trying out usb hotplugs

trying out usb hotplugs

[Martin Langer]

Hi,

usb hotplug works perfect if my usbmidi client isn't aconnected to another
midi client. But the aconnected usb midi device still remains in the clients
list, after hotpluging out. The next hotplug in of my usb device needs an
aconnect -x before or I won't see my card in /proc/asound/cards again.
But I haven't found a real problem during my tests of usb hotpluging. Thanks.


martin


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Re: trying out usb hotplugs

[Takashi Iwai]

At Thu, 28 Nov 2002 01:27:02 +0100,
Martin Langer wrote:
> 
> 
> Hi,
> 
> usb hotplug works perfect if my usbmidi client isn't aconnected to another
> midi client. But the aconnected usb midi device still remains in the clients
> list, after hotpluging out. The next hotplug in of my usb device needs an
> aconnect -x before or I won't see my card in /proc/asound/cards again.
> But I haven't found a real problem during my tests of usb hotpluging. Thanks.

yep,  when the connection exists, the connected devices (on both
sides) are regarded as active.
i'll check at which stage this activity is checked and stalled.


Takashi


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Re: trying out usb hotplugs

[Clemens Ladisch]

Takashi Iwai wrote:
> Martin Langer wrote:
> > usb hotplug works perfect if my usbmidi client isn't aconnected to another
> > midi client. But the aconnected usb midi device still remains in the clients
> > list, after hotpluging out.
>
> yep,  when the connection exists, the connected devices (on both
> sides) are regarded as active.

The sequencer design allows asynchronous removal of clients.


--- alsa-kernel/core/seq/seq_device.c.orig	Wed Aug 14 18:11:13 2002
+++ alsa-kernel/core/seq/seq_device.c	Thu Nov 28 23:05:47 2002
@@ -92,6 +92,7 @@
 static int snd_seq_device_free(snd_seq_device_t *dev);
 static int snd_seq_device_dev_free(snd_device_t *device);
 static int snd_seq_device_dev_register(snd_device_t *device);
+static int snd_seq_device_dev_disconnect(snd_device_t *device);
 static int snd_seq_device_dev_unregister(snd_device_t *device);

 static int init_device(snd_seq_device_t *dev, ops_list_t *ops);
@@ -166,6 +167,7 @@
 	static snd_device_ops_t dops = {
 		.dev_free = snd_seq_device_dev_free,
 		.dev_register = snd_seq_device_dev_register,
+		.dev_disconnect = snd_seq_device_dev_disconnect,
 		.dev_unregister = snd_seq_device_dev_unregister
 	};

@@ -265,6 +267,22 @@
 		init_device(dev, ops);

 	unlock_driver(ops);
+	return 0;
+}
+
+/*
+ * disconnect the device
+ */
+static int snd_seq_device_dev_disconnect(snd_device_t *device)
+{
+	snd_seq_device_t *dev = snd_magic_cast(snd_seq_device_t, device->device_data, return -ENXIO);
+	ops_list_t *ops;
+
+	ops = find_driver(dev->id, 0);
+	if (ops == NULL)
+		return -ENOENT;
+
+	free_device(dev, ops);
 	return 0;
 }




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Re: trying out usb hotplugs

[Takashi Iwai]

At Fri, 29 Nov 2002 08:52:43 +0100 (MET),
Clemens Ladisch wrote:
> 
> Takashi Iwai wrote:
> > Martin Langer wrote:
> > > usb hotplug works perfect if my usbmidi client isn't aconnected to another
> > > midi client. But the aconnected usb midi device still remains in the clients
> > > list, after hotpluging out.
> >
> > yep,  when the connection exists, the connected devices (on both
> > sides) are regarded as active.
> 
> The sequencer design allows asynchronous removal of clients.

yes, but this may still try to send some bytes to the unplugged
rawmidi device at the disconnection.  i'll change rawmidi code to
ignore that.

thanks for your patch, anyway!


Takashi


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Re: trying out usb hotplugs

[Jaroslav Kysela]

On Fri, 29 Nov 2002, Takashi Iwai wrote:

> At Fri, 29 Nov 2002 08:52:43 +0100 (MET),
> Clemens Ladisch wrote:
> > 
> > Takashi Iwai wrote:
> > > Martin Langer wrote:
> > > > usb hotplug works perfect if my usbmidi client isn't aconnected to another
> > > > midi client. But the aconnected usb midi device still remains in the clients
> > > > list, after hotpluging out.
> > >
> > > yep,  when the connection exists, the connected devices (on both
> > > sides) are regarded as active.
> > 
> > The sequencer design allows asynchronous removal of clients.
> 
> yes, but this may still try to send some bytes to the unplugged
> rawmidi device at the disconnection.  i'll change rawmidi code to
> ignore that.

Well, I'm trying to solve these "hotplug" problems. Unfortunately, it 
seems difficult to detect, if another task is in the middle of our 
callback. I think that we'll end up using mutexes.

						Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs



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Re: trying out usb hotplugs

[Takashi Iwai]

At Fri, 29 Nov 2002 10:39:22 +0100 (CET),
Jaroslav wrote:
> 
> On Fri, 29 Nov 2002, Takashi Iwai wrote:
> 
> > At Fri, 29 Nov 2002 08:52:43 +0100 (MET),
> > Clemens Ladisch wrote:
> > > 
> > > Takashi Iwai wrote:
> > > > Martin Langer wrote:
> > > > > usb hotplug works perfect if my usbmidi client isn't aconnected to another
> > > > > midi client. But the aconnected usb midi device still remains in the clients
> > > > > list, after hotpluging out.
> > > >
> > > > yep,  when the connection exists, the connected devices (on both
> > > > sides) are regarded as active.
> > > 
> > > The sequencer design allows asynchronous removal of clients.
> > 
> > yes, but this may still try to send some bytes to the unplugged
> > rawmidi device at the disconnection.  i'll change rawmidi code to
> > ignore that.
> 
> Well, I'm trying to solve these "hotplug" problems. Unfortunately, it 
> seems difficult to detect, if another task is in the middle of our 
> callback. I think that we'll end up using mutexes.

hmm, but mutex costs too much even for non-pluggable devices...

in the case of rawmidi and oss-mixer, we can put "disconnected" flag
and ignore the access if the flag is on at the rawmidi and oss-mixer
routines, so that the control doesn't reach to low-level functions.

at least, the sequencer connection problem seems ok.
i'm checking now whether it can work for oss-mixer, too.


Takashi


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Re: trying out usb hotplugs

[Jaroslav Kysela]

On Fri, 29 Nov 2002, Takashi Iwai wrote:

> At Fri, 29 Nov 2002 10:39:22 +0100 (CET),
> Jaroslav wrote:
> > 
> > On Fri, 29 Nov 2002, Takashi Iwai wrote:
> > 
> > > At Fri, 29 Nov 2002 08:52:43 +0100 (MET),
> > > Clemens Ladisch wrote:
> > > > 
> > > > Takashi Iwai wrote:
> > > > > Martin Langer wrote:
> > > > > > usb hotplug works perfect if my usbmidi client isn't aconnected to another
> > > > > > midi client. But the aconnected usb midi device still remains in the clients
> > > > > > list, after hotpluging out.
> > > > >
> > > > > yep,  when the connection exists, the connected devices (on both
> > > > > sides) are regarded as active.
> > > > 
> > > > The sequencer design allows asynchronous removal of clients.
> > > 
> > > yes, but this may still try to send some bytes to the unplugged
> > > rawmidi device at the disconnection.  i'll change rawmidi code to
> > > ignore that.
> > 
> > Well, I'm trying to solve these "hotplug" problems. Unfortunately, it 
> > seems difficult to detect, if another task is in the middle of our 
> > callback. I think that we'll end up using mutexes.
> 
> hmm, but mutex costs too much even for non-pluggable devices...
> 
> in the case of rawmidi and oss-mixer, we can put "disconnected" flag
> and ignore the access if the flag is on at the rawmidi and oss-mixer
> routines, so that the control doesn't reach to low-level functions.

Well, but if you check this flag at the beginning, then you don't know, if
hardware is away in the middle of operation. The point is, that we have
to finish the last operation and clean structures "when no task is
inside". Perhaps, atomic_t helps us.

						Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs



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Re: trying out usb hotplugs

[Takashi Iwai]

At Fri, 29 Nov 2002 12:24:50 +0100 (CET),
Jaroslav wrote:
> 
> On Fri, 29 Nov 2002, Takashi Iwai wrote:
> 
> > At Fri, 29 Nov 2002 10:39:22 +0100 (CET),
> > Jaroslav wrote:
> > > 
> > > On Fri, 29 Nov 2002, Takashi Iwai wrote:
> > > 
> > > > At Fri, 29 Nov 2002 08:52:43 +0100 (MET),
> > > > Clemens Ladisch wrote:
> > > > > 
> > > > > Takashi Iwai wrote:
> > > > > > Martin Langer wrote:
> > > > > > > usb hotplug works perfect if my usbmidi client isn't aconnected to another
> > > > > > > midi client. But the aconnected usb midi device still remains in the clients
> > > > > > > list, after hotpluging out.
> > > > > >
> > > > > > yep,  when the connection exists, the connected devices (on both
> > > > > > sides) are regarded as active.
> > > > > 
> > > > > The sequencer design allows asynchronous removal of clients.
> > > > 
> > > > yes, but this may still try to send some bytes to the unplugged
> > > > rawmidi device at the disconnection.  i'll change rawmidi code to
> > > > ignore that.
> > > 
> > > Well, I'm trying to solve these "hotplug" problems. Unfortunately, it 
> > > seems difficult to detect, if another task is in the middle of our 
> > > callback. I think that we'll end up using mutexes.
> > 
> > hmm, but mutex costs too much even for non-pluggable devices...
> > 
> > in the case of rawmidi and oss-mixer, we can put "disconnected" flag
> > and ignore the access if the flag is on at the rawmidi and oss-mixer
> > routines, so that the control doesn't reach to low-level functions.
> 
> Well, but if you check this flag at the beginning, then you don't know, if
> hardware is away in the middle of operation. The point is, that we have
> to finish the last operation and clean structures "when no task is
> inside".

yes.  the unplugging may happen at any time, since it's a physical
action and cannot be locked by a kernel :)
this means, the invalid access in the middle of the code cannot be
avoided by a program code unless all function is atomic.
thus, the low-level stuff should take it into account if the card is
pluggable, anyway, for example, avoiding a possible infinte loop,
etc.

in the case of usb, the real critical part depends on the usb core and
controller routine.  i hope it's ok.

the "disconnection-check-and-ignore" method is not perfect, but, if
the low level stuff doesn't go crazy even at the disconnected state,
the result wouldn't be so critical.


btw, the oss-emulation problem seems to be on the different point.
the oss-emulation accesses directly to the records without taking any
reference counters.  thus snd_*_can_unregister() passes the check even
the control (or pcm) files are still open.
i'll keep on debugging this.


Takashi


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Re: trying out usb hotplugs

[Takashi Iwai]

[-- Attachment #1: Type: text/plain, Size: 77 bytes --]

Hi,

the attached is my latest patch.
could you check it?


thanks,

Takashi

[-- Attachment #2: disconnect-fix.dif --]
[-- Type: application/octet-stream, Size: 13942 bytes --]

Index: alsa-kernel/core/control.c
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/core/control.c,v
retrieving revision 1.15
diff -u -r1.15 control.c
--- alsa-kernel/core/control.c	28 Nov 2002 09:31:13 -0000	1.15
+++ alsa-kernel/core/control.c	29 Nov 2002 11:52:05 -0000
@@ -78,6 +78,7 @@
 	ctl->pid = current->pid;
 	file->private_data = ctl;
 	write_lock_irqsave(&card->control_rwlock, flags);
+	atomic_inc(&card->ctl_use_count);
 	list_add_tail(&ctl->list, &card->ctl_files);
 	write_unlock_irqrestore(&card->control_rwlock, flags);
 	return 0;
@@ -118,10 +119,8 @@
 	card = ctl->card;
 	write_lock_irqsave(&card->control_rwlock, flags);
 	list_del(&ctl->list);
-	write_unlock_irqrestore(&card->control_rwlock, flags);
-	if (snd_ctl_can_unregister(card) == 0)
+	if (atomic_dec_and_test(&card->ctl_use_count))
 		wake_up(&card->shutdown_sleep);
-	write_lock(&card->control_owner_lock);
 	list_for_each(list, &card->controls) {
 		control = snd_kcontrol(list);
 		if (control->owner == ctl)
@@ -602,6 +601,9 @@
 	ctl = snd_magic_cast(snd_ctl_file_t, file->private_data, return -ENXIO);
 	card = ctl->card;
 	snd_assert(card != NULL, return -ENXIO);
+	if (card->ctl_shutdown)
+		return -ENODEV;
+
 	switch (cmd) {
 	case SNDRV_CTL_IOCTL_PVERSION:
 		return put_user(SNDRV_CTL_VERSION, (int *)arg) ? -EFAULT : 0;
@@ -832,12 +834,7 @@
 
 int snd_ctl_can_unregister(snd_card_t *card)
 {
-	int res;
-
-	write_lock_irq(&card->control_rwlock);
-	res = !list_empty(&card->ctl_files);
-	write_unlock_irq(&card->control_rwlock);
-	return res;
+	return atomic_read(&card->ctl_use_count) != 0;
 }
 
 int snd_ctl_unregister(snd_card_t *card)
Index: alsa-kernel/core/init.c
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/core/init.c,v
retrieving revision 1.14
diff -u -r1.14 init.c
--- alsa-kernel/core/init.c	28 Nov 2002 09:31:13 -0000	1.14
+++ alsa-kernel/core/init.c	29 Nov 2002 11:54:31 -0000
@@ -96,6 +96,7 @@
 	INIT_LIST_HEAD(&card->controls);
 	INIT_LIST_HEAD(&card->ctl_files);
 	init_waitqueue_head(&card->shutdown_sleep);
+	atomic_set(&card->ctl_use_count, 0);
 #ifdef CONFIG_PM
 	init_MUTEX(&card->power_lock);
 	init_waitqueue_head(&card->power_sleep);
@@ -138,7 +139,7 @@
 
 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
 	if (snd_mixer_oss_notify_callback)
-		snd_mixer_oss_notify_callback(card, 1);
+		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_DISCONNECT);
 #endif
 
 	/* notify all devices that we are disconnected */
@@ -174,7 +175,7 @@
 
 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
 	if (snd_mixer_oss_notify_callback)
-		snd_mixer_oss_notify_callback(card, 2);
+		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_FREE);
 #endif
 	if (snd_device_free_all(card, SNDRV_DEV_CMD_PRE) < 0) {
 		snd_printk(KERN_ERR "unable to free all devices (pre)\n");
@@ -300,7 +301,7 @@
       __skip_info:
 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
 	if (snd_mixer_oss_notify_callback)
-		snd_mixer_oss_notify_callback(card, 0);
+		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_REGISTER);
 #endif
 	return 0;
 }
Index: alsa-kernel/core/rawmidi.c
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/core/rawmidi.c,v
retrieving revision 1.21
diff -u -r1.21 rawmidi.c
--- alsa-kernel/core/rawmidi.c	28 Nov 2002 09:31:13 -0000	1.21
+++ alsa-kernel/core/rawmidi.c	29 Nov 2002 09:04:56 -0000
@@ -136,6 +136,8 @@
 	long timeout;
 	snd_rawmidi_runtime_t *runtime = substream->runtime;
 
+	if (substream->rmidi->disconnected)
+		return 0;
 	err = 0;
 	runtime->drain = 1;
 	while (runtime->avail < runtime->buffer_size) {
@@ -144,6 +146,8 @@
 			err = -ERESTARTSYS;
 			break;
 		}
+		if (substream->rmidi->disconnected)
+			return 0;
 		if (runtime->avail < runtime->buffer_size && !timeout) {
 			snd_printk(KERN_WARNING "rawmidi drain error (avail = %li, buffer_size = %li)\n", (long)runtime->avail, (long)runtime->buffer_size);
 			err = -EIO;
@@ -1070,6 +1074,9 @@
 	snd_assert(buf != NULL, return -EINVAL);
 	snd_assert(runtime->buffer != NULL, return -EINVAL);
 
+	if (substream->rmidi->disconnected)
+		return -ENODEV;
+
 	result = 0;
 	spin_lock_irqsave(&runtime->lock, flags);
 	if (substream->append) {
@@ -1480,6 +1487,7 @@
 	snd_rawmidi_t *rmidi = snd_magic_cast(snd_rawmidi_t, device->device_data, return -ENXIO);
 	int idx;
 
+	rmidi->disconnected = 1;
 	down(&register_mutex);
 	idx = (rmidi->card->number * SNDRV_RAWMIDI_DEVICES) + rmidi->device;
 	snd_rawmidi_devices[idx] = NULL;
Index: alsa-kernel/core/oss/mixer_oss.c
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/core/oss/mixer_oss.c,v
retrieving revision 1.12
diff -u -r1.12 mixer_oss.c
--- alsa-kernel/core/oss/mixer_oss.c	28 Nov 2002 09:31:13 -0000	1.12
+++ alsa-kernel/core/oss/mixer_oss.c	29 Nov 2002 12:08:01 -0000
@@ -53,6 +53,7 @@
 	fmixer = (snd_mixer_oss_file_t *)snd_kcalloc(sizeof(*fmixer), GFP_KERNEL);
 	if (fmixer == NULL)
 		return -ENOMEM;
+	atomic_inc(&card->ctl_use_count);
 	fmixer->card = card;
 	fmixer->mixer = card->mixer_oss;
 	file->private_data = fmixer;
@@ -64,6 +65,8 @@
 #ifdef LINUX_2_2
 		MOD_DEC_USE_COUNT;
 #endif
+		if (atomic_dec_and_test(&card->ctl_use_count))
+			wake_up(&card->shutdown_sleep);
 		return -EFAULT;
 	}
 	return 0;
@@ -79,6 +82,8 @@
 #ifdef LINUX_2_2
 		MOD_DEC_USE_COUNT;
 #endif
+		if (atomic_dec_and_test(&fmixer->card->ctl_use_count))
+			wake_up(&fmixer->card->shutdown_sleep);
 		kfree(fmixer);
 	}
 	return 0;
@@ -498,6 +503,10 @@
 	snd_ctl_elem_info_t *uinfo;
 	snd_ctl_elem_value_t *uctl;
 
+	/* FIXME: needs lock? */
+	if (fmixer->mixer->disconnected)
+		return;
+
 	snd_runtime_check(kctl != NULL, return);
 	uinfo = snd_kcalloc(sizeof(*uinfo), GFP_ATOMIC);
 	uctl = snd_kcalloc(sizeof(*uctl), GFP_ATOMIC);
@@ -525,6 +534,10 @@
 	snd_ctl_elem_info_t *uinfo;
 	snd_ctl_elem_value_t *uctl;
 
+	/* FIXME: needs lock? */
+	if (fmixer->mixer->disconnected)
+		return;
+
 	snd_runtime_check(kctl != NULL, return);
 	uinfo = snd_kcalloc(sizeof(*uinfo), GFP_ATOMIC);
 	uctl = snd_kcalloc(sizeof(*uctl), GFP_ATOMIC);
@@ -584,6 +597,10 @@
 	snd_ctl_elem_value_t *uctl;
 	int res;
 
+	/* FIXME: needs lock? */
+	if (fmixer->mixer->disconnected)
+		return;
+
 	snd_runtime_check(kctl != NULL, return);
 	uinfo = snd_kcalloc(sizeof(*uinfo), GFP_ATOMIC);
 	uctl = snd_kcalloc(sizeof(*uctl), GFP_ATOMIC);
@@ -614,6 +631,10 @@
 	snd_ctl_elem_value_t *uctl;
 	int res;
 
+	/* FIXME: needs lock? */
+	if (fmixer->mixer->disconnected)
+		return;
+
 	snd_runtime_check(kctl != NULL, return);
 	uinfo = snd_kcalloc(sizeof(*uinfo), GFP_ATOMIC);
 	uctl = snd_kcalloc(sizeof(*uctl), GFP_ATOMIC);
@@ -750,6 +771,10 @@
 	snd_ctl_elem_value_t *uctl;
 	int err, idx;
 	
+	/* FIXME: needs lock? */
+	if (mixer->disconnected)
+		return -ENODEV;
+
 	uinfo = snd_kcalloc(sizeof(*uinfo), GFP_KERNEL);
 	uctl = snd_kcalloc(sizeof(*uctl), GFP_KERNEL);
 	if (uinfo == NULL || uctl == NULL) {
@@ -765,7 +790,7 @@
 	for (idx = 0; idx < 32; idx++) {
 		if (!(mixer->mask_recsrc & (1 << idx)))
 			continue;
-		pslot = &fmixer->mixer->slots[idx];
+		pslot = &mixer->slots[idx];
 		slot = (struct slot *)pslot->private_data;
 		if (slot->signature != SNDRV_MIXER_OSS_SIGNATURE)
 			continue;
@@ -799,6 +824,10 @@
 	snd_ctl_elem_value_t *uctl;
 	int err, idx;
 
+	/* FIXME: needs lock? */
+	if (mixer->disconnected)
+		return -ENODEV;
+
 	uinfo = snd_kcalloc(sizeof(*uinfo), GFP_KERNEL);
 	uctl = snd_kcalloc(sizeof(*uctl), GFP_KERNEL);
 	if (uinfo == NULL || uctl == NULL) {
@@ -812,7 +841,7 @@
 	for (idx = 0; idx < 32; idx++) {
 		if (!(mixer->mask_recsrc & (1 << idx)))
 			continue;
-		pslot = &fmixer->mixer->slots[idx];
+		pslot = &mixer->slots[idx];
 		slot = (struct slot *)pslot->private_data;
 		if (slot->signature != SNDRV_MIXER_OSS_SIGNATURE)
 			continue;
@@ -1204,7 +1233,7 @@
 {
 	snd_mixer_oss_t *mixer;
 
-	if (cmd == 0) {		/* register */
+	if (cmd == SND_MIXER_OSS_NOTIFY_REGISTER) {
 		char name[128];
 		int idx, err;
 
@@ -1238,10 +1267,11 @@
 		card->mixer_oss = mixer;
 		snd_mixer_oss_build(mixer);
 		snd_mixer_oss_proc_init(mixer);
-	} else if (cmd == 1) {	/* disconnect */
+	} else if (cmd == SND_MIXER_OSS_NOTIFY_DISCONNECT) {
 		mixer = card->mixer_oss;
 		if (mixer == NULL || !mixer->oss_dev_alloc)
 			return 0;
+		mixer->disconnected = 1;
 		snd_unregister_oss_device(SNDRV_OSS_DEVICE_TYPE_MIXER, mixer->card, 0);
 		mixer->oss_dev_alloc = 0;
 	} else {		/* free */
@@ -1266,7 +1296,7 @@
 	snd_mixer_oss_notify_callback = snd_mixer_oss_notify_handler;
 	for (idx = 0; idx < SNDRV_CARDS; idx++) {
 		if (snd_cards[idx])
-			snd_mixer_oss_notify_handler(snd_cards[idx], 0);
+			snd_mixer_oss_notify_handler(snd_cards[idx], SND_MIXER_OSS_NOTIFY_REGISTER);
 	}
 	return 0;
 }
@@ -1278,7 +1308,7 @@
 	snd_mixer_oss_notify_callback = NULL;
 	for (idx = 0; idx < SNDRV_CARDS; idx++) {
 		if (snd_cards[idx])
-			snd_mixer_oss_notify_handler(snd_cards[idx], 1);
+			snd_mixer_oss_notify_handler(snd_cards[idx], SND_MIXER_OSS_NOTIFY_FREE);
 	}
 }
 
Index: alsa-kernel/core/oss/pcm_oss.c
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/core/oss/pcm_oss.c,v
retrieving revision 1.20
diff -u -r1.20 pcm_oss.c
--- alsa-kernel/core/oss/pcm_oss.c	28 Nov 2002 09:31:13 -0000	1.20
+++ alsa-kernel/core/oss/pcm_oss.c	29 Nov 2002 11:29:18 -0000
@@ -1554,13 +1554,15 @@
 		err = -ENODEV;
 		goto __error1;
 	}
+	atomic_inc(&pcm->use_count);
 	if (!try_inc_mod_count(pcm->card->module)) {
 		err = -EFAULT;
+		atomic_dec(&pcm->use_count);
 		goto __error1;
 	}
 	if (snd_task_name(current, task_name, sizeof(task_name)) < 0) {
 		err = -EFAULT;
-		goto __error1;
+		goto __error;
 	}
 	if (file->f_mode & FMODE_WRITE)
 		psetup = snd_pcm_oss_look_for_setup(pcm, SNDRV_PCM_STREAM_PLAYBACK, task_name);
@@ -1639,6 +1641,8 @@
 	up(&pcm->open_mutex);
 	wake_up(&pcm->open_wait);
 	dec_mod_count(pcm->card->module);
+	if (atomic_dec_and_test(&pcm->use_count))
+		wake_up(&pcm->card->shutdown_sleep);
 #ifdef LINUX_2_2
 	MOD_DEC_USE_COUNT;
 #endif
Index: alsa-kernel/core/seq/seq_device.c
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/core/seq/seq_device.c,v
retrieving revision 1.6
diff -u -r1.6 seq_device.c
--- alsa-kernel/core/seq/seq_device.c	13 Aug 2002 16:17:06 -0000	1.6
+++ alsa-kernel/core/seq/seq_device.c	29 Nov 2002 08:45:48 -0000
@@ -92,6 +92,7 @@
 static int snd_seq_device_free(snd_seq_device_t *dev);
 static int snd_seq_device_dev_free(snd_device_t *device);
 static int snd_seq_device_dev_register(snd_device_t *device);
+static int snd_seq_device_dev_disconnect(snd_device_t *device);
 static int snd_seq_device_dev_unregister(snd_device_t *device);
 
 static int init_device(snd_seq_device_t *dev, ops_list_t *ops);
@@ -166,6 +167,7 @@
 	static snd_device_ops_t dops = {
 		.dev_free = snd_seq_device_dev_free,
 		.dev_register = snd_seq_device_dev_register,
+		.dev_disconnect = snd_seq_device_dev_disconnect,
 		.dev_unregister = snd_seq_device_dev_unregister
 	};
 
@@ -265,6 +267,22 @@
 		init_device(dev, ops);
 
 	unlock_driver(ops);
+	return 0;
+}
+
+/*
+ * disconnect the device
+ */
+static int snd_seq_device_dev_disconnect(snd_device_t *device)
+{
+	snd_seq_device_t *dev = snd_magic_cast(snd_seq_device_t, device->device_data, return -ENXIO);
+	ops_list_t *ops;
+
+	ops = find_driver(dev->id, 0);
+	if (ops == NULL)
+		return -ENOENT;
+
+	free_device(dev, ops);
 	return 0;
 }
 
Index: alsa-kernel/include/core.h
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/include/core.h,v
retrieving revision 1.24
diff -u -r1.24 core.h
--- alsa-kernel/include/core.h	28 Nov 2002 09:31:13 -0000	1.24
+++ alsa-kernel/include/core.h	29 Nov 2002 11:53:54 -0000
@@ -140,6 +140,7 @@
 	struct list_head controls;	/* all controls for this card */
 	struct list_head ctl_files;	/* active control files */
 	int ctl_shutdown;		/* control interface is going down */
+	atomic_t ctl_use_count;		/* reference counter for control files */
 
 	snd_info_entry_t *proc_root;	/* root for soundcard specific files */
 	snd_info_entry_t *proc_id;	/* the card id */
@@ -297,6 +298,9 @@
 extern snd_card_t *snd_cards[SNDRV_CARDS];
 extern rwlock_t snd_card_rwlock;
 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
+#define SND_MIXER_OSS_NOTIFY_REGISTER	0
+#define SND_MIXER_OSS_NOTIFY_DISCONNECT	1
+#define SND_MIXER_OSS_NOTIFY_FREE	2
 extern int (*snd_mixer_oss_notify_callback)(snd_card_t *card, int cmd);
 #endif
 
Index: alsa-kernel/include/mixer_oss.h
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/include/mixer_oss.h,v
retrieving revision 1.6
diff -u -r1.6 mixer_oss.h
--- alsa-kernel/include/mixer_oss.h	28 Nov 2002 09:31:13 -0000	1.6
+++ alsa-kernel/include/mixer_oss.h	29 Nov 2002 11:53:16 -0000
@@ -61,7 +61,8 @@
 	void (*private_free_recsrc)(snd_mixer_oss_t *mixer);
 	struct semaphore reg_mutex;
 	snd_info_entry_t *proc_entry;
-	int oss_dev_alloc;
+	unsigned int oss_dev_alloc: 1;
+	unsigned int disconnected: 1;
 	/* --- */
 	int oss_recsrc;
 };
Index: alsa-kernel/include/rawmidi.h
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/include/rawmidi.h,v
retrieving revision 1.10
diff -u -r1.10 rawmidi.h
--- alsa-kernel/include/rawmidi.h	28 Nov 2002 09:31:13 -0000	1.10
+++ alsa-kernel/include/rawmidi.h	29 Nov 2002 09:05:31 -0000
@@ -118,6 +118,7 @@
 	snd_card_t *card;
 
 	atomic_t use_count;
+	unsigned int disconnected: 1;
 
 	unsigned int device;		/* device number */
 	unsigned int info_flags;	/* SNDRV_RAWMIDI_INFO_XXXX */

Re: trying out usb hotplugs

[Jaroslav Kysela]

On Fri, 29 Nov 2002, Takashi Iwai wrote:

> Hi,
> 
> the attached is my latest patch.
> could you check it?

Let's go and make things more complicated (like in my tree on disc):

1) waiting for time when all disconnected applications have closed
   all file descriptors is a bit problem, because no new/other USB devices 
   can be connected/disconnected; in my tree, I use thread to postpone 
   freeing of snd_card_t structure
2) replace file->f_op with fake operations which allows only original 
   release() callback in snd_card_disconnect(); this point makes things 
   more and more simple than your code (check all accesses), because we 
   need to count only open/release calls
3) the unfinished problem is still: how to behave, if the disconnect event
   comes in the middle of some code; you're right at this point, the 
   lowlevel driver must handle it

Please, remove from your code any checks from ioctl(), poll(), read() / 
write(). Then commit and I'll merge my tree with yours.

						Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs



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Re: trying out usb hotplugs

[Takashi Iwai]

At Fri, 29 Nov 2002 15:05:21 +0100 (CET),
Jaroslav wrote:
> 
> On Fri, 29 Nov 2002, Takashi Iwai wrote:
> 
> > Hi,
> > 
> > the attached is my latest patch.
> > could you check it?
> 
> Let's go and make things more complicated (like in my tree on disc):
> 
> 1) waiting for time when all disconnected applications have closed
>    all file descriptors is a bit problem, because no new/other USB devices 
>    can be connected/disconnected; in my tree, I use thread to postpone 
>    freeing of snd_card_t structure

right.  i didn't touch this part at all.

another possible solution is to put the pending card instance into
a stale linked-list like in pcmcia drivers.
the pending objects are released at the time when a new device is
registered and when the module is removed.
but if a kernel-thread can work well, it's better, because it will
release the resources asap.

> 2) replace file->f_op with fake operations which allows only original 
>    release() callback in snd_card_disconnect(); this point makes things 
>    more and more simple than your code (check all accesses), because we 
>    need to count only open/release calls

yes, that's a better solution.

> 3) the unfinished problem is still: how to behave, if the disconnect event
>    comes in the middle of some code; you're right at this point, the 
>    lowlevel driver must handle it
> 
> Please, remove from your code any checks from ioctl(), poll(), read() / 
> write(). Then commit and I'll merge my tree with yours.

ok.


Takashi


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Re: trying out usb hotplugs

[Takashi Iwai]

At Fri, 29 Nov 2002 15:14:28 +0100,
I wrote:
> 
> > Please, remove from your code any checks from ioctl(), poll(), read() / 
> > write(). Then commit and I'll merge my tree with yours.
> 
> ok.

done.  please merge your tree.


ciao,

Takashi


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