Re: [RFC PATCH 0/7] Fix year 2038 issue for sound subsystem

[Takashi Sakamoto]

Hi,

On Sep 21 2017 15:18, Baolin Wang wrote:
> Since many structures will use timespec type variables to record time stamp
> in uapi/asound.h, which are not year 2038 safe on 32bit system. This patchset
> tries to introduce new structures removing timespec type to compatible native
> mode and compat mode.
>
> Moreover this patchset also converts the internal structrures to use timespec64
> type and related APIs.
>
> Baolin Wang (7):
>    sound: Replace timespec with timespec64
>    sound: core: Avoid using timespec for struct snd_pcm_status
>    sound: core: Avoid using timespec for struct snd_pcm_sync_ptr
>    sound: core: Avoid using timespec for struct snd_rawmidi_status
>    sound: core: Avoid using timespec for struct snd_timer_status
>    uapi: sound: Avoid using timespec for struct snd_ctl_elem_value
>    sound: core: Avoid using timespec for struct snd_timer_tread
>
>   include/sound/pcm.h               |  113 ++++++++-
>   include/sound/timer.h             |    4 +-
>   include/uapi/sound/asound.h       |   15 +-
>   sound/core/pcm.c                  |   14 +-
>   sound/core/pcm_compat.c           |  466 +++++++++++++++++++++++++++++--------
>   sound/core/pcm_lib.c              |   33 +--
>   sound/core/pcm_native.c           |  227 ++++++++++++++----
>   sound/core/rawmidi.c              |   74 +++++-
>   sound/core/rawmidi_compat.c       |   90 +++++--
>   sound/core/timer.c                |  247 ++++++++++++++++----
>   sound/core/timer_compat.c         |   25 +-
>   sound/pci/hda/hda_controller.c    |   10 +-
>   sound/soc/intel/skylake/skl-pcm.c |    4 +-
>   13 files changed, 1046 insertions(+), 276 deletions(-)

I'm a minor Takashi in this subsystem and not those who you'd like to
talk about this issue. But I have interests in it and would like to
assist you, as long as I can do for it.

As a nitpicking, your patchset brings compilation error at
configurations for x86, and x86-64 with x32 ABI support.


## x86-64 architecture and amd64 ABI support
CONFIG_64BIT=y
CONFIG_X86_64=y

Success.


## x86-64 architecture and amd64/x32 ABI support
CONFIG_64BIT=y
CONFIG_X86_64=y
CONFIG_X86_X32=y

```
sound/core/timer_compat.c:124:54: error: array type has incomplete 
element type 'struct snd_timer_status32'
  SNDRV_TIMER_IOCTL_STATUS32 = _IOW('T', 0x14, struct snd_timer_status32),
```

This error comes from a commit 1229cccbefe7 ('sound: core: Avoid using 
timespec for struct snd_timer_status').

```
sound/core/pcm_compat.c: In function 'snd_pcm_ioctl_sync_ptr_compat':
sound/core/pcm_compat.c:623:9: error: assignment from incompatible 
pointer type [-Werror=incompatible-pointer-types]
  status = runtime->status;
         ^
sound/core/pcm_compat.c: In function 'snd_pcm_ioctl_sync_ptr_x32':
sound/core/pcm_compat.c:711:9: error: assignment from incompatible 
pointer type [-Werror=incompatible-pointer-types]
  status = runtime->status;
```

This error comes from a commit 947c463adc00('sound: core: Avoid using 
timespec
for struct snd_pcm_status').


## x86 architecture and i386 ABI support
CONFIG_X86_32=y

```
sound/core/pcm_native.c: In function 'snd_pcm_common_ioctl':
sound/core/pcm_native.c:3065:2: error: duplicate case value
  case SNDRV_PCM_IOCTL_SYNC_PTR64:
  ^~~~
sound/core/pcm_native.c:3062:2: error: previously used here
  case SNDRV_PCM_IOCTL_SYNC_PTR32:

```

This error comes from a commit c0513348a7b39 ('sound: core: Avoid using
timespec for struct snd_pcm_sync_ptr').


Your patchset brought conflicts to 'for-next' branch in a repository
which Iwai-san maintains[1]. I rebased your patchset on a commit 
729fbfc92a45 ('ALSA: line6: add support for POD HD DESKTOP') which is a 
HEAD of 'for-next' branch and pushed into my repository on github[2].


I respect your work for this issue, however it's better to check whether
your patchset is buildable or not on major configurations before
posting.


I note that at a development period for v4.5 kernel, ALSA developers
(mainly Iwai-san) fixed x32 ABI compatibility bugs. Then I prepared for
a rough set of test for ioctl command[3] to check his work. The set will
partly help your work, I think (but it's really rough).

I need more time for reviewing. At least, this week is for recovery from
my tough work to rewrite aplay[4].


[1] https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git
[2] https://github.com/takaswie/sound/tree/topic/year2038-rfc1
[3] https://github.com/takaswie/alsa-ioctl-test/
[4] [alsa-devel] [RFCv2][PATCH 00/38] alsa-utils: axfer: rewrite aplay
http://mailman.alsa-project.org/pipermail/alsa-devel/2017-September/125574.html

Thanks

Takashi Sakamoto