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ALSA: control: Simplify snd_ctl_elem_list() implementation
This patch simplifies the code of snd_ctl_elem_list() in the following ways: - Avoid a vmalloc() temporary buffer but do copy in each iteration; the vmalloc buffer was introduced at the time we took the spinlock for the ctl element management. - Use the standard list_for_each_entry() macro - Merge two loops into one; it used to be a loop for skipping until offset becomes zero and another loop to copy the data. They can be folded into a single loop easily. Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Tested-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Takashi Iwai <tiwai@suse.de>
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@ -747,11 +747,11 @@ static int snd_ctl_card_info(struct snd_card *card, struct snd_ctl_file * ctl,
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static int snd_ctl_elem_list(struct snd_card *card,
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struct snd_ctl_elem_list __user *_list)
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{
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struct list_head *plist;
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struct snd_ctl_elem_list list;
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struct snd_kcontrol *kctl;
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struct snd_ctl_elem_id *dst, *id;
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struct snd_ctl_elem_id id;
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unsigned int offset, space, jidx;
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int err = 0;
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if (copy_from_user(&list, _list, sizeof(list)))
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return -EFAULT;
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@ -760,52 +760,34 @@ static int snd_ctl_elem_list(struct snd_card *card,
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/* try limit maximum space */
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if (space > 16384)
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return -ENOMEM;
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down_read(&card->controls_rwsem);
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list.count = card->controls_count;
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list.used = 0;
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if (space > 0) {
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/* allocate temporary buffer for atomic operation */
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dst = vmalloc(space * sizeof(struct snd_ctl_elem_id));
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if (dst == NULL)
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return -ENOMEM;
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down_read(&card->controls_rwsem);
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list.count = card->controls_count;
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plist = card->controls.next;
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while (plist != &card->controls) {
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if (offset == 0)
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break;
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kctl = snd_kcontrol(plist);
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if (offset < kctl->count)
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break;
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offset -= kctl->count;
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plist = plist->next;
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}
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list.used = 0;
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id = dst;
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while (space > 0 && plist != &card->controls) {
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kctl = snd_kcontrol(plist);
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for (jidx = offset; space > 0 && jidx < kctl->count; jidx++) {
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snd_ctl_build_ioff(id, kctl, jidx);
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id++;
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space--;
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list.used++;
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list_for_each_entry(kctl, &card->controls, list) {
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if (offset >= kctl->count) {
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offset -= kctl->count;
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continue;
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}
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for (jidx = offset; jidx < kctl->count; jidx++) {
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snd_ctl_build_ioff(&id, kctl, jidx);
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if (copy_to_user(list.pids + list.used, &id,
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sizeof(id))) {
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err = -EFAULT;
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goto out;
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}
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list.used++;
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if (!--space)
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goto out;
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}
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plist = plist->next;
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offset = 0;
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}
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up_read(&card->controls_rwsem);
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if (list.used > 0 &&
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copy_to_user(list.pids, dst,
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list.used * sizeof(struct snd_ctl_elem_id))) {
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vfree(dst);
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return -EFAULT;
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}
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vfree(dst);
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} else {
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down_read(&card->controls_rwsem);
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list.count = card->controls_count;
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up_read(&card->controls_rwsem);
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}
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if (copy_to_user(_list, &list, sizeof(list)))
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return -EFAULT;
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return 0;
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out:
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up_read(&card->controls_rwsem);
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if (!err && copy_to_user(_list, &list, sizeof(list)))
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err = -EFAULT;
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return err;
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}
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static bool validate_element_member_dimension(struct snd_ctl_elem_info *info)
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