_remove() is more similar to what genpd_debug_add() > currently is.) Thanks for the details. You might want to include this in the changelog text. I'm ok with the change now if that information is in there, I missed that there are paths to create devices before debugfs is initialized. thanks, greg k-h