[PATCH v2 1/3] ALSA: pcm: introduce INFO_NO_REWINDS flag

[Takashi Iwai]

On Tue, 12 Oct 2021 17:15:56 +0200,
Pierre-Louis Bossart wrote:
> 
> > In either way, the new_ptr has to be validated beforehand that it's
> > within 0..boundary-1.  (old_ptr is assumed to be valid.)
> 
> In the 3 of the calls to pcm_lib_apply_appl_ptr(), the check is done
> already prior to calling that function
> 	if (appl_ptr >= runtime->boundary)
> 		appl_ptr -= runtime->boundary;
> 	err = pcm_lib_apply_appl_ptr(substream, appl_ptr);
> 
> 
> it's rather unclear to me why the same check is not done for sync_ptr, e.g.
> 
> if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL)) {
> 	err = pcm_lib_apply_appl_ptr(substream,	
> 			     sync_ptr.c.control.appl_ptr);
> 
> if (!(sflags & SNDRV_PCM_SYNC_PTR_APPL)) {
> 	err = pcm_lib_apply_appl_ptr(substream,
> 				scontrol.appl_ptr);
> 
> Should I add a check there, or add a check inside of
> pcm_lib_apply_appl_ptr() which would be a duplicate in the majority of
> cases?

I guess adding in pcm_lib_appl_appl_ptr() would be easier and safer.
There is even one more place that is calling pcm_lib_apply_appl_ptr()
in the very latest commit (a fix for a buggy 32bit compat ioctl).


thanks,

Takashi