From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Juergen Gross <jgross@suse.com>,
Dou Liyang <douly.fnst@cn.fujitsu.com>,
"alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>,
Takashi Iwai <tiwai@suse.de>,
"intel-gfx@lists.freedesktop.org"
<intel-gfx@lists.freedesktop.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Jiang Liu <jiang.liu@linux.intel.com>,
"Chen, Augustine" <augustine.chen@intel.com>,
"Bossart, Pierre-louis" <pierre-louis.bossart@intel.com>
Subject: Re: [Intel-gfx] [PATCH] drm/i915: Remove unused IRQ chip data of HDMI LPE audio
Date: Tue, 20 Feb 2018 20:49:36 +0200 [thread overview]
Message-ID: <20180220184936.GI5453@intel.com> (raw)
In-Reply-To: <20180129170922.GR5453@intel.com>
On Mon, Jan 29, 2018 at 07:09:22PM +0200, Ville Syrjälä wrote:
> On Wed, Dec 13, 2017 at 03:06:55PM +0100, Thomas Gleixner wrote:
> > On Wed, 13 Dec 2017, Takashi Iwai wrote:
> > > On Wed, 13 Dec 2017 12:35:54 +0100,
> > > Thomas Gleixner wrote:
> > > >
> > > > > > On Mon, 11 Dec 2017, Anand, Jerome wrote:
> > > > > > > > On Fri, 8 Dec 2017, Ville Syrjälä wrote:
> > > > > > > >
> > > > > > > > > On Fri, Dec 08, 2017 at 05:33:23PM +0800, Augustine.Chen wrote:
> > > > > > > > > > The chip data of HDMI LPE audio is set to drm_i915_private which
> > > > > > > > > > is not consistent with the expectation by x86 APIC driver.
> > > > > > > > >
> > > > > > > > > Hmm. Why is the apic code looking at data for an irq chip it
> > > > > > > > > hasn't created?
> > > > > > > > >
> > > > > > >
> > > > > > > apic code expects an irq domain to be place as generic approach.
> > > > > >
> > > > > > APIC code does not even see that interrupt at all. It's completely disconnected.
> > > > > >
> > > > >
> > > > > That's the problem - APIC just converts the chip data to its internal
> > > > > format and fails.
> > > >
> > > > How does APIC code end up to touch that interrupt at all? Call stack please.
> > >
> > > It's found in the bugzilla referred in the patch:
> > > https://bugs.freedesktop.org/show_bug.cgi?id=103731
> > >
> > > [ 87.353072] irq 298 idata->chip->name hdmi_lpe_audio_irqchip
> > > [ 87.353072] irq 298 apic_chip_data
> > > [ 87.353073] irq 298 data->domain is NULL
> > > [ 87.353120] BUG: unable to handle kernel NULL pointer dereference at (null)
> > > [ 87.353132] IP: setup_vector_irq+0x1ba/0x230
> > > [ 87.353133] PGD 0
> > >
> > > If my understanding is correct, it happens only with 4.14 and earlier
> > > kernels where __setup_vector_irq() loops over the all irqs:
> > >
> > > static void __setup_vector_irq(int cpu)
> > > {
> > > struct apic_chip_data *data;
> > > struct irq_desc *desc;
> > > int irq, vector;
> > >
> > > /* Mark the inuse vectors */
> > > for_each_irq_desc(irq, desc) {
> > > struct irq_data *idata = irq_desc_get_irq_data(desc);
> > >
> > > data = apic_chip_data(idata);
> > > if (!data || !cpumask_test_cpu(cpu, data->domain))
> > > continue;
> > > ....
> > >
> > > And since we have assigned a non-APIC chip data in the driver, the
> > > code above refers to a wrong object, leading to Oops.
> >
> > Bah crap. This information should have been provided earlier instead of
> > handwavy 'doesnt work with CONFIG_FOO and hotplug'.
> >
> > > As a further note, the setup_vector_irq() code has been changed in
> > > 4.15, and such a reference won't happen any longer. So the patch
> > > isn't necessary for now, although it's not bad to take as a cleanup.
> > > And we can eventually put Cc to stable there since it actually works
> > > around the issue above for the older kernels -- of course, with more
> > > detailed descriptions about the background.
> >
> > No, that's just tinkering. The proper fix is to make that code robust.
> >
> > Something like the completely untested patch below should do the trick.
> >
> > Thanks,
> >
> > tglx
> > ---
> > diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
> > index f3557a1eb562..02e6a3cc0d74 100644
> > --- a/arch/x86/kernel/apic/vector.c
> > +++ b/arch/x86/kernel/apic/vector.c
> > @@ -58,6 +58,9 @@ static struct apic_chip_data *apic_chip_data(struct irq_data *irq_data)
> > while (irq_data->parent_data)
> > irq_data = irq_data->parent_data;
> >
> > + if (irq_data->domain != x86_vector_domain)
> > + return NULL;
> > +
> > return irq_data->chip_data;
> > }
> >
> >
>
> Did this patch resolve the issue?
Ping.
--
Ville Syrjälä
Intel OTC
prev parent reply other threads:[~2018-02-20 18:49 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20171208093323.2212-1-augustine.chen@intel.com>
2017-12-08 11:44 ` [Intel-gfx] [PATCH] drm/i915: Remove unused IRQ chip data of HDMI LPE audio Ville Syrjälä
2017-12-08 22:51 ` Thomas Gleixner
2017-12-11 8:33 ` Anand, Jerome
2017-12-11 13:20 ` Ville Syrjälä
2017-12-11 13:23 ` Takashi Iwai
2017-12-12 9:26 ` Chen, Augustine
2017-12-12 9:45 ` Takashi Iwai
2017-12-13 9:25 ` Chen, Augustine
2017-12-12 17:06 ` Thomas Gleixner
2017-12-13 2:15 ` Anand, Jerome
2017-12-13 11:35 ` Thomas Gleixner
2017-12-13 11:52 ` Takashi Iwai
2017-12-13 14:06 ` Thomas Gleixner
2018-01-29 17:09 ` Ville Syrjälä
2018-02-20 18:49 ` Ville Syrjälä [this message]
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