[ 109/122] ALSA: hda - Fix hang caused by race during suspend.

Greg Kroah-Hartman
2012-10-11T00:26:59Z

From: Dylan Reid <dgreid@chromium.org>

commit d17344b3547669f5b6ee4fda993d03737a141bd6 upstream.

There was a race condition when the system suspends while hda_power_work
is running in the work queue. If system suspend (snd_hda_suspend)
happens after the work queue releases power_lock but before it calls
hda_call_codec_suspend, codec_suspend runs with power_on=0, causing the
codec to power up for register reads, and hanging when it calls
cancel_delayed_work_sync from the running work queue.

The call chain from the work queue will look like this:
hda_power_work <<- power_on = 1, unlock, then power_on cleard by suspend
hda_call_codec_suspend
hda_set_power_state
snd_hda_codec_read
codec_exec_verb
snd_hda_power_up
snd_hda_power_save
__snd_hda_power_up
cancel_delayed_work_sync <<-- cancelling executing wq

Fix this by waiting for the work queue to finish before starting suspend
if suspend is not happening on the work queue.

Signed-off-by: Dylan Reid <dgreid@chromium.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/pci/hda/hda_codec.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -3580,7 +3580,7 @@ static inline void hda_exec_init_verbs(s
/*
* call suspend and power-down; used both from PM and power-save
*/
-static void hda_call_codec_suspend(struct hda_codec *codec)
+static void hda_call_codec_suspend(struct hda_codec *codec, bool in_wq)
{
if (codec->patch_ops.suspend)
codec->patch_ops.suspend(codec);
@@ -3589,7 +3589,9 @@ static void hda_call_codec_suspend(struc
codec->afg ? codec->afg : codec->mfg,
AC_PWRST_D3);
#ifdef CONFIG_SND_HDA_POWER_SAVE
- cancel_delayed_work(&codec->power_work);
+ /* Cancel delayed work if we aren't currently running from it. */
+ if (!in_wq)
+ cancel_delayed_work_sync(&codec->power_work);
spin_lock(&codec->power_lock);
snd_hda_update_power_acct(codec);
trace_hda_power_down(codec);
@@ -4410,7 +4412,7 @@ static void hda_power_work(struct work_s
}
spin_unlock(&codec->power_lock);

- hda_call_codec_suspend(codec);
+ hda_call_codec_suspend(codec, true);
if (bus->ops.pm_notify)
bus->ops.pm_notify(bus);
}
@@ -5076,7 +5078,7 @@ int snd_hda_suspend(struct hda_bus *bus)

list_for_each_entry(codec, &bus->codec_list, list) {
if (hda_codec_is_power_on(codec))
- hda_call_codec_suspend(codec);
+ hda_call_codec_suspend(codec, false);
}
return 0;
}