[3.5.y.z extended stable] Patch "ALSA: hda - Move one-time init codes from generic_hdmi_init()" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

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

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 88612023fc3f2323fce3e025e0308b252ed1040f Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai at suse.de>
Date: Wed, 20 Jun 2012 16:32:22 +0200
Subject: ALSA: hda - Move one-time init codes from generic_hdmi_init()

commit 8b8d654b55648561287bd8baca0f75f964a17038 upstream.

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 <tiwai at suse.de>

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 <david.henningsson at canonical.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 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 c3cd1f8..769ba9b 100644
--- a/sound/pci/hda/patch_hdmi.c
+++ b/sound/pci/hda/patch_hdmi.c
@@ -1283,23 +1283,34 @@ 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];
-		hda_nid_t pin_nid = per_pin->pin_nid;
 		struct hdmi_eld *eld = &per_pin->sink_eld;

-		hdmi_init_pin(codec, pin_nid);
-		snd_hda_jack_detect_enable(codec, pin_nid, pin_nid);
-
 		per_pin->codec = codec;
 		INIT_DELAYED_WORK(&per_pin->work, hdmi_repoll_eld);
 		snd_hda_eld_proc_new(codec, eld, pin_idx);
 	}
+	return 0;
+}
+
+static int generic_hdmi_init(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];
+		hda_nid_t pin_nid = per_pin->pin_nid;
+
+		hdmi_init_pin(codec, pin_nid);
+		snd_hda_jack_detect_enable(codec, pin_nid, pin_nid);
+	}
 	snd_hda_jack_report_sync(codec);
 	return 0;
 }
@@ -1344,6 +1355,7 @@ static int patch_generic_hdmi(struct hda_codec *codec)
 		return -EINVAL;
 	}
 	codec->patch_ops = generic_hdmi_patch_ops;
+	generic_hdmi_init_per_pins(codec);

 	init_channel_allocations();

--
1.8.3.2