Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S944529AbcJSSQ4 (ORCPT ); Wed, 19 Oct 2016 14:16:56 -0400 Received: from mail.fireflyinternet.com ([109.228.58.192]:53292 "EHLO fireflyinternet.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S944339AbcJSSQo (ORCPT ); Wed, 19 Oct 2016 14:16:44 -0400 X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Date: Wed, 19 Oct 2016 19:16:39 +0100 From: Chris Wilson To: ville.syrjala@linux.intel.com Cc: rtc-linux@googlegroups.com, intel-gfx@lists.freedesktop.org, Gabriele Mazzotta , Alexandre Belloni , linux-kernel@vger.kernel.org Subject: Re: [Intel-gfx] [PATCH] rtc: cmos: Don't enable interrupts in the middle of the interrupt handler Message-ID: <20161019181639.GB10824@nuc-i3427.alporthouse.com> Mail-Followup-To: Chris Wilson , ville.syrjala@linux.intel.com, rtc-linux@googlegroups.com, intel-gfx@lists.freedesktop.org, Gabriele Mazzotta , Alexandre Belloni , linux-kernel@vger.kernel.org References: <1476900124-14405-1-git-send-email-ville.syrjala@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1476900124-14405-1-git-send-email-ville.syrjala@linux.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4570 Lines: 84 On Wed, Oct 19, 2016 at 09:02:04PM +0300, ville.syrjala@linux.intel.com wrote: > From: Ville Syrj?l? > > Using spin_lock_irq()/spin_unlock_irq() from within the interrupt > handler is a no-no. Let's save/restore the flags to avoid turning on > interrupts prematurely. > > We hit this in a bunch of our CI systems, but for whatever reason I > wasn't able to reproduce on my own machine, so this fix is just > based on the backtrace. > > [ 202.634918] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:2729 trace_hardirqs_on_caller+0x113/0x1b0 > [ 202.634919] DEBUG_LOCKS_WARN_ON(current->hardirq_context) > [ 202.634929] Modules linked in: snd_hda_intel i915 x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel lpc_ich snd_hda_codec_realtek snd_hda_codec_generic snd_hda_codec_hdmi snd_hda_codec snd_hwdep i2c_designware_platform i2c_designware_core snd_hda_core mei_me mei snd_pcm r8169 mii sdhci_acpi sdhci mmc_core i2c_hid [last unloaded: i915] > [ 202.634930] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G U 4.9.0-rc1-CI-CI_DRM_1734+ #1 > [ 202.634931] Hardware name: GIGABYTE M4HM87P-00/M4HM87P-00, BIOS F6 12/10/2014 > [ 202.634933] ffff88011ea03d68 ffffffff8142dce5 ffff88011ea03db8 0000000000000000 > [ 202.634934] ffff88011ea03da8 ffffffff8107e496 00000aa900000002 ffffffff81e249a0 > [ 202.634935] ffffffff81815637 ffffffff82e7c280 0000000000000000 0000000000000004 > [ 202.634936] Call Trace: > [ 202.634939] > [ 202.634939] [] dump_stack+0x67/0x92 > [ 202.634941] [] __warn+0xc6/0xe0 > [ 202.634944] [] ? _raw_spin_unlock_irq+0x27/0x50 > [ 202.634945] [] warn_slowpath_fmt+0x4a/0x50 > [ 202.634946] [] trace_hardirqs_on_caller+0x113/0x1b0 > [ 202.634948] [] trace_hardirqs_on+0xd/0x10 > [ 202.634949] [] _raw_spin_unlock_irq+0x27/0x50 > [ 202.634951] [] rtc_handler+0x32/0xa0 > [ 202.634954] [] acpi_ev_fixed_event_detect+0xd4/0xfb > [ 202.634956] [] acpi_ev_sci_xrupt_handler+0xf/0x2d > [ 202.634957] [] acpi_irq+0x11/0x2c > [ 202.634960] [] __handle_irq_event_percpu+0x58/0x370 > [ 202.634961] [] handle_irq_event_percpu+0x1e/0x50 > [ 202.634962] [] handle_irq_event+0x34/0x60 > [ 202.634963] [] handle_fasteoi_irq+0xa6/0x170 > [ 202.634966] [] handle_irq+0x15/0x20 > [ 202.634967] [] do_IRQ+0x68/0x130 > [ 202.634968] [] common_interrupt+0x89/0x89 > [ 202.634970] > [ 202.634970] [] ? mwait_idle+0x93/0x210 > [ 202.634971] [] ? mwait_idle+0x8a/0x210 > [ 202.634972] [] arch_cpu_idle+0xa/0x10 > [ 202.634973] [] default_idle_call+0x1e/0x30 > [ 202.634974] [] cpu_startup_entry+0x17c/0x1f0 > [ 202.634976] [] rest_init+0x127/0x130 > [ 202.634978] [] start_kernel+0x3f6/0x403 > [ 202.634980] [] x86_64_start_reservations+0x2a/0x2c > [ 202.634981] [] x86_64_start_kernel+0x173/0x186 > [ 202.634982] ---[ end trace 293c99618fa08d34 ]--- > > Cc: Gabriele Mazzotta > Cc: Alexandre Belloni > Fixes: 983bf1256edb ("rtc: cmos: Clear ACPI-driven alarms upon resume") > Signed-off-by: Ville Syrj?l? > --- > drivers/rtc/rtc-cmos.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c > index dd3d59806ffa..19cd49ad92dc 100644 > --- a/drivers/rtc/rtc-cmos.c > +++ b/drivers/rtc/rtc-cmos.c > @@ -996,8 +996,9 @@ static u32 rtc_handler(void *context) > struct cmos_rtc *cmos = dev_get_drvdata(dev); > unsigned char rtc_control = 0; > unsigned char rtc_intr; > + unsigned long flags; > > - spin_lock_irq(&rtc_lock); > + spin_lock_irqsave(&rtc_lock, flags); My reading of the acpi fixed event handlers suggests that this can only be called from interrupt context. Anyway using irqsave is correct (just may be optimised away to a plain spin_lock() if the condition that this is only called in irq context is satisfied). Reviewed-by: Chris Wilson -Chris -- Chris Wilson, Intel Open Source Technology Centre