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ctl: ext: Fail with error code if snd_ctl_ext_callback::read_event() callback is not defined

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The snd_ctl_ext_callback::read_event() callback is only optional
if no poll descriptor was given via
snd_ctl_ext_t::poll_fd
or
snd_ctl_ext_callback::snd_ctl_ext_poll_descriptors().

If a poll descriptor is given the
snd_ctl_ext_callback::read_event()
callback has also to be defined
because there is no minigful default behavior.

This callback will be called when ever the poll() on
the file descriptor indicates that there is an event pending.
Therefore returning a 0 which indicates that there is no event makes no
sense.

Signed-off-by: Timo Wischer <twischer@de.adit-jv.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Timo Wischer 2017-10-05 16:25:23 +02:00 • committed by Takashi Iwai
parent 8c0b17bca3
commit 98d2c12ac2
1 changed files with 6 additions and 2 deletions
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8
src/control/control_ext.c
View file

@ -415,8 +415,12 @@ static int snd_ctl_ext_read(snd_ctl_t *handle, snd_ctl_event_t *event)
{
snd_ctl_ext_t *ext = handle->private_data;
memset(event, 0, sizeof(*event));
return ext->callback->read_event(ext, &event->data.elem.id, &event->data.elem.mask);
if (ext->callback->read_event) {
memset(event, 0, sizeof(*event));
return ext->callback->read_event(ext, &event->data.elem.id, &event->data.elem.mask);
}
return -EINVAL;
}
static int snd_ctl_ext_poll_descriptors_count(snd_ctl_t *handle)