From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934725AbcIOOXw (ORCPT ); Thu, 15 Sep 2016 10:23:52 -0400 Received: from metis.ext.4.pengutronix.de ([92.198.50.35]:50757 "EHLO metis.ext.4.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763064AbcIOOXf (ORCPT ); Thu, 15 Sep 2016 10:23:35 -0400 Date: Thu, 15 Sep 2016 16:23:26 +0200 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Vladimir Zapolskiy Cc: Guenter Roeck , Shawn Guo , "linux-kernel@vger.kernel.org" , Greg Kroah-Hartman , Linus Walleij Subject: Re: Crashing 'kzm' target in next-20160913 due to 'gpio: mxc: shift gpio_mxc_init() to subsys_initcall level' Message-ID: <20160915142326.lktxsck3idykemds@pengutronix.de> References: <9befb559-499a-dd70-cd44-60d5fce2e5d6@roeck-us.net> <99993063-6692-0870-12fa-64cf13d507f6@mentor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <99993063-6692-0870-12fa-64cf13d507f6@mentor.com> User-Agent: Mutt/1.6.2-neo (2016-06-11) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 15, 2016 at 04:35:04PM +0300, Vladimir Zapolskiy wrote: > Hi Guenter, > > On 09/14/2016 06:20 AM, Guenter Roeck wrote: > > Hi Vladimir, > > > > your commit e188cbf7564f ("gpio: mxc: shift gpio_mxc_init() to subsys_initcall level") > > in -next causes the following crash when running the 'kzm' target (and most likely > > the real thing) with qemu. > > > > [ 1.211426] Unable to handle kernel NULL pointer dereference at virtual address 0000000c > > [ 1.211600] pgd = c0004000 > > [ 1.211680] [0000000c] *pgd=00000000 > > [ 1.212067] Internal error: Oops: 5 [#1] SMP ARM > > [ 1.212245] Modules linked in: > > [ 1.212542] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.8.0-rc6-next-20160913 #1 > > [ 1.212671] Hardware name: Kyoto Microcomputer Co., Ltd. KZM-ARM11-01 > > [ 1.212825] task: c6848000 task.stack: c683e000 > > [ 1.213231] PC is at platform_get_irq+0xc0/0xe8 > > > > See http://kerneltests.org/builders/qemu-arm-next/builds/525/steps/qemubuildcommand/logs/stdio > > for a complete log. > > > > Problem is quite subtle. The change causes the gpio driver to be installed later. > > As a result, kzm_init_smsc9118() fails to initialize the gpio pins correctly. > > gpio_request() in that function returns -EPROBE_DEFER, which is ignored, > > gpio_to_irq() then returns -22 which is unconditionally assigned as interrupt number. > > platform_get_irq(), as called from the smsc driver, gets this negative interrupt > > number, and passes it unconditionally to irq_get_irq_data(), which returns NULL. > > The NULL pointer is then passed to irqd_set_trigger_type() which, not entirely > > surprisingly, crashes. > > > > So, in other words, lots of bugs here. Nevertheless, I would suggest to keep using > > postcore_initcall(), at least until it is sure that all gpio clients handle -EPROBE_DEFER > > correctly. > > I'm inviting Shawn and Uwe to the discussion. > > The proper fix in this particular case should be like this one: > > diff --git a/arch/arm/mach-imx/mach-kzm_arm11_01.c b/arch/arm/mach-imx/mach-kzm_arm11_01.c > index 31df4361996f..8288acfe7221 100644 > --- a/arch/arm/mach-imx/mach-kzm_arm11_01.c > +++ b/arch/arm/mach-imx/mach-kzm_arm11_01.c > @@ -245,13 +245,17 @@ static void __init kzm_board_init(void) > mxc_iomux_setup_multiple_pins(kzm_pins, > ARRAY_SIZE(kzm_pins), "kzm"); > - kzm_init_ext_uart(); > - kzm_init_smsc9118(); > kzm_init_imx_uart(); > pr_info("Clock input source is 26MHz\n"); > } > +static void __init kzm_late_init(void) > +{ > + kzm_init_ext_uart(); > + kzm_init_smsc9118(); > +} > + > /* > * This structure defines static mappings for the kzm-arm11-01 board. > */ > @@ -291,5 +295,6 @@ MACHINE_START(KZM_ARM11_01, "Kyoto Microcomputer Co., Ltd. KZM-ARM11-01") > .init_irq = mx31_init_irq, > .init_time = kzm_timer_init, > .init_machine = kzm_board_init, > + .init_late = kzm_late_init, > .restart = mxc_restart, > MACHINE_END That + checking the return code of gpio_request and the other calls. Or better, convert the machine to dt. > But I agree that there might be more legacy boards (i.MX31 only IMHO), > which may attempt to manipulate GPIO lines before subsys_initcall() > level. I wouldn't revert anything for legacy boards. That's the chance to say in the near future: They stopped working in September 2016, obviously nobody cares, let's rip them. :-) Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |