At Fri, 28 Sep 2012 15:57:01 -0700, Dylan Reid wrote:

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

I queued it for 3.7 kernel with Cc to stable. Thanks!

Takashi

---

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

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c index 960800b..c0ab72c 100644 --- a/sound/pci/hda/hda_codec.c +++ b/sound/pci/hda/hda_codec.c @@ -3612,7 +3612,7 @@ static inline void hda_exec_init_verbs(struct hda_codec *codec) {}

• call suspend and power-down; used both from PM and power-save
• this function returns the power state in the end

*/ -static unsigned int hda_call_codec_suspend(struct hda_codec *codec) +static unsigned int hda_call_codec_suspend(struct hda_codec *codec, bool in_wq) { unsigned int state;

@@ -3620,7 +3620,9 @@ static unsigned int hda_call_codec_suspend(struct hda_codec *codec) codec->patch_ops.suspend(codec); hda_cleanup_all_streams(codec); state = hda_set_power_state(codec, AC_PWRST_D3);

• 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);

@@ -4478,7 +4480,7 @@ static void hda_power_work(struct work_struct *work) } spin_unlock(&codec->power_lock);

• state = hda_call_codec_suspend(codec);

• state = hda_call_codec_suspend(codec, true); codec->pm_down_notified = 0; if (!bus->power_keep_link_on && (state & AC_PWRST_CLK_STOP_OK)) { codec->pm_down_notified = 1;

@@ -5127,7 +5129,7 @@ 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;

}

1.7.12.146.g16d26b1