ALSA: usb-audio: Fix races at disconnection

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 32 insertions, 17 deletions

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 55e19e1b80ec..55e741c5f231 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -71,6 +71,8 @@ static snd_pcm_uframes_t snd_usb_pcm_pointer(struct snd_pcm_substream *substream
         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,
@@ -444,7 +446,6 @@ static int configure_endpoint(struct snd_usb_substream *subs)
 {
         int ret;
 
-        mutex_lock(&subs->stream->chip->shutdown_mutex);
         /* format changed */
         stop_endpoints(subs, 0, 0, 0);
         ret = snd_usb_endpoint_set_params(subs->data_endpoint,
@@ -455,7 +456,7 @@ static int configure_endpoint(struct snd_usb_substream *subs)
                                           subs->cur_audiofmt,
                                           subs->sync_endpoint);
         if (ret < 0)
-                goto unlock;
+                return ret;
 
         if (subs->sync_endpoint)
                 ret = snd_usb_endpoint_set_params(subs->data_endpoint,
@@ -465,9 +466,6 @@ static int configure_endpoint(struct snd_usb_substream *subs)
                                                   subs->cur_rate,
                                                   subs->cur_audiofmt,
                                                   NULL);
-
-unlock:
-        mutex_unlock(&subs->stream->chip->shutdown_mutex);
         return ret;
 }
 
@@ -505,7 +503,13 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
                 return -EINVAL;
         }
 
-        if ((ret = set_format(subs, fmt)) < 0)
+        mutex_lock(&subs->stream->chip->shutdown_mutex);
+        if (subs->stream->chip->shutdown)
+                ret = -ENODEV;
+        else
+                ret = set_format(subs, fmt);
+        mutex_unlock(&subs->stream->chip->shutdown_mutex);
+        if (ret < 0)
                 return ret;
 
         subs->interface = fmt->iface;
@@ -528,8 +532,10 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream)
         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);
 }
@@ -552,12 +558,19 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
                 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;
+        }
 
         ret = set_format(subs, subs->cur_audiofmt);
         if (ret < 0)
-                return ret;
+                goto unlock;
 
         iface = usb_ifnum_to_if(subs->dev, subs->cur_audiofmt->iface);
         alts = &iface->altsetting[subs->cur_audiofmt->altset_idx];
@@ -567,12 +580,12 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
                                        subs->cur_audiofmt,
                                        subs->cur_rate);
         if (ret < 0)
-                return ret;
+                goto unlock;
 
         if (subs->need_setup_ep) {
                 ret = configure_endpoint(subs);
                 if (ret < 0)
-                        return ret;
+                        goto unlock;
                 subs->need_setup_ep = false;
         }
 
@@ -592,9 +605,11 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
         /* 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 =
@@ -647,7 +662,7 @@ static int hw_check_valid_format(struct snd_usb_substream *subs,
                 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);
@@ -925,7 +940,7 @@ static int setup_hw_info(struct snd_pcm_runtime *runtime, struct snd_usb_substre
                 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)