[PATCH 0/2] USB-audio disconnection race fixes (v2)

[PATCH 0/2] USB-audio disconnection race fixes (v2)

[Takashi Iwai]

Hi,

this is a series of fixes for the disconnection races in USB-audio.
A couple of new patches to improve and cover more points since the
previous patch set.


Takashi

[PATCH 1/4] ALSA: PCM: Fix some races at disconnection

[Takashi Iwai]

Fix races at PCM disconnection:
- while a PCM device is being opened or closed
- while the PCM state is being changed without lock in prepare,
  hw_params, hw_free ops

Signed-off-by: Takashi Iwai <tiwai-l3A5Bk7waGM@public.gmane.org>
---
 sound/core/pcm.c        |  7 ++++++-
 sound/core/pcm_native.c | 16 ++++++++++++----
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index f299194..993b240 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -1086,11 +1086,15 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 	if (list_empty(&pcm->list))
 		goto unlock;
 
+	mutex_lock(&pcm->open_mutex);
 	list_del_init(&pcm->list);
 	for (cidx = 0; cidx < 2; cidx++)
-		for (substream = pcm->streams[cidx].substream; substream; substream = substream->next)
+		for (substream = pcm->streams[cidx].substream; substream; substream = substream->next) {
+			snd_pcm_stream_lock_irq(substream);
 			if (substream->runtime)
 				substream->runtime->status->state = SNDRV_PCM_STATE_DISCONNECTED;
+			snd_pcm_stream_unlock_irq(substream);
+		}
 	list_for_each_entry(notify, &snd_pcm_notify_list, list) {
 		notify->n_disconnect(pcm);
 	}
@@ -1110,6 +1114,7 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 			pcm->streams[cidx].chmap_kctl = NULL;
 		}
 	}
+	mutex_unlock(&pcm->open_mutex);
  unlock:
 	mutex_unlock(&register_mutex);
 	return 0;
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 5e12e5b..8753c89 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -369,6 +369,14 @@ static int period_to_usecs(struct snd_pcm_runtime *runtime)
 	return usecs;
 }
 
+static void snd_pcm_set_state(struct snd_pcm_substream *substream, int state)
+{
+	snd_pcm_stream_lock_irq(substream);
+	if (substream->runtime->status->state != SNDRV_PCM_STATE_DISCONNECTED)
+		substream->runtime->status->state = state;
+	snd_pcm_stream_unlock_irq(substream);
+}
+
 static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
 			     struct snd_pcm_hw_params *params)
 {
@@ -452,7 +460,7 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
 		runtime->boundary *= 2;
 
 	snd_pcm_timer_resolution_change(substream);
-	runtime->status->state = SNDRV_PCM_STATE_SETUP;
+	snd_pcm_set_state(substream, SNDRV_PCM_STATE_SETUP);
 
 	if (pm_qos_request_active(&substream->latency_pm_qos_req))
 		pm_qos_remove_request(&substream->latency_pm_qos_req);
@@ -464,7 +472,7 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
 	/* hardware might be unusable from this time,
 	   so we force application to retry to set
 	   the correct hardware parameter settings */
-	runtime->status->state = SNDRV_PCM_STATE_OPEN;
+	snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
 	if (substream->ops->hw_free != NULL)
 		substream->ops->hw_free(substream);
 	return err;
@@ -512,7 +520,7 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
 		return -EBADFD;
 	if (substream->ops->hw_free)
 		result = substream->ops->hw_free(substream);
-	runtime->status->state = SNDRV_PCM_STATE_OPEN;
+	snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
 	pm_qos_remove_request(&substream->latency_pm_qos_req);
 	return result;
 }
@@ -1320,7 +1328,7 @@ static void snd_pcm_post_prepare(struct snd_pcm_substream *substream, int state)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	runtime->control->appl_ptr = runtime->status->hw_ptr;
-	runtime->status->state = SNDRV_PCM_STATE_PREPARED;
+	snd_pcm_set_state(substream, SNDRV_PCM_STATE_PREPARED);
 }
 
 static struct action_ops snd_pcm_action_prepare = {
-- 
1.7.12.3

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[PATCH 2/4] ALSA: usb-audio: Fix races at disconnection (v2)

[Takashi Iwai]

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.

Signed-off-by: Takashi Iwai <tiwai-l3A5Bk7waGM@public.gmane.org>
---
v1->v2: fix unbalanced mutex_unlock in mixer.c

 sound/usb/card.h   |  1 +
 sound/usb/mixer.c  | 65 ++++++++++++++++++++++++++++++++++++------------------
 sound/usb/pcm.c    | 49 ++++++++++++++++++++++++++--------------
 sound/usb/proc.c   |  4 ++--
 sound/usb/stream.c |  1 +
 5 files changed, 79 insertions(+), 41 deletions(-)

diff --git a/sound/usb/card.h b/sound/usb/card.h
index afa4f9e..814cb35 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -126,6 +126,7 @@ struct snd_usb_substream {
 	struct snd_usb_endpoint *sync_endpoint;
 	unsigned long flags;
 	bool need_setup_ep;		/* (re)configure EP at prepare? */
+	unsigned int speed;		/* USB_SPEED_XXX */
 
 	u64 formats;			/* format bitmasks (all or'ed) */
 	unsigned int num_formats;		/* number of supported audio formats (list) */
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index fe56c9d..c2ef11c 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -287,25 +287,32 @@ static int get_ctl_value_v1(struct usb_mixer_elem_info *cval, int request, int v
 	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_mixer_elem_info *cval, int request, int v
 	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_mixer_elem_info *cval, int request, int v
 	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 usb_mixer_elem_info *cval,
 {
 	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 usb_mixer_elem_info *cval,
 	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)
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 55e19e1..55e741c 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)
diff --git a/sound/usb/proc.c b/sound/usb/proc.c
index ebc1a5b..d218f76 100644
--- a/sound/usb/proc.c
+++ b/sound/usb/proc.c
@@ -108,7 +108,7 @@ static void proc_dump_substream_formats(struct snd_usb_substream *subs, struct s
 			}
 			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 snd_usb_substream *subs,
 		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);
diff --git a/sound/usb/stream.c b/sound/usb/stream.c
index 083ed81..1de0c8c 100644
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -90,6 +90,7 @@ static void snd_usb_init_substream(struct snd_usb_stream *as,
 	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);
 
-- 
1.7.12.3

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[PATCH 3/4] ALSA: usb-audio: Use rwsem for disconnect protection

[Takashi Iwai]

Replace mutex with rwsem for codec->shutdown protection so that
concurrent accesses are allowed.

Also add the protection to snd_usb_autosuspend() and
snd_usb_autoresume(), too.

Signed-off-by: Takashi Iwai <tiwai-l3A5Bk7waGM@public.gmane.org>
---
 sound/usb/card.c     | 12 ++++++++----
 sound/usb/mixer.c    | 12 ++++++------
 sound/usb/pcm.c      | 12 ++++++------
 sound/usb/usbaudio.h |  2 +-
 4 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 561bb74..282f0fc 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -339,7 +339,7 @@ static int snd_usb_audio_create(struct usb_device *dev, int idx,
 	}
 
 	mutex_init(&chip->mutex);
-	mutex_init(&chip->shutdown_mutex);
+	init_rwsem(&chip->shutdown_rwsem);
 	chip->index = idx;
 	chip->dev = dev;
 	chip->card = card;
@@ -560,7 +560,7 @@ static void snd_usb_audio_disconnect(struct usb_device *dev,
 
 	card = chip->card;
 	mutex_lock(&register_mutex);
-	mutex_lock(&chip->shutdown_mutex);
+	down_write(&chip->shutdown_rwsem);
 	chip->shutdown = 1;
 	chip->num_interfaces--;
 	if (chip->num_interfaces <= 0) {
@@ -582,11 +582,11 @@ static void snd_usb_audio_disconnect(struct usb_device *dev,
 			snd_usb_mixer_disconnect(p);
 		}
 		usb_chip[chip->index] = NULL;
-		mutex_unlock(&chip->shutdown_mutex);
+		up_write(&chip->shutdown_rwsem);
 		mutex_unlock(&register_mutex);
 		snd_card_free_when_closed(card);
 	} else {
-		mutex_unlock(&chip->shutdown_mutex);
+		up_write(&chip->shutdown_rwsem);
 		mutex_unlock(&register_mutex);
 	}
 }
@@ -618,16 +618,20 @@ int snd_usb_autoresume(struct snd_usb_audio *chip)
 {
 	int err = -ENODEV;
 
+	down_read(&chip->shutdown_rwsem);
 	if (!chip->shutdown && !chip->probing)
 		err = usb_autopm_get_interface(chip->pm_intf);
+	up_read(&chip->shutdown_rwsem);
 
 	return err;
 }
 
 void snd_usb_autosuspend(struct snd_usb_audio *chip)
 {
+	down_read(&chip->shutdown_rwsem);
 	if (!chip->shutdown && !chip->probing)
 		usb_autopm_put_interface(chip->pm_intf);
+	up_read(&chip->shutdown_rwsem);
 }
 
 static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index c2ef11c..298070e 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -292,7 +292,7 @@ static int get_ctl_value_v1(struct usb_mixer_elem_info *cval, int request, int v
 	err = snd_usb_autoresume(cval->mixer->chip);
 	if (err < 0)
 		return -EIO;
-	mutex_lock(&chip->shutdown_mutex);
+	down_read(&chip->shutdown_rwsem);
 	while (timeout-- > 0) {
 		if (chip->shutdown)
 			break;
@@ -310,7 +310,7 @@ static int get_ctl_value_v1(struct usb_mixer_elem_info *cval, int request, int v
 	err = -EINVAL;
 
  out:
-	mutex_unlock(&chip->shutdown_mutex);
+	up_read(&chip->shutdown_rwsem);
 	snd_usb_autosuspend(cval->mixer->chip);
 	return err;
 }
@@ -337,7 +337,7 @@ static int get_ctl_value_v2(struct usb_mixer_elem_info *cval, int request, int v
 	if (ret)
 		goto error;
 
-	mutex_lock(&chip->shutdown_mutex);
+	down_read(&chip->shutdown_rwsem);
 	if (chip->shutdown)
 		ret = -ENODEV;
 	else {
@@ -346,7 +346,7 @@ static int get_ctl_value_v2(struct usb_mixer_elem_info *cval, int request, int v
 			      USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
 			      validx, idx, buf, size);
 	}
-	mutex_unlock(&chip->shutdown_mutex);
+	up_read(&chip->shutdown_rwsem);
 	snd_usb_autosuspend(chip);
 
 	if (ret < 0) {
@@ -453,7 +453,7 @@ int snd_usb_mixer_set_ctl_value(struct usb_mixer_elem_info *cval,
 	err = snd_usb_autoresume(chip);
 	if (err < 0)
 		return -EIO;
-	mutex_lock(&chip->shutdown_mutex);
+	down_read(&chip->shutdown_rwsem);
 	while (timeout-- > 0) {
 		if (chip->shutdown)
 			break;
@@ -471,7 +471,7 @@ int snd_usb_mixer_set_ctl_value(struct usb_mixer_elem_info *cval,
 	err = -EINVAL;
 
  out:
-	mutex_unlock(&chip->shutdown_mutex);
+	up_read(&chip->shutdown_rwsem);
 	snd_usb_autosuspend(chip);
 	return err;
 }
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 55e741c..37428f7 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -503,12 +503,12 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
 		return -EINVAL;
 	}
 
-	mutex_lock(&subs->stream->chip->shutdown_mutex);
+	down_read(&subs->stream->chip->shutdown_rwsem);
 	if (subs->stream->chip->shutdown)
 		ret = -ENODEV;
 	else
 		ret = set_format(subs, fmt);
-	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	up_read(&subs->stream->chip->shutdown_rwsem);
 	if (ret < 0)
 		return ret;
 
@@ -531,12 +531,12 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream)
 	subs->cur_audiofmt = NULL;
 	subs->cur_rate = 0;
 	subs->period_bytes = 0;
-	mutex_lock(&subs->stream->chip->shutdown_mutex);
+	down_read(&subs->stream->chip->shutdown_rwsem);
 	if (!subs->stream->chip->shutdown) {
 		stop_endpoints(subs, 0, 1, 1);
 		deactivate_endpoints(subs);
 	}
-	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	up_read(&subs->stream->chip->shutdown_rwsem);
 	return snd_pcm_lib_free_vmalloc_buffer(substream);
 }
 
@@ -558,7 +558,7 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
 		return -ENXIO;
 	}
 
-	mutex_lock(&subs->stream->chip->shutdown_mutex);
+	down_read(&subs->stream->chip->shutdown_rwsem);
 	if (subs->stream->chip->shutdown) {
 		ret = -ENODEV;
 		goto unlock;
@@ -608,7 +608,7 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
 		ret = start_endpoints(subs, 1);
 
  unlock:
-	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	up_read(&subs->stream->chip->shutdown_rwsem);
 	return ret;
 }
 
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index b8233eb..ef42797 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -37,7 +37,7 @@ struct snd_usb_audio {
 	struct usb_interface *pm_intf;
 	u32 usb_id;
 	struct mutex mutex;
-	struct mutex shutdown_mutex;
+	struct rw_semaphore shutdown_rwsem;
 	unsigned int shutdown:1;
 	unsigned int probing:1;
 	unsigned int autosuspended:1;	
-- 
1.7.12.3

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[PATCH 4/4] ALSA: usb-audio: Fix races at disconnection in mixer_quirks.c

[Takashi Iwai]

Similar like the previous commit, cover with chip->shutdown_rwsem
and chip->shutdown checks.

Signed-off-by: Takashi Iwai <tiwai-l3A5Bk7waGM@public.gmane.org>
---
 sound/usb/mixer_quirks.c | 58 ++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 51 insertions(+), 7 deletions(-)

diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
index 690000d..ae2b714 100644
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -283,6 +283,11 @@ static int snd_audigy2nx_led_put(struct snd_kcontrol *kcontrol, struct snd_ctl_e
 	if (value > 1)
 		return -EINVAL;
 	changed = value != mixer->audigy2nx_leds[index];
+	down_read(&mixer->chip->shutdown_rwsem);
+	if (mixer->chip->shutdown) {
+		err = -ENODEV;
+		goto out;
+	}
 	if (mixer->chip->usb_id == USB_ID(0x041e, 0x3042))
 		err = snd_usb_ctl_msg(mixer->chip->dev,
 			      usb_sndctrlpipe(mixer->chip->dev, 0), 0x24,
@@ -299,6 +304,8 @@ static int snd_audigy2nx_led_put(struct snd_kcontrol *kcontrol, struct snd_ctl_e
 			      usb_sndctrlpipe(mixer->chip->dev, 0), 0x24,
 			      USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_OTHER,
 			      value, index + 2, NULL, 0);
+ out:
+	up_read(&mixer->chip->shutdown_rwsem);
 	if (err < 0)
 		return err;
 	mixer->audigy2nx_leds[index] = value;
@@ -392,11 +399,16 @@ static void snd_audigy2nx_proc_read(struct snd_info_entry *entry,
 
 	for (i = 0; jacks[i].name; ++i) {
 		snd_iprintf(buffer, "%s: ", jacks[i].name);
-		err = snd_usb_ctl_msg(mixer->chip->dev,
+		down_read(&mixer->chip->shutdown_rwsem);
+		if (mixer->chip->shutdown)
+			err = 0;
+		else
+			err = snd_usb_ctl_msg(mixer->chip->dev,
 				      usb_rcvctrlpipe(mixer->chip->dev, 0),
 				      UAC_GET_MEM, USB_DIR_IN | USB_TYPE_CLASS |
 				      USB_RECIP_INTERFACE, 0,
 				      jacks[i].unitid << 8, buf, 3);
+		up_read(&mixer->chip->shutdown_rwsem);
 		if (err == 3 && (buf[0] == 3 || buf[0] == 6))
 			snd_iprintf(buffer, "%02x %02x\n", buf[1], buf[2]);
 		else
@@ -426,10 +438,15 @@ static int snd_xonar_u1_switch_put(struct snd_kcontrol *kcontrol,
 	else
 		new_status = old_status & ~0x02;
 	changed = new_status != old_status;
-	err = snd_usb_ctl_msg(mixer->chip->dev,
+	down_read(&mixer->chip->shutdown_rwsem);
+	if (mixer->chip->shutdown)
+		err = -ENODEV;
+	else
+		err = snd_usb_ctl_msg(mixer->chip->dev,
 			      usb_sndctrlpipe(mixer->chip->dev, 0), 0x08,
 			      USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_OTHER,
 			      50, 0, &new_status, 1);
+	up_read(&mixer->chip->shutdown_rwsem);
 	if (err < 0)
 		return err;
 	mixer->xonar_u1_status = new_status;
@@ -468,11 +485,17 @@ static int snd_nativeinstruments_control_get(struct snd_kcontrol *kcontrol,
 	u8 bRequest = (kcontrol->private_value >> 16) & 0xff;
 	u16 wIndex = kcontrol->private_value & 0xffff;
 	u8 tmp;
+	int ret;
 
-	int ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), bRequest,
+	down_read(&mixer->chip->shutdown_rwsem);
+	if (mixer->chip->shutdown)
+		ret = -ENODEV;
+	else
+		ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), bRequest,
 				  USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 				  0, cpu_to_le16(wIndex),
 				  &tmp, sizeof(tmp), 1000);
+	up_read(&mixer->chip->shutdown_rwsem);
 
 	if (ret < 0) {
 		snd_printk(KERN_ERR
@@ -493,11 +516,17 @@ static int snd_nativeinstruments_control_put(struct snd_kcontrol *kcontrol,
 	u8 bRequest = (kcontrol->private_value >> 16) & 0xff;
 	u16 wIndex = kcontrol->private_value & 0xffff;
 	u16 wValue = ucontrol->value.integer.value[0];
+	int ret;
 
-	int ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), bRequest,
+	down_read(&mixer->chip->shutdown_rwsem);
+	if (mixer->chip->shutdown)
+		ret = -ENODEV;
+	else
+		ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), bRequest,
 				  USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
 				  cpu_to_le16(wValue), cpu_to_le16(wIndex),
 				  NULL, 0, 1000);
+	up_read(&mixer->chip->shutdown_rwsem);
 
 	if (ret < 0) {
 		snd_printk(KERN_ERR
@@ -656,11 +685,16 @@ static int snd_ftu_eff_switch_get(struct snd_kcontrol *kctl,
 		return -EINVAL;
 
 
-	err = snd_usb_ctl_msg(chip->dev,
+	down_read(&mixer->chip->shutdown_rwsem);
+	if (mixer->chip->shutdown)
+		err = -ENODEV;
+	else
+		err = snd_usb_ctl_msg(chip->dev,
 			usb_rcvctrlpipe(chip->dev, 0), UAC_GET_CUR,
 			USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
 			validx << 8, snd_usb_ctrl_intf(chip) | (id << 8),
 			value, val_len);
+	up_read(&mixer->chip->shutdown_rwsem);
 	if (err < 0)
 		return err;
 
@@ -703,11 +737,16 @@ static int snd_ftu_eff_switch_put(struct snd_kcontrol *kctl,
 
 	if (!pval->is_cached) {
 		/* Read current value */
-		err = snd_usb_ctl_msg(chip->dev,
+		down_read(&mixer->chip->shutdown_rwsem);
+		if (mixer->chip->shutdown)
+			err = -ENODEV;
+		else
+			err = snd_usb_ctl_msg(chip->dev,
 				usb_rcvctrlpipe(chip->dev, 0), UAC_GET_CUR,
 				USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
 				validx << 8, snd_usb_ctrl_intf(chip) | (id << 8),
 				value, val_len);
+		up_read(&mixer->chip->shutdown_rwsem);
 		if (err < 0)
 			return err;
 
@@ -719,11 +758,16 @@ static int snd_ftu_eff_switch_put(struct snd_kcontrol *kctl,
 	if (cur_val != new_val) {
 		value[0] = new_val;
 		value[1] = 0;
-		err = snd_usb_ctl_msg(chip->dev,
+		down_read(&mixer->chip->shutdown_rwsem);
+		if (mixer->chip->shutdown)
+			err = -ENODEV;
+		else
+			err = snd_usb_ctl_msg(chip->dev,
 				usb_sndctrlpipe(chip->dev, 0), UAC_SET_CUR,
 				USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT,
 				validx << 8, snd_usb_ctrl_intf(chip) | (id << 8),
 				value, val_len);
+		up_read(&mixer->chip->shutdown_rwsem);
 		if (err < 0)
 			return err;
 
-- 
1.7.12.3

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[PATCH 0/2] Yet more USB-audio disconnection race fixes

[Takashi Iwai]

Hi,

these two patches are applied on the top of previous four patches for
fixing races at disconnection of USB-audio devices.  These rather
cover the core codes than USB-specific.

The whole six patches are found in topic/usb-disconnect-fix branch of
sound-unstable git tree, too.
  git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-unstable.git


Takashi
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[PATCH 1/2] ALSA: Add a reference counter to card instance

[Takashi Iwai]

For more strict protection for wild disconnections, a refcount is
introduced to the card instance, and let it up/down when an object is
referred via snd_lookup_*() in the open ops.

The free-after-last-close check is also changed to check this refcount
instead of the empty list, too.

Signed-off-by: Takashi Iwai <tiwai-l3A5Bk7waGM@public.gmane.org>
---
 include/sound/core.h          |  3 +++
 sound/core/compress_offload.c |  9 ++++++--
 sound/core/control.c          |  3 +++
 sound/core/hwdep.c            |  5 ++++-
 sound/core/init.c             | 50 ++++++++++++++++++++++++++-----------------
 sound/core/oss/mixer_oss.c    | 10 +++++++--
 sound/core/oss/pcm_oss.c      |  2 ++
 sound/core/pcm_native.c       |  9 ++++++--
 sound/core/rawmidi.c          |  6 +++++-
 sound/core/sound.c            | 11 ++++++++--
 sound/core/sound_oss.c        | 10 +++++++--
 11 files changed, 86 insertions(+), 32 deletions(-)

diff --git a/include/sound/core.h b/include/sound/core.h
index bc05668..93896ad 100644
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -132,6 +132,7 @@ struct snd_card {
 	int shutdown;			/* this card is going down */
 	int free_on_last_close;		/* free in context of file_release */
 	wait_queue_head_t shutdown_sleep;
+	atomic_t refcount;		/* refcount for disconnection */
 	struct device *dev;		/* device assigned to this card */
 	struct device *card_dev;	/* cardX object for sysfs */
 
@@ -189,6 +190,7 @@ struct snd_minor {
 	const struct file_operations *f_ops;	/* file operations */
 	void *private_data;		/* private data for f_ops->open */
 	struct device *dev;		/* device for sysfs */
+	struct snd_card *card_ptr;	/* assigned card instance */
 };
 
 /* return a device pointer linked to each sound device as a parent */
@@ -295,6 +297,7 @@ int snd_card_info_done(void);
 int snd_component_add(struct snd_card *card, const char *component);
 int snd_card_file_add(struct snd_card *card, struct file *file);
 int snd_card_file_remove(struct snd_card *card, struct file *file);
+void snd_card_unref(struct snd_card *card);
 
 #define snd_card_set_dev(card, devptr) ((card)->dev = (devptr))
 
diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index c40ae57..ad11dc9 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -100,12 +100,15 @@ static int snd_compr_open(struct inode *inode, struct file *f)
 
 	if (dirn != compr->direction) {
 		pr_err("this device doesn't support this direction\n");
+		snd_card_unref(compr->card);
 		return -EINVAL;
 	}
 
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
-	if (!data)
+	if (!data) {
+		snd_card_unref(compr->card);
 		return -ENOMEM;
+	}
 	data->stream.ops = compr->ops;
 	data->stream.direction = dirn;
 	data->stream.private_data = compr->private_data;
@@ -113,6 +116,7 @@ static int snd_compr_open(struct inode *inode, struct file *f)
 	runtime = kzalloc(sizeof(*runtime), GFP_KERNEL);
 	if (!runtime) {
 		kfree(data);
+		snd_card_unref(compr->card);
 		return -ENOMEM;
 	}
 	runtime->state = SNDRV_PCM_STATE_OPEN;
@@ -126,7 +130,8 @@ static int snd_compr_open(struct inode *inode, struct file *f)
 		kfree(runtime);
 		kfree(data);
 	}
-	return ret;
+	snd_card_unref(compr->card);
+	return 0;
 }
 
 static int snd_compr_free(struct inode *inode, struct file *f)
diff --git a/sound/core/control.c b/sound/core/control.c
index 7e86a5b..9768a39 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -86,6 +86,7 @@ static int snd_ctl_open(struct inode *inode, struct file *file)
 	write_lock_irqsave(&card->ctl_files_rwlock, flags);
 	list_add_tail(&ctl->list, &card->ctl_files);
 	write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
+	snd_card_unref(card);
 	return 0;
 
       __error:
@@ -93,6 +94,8 @@ static int snd_ctl_open(struct inode *inode, struct file *file)
       __error2:
 	snd_card_file_remove(card, file);
       __error1:
+	if (card)
+		snd_card_unref(card);
       	return err;
 }
 
diff --git a/sound/core/hwdep.c b/sound/core/hwdep.c
index 75ea16f..53a6ba5 100644
--- a/sound/core/hwdep.c
+++ b/sound/core/hwdep.c
@@ -100,8 +100,10 @@ static int snd_hwdep_open(struct inode *inode, struct file * file)
 	if (hw == NULL)
 		return -ENODEV;
 
-	if (!try_module_get(hw->card->module))
+	if (!try_module_get(hw->card->module)) {
+		snd_card_unref(hw->card);
 		return -EFAULT;
+	}
 
 	init_waitqueue_entry(&wait, current);
 	add_wait_queue(&hw->open_wait, &wait);
@@ -148,6 +150,7 @@ static int snd_hwdep_open(struct inode *inode, struct file * file)
 	mutex_unlock(&hw->open_mutex);
 	if (err < 0)
 		module_put(hw->card->module);
+	snd_card_unref(hw->card);
 	return err;
 }
 
diff --git a/sound/core/init.c b/sound/core/init.c
index d8ec849..7b012d1 100644
--- a/sound/core/init.c
+++ b/sound/core/init.c
@@ -213,6 +213,7 @@ int snd_card_create(int idx, const char *xid,
 	spin_lock_init(&card->files_lock);
 	INIT_LIST_HEAD(&card->files_list);
 	init_waitqueue_head(&card->shutdown_sleep);
+	atomic_set(&card->refcount, 0);
 #ifdef CONFIG_PM
 	mutex_init(&card->power_lock);
 	init_waitqueue_head(&card->power_sleep);
@@ -446,21 +447,36 @@ static int snd_card_do_free(struct snd_card *card)
 	return 0;
 }
 
+/**
+ * snd_card_unref - release the reference counter
+ * @card: the card instance
+ *
+ * Decrements the reference counter.  When it reaches to zero, wake up
+ * the sleeper and call the destructor if needed.
+ */
+void snd_card_unref(struct snd_card *card)
+{
+	if (atomic_dec_and_test(&card->refcount)) {
+		wake_up(&card->shutdown_sleep);
+		if (card->free_on_last_close)
+			snd_card_do_free(card);
+	}
+}
+EXPORT_SYMBOL(snd_card_unref);
+
 int snd_card_free_when_closed(struct snd_card *card)
 {
-	int free_now = 0;
-	int ret = snd_card_disconnect(card);
-	if (ret)
-		return ret;
+	int ret;
 
-	spin_lock(&card->files_lock);
-	if (list_empty(&card->files_list))
-		free_now = 1;
-	else
-		card->free_on_last_close = 1;
-	spin_unlock(&card->files_lock);
+	atomic_inc(&card->refcount);
+	ret = snd_card_disconnect(card);
+	if (ret) {
+		atomic_dec(&card->refcount);
+		return ret;
+	}
 
-	if (free_now)
+	card->free_on_last_close = 1;
+	if (atomic_dec_and_test(&card->refcount))
 		snd_card_do_free(card);
 	return 0;
 }
@@ -474,7 +490,7 @@ int snd_card_free(struct snd_card *card)
 		return ret;
 
 	/* wait, until all devices are ready for the free operation */
-	wait_event(card->shutdown_sleep, list_empty(&card->files_list));
+	wait_event(card->shutdown_sleep, !atomic_read(&card->refcount));
 	snd_card_do_free(card);
 	return 0;
 }
@@ -886,6 +902,7 @@ int snd_card_file_add(struct snd_card *card, struct file *file)
 		return -ENODEV;
 	}
 	list_add(&mfile->list, &card->files_list);
+	atomic_inc(&card->refcount);
 	spin_unlock(&card->files_lock);
 	return 0;
 }
@@ -908,7 +925,6 @@ EXPORT_SYMBOL(snd_card_file_add);
 int snd_card_file_remove(struct snd_card *card, struct file *file)
 {
 	struct snd_monitor_file *mfile, *found = NULL;
-	int last_close = 0;
 
 	spin_lock(&card->files_lock);
 	list_for_each_entry(mfile, &card->files_list, list) {
@@ -923,19 +939,13 @@ int snd_card_file_remove(struct snd_card *card, struct file *file)
 			break;
 		}
 	}
-	if (list_empty(&card->files_list))
-		last_close = 1;
 	spin_unlock(&card->files_lock);
-	if (last_close) {
-		wake_up(&card->shutdown_sleep);
-		if (card->free_on_last_close)
-			snd_card_do_free(card);
-	}
 	if (!found) {
 		snd_printk(KERN_ERR "ALSA card file remove problem (%p)\n", file);
 		return -ENOENT;
 	}
 	kfree(found);
+	snd_card_unref(card);
 	return 0;
 }
 
diff --git a/sound/core/oss/mixer_oss.c b/sound/core/oss/mixer_oss.c
index 29f6ded..a9a2e63 100644
--- a/sound/core/oss/mixer_oss.c
+++ b/sound/core/oss/mixer_oss.c
@@ -52,14 +52,19 @@ static int snd_mixer_oss_open(struct inode *inode, struct file *file)
 					 SNDRV_OSS_DEVICE_TYPE_MIXER);
 	if (card == NULL)
 		return -ENODEV;
-	if (card->mixer_oss == NULL)
+	if (card->mixer_oss == NULL) {
+		snd_card_unref(card);
 		return -ENODEV;
+	}
 	err = snd_card_file_add(card, file);
-	if (err < 0)
+	if (err < 0) {
+		snd_card_unref(card);
 		return err;
+	}
 	fmixer = kzalloc(sizeof(*fmixer), GFP_KERNEL);
 	if (fmixer == NULL) {
 		snd_card_file_remove(card, file);
+		snd_card_unref(card);
 		return -ENOMEM;
 	}
 	fmixer->card = card;
@@ -68,6 +73,7 @@ static int snd_mixer_oss_open(struct inode *inode, struct file *file)
 	if (!try_module_get(card->module)) {
 		kfree(fmixer);
 		snd_card_file_remove(card, file);
+		snd_card_unref(card);
 		return -EFAULT;
 	}
 	return 0;
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index 08fde00..2529e01 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -2457,6 +2457,8 @@ static int snd_pcm_oss_open(struct inode *inode, struct file *file)
       __error2:
       	snd_card_file_remove(pcm->card, file);
       __error1:
+	if (pcm)
+		snd_card_unref(pcm->card);
 	return err;
 }
 
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 8753c89..48c6a70 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1642,6 +1642,7 @@ static int snd_pcm_link(struct snd_pcm_substream *substream, int fd)
 	write_unlock_irq(&snd_pcm_link_rwlock);
 	up_write(&snd_pcm_link_rwsem);
  _nolock:
+	snd_card_unref(substream1->pcm->card);
 	fput_light(file, fput_needed);
 	if (res < 0)
 		kfree(group);
@@ -2116,7 +2117,9 @@ static int snd_pcm_playback_open(struct inode *inode, struct file *file)
 		return err;
 	pcm = snd_lookup_minor_data(iminor(inode),
 				    SNDRV_DEVICE_TYPE_PCM_PLAYBACK);
-	return snd_pcm_open(file, pcm, SNDRV_PCM_STREAM_PLAYBACK);
+	err = snd_pcm_open(file, pcm, SNDRV_PCM_STREAM_PLAYBACK);
+	snd_card_unref(pcm->card);
+	return err;
 }
 
 static int snd_pcm_capture_open(struct inode *inode, struct file *file)
@@ -2127,7 +2130,9 @@ static int snd_pcm_capture_open(struct inode *inode, struct file *file)
 		return err;
 	pcm = snd_lookup_minor_data(iminor(inode),
 				    SNDRV_DEVICE_TYPE_PCM_CAPTURE);
-	return snd_pcm_open(file, pcm, SNDRV_PCM_STREAM_CAPTURE);
+	err = snd_pcm_open(file, pcm, SNDRV_PCM_STREAM_CAPTURE);
+	snd_card_unref(pcm->card);
+	return err;
 }
 
 static int snd_pcm_open(struct file *file, struct snd_pcm *pcm, int stream)
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index ebf6e49..7d4f62a 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -379,8 +379,10 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
 	if (rmidi == NULL)
 		return -ENODEV;
 
-	if (!try_module_get(rmidi->card->module))
+	if (!try_module_get(rmidi->card->module)) {
+		snd_card_unref(rmidi->card);
 		return -ENXIO;
+	}
 
 	mutex_lock(&rmidi->open_mutex);
 	card = rmidi->card;
@@ -440,6 +442,7 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
 #endif
 	file->private_data = rawmidi_file;
 	mutex_unlock(&rmidi->open_mutex);
+	snd_card_unref(rmidi->card);
 	return 0;
 
  __error:
@@ -447,6 +450,7 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
  __error_card:
 	mutex_unlock(&rmidi->open_mutex);
 	module_put(rmidi->card->module);
+	snd_card_unref(rmidi->card);
 	return err;
 }
 
diff --git a/sound/core/sound.c b/sound/core/sound.c
index 6439760..89780c3 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -98,6 +98,10 @@ static void snd_request_other(int minor)
  *
  * Checks that a minor device with the specified type is registered, and returns
  * its user data pointer.
+ *
+ * This function increments the reference counter of the card instance
+ * if an associated instance with the given minor number and type is found.
+ * The caller must call snd_card_unref() appropriately later.
  */
 void *snd_lookup_minor_data(unsigned int minor, int type)
 {
@@ -108,9 +112,11 @@ void *snd_lookup_minor_data(unsigned int minor, int type)
 		return NULL;
 	mutex_lock(&sound_mutex);
 	mreg = snd_minors[minor];
-	if (mreg && mreg->type == type)
+	if (mreg && mreg->type == type) {
 		private_data = mreg->private_data;
-	else
+		if (mreg->card_ptr)
+			atomic_inc(&mreg->card_ptr->refcount);
+	} else
 		private_data = NULL;
 	mutex_unlock(&sound_mutex);
 	return private_data;
@@ -275,6 +281,7 @@ int snd_register_device_for_dev(int type, struct snd_card *card, int dev,
 	preg->device = dev;
 	preg->f_ops = f_ops;
 	preg->private_data = private_data;
+	preg->card_ptr = card;
 	mutex_lock(&sound_mutex);
 #ifdef CONFIG_SND_DYNAMIC_MINORS
 	minor = snd_find_free_minor(type);
diff --git a/sound/core/sound_oss.c b/sound/core/sound_oss.c
index e952833..e1d79ee 100644
--- a/sound/core/sound_oss.c
+++ b/sound/core/sound_oss.c
@@ -40,6 +40,9 @@
 static struct snd_minor *snd_oss_minors[SNDRV_OSS_MINORS];
 static DEFINE_MUTEX(sound_oss_mutex);
 
+/* NOTE: This function increments the refcount of the associated card like
+ * snd_lookup_minor_data(); the caller must call snd_card_unref() appropriately
+ */
 void *snd_lookup_oss_minor_data(unsigned int minor, int type)
 {
 	struct snd_minor *mreg;
@@ -49,9 +52,11 @@ void *snd_lookup_oss_minor_data(unsigned int minor, int type)
 		return NULL;
 	mutex_lock(&sound_oss_mutex);
 	mreg = snd_oss_minors[minor];
-	if (mreg && mreg->type == type)
+	if (mreg && mreg->type == type) {
 		private_data = mreg->private_data;
-	else
+		if (mreg->card_ptr)
+			atomic_inc(&mreg->card_ptr->refcount);
+	} else
 		private_data = NULL;
 	mutex_unlock(&sound_oss_mutex);
 	return private_data;
@@ -123,6 +128,7 @@ int snd_register_oss_device(int type, struct snd_card *card, int dev,
 	preg->device = dev;
 	preg->f_ops = f_ops;
 	preg->private_data = private_data;
+	preg->card_ptr = card;
 	mutex_lock(&sound_oss_mutex);
 	snd_oss_minors[minor] = preg;
 	minor_unit = SNDRV_MINOR_OSS_DEVICE(minor);
-- 
1.7.12.3

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[PATCH 2/2] ALSA: Avoid endless sleep after disconnect

[Takashi Iwai]

When disconnect callback is called, each component should wake up
sleepers and check card->shutdown flag for avoiding the endless sleep
blocking the proper resource release.

Signed-off-by: Takashi Iwai <tiwai-l3A5Bk7waGM@public.gmane.org>
---
 sound/core/control.c     |  2 ++
 sound/core/hwdep.c       |  7 +++++++
 sound/core/oss/pcm_oss.c |  4 ++++
 sound/core/pcm.c         |  6 +++++-
 sound/core/pcm_native.c  |  8 ++++++++
 sound/core/rawmidi.c     | 20 ++++++++++++++++++++
 6 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/sound/core/control.c b/sound/core/control.c
index 9768a39..8c7c2c9 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -1437,6 +1437,8 @@ static ssize_t snd_ctl_read(struct file *file, char __user *buffer,
 			spin_unlock_irq(&ctl->read_lock);
 			schedule();
 			remove_wait_queue(&ctl->change_sleep, &wait);
+			if (ctl->card->shutdown)
+				return -ENODEV;
 			if (signal_pending(current))
 				return -ERESTARTSYS;
 			spin_lock_irq(&ctl->read_lock);
diff --git a/sound/core/hwdep.c b/sound/core/hwdep.c
index 53a6ba5..3f7f662 100644
--- a/sound/core/hwdep.c
+++ b/sound/core/hwdep.c
@@ -131,6 +131,10 @@ static int snd_hwdep_open(struct inode *inode, struct file * file)
 		mutex_unlock(&hw->open_mutex);
 		schedule();
 		mutex_lock(&hw->open_mutex);
+		if (hw->card->shutdown) {
+			err = -ENODEV;
+			break;
+		}
 		if (signal_pending(current)) {
 			err = -ERESTARTSYS;
 			break;
@@ -462,12 +466,15 @@ static int snd_hwdep_dev_disconnect(struct snd_device *device)
 		mutex_unlock(&register_mutex);
 		return -EINVAL;
 	}
+	mutex_lock(&hwdep->open_mutex);
+	wake_up(&hwdep->open_wait);
 #ifdef CONFIG_SND_OSSEMUL
 	if (hwdep->ossreg)
 		snd_unregister_oss_device(hwdep->oss_type, hwdep->card, hwdep->device);
 #endif
 	snd_unregister_device(SNDRV_DEVICE_TYPE_HWDEP, hwdep->card, hwdep->device);
 	list_del_init(&hwdep->list);
+	mutex_unlock(&hwdep->open_mutex);
 	mutex_unlock(&register_mutex);
 	return 0;
 }
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index 2529e01..f337b66 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -2441,6 +2441,10 @@ static int snd_pcm_oss_open(struct inode *inode, struct file *file)
 		mutex_unlock(&pcm->open_mutex);
 		schedule();
 		mutex_lock(&pcm->open_mutex);
+		if (pcm->card->shutdown) {
+			err = -ENODEV;
+			break;
+		}
 		if (signal_pending(current)) {
 			err = -ERESTARTSYS;
 			break;
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 993b240..030102c 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -1087,12 +1087,16 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 		goto unlock;
 
 	mutex_lock(&pcm->open_mutex);
+	wake_up(&pcm->open_wait);
 	list_del_init(&pcm->list);
 	for (cidx = 0; cidx < 2; cidx++)
 		for (substream = pcm->streams[cidx].substream; substream; substream = substream->next) {
 			snd_pcm_stream_lock_irq(substream);
-			if (substream->runtime)
+			if (substream->runtime) {
 				substream->runtime->status->state = SNDRV_PCM_STATE_DISCONNECTED;
+				wake_up(&substream->runtime->sleep);
+				wake_up(&substream->runtime->tsleep);
+			}
 			snd_pcm_stream_unlock_irq(substream);
 		}
 	list_for_each_entry(notify, &snd_pcm_notify_list, list) {
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 48c6a70..6e8872d 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1518,6 +1518,10 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream,
 		down_read(&snd_pcm_link_rwsem);
 		snd_pcm_stream_lock_irq(substream);
 		remove_wait_queue(&to_check->sleep, &wait);
+		if (card->shutdown) {
+			result = -ENODEV;
+			break;
+		}
 		if (tout == 0) {
 			if (substream->runtime->status->state == SNDRV_PCM_STATE_SUSPENDED)
 				result = -ESTRPIPE;
@@ -2169,6 +2173,10 @@ static int snd_pcm_open(struct file *file, struct snd_pcm *pcm, int stream)
 		mutex_unlock(&pcm->open_mutex);
 		schedule();
 		mutex_lock(&pcm->open_mutex);
+		if (pcm->card->shutdown) {
+			err = -ENODEV;
+			break;
+		}
 		if (signal_pending(current)) {
 			err = -ERESTARTSYS;
 			break;
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index 7d4f62a..1bb95ae 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -424,6 +424,10 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
 		mutex_unlock(&rmidi->open_mutex);
 		schedule();
 		mutex_lock(&rmidi->open_mutex);
+		if (rmidi->card->shutdown) {
+			err = -ENODEV;
+			break;
+		}
 		if (signal_pending(current)) {
 			err = -ERESTARTSYS;
 			break;
@@ -995,6 +999,8 @@ static ssize_t snd_rawmidi_read(struct file *file, char __user *buf, size_t coun
 			spin_unlock_irq(&runtime->lock);
 			schedule();
 			remove_wait_queue(&runtime->sleep, &wait);
+			if (rfile->rmidi->card->shutdown)
+				return -ENODEV;
 			if (signal_pending(current))
 				return result > 0 ? result : -ERESTARTSYS;
 			if (!runtime->avail)
@@ -1238,6 +1244,8 @@ static ssize_t snd_rawmidi_write(struct file *file, const char __user *buf,
 			spin_unlock_irq(&runtime->lock);
 			timeout = schedule_timeout(30 * HZ);
 			remove_wait_queue(&runtime->sleep, &wait);
+			if (rfile->rmidi->card->shutdown)
+				return -ENODEV;
 			if (signal_pending(current))
 				return result > 0 ? result : -ERESTARTSYS;
 			if (!runtime->avail && !timeout)
@@ -1613,9 +1621,20 @@ static int snd_rawmidi_dev_register(struct snd_device *device)
 static int snd_rawmidi_dev_disconnect(struct snd_device *device)
 {
 	struct snd_rawmidi *rmidi = device->device_data;
+	int dir;
 
 	mutex_lock(&register_mutex);
+	mutex_lock(&rmidi->open_mutex);
+	wake_up(&rmidi->open_wait);
 	list_del_init(&rmidi->list);
+	for (dir = 0; dir < 2; dir++) {
+		struct snd_rawmidi_substream *s;
+		list_for_each_entry(s, &rmidi->streams[dir].substreams, list) {
+			if (s->runtime)
+				wake_up(&s->runtime->sleep);
+		}
+	}
+
 #ifdef CONFIG_SND_OSSEMUL
 	if (rmidi->ossreg) {
 		if ((int)rmidi->device == midi_map[rmidi->card->number]) {
@@ -1630,6 +1649,7 @@ static int snd_rawmidi_dev_disconnect(struct snd_device *device)
 	}
 #endif /* CONFIG_SND_OSSEMUL */
 	snd_unregister_device(SNDRV_DEVICE_TYPE_RAWMIDI, rmidi->card, rmidi->device);
+	mutex_unlock(&rmidi->open_mutex);
 	mutex_unlock(&register_mutex);
 	return 0;
 }
-- 
1.7.12.3

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