On Fri, 13 Jun 2025 13:03:04 +0200,
Christophe Leroy wrote:
>
>
>
> Le 13/06/2025 à 11:29, Takashi Iwai a écrit :
> > On Thu, 12 Jun 2025 12:51:05 +0200,
> > Christophe Leroy wrote:
> >>
> >> Now that snd_pcm_sync_ptr_get_user() and snd_pcm_sync_ptr_put_user()
> >> are converted to user_access_begin/user_access_end(),
> >> snd_pcm_sync_ptr_get_user() is more efficient than a raw get_user()
> >> followed by a copy_from_user(). And because copy_{to/from}_user() are
> >> generic functions focussed on transfer of big data blocks to/from user,
> >> snd_pcm_sync_ptr_put_user() is also more efficient for small amont of
> >> data.
> >>
> >> So use snd_pcm_sync_ptr_get_user() and snd_pcm_sync_ptr_put_user() in
> >> snd_pcm_sync_ptr() too.
> >>
> >> In order to have snd_pcm_mmap_status32 similar to snd_pcm_mmap_status,
> >> replace to tsamp_{sec/nsec} and audio_tstamp_{sec/nsec} by equivalent
> >> struct __snd_timespec.
> >>
> >> snd_pcm_ioctl_sync_ptr_buggy() is left as it is because the conversion
> >> wouldn't be straigh-forward do to the workaround it provides.
> >>
> >> Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
> >
> > Through a quick glance, all patches look almost fine, but one favor to
> > ask: this patch contains the convert from s32/s32 pair to struct
> > __snd_timespec. It should be factored out to a prerequisite patch
> > instead of burying in a big change.
>
> Shall I understand you prefer this series over the more simple "ALSA:
> pcm: Convert snd_pcm_ioctl_sync_ptr_{compat/x32} to
> user_access_begin/user_access_end()" patch ?
Err, no, sorry for ambiguity.
I wanted to move the replacement of tstamp_sec/nsec with struct
__snd_timespec as a small preliminary patch from patch#3.
That is,
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -3103,11 +3103,9 @@ struct snd_pcm_mmap_status32 {
snd_pcm_state_t state;
s32 pad1;
u32 hw_ptr;
- s32 tstamp_sec;
- s32 tstamp_nsec;
+ struct __snd_timespec tstamp;
snd_pcm_state_t suspended_state;
- s32 audio_tstamp_sec;
- s32 audio_tstamp_nsec;
+ struct __snd_timespec audio_tstamp;
} __packed;
etc. By factoring this out, it becomes clear that the timespec
compatibility is fully cared.
__snd_timespec may be defined in different ways on user-space, but in
the kernel code, it's a single definition of s32/s32 pair. This needs
to be emphasized.
thanks,
Takashi
