[PATCH 0/4] Internal PCM fixes / cleanups

[PATCH 0/4] Internal PCM fixes / cleanups

[Takashi Iwai]

Hi,

while reading the internal PCM (BE) handling code again, I noticed a
few potential bugs.  Here are fix and cleanup patches.


Takashi

===

Takashi Iwai (4):
  ALSA: pcm: Minor refactoring in snd_pcm_attach_substream()
  ALSA: pcm: Don't add internal PCMs to PCM device list
  ALSA: pcm: Don't notify internal PCMs
  ALSA: pcm: Don't ignore internal PCMs in snd_pcm_dev_disconnect()

 sound/core/pcm.c | 92 +++++++++++++++++++++++++-------------------------------
 1 file changed, 41 insertions(+), 51 deletions(-)

-- 
2.3.0

[PATCH 1/4] ALSA: pcm: Minor refactoring in snd_pcm_attach_substream()

[Takashi Iwai]

No functional changes at all.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/pcm.c | 41 +++++++++++++++--------------------------
 1 file changed, 15 insertions(+), 26 deletions(-)

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 0345e53a340c..89206e9c3578 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -919,6 +919,9 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
 
 	if (snd_BUG_ON(!pcm || !rsubstream))
 		return -ENXIO;
+	if (snd_BUG_ON(stream != SNDRV_PCM_STREAM_PLAYBACK ||
+		       stream != SNDRV_PCM_STREAM_CAPTURE))
+		return -EINVAL;
 	*rsubstream = NULL;
 	pstr = &pcm->streams[stream];
 	if (pstr->substream == NULL || pstr->substream_count == 0)
@@ -927,25 +930,14 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
 	card = pcm->card;
 	prefer_subdevice = snd_ctl_get_preferred_subdevice(card, SND_CTL_SUBDEV_PCM);
 
-	switch (stream) {
-	case SNDRV_PCM_STREAM_PLAYBACK:
-		if (pcm->info_flags & SNDRV_PCM_INFO_HALF_DUPLEX) {
-			for (substream = pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream; substream; substream = substream->next) {
-				if (SUBSTREAM_BUSY(substream))
-					return -EAGAIN;
-			}
-		}
-		break;
-	case SNDRV_PCM_STREAM_CAPTURE:
-		if (pcm->info_flags & SNDRV_PCM_INFO_HALF_DUPLEX) {
-			for (substream = pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream; substream; substream = substream->next) {
-				if (SUBSTREAM_BUSY(substream))
-					return -EAGAIN;
-			}
+	if (pcm->info_flags & SNDRV_PCM_INFO_HALF_DUPLEX) {
+		int opposite = !stream;
+
+		for (substream = pcm->streams[opposite].substream; substream;
+		     substream = substream->next) {
+			if (SUBSTREAM_BUSY(substream))
+				return -EAGAIN;
 		}
-		break;
-	default:
-		return -EINVAL;
 	}
 
 	if (file->f_flags & O_APPEND) {
@@ -968,15 +960,12 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
 		return 0;
 	}
 
-	if (prefer_subdevice >= 0) {
-		for (substream = pstr->substream; substream; substream = substream->next)
-			if (!SUBSTREAM_BUSY(substream) && substream->number == prefer_subdevice)
-				goto __ok;
-	}
-	for (substream = pstr->substream; substream; substream = substream->next)
-		if (!SUBSTREAM_BUSY(substream))
+	for (substream = pstr->substream; substream; substream = substream->next) {
+		if (!SUBSTREAM_BUSY(substream) &&
+		    (prefer_subdevice == -1 ||
+		     substream->number == prefer_subdevice))
 			break;
-      __ok:
+	}
 	if (substream == NULL)
 		return -EAGAIN;
 
-- 
2.3.0

Re: [PATCH 1/4] ALSA: pcm: Minor refactoring in snd_pcm_attach_substream()

[Takashi Iwai]

At Fri, 20 Feb 2015 17:23:25 +0100,
Takashi Iwai wrote:
> 
> No functional changes at all.
> 
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> ---
>  sound/core/pcm.c | 41 +++++++++++++++--------------------------
>  1 file changed, 15 insertions(+), 26 deletions(-)
> 
> diff --git a/sound/core/pcm.c b/sound/core/pcm.c
> index 0345e53a340c..89206e9c3578 100644
> --- a/sound/core/pcm.c
> +++ b/sound/core/pcm.c
> @@ -919,6 +919,9 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
>  
>  	if (snd_BUG_ON(!pcm || !rsubstream))
>  		return -ENXIO;
> +	if (snd_BUG_ON(stream != SNDRV_PCM_STREAM_PLAYBACK ||
> +		       stream != SNDRV_PCM_STREAM_CAPTURE))

Gah, this must be &&.  Fixed in the topic/pcm-internal branch.


Takashi

[PATCH 2/4] ALSA: pcm: Don't add internal PCMs to PCM device list

[Takashi Iwai]

An internal PCM object shouldn't be added to the PCM device list, as
it's never accessed directly from the user-space, and it has no proc
or any similar accesses.  Currently, it's excluded in snd_pcm_get()
and snd_pcm_next(), but it's easier not to add such an object to the
list.

Actually, the whole snd_pcm_dev_register() can be skipped for an
internal PCM.  So this patch changes the code there, but also
addresses the uninitialized list_head access.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/pcm.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 89206e9c3578..92bbb5143b83 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -49,8 +49,6 @@ static struct snd_pcm *snd_pcm_get(struct snd_card *card, int device)
 	struct snd_pcm *pcm;
 
 	list_for_each_entry(pcm, &snd_pcm_devices, list) {
-		if (pcm->internal)
-			continue;
 		if (pcm->card == card && pcm->device == device)
 			return pcm;
 	}
@@ -62,8 +60,6 @@ static int snd_pcm_next(struct snd_card *card, int device)
 	struct snd_pcm *pcm;
 
 	list_for_each_entry(pcm, &snd_pcm_devices, list) {
-		if (pcm->internal)
-			continue;
 		if (pcm->card == card && pcm->device > device)
 			return pcm->device;
 		else if (pcm->card->number > card->number)
@@ -76,6 +72,9 @@ static int snd_pcm_add(struct snd_pcm *newpcm)
 {
 	struct snd_pcm *pcm;
 
+	if (newpcm->internal)
+		return 0;
+
 	list_for_each_entry(pcm, &snd_pcm_devices, list) {
 		if (pcm->card == newpcm->card && pcm->device == newpcm->device)
 			return -EBUSY;
@@ -782,6 +781,9 @@ static int _snd_pcm_new(struct snd_card *card, const char *id, int device,
 	pcm->card = card;
 	pcm->device = device;
 	pcm->internal = internal;
+	mutex_init(&pcm->open_mutex);
+	init_waitqueue_head(&pcm->open_wait);
+	INIT_LIST_HEAD(&pcm->list);
 	if (id)
 		strlcpy(pcm->id, id, sizeof(pcm->id));
 	if ((err = snd_pcm_new_stream(pcm, SNDRV_PCM_STREAM_PLAYBACK, playback_count)) < 0) {
@@ -792,8 +794,6 @@ static int _snd_pcm_new(struct snd_card *card, const char *id, int device,
 		snd_pcm_free(pcm);
 		return err;
 	}
-	mutex_init(&pcm->open_mutex);
-	init_waitqueue_head(&pcm->open_wait);
 	if ((err = snd_device_new(card, SNDRV_DEV_PCM, pcm, &ops)) < 0) {
 		snd_pcm_free(pcm);
 		return err;
@@ -1075,15 +1075,16 @@ static int snd_pcm_dev_register(struct snd_device *device)
 	if (snd_BUG_ON(!device || !device->device_data))
 		return -ENXIO;
 	pcm = device->device_data;
+	if (pcm->internal)
+		return 0;
+
 	mutex_lock(&register_mutex);
 	err = snd_pcm_add(pcm);
-	if (err) {
-		mutex_unlock(&register_mutex);
-		return err;
-	}
+	if (err)
+		goto unlock;
 	for (cidx = 0; cidx < 2; cidx++) {
 		int devtype = -1;
-		if (pcm->streams[cidx].substream == NULL || pcm->internal)
+		if (pcm->streams[cidx].substream == NULL)
 			continue;
 		switch (cidx) {
 		case SNDRV_PCM_STREAM_PLAYBACK:
@@ -1098,9 +1099,8 @@ static int snd_pcm_dev_register(struct snd_device *device)
 					  &snd_pcm_f_ops[cidx], pcm,
 					  &pcm->streams[cidx].dev);
 		if (err < 0) {
-			list_del(&pcm->list);
-			mutex_unlock(&register_mutex);
-			return err;
+			list_del_init(&pcm->list);
+			goto unlock;
 		}
 
 		for (substream = pcm->streams[cidx].substream; substream; substream = substream->next)
@@ -1110,8 +1110,9 @@ static int snd_pcm_dev_register(struct snd_device *device)
 	list_for_each_entry(notify, &snd_pcm_notify_list, list)
 		notify->n_register(pcm);
 
+ unlock:
 	mutex_unlock(&register_mutex);
-	return 0;
+	return err;
 }
 
 static int snd_pcm_dev_disconnect(struct snd_device *device)
-- 
2.3.0

[PATCH 3/4] ALSA: pcm: Don't notify internal PCMs

[Takashi Iwai]

Notifier shouldn't listen to the changes of internal PCMs.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/pcm.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 92bbb5143b83..3cf345426171 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -888,8 +888,9 @@ static int snd_pcm_free(struct snd_pcm *pcm)
 
 	if (!pcm)
 		return 0;
-	list_for_each_entry(notify, &snd_pcm_notify_list, list) {
-		notify->n_unregister(pcm);
+	if (!pcm->internal) {
+		list_for_each_entry(notify, &snd_pcm_notify_list, list)
+			notify->n_unregister(pcm);
 	}
 	if (pcm->private_free)
 		pcm->private_free(pcm);
@@ -1129,7 +1130,7 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 	mutex_lock(&pcm->open_mutex);
 	wake_up(&pcm->open_wait);
 	list_del_init(&pcm->list);
-	for (cidx = 0; cidx < 2; cidx++)
+	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) {
@@ -1139,8 +1140,10 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 			}
 			snd_pcm_stream_unlock_irq(substream);
 		}
-	list_for_each_entry(notify, &snd_pcm_notify_list, list) {
-		notify->n_disconnect(pcm);
+	}
+	if (!pcm->internal) {
+		list_for_each_entry(notify, &snd_pcm_notify_list, list)
+			notify->n_disconnect(pcm);
 	}
 	for (cidx = 0; cidx < 2; cidx++) {
 		snd_unregister_device(&pcm->streams[cidx].dev);
-- 
2.3.0

[PATCH 4/4] ALSA: pcm: Don't ignore internal PCMs in snd_pcm_dev_disconnect()

[Takashi Iwai]

Some codes in snd_pcm_dev_disconnect() are still valid even for
internal PCMs, but they are skipped because of the check of
list_empty(&pcm->list) at the beginning.  Remove this check and put
pcm->internal checks appropriately for internal PCM object to process
through this function.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/pcm.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 3cf345426171..64e726658ca1 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -1124,9 +1124,6 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 	int cidx;
 
 	mutex_lock(&register_mutex);
-	if (list_empty(&pcm->list))
-		goto unlock;
-
 	mutex_lock(&pcm->open_mutex);
 	wake_up(&pcm->open_wait);
 	list_del_init(&pcm->list);
@@ -1146,14 +1143,14 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 			notify->n_disconnect(pcm);
 	}
 	for (cidx = 0; cidx < 2; cidx++) {
-		snd_unregister_device(&pcm->streams[cidx].dev);
+		if (!pcm->internal)
+			snd_unregister_device(&pcm->streams[cidx].dev);
 		if (pcm->streams[cidx].chmap_kctl) {
 			snd_ctl_remove(pcm->card, pcm->streams[cidx].chmap_kctl);
 			pcm->streams[cidx].chmap_kctl = NULL;
 		}
 	}
 	mutex_unlock(&pcm->open_mutex);
- unlock:
 	mutex_unlock(&register_mutex);
 	return 0;
 }
-- 
2.3.0

Re: [PATCH 0/4] Internal PCM fixes / cleanups

[Liam Girdwood]

On Fri, 2015-02-20 at 17:23 +0100, Takashi Iwai wrote:
> Hi,
> 
> while reading the internal PCM (BE) handling code again, I noticed a
> few potential bugs.  Here are fix and cleanup patches.
> 
> 
> Takashi
> 
> ===
> 
> Takashi Iwai (4):
>   ALSA: pcm: Minor refactoring in snd_pcm_attach_substream()
>   ALSA: pcm: Don't add internal PCMs to PCM device list
>   ALSA: pcm: Don't notify internal PCMs
>   ALSA: pcm: Don't ignore internal PCMs in snd_pcm_dev_disconnect()
> 
>  sound/core/pcm.c | 92 +++++++++++++++++++++++++-------------------------------
>  1 file changed, 41 insertions(+), 51 deletions(-)
> 

All

Acked-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

Re: [PATCH 0/4] Internal PCM fixes / cleanups

[Takashi Iwai]

At Fri, 20 Feb 2015 18:42:23 +0000,
Liam Girdwood wrote:
> 
> On Fri, 2015-02-20 at 17:23 +0100, Takashi Iwai wrote:
> > Hi,
> > 
> > while reading the internal PCM (BE) handling code again, I noticed a
> > few potential bugs.  Here are fix and cleanup patches.
> > 
> > 
> > Takashi
> > 
> > ===
> > 
> > Takashi Iwai (4):
> >   ALSA: pcm: Minor refactoring in snd_pcm_attach_substream()
> >   ALSA: pcm: Don't add internal PCMs to PCM device list
> >   ALSA: pcm: Don't notify internal PCMs
> >   ALSA: pcm: Don't ignore internal PCMs in snd_pcm_dev_disconnect()
> > 
> >  sound/core/pcm.c | 92 +++++++++++++++++++++++++-------------------------------
> >  1 file changed, 41 insertions(+), 51 deletions(-)
> > 
> 
> All
> 
> Acked-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

Thanks, added your ack to topic/pcm-internal branch.


Takashi