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

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Dylan Reid 2012-09-28 15:57:01 -07:00 committed by Takashi Iwai
parent 395d9dd5dd
commit d17344b354
1 changed files with 6 additions and 4 deletions
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10
sound/pci/hda/hda_codec.c
View File

@ -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;
}