From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755144AbeEaNZp (ORCPT ); Thu, 31 May 2018 09:25:45 -0400 Received: from mail-lf0-f66.google.com ([209.85.215.66]:38092 "EHLO mail-lf0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754820AbeEaNZn (ORCPT ); Thu, 31 May 2018 09:25:43 -0400 X-Google-Smtp-Source: ADUXVKLiPj6QDYM24E9n+nqrQybIJfmdqJXADjiCriV/gAm9lZ9HYyv5xtwR7BkmjKILX/EJ9Si+FQ== Date: Thu, 31 May 2018 15:25:38 +0200 From: Johan Hovold To: Roger Quadros , balbi@kernel.org Cc: balbi@kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] usb: dwc3: of_simple: don't call pm_runtime_set_active() Message-ID: <20180531132538.GH3259@localhost> References: <1527518174-27860-1-git-send-email-rogerq@ti.com> <1527518174-27860-2-git-send-email-rogerq@ti.com> <20180528152030.GA3261@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180528152030.GA3261@localhost> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Felipe, On Mon, May 28, 2018 at 05:41:48PM +0200, Johan Hovold wrote: > On Mon, May 28, 2018 at 05:36:14PM +0300, Roger Quadros wrote: > > Don't call pm_runtime_set_active() as it will prevent the device > > from being activated in the next pm_runtime_get_sync() call. > > > > Also call pm_runtime_get_sync() before of_platform_populate(). > > This paragraph describes what you do, but not why do it. > > > Signed-off-by: Roger Quadros > > --- > > drivers/usb/dwc3/dwc3-of-simple.c | 7 +++---- > > 1 file changed, 3 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/usb/dwc3/dwc3-of-simple.c b/drivers/usb/dwc3/dwc3-of-simple.c > > index e98d221..2cbb5c0 100644 > > --- a/drivers/usb/dwc3/dwc3-of-simple.c > > +++ b/drivers/usb/dwc3/dwc3-of-simple.c > > @@ -121,6 +121,9 @@ static int dwc3_of_simple_probe(struct platform_device *pdev) > > if (ret) > > goto err_resetc_assert; > > > > + pm_runtime_enable(dev); > > + pm_runtime_get_sync(dev); > > This breaks runtime pm as you now get a second round of clock enables > which are never balanced on runtime suspend (the clocks are first > enabled in dwc3_of_simple_clk_init() above and with your change again in > dwc3_of_simple_runtime_resume()). > > On the other hand, we currently return from probe() with a positive RPM > count so perhaps the RPM callbacks can just be removed altogether (i.e. > unless some other entity drops that count at some point before > remove()). > > > ret = of_platform_populate(np, NULL, NULL, dev); > > if (ret) { > > for (i = 0; i < simple->num_clocks; i++) { > > @@ -131,10 +134,6 @@ static int dwc3_of_simple_probe(struct platform_device *pdev) > > goto err_resetc_assert; > > } > > > > - pm_runtime_set_active(dev); > > - pm_runtime_enable(dev); > > - pm_runtime_get_sync(dev); > > - > > return 0; > > > > err_resetc_assert: > > Also note that there's currently a use-after-free in remove(), where > pm_runtime_put_sync() is called after the clocks have been put. > Something like the below (untested) patch should fix it. What about the use-after-free in remove? Shall I resubmit the fix below separately? Thanks, Johan > From 35c384c31010c344d403c26fc0a1dde0fd68ef4a Mon Sep 17 00:00:00 2001 > From: Johan Hovold > Date: Mon, 28 May 2018 17:31:45 +0200 > Subject: [PATCH] usb: dwc3: of-simple: fix use-after-free on remove > > The clocks have already been explicitly disabled and put as part of > remove() so the runtime suspend callback must not be run when balancing > the runtime PM usage count before returning. > > Fixes: 16adc674d0d6 ("usb: dwc3: add generic OF glue layer") > Signed-off-by: Johan Hovold > --- > drivers/usb/dwc3/dwc3-of-simple.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/dwc3/dwc3-of-simple.c b/drivers/usb/dwc3/dwc3-of-simple.c > index cb2ee96fd3e8..b9c869cd6585 100644 > --- a/drivers/usb/dwc3/dwc3-of-simple.c > +++ b/drivers/usb/dwc3/dwc3-of-simple.c > @@ -165,8 +165,9 @@ static int dwc3_of_simple_remove(struct platform_device *pdev) > > reset_control_put(simple->resets); > > - pm_runtime_put_sync(dev); > + pm_runtime_put_noidle(dev); > pm_runtime_disable(dev); > + pm_runtime_set_suspended(dev); > > return 0; > }