On Thu, 02 Dec 2021 16:06:07 +0100, Alan Young wrote: > > When control_compat.c:copy_ctl_value_to_user() is used, by > ctl_elem_read_user() & ctl_elem_write_user(), it must also copy back the > snd_ctl_elem_id value that may have been updated (filled in) by the call > to snd_ctl_elem_read/snd_ctl_elem_write(). > > This matches the functionality provided by snd_ctl_elem_read_user() and > snd_ctl_elem_write_user(), via snd_ctl_build_ioff(). > > Without this, and without making additional calls to snd_ctl_info() > which are unnecessary when using the non-compat calls, a userspace > application will not know the numid value for the element and > consequently will not be able to use the poll/read interface on the > control file to determine which elements have updates. > > Signed-off-by: Alan Young <consult.awy@xxxxxxxxx> Thanks, applied (with Cc to stable). Takashi
