ALSA: control: code refactoring TLV ioctl handler

In a design of ALSA control core, execution path bifurcates depending on
target element. When a set with the target element has a handler, it's
called. Else, registered buffer is copied to user space. These two
operations are apparently different.  In current implementation, they're
on the same function with a condition statement. This makes it a bit hard
to understand conditions of each case.

This commit splits codes for these two cases.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/control.c b/sound/core/control.c
index 989292f..9238900 100644 (file)
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -1394,65 +1394,115 @@ static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)
        return 0;
 }
 
+static int call_tlv_handler(struct snd_ctl_file *file, int op_flag,
+                           struct snd_kcontrol *kctl,
+                           struct snd_ctl_elem_id *id,
+                           unsigned int __user *buf, unsigned int size)
+{
+       static const struct {
+               int op;
+               int perm;
+       } pairs[] = {
+               {SNDRV_CTL_TLV_OP_READ,  SNDRV_CTL_ELEM_ACCESS_TLV_READ},
+               {SNDRV_CTL_TLV_OP_WRITE, SNDRV_CTL_ELEM_ACCESS_TLV_WRITE},
+               {SNDRV_CTL_TLV_OP_CMD,   SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND},
+       };
+       struct snd_kcontrol_volatile *vd = &kctl->vd[snd_ctl_get_ioff(kctl, id)];
+       int i;
+       int err;
+
+       /* Check support of the request for this element. */
+       for (i = 0; i < ARRAY_SIZE(pairs); ++i) {
+               if (op_flag == pairs[i].op && (vd->access & pairs[i].perm))
+                       break;
+       }
+       if (i == ARRAY_SIZE(pairs))
+               return -ENXIO;
+
+       if (kctl->tlv.c == NULL)
+               return -ENXIO;
+
+       /* When locked, this is unavailable. */
+       if (vd->owner != NULL && vd->owner != file)
+               return -EPERM;
+
+       err = kctl->tlv.c(kctl, op_flag, size, buf);
+       if (err < 0)
+               return err;
+
+       if (err > 0)
+               snd_ctl_notify(file->card, SNDRV_CTL_EVENT_MASK_TLV, id);
+
+       return 0;
+}
+
+static int read_tlv_buf(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id,
+                       unsigned int __user *buf, unsigned int size)
+{
+       struct snd_kcontrol_volatile *vd = &kctl->vd[snd_ctl_get_ioff(kctl, id)];
+       unsigned int len;
+
+       if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ))
+               return -ENXIO;
+
+       if (kctl->tlv.p == NULL)
+               return -ENXIO;
+
+       len = sizeof(unsigned int) * 2 + kctl->tlv.p[1];
+       if (size < len)
+               return -ENOMEM;
+
+       if (copy_to_user(buf, kctl->tlv.p, len))
+               return -EFAULT;
+
+       return 0;
+}
+
 static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
-                             struct snd_ctl_tlv __user *_tlv,
+                            struct snd_ctl_tlv __user *buf,
                              int op_flag)
 {
-       struct snd_card *card = file->card;
-       struct snd_ctl_tlv tlv;
+       struct snd_ctl_tlv header;
+       unsigned int *container;
+       unsigned int container_size;
        struct snd_kcontrol *kctl;
+       struct snd_ctl_elem_id id;
        struct snd_kcontrol_volatile *vd;
-       unsigned int len;
 
-       if (copy_from_user(&tlv, _tlv, sizeof(tlv)))
+       if (copy_from_user(&header, buf, sizeof(header)))
                return -EFAULT;
-       if (tlv.length < sizeof(unsigned int) * 2)
+
+       /* In design of control core, numerical ID starts at 1. */
+       if (header.numid == 0)
                return -EINVAL;
-       if (!tlv.numid)
+
+       /* At least, container should include type and length fields.  */
+       if (header.length < sizeof(unsigned int) * 2)
                return -EINVAL;
+       container_size = header.length;
+       container = buf->tlv;
 
-       kctl = snd_ctl_find_numid(card, tlv.numid);
+       kctl = snd_ctl_find_numid(file->card, header.numid);
        if (kctl == NULL)
                return -ENOENT;
 
-       if (kctl->tlv.p == NULL)
-               return -ENXIO;
-
-       vd = &kctl->vd[tlv.numid - kctl->id.numid];
-       if ((op_flag == SNDRV_CTL_TLV_OP_READ &&
-            (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ) == 0) ||
-           (op_flag == SNDRV_CTL_TLV_OP_WRITE &&
-            (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE) == 0) ||
-           (op_flag == SNDRV_CTL_TLV_OP_CMD &&
-            (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND) == 0))
-               return -ENXIO;
+       /* Calculate index of the element in this set. */
+       id = kctl->id;
+       snd_ctl_build_ioff(&id, kctl, header.numid - id.numid);
+       vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
 
        if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
-               int err;
-
-               if (vd->owner != NULL && vd->owner != file)
-                       return -EPERM;
-
-               err = kctl->tlv.c(kctl, op_flag, tlv.length, _tlv->tlv);
-               if (err < 0)
-                       return err;
-               if (err > 0) {
-                       struct snd_ctl_elem_id id = kctl->id;
-                       snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_TLV, &id);
-               }
+               return call_tlv_handler(file, op_flag, kctl, &id, container,
+                                       container_size);
        } else {
-               if (op_flag != SNDRV_CTL_TLV_OP_READ)
-                       return -ENXIO;
-
-               len = kctl->tlv.p[1] + 2 * sizeof(unsigned int);
-               if (tlv.length < len)
-                       return -ENOMEM;
-
-               if (copy_to_user(_tlv->tlv, kctl->tlv.p, len))
-                       return -EFAULT;
+               if (op_flag == SNDRV_CTL_TLV_OP_READ) {
+                       return read_tlv_buf(kctl, &id, container,
+                                           container_size);
+               }
        }
 
-       return 0;
+       /* Not supported. */
+       return -ENXIO;
 }
 
 static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)