On Fri, 13 Jun 2025 14:46:46 +0200,
Christophe Leroy wrote:

Le 13/06/2025 à 14:37, Takashi Iwai a écrit :

quoted

On Fri, 13 Jun 2025 13:03:04 +0200,
Christophe Leroy wrote:

quoted

Le 13/06/2025 à 11:29, Takashi Iwai a écrit :

quoted

On Thu, 12 Jun 2025 12:51:05 +0200,
Christophe Leroy wrote:

quoted

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 <redacted>

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.

Then I'm lost.

I sent two alternative proposals:
A/ Single patch, simple, handling only two fonctions
snd_pcm_ioctl_sync_ptr_{compat/x32} , without refactoring. [1]
B/ This RFC series, more elaborate, refactoring and putting user copy
into helper macros. [2]

So the question was to be sure you prefer alternative B over
alternative A. I guess the answer is YES as you asking me improve it.

Right, let's go with the RFC series with refactoring.


thanks,

Takashi

[1]
https://patchwork.ozlabs.org/project/linuxppc-dev/patch/8df11af98033e4cb4d9b0f16d6e9d5b69110b036.1749724057.git.christophe.leroy@csgroup.eu/
[2]
https://patchwork.ozlabs.org/project/linuxppc-dev/list/?state=*&series=460665

quoted

I wanted to move the replacement of tstamp_sec/nsec with struct
__snd_timespec as a small preliminary patch from patch#3.
That is,

Yes that's what I understood.

Thanks
Christophe

quoted

--- 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