ALSA: hda - Fix abuse of snd_hda_lock_devices() for DSP loader

The current DSP loader code abuses snd_hda_lock_devices() for ensuring
the DSP loader not conflicting with the other normal operations.  But
this trick obviously doesn't work for the PM resume since the streams
are kept opened there where snd_hda_lock_devices() returns -EBUSY.
That means we need another lock mechanism instead of abuse.

This patch provides the new lock state to azx_dev.  Theoretically it's
possible that the DSP loader conflicts with the stream that has been
already assigned for another PCM.  If it's running, the DSP loader
should simply fail.  If not -- it's the case for PM resume --, we
should assign this stream temporarily to the DSP loader, and take it
back to the PCM after finishing DSP loading.  If the PCM is operated
during the DSP loading, it should get an error, too.

Reported-and-tested-by: Dylan Reid <dgreid@chromium.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 4cea6bb6..418bfc0 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -415,6 +415,8 @@
 	unsigned int opened :1;
 	unsigned int running :1;
 	unsigned int irq_pending :1;
+	unsigned int prepared:1;
+	unsigned int locked:1;
 	/*
 	 * For VIA:
 	 *  A flag to ensure DMA position is 0
@@ -426,8 +428,25 @@
 
 	struct timecounter  azx_tc;
 	struct cyclecounter azx_cc;
+
+#ifdef CONFIG_SND_HDA_DSP_LOADER
+	struct mutex dsp_mutex;
+#endif
 };
 
+/* DSP lock helpers */
+#ifdef CONFIG_SND_HDA_DSP_LOADER
+#define dsp_lock_init(dev)	mutex_init(&(dev)->dsp_mutex)
+#define dsp_lock(dev)		mutex_lock(&(dev)->dsp_mutex)
+#define dsp_unlock(dev)		mutex_unlock(&(dev)->dsp_mutex)
+#define dsp_is_locked(dev)	((dev)->locked)
+#else
+#define dsp_lock_init(dev)	do {} while (0)
+#define dsp_lock(dev)		do {} while (0)
+#define dsp_unlock(dev)		do {} while (0)
+#define dsp_is_locked(dev)	0
+#endif
+
 /* CORB/RIRB */
 struct azx_rb {
 	u32 *buf;		/* CORB/RIRB buffer
@@ -527,6 +546,10 @@
 
 	/* card list (for power_save trigger) */
 	struct list_head list;
+
+#ifdef CONFIG_SND_HDA_DSP_LOADER
+	struct azx_dev saved_azx_dev;
+#endif
 };
 
 #define CREATE_TRACE_POINTS
@@ -1793,15 +1816,25 @@
 		dev = chip->capture_index_offset;
 		nums = chip->capture_streams;
 	}
-	for (i = 0; i < nums; i++, dev++)
-		if (!chip->azx_dev[dev].opened) {
-			res = &chip->azx_dev[dev];
-			if (res->assigned_key == key)
-				break;
+	for (i = 0; i < nums; i++, dev++) {
+		struct azx_dev *azx_dev = &chip->azx_dev[dev];
+		dsp_lock(azx_dev);
+		if (!azx_dev->opened && !dsp_is_locked(azx_dev)) {
+			res = azx_dev;
+			if (res->assigned_key == key) {
+				res->opened = 1;
+				res->assigned_key = key;
+				dsp_unlock(azx_dev);
+				return azx_dev;
+			}
 		}
+		dsp_unlock(azx_dev);
+	}
 	if (res) {
+		dsp_lock(res);
 		res->opened = 1;
 		res->assigned_key = key;
+		dsp_unlock(res);
 	}
 	return res;
 }
@@ -2009,6 +2042,12 @@
 	struct azx_dev *azx_dev = get_azx_dev(substream);
 	int ret;
 
+	dsp_lock(azx_dev);
+	if (dsp_is_locked(azx_dev)) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
 	mark_runtime_wc(chip, azx_dev, substream, false);
 	azx_dev->bufsize = 0;
 	azx_dev->period_bytes = 0;
@@ -2016,8 +2055,10 @@
 	ret = snd_pcm_lib_malloc_pages(substream,
 					params_buffer_bytes(hw_params));
 	if (ret < 0)
-		return ret;
+		goto unlock;
 	mark_runtime_wc(chip, azx_dev, substream, true);
+ unlock:
+	dsp_unlock(azx_dev);
 	return ret;
 }
 
@@ -2029,16 +2070,21 @@
 	struct hda_pcm_stream *hinfo = apcm->hinfo[substream->stream];
 
 	/* reset BDL address */
-	azx_sd_writel(azx_dev, SD_BDLPL, 0);
-	azx_sd_writel(azx_dev, SD_BDLPU, 0);
-	azx_sd_writel(azx_dev, SD_CTL, 0);
-	azx_dev->bufsize = 0;
-	azx_dev->period_bytes = 0;
-	azx_dev->format_val = 0;
+	dsp_lock(azx_dev);
+	if (!dsp_is_locked(azx_dev)) {
+		azx_sd_writel(azx_dev, SD_BDLPL, 0);
+		azx_sd_writel(azx_dev, SD_BDLPU, 0);
+		azx_sd_writel(azx_dev, SD_CTL, 0);
+		azx_dev->bufsize = 0;
+		azx_dev->period_bytes = 0;
+		azx_dev->format_val = 0;
+	}
 
 	snd_hda_codec_cleanup(apcm->codec, hinfo, substream);
 
 	mark_runtime_wc(chip, azx_dev, substream, false);
+	azx_dev->prepared = 0;
+	dsp_unlock(azx_dev);
 	return snd_pcm_lib_free_pages(substream);
 }
 
@@ -2055,6 +2101,12 @@
 		snd_hda_spdif_out_of_nid(apcm->codec, hinfo->nid);
 	unsigned short ctls = spdif ? spdif->ctls : 0;
 
+	dsp_lock(azx_dev);
+	if (dsp_is_locked(azx_dev)) {
+		err = -EBUSY;
+		goto unlock;
+	}
+
 	azx_stream_reset(chip, azx_dev);
 	format_val = snd_hda_calc_stream_format(runtime->rate,
 						runtime->channels,
@@ -2065,7 +2117,8 @@
 		snd_printk(KERN_ERR SFX
 			   "%s: invalid format_val, rate=%d, ch=%d, format=%d\n",
 			   pci_name(chip->pci), runtime->rate, runtime->channels, runtime->format);
-		return -EINVAL;
+		err = -EINVAL;
+		goto unlock;
 	}
 
 	bufsize = snd_pcm_lib_buffer_bytes(substream);
@@ -2084,7 +2137,7 @@
 		azx_dev->no_period_wakeup = runtime->no_period_wakeup;
 		err = azx_setup_periods(chip, substream, azx_dev);
 		if (err < 0)
-			return err;
+			goto unlock;
 	}
 
 	/* wallclk has 24Mhz clock source */
@@ -2101,8 +2154,14 @@
 	if ((chip->driver_caps & AZX_DCAPS_CTX_WORKAROUND) &&
 	    stream_tag > chip->capture_streams)
 		stream_tag -= chip->capture_streams;
-	return snd_hda_codec_prepare(apcm->codec, hinfo, stream_tag,
+	err = snd_hda_codec_prepare(apcm->codec, hinfo, stream_tag,
 				     azx_dev->format_val, substream);
+
+ unlock:
+	if (!err)
+		azx_dev->prepared = 1;
+	dsp_unlock(azx_dev);
+	return err;
 }
 
 static int azx_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
@@ -2117,6 +2176,9 @@
 	azx_dev = get_azx_dev(substream);
 	trace_azx_pcm_trigger(chip, azx_dev, cmd);
 
+	if (dsp_is_locked(azx_dev) || !azx_dev->prepared)
+		return -EPIPE;
+
 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START:
 		rstart = 1;
@@ -2621,17 +2683,27 @@
 	struct azx_dev *azx_dev;
 	int err;
 
-	if (snd_hda_lock_devices(bus))
-		return -EBUSY;
+	azx_dev = azx_get_dsp_loader_dev(chip);
+
+	dsp_lock(azx_dev);
+	spin_lock_irq(&chip->reg_lock);
+	if (azx_dev->running || azx_dev->locked) {
+		spin_unlock_irq(&chip->reg_lock);
+		err = -EBUSY;
+		goto unlock;
+	}
+	azx_dev->prepared = 0;
+	chip->saved_azx_dev = *azx_dev;
+	azx_dev->locked = 1;
+	spin_unlock_irq(&chip->reg_lock);
 
 	err = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV_SG,
 				  snd_dma_pci_data(chip->pci),
 				  byte_size, bufp);
 	if (err < 0)
-		goto unlock;
+		goto err_alloc;
 
 	mark_pages_wc(chip, bufp, true);
-	azx_dev = azx_get_dsp_loader_dev(chip);
 	azx_dev->bufsize = byte_size;
 	azx_dev->period_bytes = byte_size;
 	azx_dev->format_val = format;
@@ -2649,13 +2721,20 @@
 		goto error;
 
 	azx_setup_controller(chip, azx_dev);
+	dsp_unlock(azx_dev);
 	return azx_dev->stream_tag;
 
  error:
 	mark_pages_wc(chip, bufp, false);
 	snd_dma_free_pages(bufp);
-unlock:
-	snd_hda_unlock_devices(bus);
+ err_alloc:
+	spin_lock_irq(&chip->reg_lock);
+	if (azx_dev->opened)
+		*azx_dev = chip->saved_azx_dev;
+	azx_dev->locked = 0;
+	spin_unlock_irq(&chip->reg_lock);
+ unlock:
+	dsp_unlock(azx_dev);
 	return err;
 }
 
@@ -2677,9 +2756,10 @@
 	struct azx *chip = bus->private_data;
 	struct azx_dev *azx_dev = azx_get_dsp_loader_dev(chip);
 
-	if (!dmab->area)
+	if (!dmab->area || !azx_dev->locked)
 		return;
 
+	dsp_lock(azx_dev);
 	/* reset BDL address */
 	azx_sd_writel(azx_dev, SD_BDLPL, 0);
 	azx_sd_writel(azx_dev, SD_BDLPU, 0);
@@ -2692,7 +2772,12 @@
 	snd_dma_free_pages(dmab);
 	dmab->area = NULL;
 
-	snd_hda_unlock_devices(bus);
+	spin_lock_irq(&chip->reg_lock);
+	if (azx_dev->opened)
+		*azx_dev = chip->saved_azx_dev;
+	azx_dev->locked = 0;
+	spin_unlock_irq(&chip->reg_lock);
+	dsp_unlock(azx_dev);
 }
 #endif /* CONFIG_SND_HDA_DSP_LOADER */
 
@@ -3481,6 +3566,7 @@
 	}
 
 	for (i = 0; i < chip->num_streams; i++) {
+		dsp_lock_init(&chip->azx_dev[i]);
 		/* allocate memory for the BDL for each stream */
 		err = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV,
 					  snd_dma_pci_data(chip->pci),