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authorTakashi Iwai <tiwai@suse.de>2017-05-22 17:43:04 +0200
committerTakashi Iwai <tiwai@suse.de>2017-05-23 07:03:55 +0200
commit53e7bf452584e73df8a529a2b157a1225a52637f (patch)
tree697697b2c5ccd436f4c801458025a21c757c6b43 /sound/core/control.c
parenta02cb8f8def634159b60c3a4d6ba16e471b46e0c (diff)
downloadlinux-53e7bf452584e73df8a529a2b157a1225a52637f.tar.bz2
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>
Diffstat (limited to 'sound/core/control.c')
-rw-r--r--sound/core/control.c66
1 files changed, 24 insertions, 42 deletions
diff --git a/sound/core/control.c b/sound/core/control.c
index c109b82eef4b..47080da8451a 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -747,11 +747,11 @@ static int snd_ctl_card_info(struct snd_card *card, struct snd_ctl_file * ctl,
static int snd_ctl_elem_list(struct snd_card *card,
struct snd_ctl_elem_list __user *_list)
{
- struct list_head *plist;
struct snd_ctl_elem_list list;
struct snd_kcontrol *kctl;
- struct snd_ctl_elem_id *dst, *id;
+ struct snd_ctl_elem_id id;
unsigned int offset, space, jidx;
+ int err = 0;
if (copy_from_user(&list, _list, sizeof(list)))
return -EFAULT;
@@ -760,52 +760,34 @@ static int snd_ctl_elem_list(struct snd_card *card,
/* try limit maximum space */
if (space > 16384)
return -ENOMEM;
+ down_read(&card->controls_rwsem);
+ list.count = card->controls_count;
+ list.used = 0;
if (space > 0) {
- /* allocate temporary buffer for atomic operation */
- dst = vmalloc(space * sizeof(struct snd_ctl_elem_id));
- if (dst == NULL)
- return -ENOMEM;
- down_read(&card->controls_rwsem);
- list.count = card->controls_count;
- plist = card->controls.next;
- while (plist != &card->controls) {
- if (offset == 0)
- break;
- kctl = snd_kcontrol(plist);
- if (offset < kctl->count)
- break;
- offset -= kctl->count;
- plist = plist->next;
- }
- list.used = 0;
- id = dst;
- while (space > 0 && plist != &card->controls) {
- kctl = snd_kcontrol(plist);
- for (jidx = offset; space > 0 && jidx < kctl->count; jidx++) {
- snd_ctl_build_ioff(id, kctl, jidx);
- id++;
- space--;
+ list_for_each_entry(kctl, &card->controls, list) {
+ if (offset >= kctl->count) {
+ offset -= kctl->count;
+ continue;
+ }
+ for (jidx = offset; jidx < kctl->count; jidx++) {
+ snd_ctl_build_ioff(&id, kctl, jidx);
+ if (copy_to_user(list.pids + list.used, &id,
+ sizeof(id))) {
+ err = -EFAULT;
+ goto out;
+ }
list.used++;
+ if (!--space)
+ goto out;
}
- plist = plist->next;
offset = 0;
}
- up_read(&card->controls_rwsem);
- if (list.used > 0 &&
- copy_to_user(list.pids, dst,
- list.used * sizeof(struct snd_ctl_elem_id))) {
- vfree(dst);
- return -EFAULT;
- }
- vfree(dst);
- } else {
- down_read(&card->controls_rwsem);
- list.count = card->controls_count;
- up_read(&card->controls_rwsem);
}
- if (copy_to_user(_list, &list, sizeof(list)))
- return -EFAULT;
- return 0;
+ out:
+ up_read(&card->controls_rwsem);
+ if (!err && copy_to_user(_list, &list, sizeof(list)))
+ err = -EFAULT;
+ return err;
}
static bool validate_element_member_dimension(struct snd_ctl_elem_info *info)