'cat /proc/asound/card0/codec0' cause kernel panic (battery mode)

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 1212160

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

The commit that I believe fixes this bug is

commit 8b8d654b55648561287bd8baca0f75f964a17038
Author: Takashi Iwai <email address hidden>
Date: Wed Jun 20 16:32:22 2012 +0200

    ALSA: hda - Move one-time init codes from generic_hdmi_init()

Upstream would like to confirm that it's really the generic_hdmi_init patch that fixes the OOPS and nothing else, before accepting it into stable tree. I've therefore made a special DKMS package which contains only the 3.5 kernel + the specific patch. Can you test it and verify that this fixes the OOPS? Thanks.

TEST CASE:
1. Install 12.04.2, boot to desktop and run update (3.5.0-43) on 201303-13027
2. Install the proprietary video driver (fglrx-updates)
3. Reboot in battery mode (no AC connected)
4. Insert HDMI cable
5. execute 'cat /proc/asound/card0/codec0'
6. Kernel panic occurred, caps lock LED flashing, reboot
7. Install the deb file from comment #3
8. Repeat 3-5

VERIFICATION DONE

Expected result:
1. Kernel panic should happen on step 6
2. It won't happen again after the deb file was installed

Actual result:
Kernel panic occurred as expected, the patch works as expected

Thanks

Thanks PHLin for the test!

Hi,

This is a real oldie, but better late than never.

A while back, I discovered that this patch would help against a kernel
panic when "cat /proc/asound/card0/codec0" was executed on this machine,
which was running an fglrx driver.

I asked for a stable backport, but Takashi wanted testing to make sure
this was actually fixed by the patch [1]. And now, several months later,
I have this confirmation [2].

The test was conducted on an 3.5 Ubuntu kernel, based on the 3.5
extended stable tree, but would apply equally well to 3.4.

I'm attaching the backported patch - it applied cleanly, I've just added
an extra section with an explanation.

--
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic

[1]
http://mailman.alsa-project.org/pipermail/alsa-devel/2013-March/060132.html

[2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1212160/comments/4

On Tue, Nov 12, 2013 at 01:33:11PM +0100, David Henningsson wrote:
> Hi,
>
> This is a real oldie, but better late than never.
>
> A while back, I discovered that this patch would help against a kernel
> panic when "cat /proc/asound/card0/codec0" was executed on this machine,
> which was running an fglrx driver.
>
> I asked for a stable backport, but Takashi wanted testing to make sure
> this was actually fixed by the patch [1]. And now, several months later,
> I have this confirmation [2].
>
> The test was conducted on an 3.5 Ubuntu kernel, based on the 3.5
> extended stable tree, but would apply equally well to 3.4.
>
> I'm attaching the backported patch - it applied cleanly, I've just added
> an extra section with an explanation.
>

Thank you David, I'll queue it for the 3.5 kernel.

Cheers,
--
Luis

> -- David Henningsson, Canonical Ltd. https://launchpad.net/~diwic
>
> [1]
> http://mailman.alsa-project.org/pipermail/alsa-devel/2013-March/060132.html
>
> [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1212160/comments/4

> From 76aabf83ca9c8cff2dd9e3bb5300e3778e0baf7d Mon Sep 17 00:00:00 2001
> From: Takashi Iwai <email address hidden>
> Date: Wed, 20 Jun 2012 16:32:22 +0200
> Subject: [PATCH] ALSA: hda - Move one-time init codes from
> generic_hdmi_init()
>
> The codes to initialize work struct or create a proc interface should
> be called only once and never although it's called many times through
> the init callback. Move that stuff into patch_generic_hdmi() so that
> it's called only once.
>
> Signed-off-by: Takashi Iwai <email address hidden>
>
> (cherry picked from commit 8b8d654b55648561287bd8baca0f75f964a17038)
>
> This is being backported to 3.4 and 3.5 due to prevention of kernel
> panic. The kernel panic was observed by executing
> 'cat /proc/asound/card0/codec0' on a particular machine, which was
> - running in battery mode
> - having an external HDMI monitor connected
> - running the fglrx driver.
>
> In short, the one-time init code initializes a delayed_work struct.
> Then, I believe the following happened:
> 1) the delayed_work was activated
> 2) the delayed_work struct was reinitialized by the init code
> 3) when the delayed_work timed out (ready to run the callback function),
> the kernel panic happened because the delayed_work struct had
> been corrupted in step 2.
>
> BugLink: https://bugs.launchpad.net/bugs/1212160
> Signed-off-by: David Henningsson <email address hidden>
> ---
> sound/pci/hda/patch_hdmi.c | 22 +++++++++++++++++-----
> 1 file changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
> index 02a6e3f..ef917bf 100644
> --- a/sound/pci/hda/patch_hdmi.c
> +++ b/sound/pci/hda/patch_hdmi.c
> @@ -1282,23 +1282,34 @@ static int generic_hdmi_build_controls(struct hda_codec *codec)
> return 0;
> }
>
> -static int generic_hdmi_init(struct hda_codec *codec)
> +static int generic_hdmi_init_per_pins(struct hda_codec *codec)
> {
> struct hdmi_spec *spec = codec->spec;
> int pin_idx;
>
> for (pin_idx = 0; pin_idx < spec->num_pins; pin_idx++) {
> struct hdmi_spec_per_pin *per_pin = &spec->pins[pin_idx];
...

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-quantal' to 'verification-done-quantal'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

Came from upstream stable.

This bug was fixed in the package linux - 3.5.0-45.68

---------------
linux (3.5.0-45.68) quantal; urgency=low

  [Steve Conklin]

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