ALSA: timer - Fix Oops at closing slave timer
[linux-2.6.git] / sound / core / control.c
index c89ca0d..f8c5be4 100644 (file)
@@ -19,7 +19,6 @@
  *
  */
 
-#include <sound/driver.h>
 #include <linux/threads.h>
 #include <linux/interrupt.h>
 #include <linux/slab.h>
@@ -32,6 +31,7 @@
 
 /* max number of user-defined controls */
 #define MAX_USER_CONTROLS      32
+#define MAX_CONTROL_COUNT      1028
 
 struct snd_kctl_ioctl {
        struct list_head list;          /* list of all ioctls */
@@ -51,6 +51,10 @@ static int snd_ctl_open(struct inode *inode, struct file *file)
        struct snd_ctl_file *ctl;
        int err;
 
+       err = nonseekable_open(inode, file);
+       if (err < 0)
+               return err;
+
        card = snd_lookup_minor_data(iminor(inode), SNDRV_DEVICE_TYPE_CONTROL);
        if (!card) {
                err = -ENODEV;
@@ -76,7 +80,7 @@ static int snd_ctl_open(struct inode *inode, struct file *file)
        ctl->card = card;
        ctl->prefer_pcm_subdevice = -1;
        ctl->prefer_rawmidi_subdevice = -1;
-       ctl->pid = current->pid;
+       ctl->pid = get_pid(task_pid(current));
        file->private_data = ctl;
        write_lock_irqsave(&card->ctl_files_rwlock, flags);
        list_add_tail(&ctl->list, &card->ctl_files);
@@ -114,7 +118,6 @@ static int snd_ctl_release(struct inode *inode, struct file *file)
        unsigned int idx;
 
        ctl = file->private_data;
-       fasync_helper(-1, file, 0, &ctl->fasync);
        file->private_data = NULL;
        card = ctl->card;
        write_lock_irqsave(&card->ctl_files_rwlock, flags);
@@ -127,6 +130,7 @@ static int snd_ctl_release(struct inode *inode, struct file *file)
                                control->vd[idx].owner = NULL;
        up_write(&card->controls_rwsem);
        snd_ctl_empty_read_queue(ctl);
+       put_pid(ctl->pid);
        kfree(ctl);
        module_put(card->module);
        snd_card_file_remove(card, file);
@@ -140,7 +144,8 @@ void snd_ctl_notify(struct snd_card *card, unsigned int mask,
        struct snd_ctl_file *ctl;
        struct snd_kctl_event *ev;
        
-       snd_assert(card != NULL && id != NULL, return);
+       if (snd_BUG_ON(!card || !id))
+               return;
        read_lock(&card->ctl_files_rwlock);
 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
        card->mixer_oss_change_count++;
@@ -189,8 +194,12 @@ static struct snd_kcontrol *snd_ctl_new(struct snd_kcontrol *control,
        struct snd_kcontrol *kctl;
        unsigned int idx;
        
-       snd_assert(control != NULL, return NULL);
-       snd_assert(control->count > 0, return NULL);
+       if (snd_BUG_ON(!control || !control->count))
+               return NULL;
+
+       if (control->count > MAX_CONTROL_COUNT)
+               return NULL;
+
        kctl = kzalloc(sizeof(*kctl) + sizeof(struct snd_kcontrol_volatile) * control->count, GFP_KERNEL);
        if (kctl == NULL) {
                snd_printk(KERN_ERR "Cannot allocate control instance\n");
@@ -219,21 +228,27 @@ struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new *ncontrol,
        struct snd_kcontrol kctl;
        unsigned int access;
        
-       snd_assert(ncontrol != NULL, return NULL);
-       snd_assert(ncontrol->info != NULL, return NULL);
+       if (snd_BUG_ON(!ncontrol || !ncontrol->info))
+               return NULL;
        memset(&kctl, 0, sizeof(kctl));
        kctl.id.iface = ncontrol->iface;
        kctl.id.device = ncontrol->device;
        kctl.id.subdevice = ncontrol->subdevice;
-       if (ncontrol->name)
+       if (ncontrol->name) {
                strlcpy(kctl.id.name, ncontrol->name, sizeof(kctl.id.name));
+               if (strcmp(ncontrol->name, kctl.id.name) != 0)
+                       snd_printk(KERN_WARNING
+                                  "Control name '%s' truncated to '%s'\n",
+                                  ncontrol->name, kctl.id.name);
+       }
        kctl.id.index = ncontrol->index;
        kctl.count = ncontrol->count ? ncontrol->count : 1;
        access = ncontrol->access == 0 ? SNDRV_CTL_ELEM_ACCESS_READWRITE :
                 (ncontrol->access & (SNDRV_CTL_ELEM_ACCESS_READWRITE|
                                      SNDRV_CTL_ELEM_ACCESS_INACTIVE|
-                                     SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE|
-                                     SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK));
+                                     SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE|
+                                     SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND|
+                                     SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK));
        kctl.info = ncontrol->info;
        kctl.get = ncontrol->get;
        kctl.put = ncontrol->put;
@@ -264,33 +279,31 @@ void snd_ctl_free_one(struct snd_kcontrol *kcontrol)
 
 EXPORT_SYMBOL(snd_ctl_free_one);
 
-static unsigned int snd_ctl_hole_check(struct snd_card *card,
-                                      unsigned int count)
+static bool snd_ctl_remove_numid_conflict(struct snd_card *card,
+                                         unsigned int count)
 {
        struct snd_kcontrol *kctl;
 
        list_for_each_entry(kctl, &card->controls, list) {
-               if ((kctl->id.numid <= card->last_numid &&
-                    kctl->id.numid + kctl->count > card->last_numid) ||
-                   (kctl->id.numid <= card->last_numid + count - 1 &&
-                    kctl->id.numid + kctl->count > card->last_numid + count - 1))
-                       return card->last_numid = kctl->id.numid + kctl->count - 1;
+               if (kctl->id.numid < card->last_numid + 1 + count &&
+                   kctl->id.numid + kctl->count > card->last_numid + 1) {
+                       card->last_numid = kctl->id.numid + kctl->count - 1;
+                       return true;
+               }
        }
-       return card->last_numid;
+       return false;
 }
 
 static int snd_ctl_find_hole(struct snd_card *card, unsigned int count)
 {
-       unsigned int last_numid, iter = 100000;
+       unsigned int iter = 100000;
 
-       last_numid = card->last_numid;
-       while (last_numid != snd_ctl_hole_check(card, count)) {
+       while (snd_ctl_remove_numid_conflict(card, count)) {
                if (--iter == 0) {
                        /* this situation is very unlikely */
                        snd_printk(KERN_ERR "unable to allocate new control numid\n");
                        return -ENOMEM;
                }
-               last_numid = card->last_numid;
        }
        return 0;
 }
@@ -316,8 +329,8 @@ int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
 
        if (! kcontrol)
                return err;
-       snd_assert(card != NULL, goto error);
-       snd_assert(kcontrol->info != NULL, goto error);
+       if (snd_BUG_ON(!card || !kcontrol->info))
+               goto error;
        id = kcontrol->id;
        down_write(&card->controls_rwsem);
        if (snd_ctl_find_id(card, &id)) {
@@ -353,6 +366,70 @@ int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
 EXPORT_SYMBOL(snd_ctl_add);
 
 /**
+ * snd_ctl_replace - replace the control instance of the card
+ * @card: the card instance
+ * @kcontrol: the control instance to replace
+ * @add_on_replace: add the control if not already added
+ *
+ * Replaces the given control.  If the given control does not exist
+ * and the add_on_replace flag is set, the control is added.  If the
+ * control exists, it is destroyed first.
+ *
+ * Returns zero if successful, or a negative error code on failure.
+ *
+ * It frees automatically the control which cannot be added or replaced.
+ */
+int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
+                   bool add_on_replace)
+{
+       struct snd_ctl_elem_id id;
+       unsigned int idx;
+       struct snd_kcontrol *old;
+       int ret;
+
+       if (!kcontrol)
+               return -EINVAL;
+       if (snd_BUG_ON(!card || !kcontrol->info)) {
+               ret = -EINVAL;
+               goto error;
+       }
+       id = kcontrol->id;
+       down_write(&card->controls_rwsem);
+       old = snd_ctl_find_id(card, &id);
+       if (!old) {
+               if (add_on_replace)
+                       goto add;
+               up_write(&card->controls_rwsem);
+               ret = -EINVAL;
+               goto error;
+       }
+       ret = snd_ctl_remove(card, old);
+       if (ret < 0) {
+               up_write(&card->controls_rwsem);
+               goto error;
+       }
+add:
+       if (snd_ctl_find_hole(card, kcontrol->count) < 0) {
+               up_write(&card->controls_rwsem);
+               ret = -ENOMEM;
+               goto error;
+       }
+       list_add_tail(&kcontrol->list, &card->controls);
+       card->controls_count += kcontrol->count;
+       kcontrol->id.numid = card->last_numid + 1;
+       card->last_numid += kcontrol->count;
+       up_write(&card->controls_rwsem);
+       for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
+               snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
+       return 0;
+
+error:
+       snd_ctl_free_one(kcontrol);
+       return ret;
+}
+EXPORT_SYMBOL(snd_ctl_replace);
+
+/**
  * snd_ctl_remove - remove the control from the card and release it
  * @card: the card instance
  * @kcontrol: the control instance to remove
@@ -368,7 +445,8 @@ int snd_ctl_remove(struct snd_card *card, struct snd_kcontrol *kcontrol)
        struct snd_ctl_elem_id id;
        unsigned int idx;
 
-       snd_assert(card != NULL && kcontrol != NULL, return -EINVAL);
+       if (snd_BUG_ON(!card || !kcontrol))
+               return -EINVAL;
        list_del(&kcontrol->list);
        card->controls_count -= kcontrol->count;
        id = kcontrol->id;
@@ -409,7 +487,7 @@ int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)
 EXPORT_SYMBOL(snd_ctl_remove_id);
 
 /**
- * snd_ctl_remove_unlocked_id - remove the unlocked control of the given id and release it
+ * snd_ctl_remove_user_ctl - remove and release the unlocked user control
  * @file: active control handle
  * @id: the control id to remove
  *
@@ -418,8 +496,8 @@ EXPORT_SYMBOL(snd_ctl_remove_id);
  * 
  * Returns 0 if successful, or a negative error code on failure.
  */
-static int snd_ctl_remove_unlocked_id(struct snd_ctl_file * file,
-                                     struct snd_ctl_elem_id *id)
+static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
+                                  struct snd_ctl_elem_id *id)
 {
        struct snd_card *card = file->card;
        struct snd_kcontrol *kctl;
@@ -428,20 +506,74 @@ static int snd_ctl_remove_unlocked_id(struct snd_ctl_file * file,
        down_write(&card->controls_rwsem);
        kctl = snd_ctl_find_id(card, id);
        if (kctl == NULL) {
-               up_write(&card->controls_rwsem);
-               return -ENOENT;
+               ret = -ENOENT;
+               goto error;
+       }
+       if (!(kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_USER)) {
+               ret = -EINVAL;
+               goto error;
        }
        for (idx = 0; idx < kctl->count; idx++)
                if (kctl->vd[idx].owner != NULL && kctl->vd[idx].owner != file) {
-                       up_write(&card->controls_rwsem);
-                       return -EBUSY;
+                       ret = -EBUSY;
+                       goto error;
                }
        ret = snd_ctl_remove(card, kctl);
+       if (ret < 0)
+               goto error;
+       card->user_ctl_count--;
+error:
        up_write(&card->controls_rwsem);
        return ret;
 }
 
 /**
+ * snd_ctl_activate_id - activate/inactivate the control of the given id
+ * @card: the card instance
+ * @id: the control id to activate/inactivate
+ * @active: non-zero to activate
+ *
+ * Finds the control instance with the given id, and activate or
+ * inactivate the control together with notification, if changed.
+ *
+ * Returns 0 if unchanged, 1 if changed, or a negative error code on failure.
+ */
+int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
+                       int active)
+{
+       struct snd_kcontrol *kctl;
+       struct snd_kcontrol_volatile *vd;
+       unsigned int index_offset;
+       int ret;
+
+       down_write(&card->controls_rwsem);
+       kctl = snd_ctl_find_id(card, id);
+       if (kctl == NULL) {
+               ret = -ENOENT;
+               goto unlock;
+       }
+       index_offset = snd_ctl_get_ioff(kctl, &kctl->id);
+       vd = &kctl->vd[index_offset];
+       ret = 0;
+       if (active) {
+               if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
+                       goto unlock;
+               vd->access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+       } else {
+               if (vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)
+                       goto unlock;
+               vd->access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+       }
+       ret = 1;
+ unlock:
+       up_write(&card->controls_rwsem);
+       if (ret > 0)
+               snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO, id);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
+
+/**
  * snd_ctl_rename_id - replace the id of a control on the card
  * @card: the card instance
  * @src_id: the old id
@@ -488,7 +620,8 @@ struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card, unsigned int numi
 {
        struct snd_kcontrol *kctl;
 
-       snd_assert(card != NULL && numid != 0, return NULL);
+       if (snd_BUG_ON(!card || !numid))
+               return NULL;
        list_for_each_entry(kctl, &card->controls, list) {
                if (kctl->id.numid <= numid && kctl->id.numid + kctl->count > numid)
                        return kctl;
@@ -515,7 +648,8 @@ struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
 {
        struct snd_kcontrol *kctl;
 
-       snd_assert(card != NULL && id != NULL, return NULL);
+       if (snd_BUG_ON(!card || !id))
+               return NULL;
        if (id->numid != 0)
                return snd_ctl_find_numid(card, id->numid);
        list_for_each_entry(kctl, &card->controls, list) {
@@ -570,13 +704,12 @@ static int snd_ctl_elem_list(struct snd_card *card,
        struct snd_ctl_elem_list list;
        struct snd_kcontrol *kctl;
        struct snd_ctl_elem_id *dst, *id;
-       unsigned int offset, space, first, jidx;
+       unsigned int offset, space, jidx;
        
        if (copy_from_user(&list, _list, sizeof(list)))
                return -EFAULT;
        offset = list.offset;
        space = list.space;
-       first = 0;
        /* try limit maximum space */
        if (space > 16384)
                return -ENOMEM;
@@ -648,7 +781,7 @@ static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
 #endif
        result = kctl->info(kctl, info);
        if (result >= 0) {
-               snd_assert(info->access == 0, );
+               snd_BUG_ON(info->access);
                index_offset = snd_ctl_get_ioff(kctl, &info->id);
                vd = &kctl->vd[index_offset];
                snd_ctl_build_ioff(&info->id, kctl, index_offset);
@@ -657,7 +790,7 @@ static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
                        info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
                        if (vd->owner == ctl)
                                info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;
-                       info->owner = vd->owner_pid;
+                       info->owner = pid_vnr(vd->owner->pid);
                } else {
                        info->owner = -1;
                }
@@ -685,7 +818,8 @@ static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
        return result;
 }
 
-int snd_ctl_elem_read(struct snd_card *card, struct snd_ctl_elem_value *control)
+static int snd_ctl_elem_read(struct snd_card *card,
+                            struct snd_ctl_elem_value *control)
 {
        struct snd_kcontrol *kctl;
        struct snd_kcontrol_volatile *vd;
@@ -715,14 +849,11 @@ static int snd_ctl_elem_read_user(struct snd_card *card,
 {
        struct snd_ctl_elem_value *control;
        int result;
-       
-       control = kmalloc(sizeof(*control), GFP_KERNEL);
-       if (control == NULL)
-               return -ENOMEM; 
-       if (copy_from_user(control, _control, sizeof(*control))) {
-               kfree(control);
-               return -EFAULT;
-       }
+
+       control = memdup_user(_control, sizeof(*control));
+       if (IS_ERR(control))
+               return PTR_ERR(control);
+
        snd_power_lock(card);
        result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
        if (result >= 0)
@@ -735,8 +866,8 @@ static int snd_ctl_elem_read_user(struct snd_card *card,
        return result;
 }
 
-int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
-                      struct snd_ctl_elem_value *control)
+static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
+                             struct snd_ctl_elem_value *control)
 {
        struct snd_kcontrol *kctl;
        struct snd_kcontrol_volatile *vd;
@@ -776,13 +907,10 @@ static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
        struct snd_card *card;
        int result;
 
-       control = kmalloc(sizeof(*control), GFP_KERNEL);
-       if (control == NULL)
-               return -ENOMEM; 
-       if (copy_from_user(control, _control, sizeof(*control))) {
-               kfree(control);
-               return -EFAULT;
-       }
+       control = memdup_user(_control, sizeof(*control));
+       if (IS_ERR(control))
+               return PTR_ERR(control);
+
        card = file->card;
        snd_power_lock(card);
        result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
@@ -817,7 +945,6 @@ static int snd_ctl_elem_lock(struct snd_ctl_file *file,
                        result = -EBUSY;
                else {
                        vd->owner = file;
-                       vd->owner_pid = current->pid;
                        result = 0;
                }
        }
@@ -848,7 +975,6 @@ static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
                        result = -EPERM;
                else {
                        vd->owner = NULL;
-                       vd->owner_pid = 0;
                        result = 0;
                }
        }
@@ -908,13 +1034,10 @@ static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kcontrol,
        if (op_flag > 0) {
                if (size > 1024 * 128)  /* sane value */
                        return -EINVAL;
-               new_data = kmalloc(size, GFP_KERNEL);
-               if (new_data == NULL)
-                       return -ENOMEM;
-               if (copy_from_user(new_data, tlv, size)) {
-                       kfree(new_data);
-                       return -EFAULT;
-               }
+
+               new_data = memdup_user(tlv, size);
+               if (IS_ERR(new_data))
+                       return PTR_ERR(new_data);
                change = ue->tlv_data_size != size;
                if (!change)
                        change = memcmp(ue->tlv_data, new_data, size);
@@ -952,7 +1075,7 @@ static int snd_ctl_elem_add(struct snd_ctl_file *file,
        
        if (card->user_ctl_count >= MAX_USER_CONTROLS)
                return -ENOMEM;
-       if (info->count > 1024)
+       if (info->count < 1)
                return -EINVAL;
        access = info->access == 0 ? SNDRV_CTL_ELEM_ACCESS_READWRITE :
                (info->access & (SNDRV_CTL_ELEM_ACCESS_READWRITE|
@@ -1053,18 +1176,10 @@ static int snd_ctl_elem_remove(struct snd_ctl_file *file,
                               struct snd_ctl_elem_id __user *_id)
 {
        struct snd_ctl_elem_id id;
-       int err;
 
        if (copy_from_user(&id, _id, sizeof(id)))
                return -EFAULT;
-       err = snd_ctl_remove_unlocked_id(file, &id);
-       if (! err) {
-               struct snd_card *card = file->card;
-               down_write(&card->controls_rwsem);
-               card->user_ctl_count--;
-               up_write(&card->controls_rwsem);
-       }
-       return err;
+       return snd_ctl_remove_user_ctl(file, &id);
 }
 
 static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)
@@ -1101,7 +1216,7 @@ static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
 
        if (copy_from_user(&tlv, _tlv, sizeof(tlv)))
                return -EFAULT;
-       if (tlv.length < sizeof(unsigned int) * 3)
+       if (tlv.length < sizeof(unsigned int) * 2)
                return -EINVAL;
        down_read(&card->controls_rwsem);
        kctl = snd_ctl_find_numid(card, tlv.numid);
@@ -1121,7 +1236,7 @@ static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
                goto __kctl_end;
        }
        if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
-               if (file && vd->owner != NULL && vd->owner != file) {
+               if (vd->owner != NULL && vd->owner != file) {
                        err = -EPERM;
                        goto __kctl_end;
                }
@@ -1160,7 +1275,8 @@ static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg
 
        ctl = file->private_data;
        card = ctl->card;
-       snd_assert(card != NULL, return -ENXIO);
+       if (snd_BUG_ON(!card))
+               return -ENXIO;
        switch (cmd) {
        case SNDRV_CTL_IOCTL_PVERSION:
                return put_user(SNDRV_CTL_VERSION, ip) ? -EFAULT : 0;
@@ -1222,7 +1338,8 @@ static ssize_t snd_ctl_read(struct file *file, char __user *buffer,
        ssize_t result = 0;
 
        ctl = file->private_data;
-       snd_assert(ctl != NULL && ctl->card != NULL, return -ENXIO);
+       if (snd_BUG_ON(!ctl || !ctl->card))
+               return -ENXIO;
        if (!ctl->subscribed)
                return -EBADFD;
        if (count < sizeof(struct snd_ctl_event))
@@ -1328,7 +1445,8 @@ static int _snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn,
 {
        struct snd_kctl_ioctl *p;
 
-       snd_assert(fcn != NULL, return -EINVAL);
+       if (snd_BUG_ON(!fcn))
+               return -EINVAL;
        down_write(&snd_ioctl_rwsem);
        list_for_each_entry(p, lists, list) {
                if (p->fioctl == fcn) {
@@ -1362,12 +1480,9 @@ EXPORT_SYMBOL(snd_ctl_unregister_ioctl_compat);
 static int snd_ctl_fasync(int fd, struct file * file, int on)
 {
        struct snd_ctl_file *ctl;
-       int err;
+
        ctl = file->private_data;
-       err = fasync_helper(fd, file, on, &ctl->fasync);
-       if (err < 0)
-               return err;
-       return 0;
+       return fasync_helper(fd, file, on, &ctl->fasync);
 }
 
 /*
@@ -1389,6 +1504,7 @@ static const struct file_operations snd_ctl_f_ops =
        .read =         snd_ctl_read,
        .open =         snd_ctl_open,
        .release =      snd_ctl_release,
+       .llseek =       no_llseek,
        .poll =         snd_ctl_poll,
        .unlocked_ioctl =       snd_ctl_ioctl,
        .compat_ioctl = snd_ctl_ioctl_compat,
@@ -1404,9 +1520,11 @@ static int snd_ctl_dev_register(struct snd_device *device)
        int err, cardnum;
        char name[16];
 
-       snd_assert(card != NULL, return -ENXIO);
+       if (snd_BUG_ON(!card))
+               return -ENXIO;
        cardnum = card->number;
-       snd_assert(cardnum >= 0 && cardnum < SNDRV_CARDS, return -ENXIO);
+       if (snd_BUG_ON(cardnum < 0 || cardnum >= SNDRV_CARDS))
+               return -ENXIO;
        sprintf(name, "controlC%i", cardnum);
        if ((err = snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
                                       &snd_ctl_f_ops, card, name)) < 0)
@@ -1423,16 +1541,18 @@ static int snd_ctl_dev_disconnect(struct snd_device *device)
        struct snd_ctl_file *ctl;
        int err, cardnum;
 
-       snd_assert(card != NULL, return -ENXIO);
+       if (snd_BUG_ON(!card))
+               return -ENXIO;
        cardnum = card->number;
-       snd_assert(cardnum >= 0 && cardnum < SNDRV_CARDS, return -ENXIO);
+       if (snd_BUG_ON(cardnum < 0 || cardnum >= SNDRV_CARDS))
+               return -ENXIO;
 
-       down_read(&card->controls_rwsem);
+       read_lock(&card->ctl_files_rwlock);
        list_for_each_entry(ctl, &card->ctl_files, list) {
                wake_up(&ctl->change_sleep);
                kill_fasync(&ctl->fasync, SIGIO, POLL_ERR);
        }
-       up_read(&card->controls_rwsem);
+       read_unlock(&card->ctl_files_rwlock);
 
        if ((err = snd_unregister_device(SNDRV_DEVICE_TYPE_CONTROL,
                                         card, -1)) < 0)
@@ -1469,12 +1589,13 @@ int snd_ctl_create(struct snd_card *card)
                .dev_disconnect = snd_ctl_dev_disconnect,
        };
 
-       snd_assert(card != NULL, return -ENXIO);
+       if (snd_BUG_ON(!card))
+               return -ENXIO;
        return snd_device_new(card, SNDRV_DEV_CONTROL, card, &ops);
 }
 
 /*
- * Frequently used control callbacks
+ * Frequently used control callbacks/helpers
  */
 int snd_ctl_boolean_mono_info(struct snd_kcontrol *kcontrol,
                              struct snd_ctl_elem_info *uinfo)
@@ -1499,3 +1620,29 @@ int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol,
 }
 
 EXPORT_SYMBOL(snd_ctl_boolean_stereo_info);
+
+/**
+ * snd_ctl_enum_info - fills the info structure for an enumerated control
+ * @info: the structure to be filled
+ * @channels: the number of the control's channels; often one
+ * @items: the number of control values; also the size of @names
+ * @names: an array containing the names of all control values
+ *
+ * Sets all required fields in @info to their appropriate values.
+ * If the control's accessibility is not the default (readable and writable),
+ * the caller has to fill @info->access.
+ */
+int snd_ctl_enum_info(struct snd_ctl_elem_info *info, unsigned int channels,
+                     unsigned int items, const char *const names[])
+{
+       info->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
+       info->count = channels;
+       info->value.enumerated.items = items;
+       if (info->value.enumerated.item >= items)
+               info->value.enumerated.item = items - 1;
+       strlcpy(info->value.enumerated.name,
+               names[info->value.enumerated.item],
+               sizeof(info->value.enumerated.name));
+       return 0;
+}
+EXPORT_SYMBOL(snd_ctl_enum_info);