ALSA: hda - Fix hang caused by race during suspend.

dgreid · gregkh · commit 22e22876160b · 2012-10-13T05:50:33.000+09:00
commit d17344b 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>
diff --git 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(struct hda_codec *codec) {}
 /*
  * 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(struct hda_codec *codec)
 			    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_struct *work)
 	}
 	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;
 }
