[ 38/66] ALSA: usb-audio: Fix races at disconnection

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Takashi Iwai <tiwai@suse.de>

commit 978520b75f0a1ce82b17e1e8186417250de6d545 upstream.

Close some races at disconnection of a USB audio device by adding the
chip->shutdown_mutex and chip->shutdown check at appropriate places.

The spots to put bandaids are:
- PCM prepare, hw_params and hw_free
- where the usb device is accessed for communication or get speed, in
 mixer.c and others; the device speed is now cached in subs->speed
 instead of accessing to chip->dev

The accesses in PCM open and close don't need the mutex protection
because these are already handled in the core PCM disconnection code.

The autosuspend/autoresume codes are still uncovered by this patch
because of possible mutex deadlocks.  They'll be covered by the
upcoming change to rwsem.

Also the mixer codes are untouched, too.  These will be fixed in
another patch, too.

Reported-by: Matthieu CASTET <matthieu.castet@parrot.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 sound/usb/card.h   |    1 
 sound/usb/mixer.c  |   65 +++++++++++++++++++++++++++++++++++------------------
 sound/usb/pcm.c    |   45 ++++++++++++++++++++++++++----------
 sound/usb/proc.c   |    4 +--
 sound/usb/stream.c |    1 
 5 files changed, 79 insertions(+), 37 deletions(-)

--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -125,6 +125,7 @@ struct snd_usb_substream {
 	struct snd_usb_endpoint *data_endpoint;
 	struct snd_usb_endpoint *sync_endpoint;
 	unsigned long flags;
+	unsigned int speed;		/* USB_SPEED_XXX */
 
 	u64 formats;			/* format bitmasks (all or'ed) */
 	unsigned int num_formats;		/* number of supported audio formats (list) */
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -287,25 +287,32 @@ static int get_ctl_value_v1(struct usb_m
 	unsigned char buf[2];
 	int val_len = cval->val_type >= USB_MIXER_S16 ? 2 : 1;
 	int timeout = 10;
-	int err;
+	int idx = 0, err;
 
 	err = snd_usb_autoresume(cval->mixer->chip);
 	if (err < 0)
 		return -EIO;
+	mutex_lock(&chip->shutdown_mutex);
 	while (timeout-- > 0) {
+		if (chip->shutdown)
+			break;
+		idx = snd_usb_ctrl_intf(chip) | (cval->id << 8);
 		if (snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0), request,
 				    USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
-				    validx, snd_usb_ctrl_intf(chip) | (cval->id << 8),
-				    buf, val_len) >= val_len) {
+				    validx, idx, buf, val_len) >= val_len) {
 			*value_ret = convert_signed_value(cval, snd_usb_combine_bytes(buf, val_len));
-			snd_usb_autosuspend(cval->mixer->chip);
-			return 0;
+			err = 0;
+			goto out;
 		}
 	}
-	snd_usb_autosuspend(cval->mixer->chip);
 	snd_printdd(KERN_ERR "cannot get ctl value: req = %#x, wValue = %#x, wIndex = %#x, type = %d\n",
-		    request, validx, snd_usb_ctrl_intf(chip) | (cval->id << 8), cval->val_type);
-	return -EINVAL;
+		    request, validx, idx, cval->val_type);
+	err = -EINVAL;
+
+ out:
+	mutex_unlock(&chip->shutdown_mutex);
+	snd_usb_autosuspend(cval->mixer->chip);
+	return err;
 }
 
 static int get_ctl_value_v2(struct usb_mixer_elem_info *cval, int request, int validx, int *value_ret)
@@ -313,7 +320,7 @@ static int get_ctl_value_v2(struct usb_m
 	struct snd_usb_audio *chip = cval->mixer->chip;
 	unsigned char buf[2 + 3*sizeof(__u16)]; /* enough space for one range */
 	unsigned char *val;
-	int ret, size;
+	int idx = 0, ret, size;
 	__u8 bRequest;
 
 	if (request == UAC_GET_CUR) {
@@ -330,16 +337,22 @@ static int get_ctl_value_v2(struct usb_m
 	if (ret)
 		goto error;
 
-	ret = snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0), bRequest,
+	mutex_lock(&chip->shutdown_mutex);
+	if (chip->shutdown)
+		ret = -ENODEV;
+	else {
+		idx = snd_usb_ctrl_intf(chip) | (cval->id << 8);
+		ret = snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0), bRequest,
 			      USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
-			      validx, snd_usb_ctrl_intf(chip) | (cval->id << 8),
-			      buf, size);
+			      validx, idx, buf, size);
+	}
+	mutex_unlock(&chip->shutdown_mutex);
 	snd_usb_autosuspend(chip);
 
 	if (ret < 0) {
 error:
 		snd_printk(KERN_ERR "cannot get ctl value: req = %#x, wValue = %#x, wIndex = %#x, type = %d\n",
-			   request, validx, snd_usb_ctrl_intf(chip) | (cval->id << 8), cval->val_type);
+			   request, validx, idx, cval->val_type);
 		return ret;
 	}
 
@@ -417,7 +430,7 @@ int snd_usb_mixer_set_ctl_value(struct u
 {
 	struct snd_usb_audio *chip = cval->mixer->chip;
 	unsigned char buf[2];
-	int val_len, err, timeout = 10;
+	int idx = 0, val_len, err, timeout = 10;
 
 	if (cval->mixer->protocol == UAC_VERSION_1) {
 		val_len = cval->val_type >= USB_MIXER_S16 ? 2 : 1;
@@ -440,19 +453,27 @@ int snd_usb_mixer_set_ctl_value(struct u
 	err = snd_usb_autoresume(chip);
 	if (err < 0)
 		return -EIO;
-	while (timeout-- > 0)
+	mutex_lock(&chip->shutdown_mutex);
+	while (timeout-- > 0) {
+		if (chip->shutdown)
+			break;
+		idx = snd_usb_ctrl_intf(chip) | (cval->id << 8);
 		if (snd_usb_ctl_msg(chip->dev,
 				    usb_sndctrlpipe(chip->dev, 0), request,
 				    USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT,
-				    validx, snd_usb_ctrl_intf(chip) | (cval->id << 8),
-				    buf, val_len) >= 0) {
-			snd_usb_autosuspend(chip);
-			return 0;
+				    validx, idx, buf, val_len) >= 0) {
+			err = 0;
+			goto out;
 		}
-	snd_usb_autosuspend(chip);
+	}
 	snd_printdd(KERN_ERR "cannot set ctl value: req = %#x, wValue = %#x, wIndex = %#x, type = %d, data = %#x/%#x\n",
-		    request, validx, snd_usb_ctrl_intf(chip) | (cval->id << 8), cval->val_type, buf[0], buf[1]);
-	return -EINVAL;
+		    request, validx, idx, cval->val_type, buf[0], buf[1]);
+	err = -EINVAL;
+
+ out:
+	mutex_unlock(&chip->shutdown_mutex);
+	snd_usb_autosuspend(chip);
+	return err;
 }
 
 static int set_cur_ctl_value(struct usb_mixer_elem_info *cval, int validx, int value)
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -71,6 +71,8 @@ static snd_pcm_uframes_t snd_usb_pcm_poi
 	unsigned int hwptr_done;
 
 	subs = (struct snd_usb_substream *)substream->runtime->private_data;
+	if (subs->stream->chip->shutdown)
+		return SNDRV_PCM_POS_XRUN;
 	spin_lock(&subs->lock);
 	hwptr_done = subs->hwptr_done;
 	substream->runtime->delay = snd_usb_pcm_delay(subs,
@@ -471,8 +473,14 @@ static int snd_usb_hw_params(struct snd_
 	changed = subs->cur_audiofmt != fmt ||
 		subs->period_bytes != params_period_bytes(hw_params) ||
 		subs->cur_rate != rate;
+
+	mutex_lock(&subs->stream->chip->shutdown_mutex);
+	if (subs->stream->chip->shutdown) {
+		ret = -ENODEV;
+		goto unlock;
+	}
 	if ((ret = set_format(subs, fmt)) < 0)
-		return ret;
+		goto unlock;
 
 	if (subs->cur_rate != rate) {
 		struct usb_host_interface *alts;
@@ -481,12 +489,11 @@ static int snd_usb_hw_params(struct snd_
 		alts = &iface->altsetting[fmt->altset_idx];
 		ret = snd_usb_init_sample_rate(subs->stream->chip, fmt->iface, alts, fmt, rate);
 		if (ret < 0)
-			return ret;
+			goto unlock;
 		subs->cur_rate = rate;
 	}
 
 	if (changed) {
-		mutex_lock(&subs->stream->chip->shutdown_mutex);
 		/* format changed */
 		stop_endpoints(subs, 0, 0, 0);
 		ret = snd_usb_endpoint_set_params(subs->data_endpoint, hw_params, fmt,
@@ -497,8 +504,6 @@ static int snd_usb_hw_params(struct snd_
 		if (subs->sync_endpoint)
 			ret = snd_usb_endpoint_set_params(subs->sync_endpoint,
 							  hw_params, fmt, NULL);
-unlock:
-		mutex_unlock(&subs->stream->chip->shutdown_mutex);
 	}
 
 	if (ret == 0) {
@@ -506,6 +511,8 @@ unlock:
 		subs->altset_idx = fmt->altset_idx;
 	}
 
+unlock:
+	mutex_unlock(&subs->stream->chip->shutdown_mutex);
 	return ret;
 }
 
@@ -522,8 +529,10 @@ static int snd_usb_hw_free(struct snd_pc
 	subs->cur_rate = 0;
 	subs->period_bytes = 0;
 	mutex_lock(&subs->stream->chip->shutdown_mutex);
-	stop_endpoints(subs, 0, 1, 1);
-	deactivate_endpoints(subs);
+	if (!subs->stream->chip->shutdown) {
+		stop_endpoints(subs, 0, 1, 1);
+		deactivate_endpoints(subs);
+	}
 	mutex_unlock(&subs->stream->chip->shutdown_mutex);
 	return snd_pcm_lib_free_vmalloc_buffer(substream);
 }
@@ -537,14 +546,22 @@ static int snd_usb_pcm_prepare(struct sn
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct snd_usb_substream *subs = runtime->private_data;
+	int ret = 0;
 
 	if (! subs->cur_audiofmt) {
 		snd_printk(KERN_ERR "usbaudio: no format is specified!\n");
 		return -ENXIO;
 	}
 
-	if (snd_BUG_ON(!subs->data_endpoint))
-		return -EIO;
+	mutex_lock(&subs->stream->chip->shutdown_mutex);
+	if (subs->stream->chip->shutdown) {
+		ret = -ENODEV;
+		goto unlock;
+	}
+	if (snd_BUG_ON(!subs->data_endpoint)) {
+		ret = -EIO;
+		goto unlock;
+	}
 
 	/* some unit conversions in runtime */
 	subs->data_endpoint->maxframesize =
@@ -562,9 +579,11 @@ static int snd_usb_pcm_prepare(struct sn
 	/* for playback, submit the URBs now; otherwise, the first hwptr_done
 	 * updates for all URBs would happen at the same time when starting */
 	if (subs->direction == SNDRV_PCM_STREAM_PLAYBACK)
-		return start_endpoints(subs, 1);
+		ret = start_endpoints(subs, 1);
 
-	return 0;
+ unlock:
+	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	return ret;
 }
 
 static struct snd_pcm_hardware snd_usb_hardware =
@@ -617,7 +636,7 @@ static int hw_check_valid_format(struct
 		return 0;
 	}
 	/* check whether the period time is >= the data packet interval */
-	if (snd_usb_get_speed(subs->dev) != USB_SPEED_FULL) {
+	if (subs->speed != USB_SPEED_FULL) {
 		ptime = 125 * (1 << fp->datainterval);
 		if (ptime > pt->max || (ptime == pt->max && pt->openmax)) {
 			hwc_debug("   > check: ptime %u > max %u\n", ptime, pt->max);
@@ -895,7 +914,7 @@ static int setup_hw_info(struct snd_pcm_
 		return err;
 
 	param_period_time_if_needed = SNDRV_PCM_HW_PARAM_PERIOD_TIME;
-	if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
+	if (subs->speed == USB_SPEED_FULL)
 		/* full speed devices have fixed data packet interval */
 		ptmin = 1000;
 	if (ptmin == 1000)
--- a/sound/usb/proc.c
+++ b/sound/usb/proc.c
@@ -108,7 +108,7 @@ static void proc_dump_substream_formats(
 			}
 			snd_iprintf(buffer, "\n");
 		}
-		if (snd_usb_get_speed(subs->dev) != USB_SPEED_FULL)
+		if (subs->speed != USB_SPEED_FULL)
 			snd_iprintf(buffer, "    Data packet interval: %d us\n",
 				    125 * (1 << fp->datainterval));
 		// snd_iprintf(buffer, "    Max Packet Size = %d\n", fp->maxpacksize);
@@ -124,7 +124,7 @@ static void proc_dump_ep_status(struct s
 		return;
 	snd_iprintf(buffer, "    Packet Size = %d\n", ep->curpacksize);
 	snd_iprintf(buffer, "    Momentary freq = %u Hz (%#x.%04x)\n",
-		    snd_usb_get_speed(subs->dev) == USB_SPEED_FULL
+		    subs->speed == USB_SPEED_FULL
 		    ? get_full_speed_hz(ep->freqm)
 		    : get_high_speed_hz(ep->freqm),
 		    ep->freqm >> 16, ep->freqm & 0xffff);
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -90,6 +90,7 @@ static void snd_usb_init_substream(struc
 	subs->direction = stream;
 	subs->dev = as->chip->dev;
 	subs->txfr_quirk = as->chip->txfr_quirk;
+	subs->speed = snd_usb_get_speed(subs->dev);
 
 	snd_usb_set_pcm_ops(as->pcm, stream);