ALSA: usb-audio: Fix races at disconnection
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>
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 67a4d6d..4f49ca7 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -67,6 +67,8 @@
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,
@@ -373,8 +375,14 @@
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;
@@ -383,12 +391,11 @@
alts = &iface->altsetting[fmt->altset_idx];
ret = snd_usb_init_sample_rate(subs->stream->chip, subs->interface, 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 */
snd_usb_release_substream_urbs(subs, 0);
/* influenced: period_bytes, channels, rate, format, */
@@ -396,9 +403,10 @@
params_rate(hw_params),
snd_pcm_format_physical_width(params_format(hw_params)) *
params_channels(hw_params));
- mutex_unlock(&subs->stream->chip->shutdown_mutex);
}
+unlock:
+ mutex_unlock(&subs->stream->chip->shutdown_mutex);
return ret;
}
@@ -429,12 +437,18 @@
{
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;
}
+ mutex_lock(&subs->stream->chip->shutdown_mutex);
+ if (subs->stream->chip->shutdown) {
+ ret = -ENODEV;
+ goto unlock;
+ }
/* some unit conversions in runtime */
subs->maxframesize = bytes_to_frames(runtime, subs->maxpacksize);
subs->curframesize = bytes_to_frames(runtime, subs->curpacksize);
@@ -447,7 +461,10 @@
subs->last_frame_number = 0;
runtime->delay = 0;
- return snd_usb_substream_prepare(subs, runtime);
+ ret = snd_usb_substream_prepare(subs, runtime);
+ unlock:
+ mutex_unlock(&subs->stream->chip->shutdown_mutex);
+ return ret;
}
static struct snd_pcm_hardware snd_usb_hardware =
@@ -500,7 +517,7 @@
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);
@@ -778,7 +795,7 @@
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)