ASoC: SOF: core: harden shutdown helper

When the probe is handled in a workqueue, we must use
cancel_work_sync() in the shutdown helper to avoid possible race
conditions.

We must also take care of possible errors happening in a probe
workqueue or during pm_runtime resume (called e.g. before shutdown for
PCI devices). We should really only try to access hardware registers
and initiate IPCs if the DSP is fully booted.

Fixes: daff7f14 ("ASoC: SOF: add snd_sof_device_shutdown() helper for shutdown")
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Libin Yang <libin.yang@intel.com>
Link: https://lore.kernel.org/r/20210322163728.16616-3-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/core.c

@@ -399,7 +399,13 @@ int snd_sof_device_shutdown(struct device *dev)
 {
 	struct snd_sof_dev *sdev = dev_get_drvdata(dev);
 
-	return snd_sof_shutdown(sdev);
+	if (IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE))
+		cancel_work_sync(&sdev->probe_work);
+
+	if (sdev->fw_state == SOF_FW_BOOT_COMPLETE)
+		return snd_sof_shutdown(sdev);
+
+	return 0;
 }
 EXPORT_SYMBOL(snd_sof_device_shutdown);