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Subject[PATCH v7 0/8] Fix year 2038 issue for sound subsystem
Date
This is a series I worked on with Baolin in 2017 and 2018, but we
never quite managed to finish up the last pieces. During the
ALSA developer meetup at ELC-E 2018 in Edinburgh, a decision was
made to go with this approach for keeping best compatibility
with existing source code, and then I failed to follow up by
resending the patches.

Now I have patches for all remaining time_t uses in the kernel,
so it's absolutely time to revisit them. I have done more
review of the patches myself and found a couple of minor issues
that I have fixed up, otherwise the series is still the same as
before.

Conceptually, the idea of these patches is:

- 64-bit applications should see no changes at all, neither
compile-time nor run-time.

- 32-bit code compiled with a 64-bit time_t currently
does not work with ALSA, and requires kernel changes and/or
sound/asound.h changes

- Most 32-bit code using these interfaces will work correctly
on a modified kernel, with or without the uapi header changes.

- 32-bit code using SNDRV_TIMER_IOCTL_TREAD requires the
updated header file for 64-bit time_t support

- 32-bit i386 user space with 64-bit time_t is broken for
SNDRV_PCM_IOCTL_STATUS, SNDRV_RAWMIDI_IOCTL_STATUS and
SNDRV_PCM_IOCTL_SYNC_PTR because of i386 alignment. This is also
addressed by the updated uapi header.

- PCM mmap is currently supported on native x86 kernels
(both 32-bit and 64-bit) but not for compat mode. This series breaks
the 32-bit native mmap support for 32-bit time_t, but instead allows
it for 64-bit time_t on both native and compat kernels. This seems to
be the best trade-off, as mmap support is optional already, and most
32-bit code runs in compat mode anyway.

- I've tried to avoid breaking compilation of 32-bit code
as much as possible. Anything that does break however is likely code
that is already broken on 64-bit time_t and needs source changes to
fix them.

I hope I addressed all review comments by now, so please pull this
for linux-5.6.

A git branch with the same contents is available for testing at [1].

Arnd

[1] https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git y2038-alsa-v7
[2] https://lore.kernel.org/lkml/CAK8P3a2Os66+iwQYf97qh05W2JP8rmWao8zmKoHiXqVHvyYAJA@mail.gmail.com/T/#m6519cb07cfda08adf1dedea6596bb98892b4d5dc

Changes since v6: (Arnd):
- Add a patch to update the API versions
- Hide a timespec reference in #ifndef __KERNEL__ to remove the
last reference to time_t
- Use a more readable way to do padding and describe it in the
changelog
- Rebase to linux-5.5-rc1, changing include/sound/soc-component.h
and sound/drivers/aloop.c as needed.

Changes since v5 (Arnd):
- Rebased to linux-5.4-rc4
- Updated to completely remove timespec and time_t references from alsa
- found and fixed a few bugs

Changes since v4 (Baolin):
- Add patch 5 to change trigger_tstamp member of struct snd_pcm_runtime.
- Add patch 8 to change internal timespec.
- Add more explanation in commit message.
- Use ktime_get_real_ts64() in patch 6.
- Split common code out into a separate function in patch 6.
- Fix tu->tread bug in patch 6 and remove #if __BITS_PER_LONG == 64 macro.

Changes since v3:
- Move struct snd_pcm_status32 to pcm.h file.
- Modify comments and commit message.
- Add new patch2 ~ patch6.

Changes since v2:
- Renamed all structures to make clear.
- Remove CONFIG_X86_X32 macro and introduced new compat_snd_pcm_status64_x86_32.

Changes since v1:
- Add one macro for struct snd_pcm_status_32 which only active in 32bits kernel.
- Convert pcm_compat.c to use struct snd_pcm_status_64.
- Convert pcm_native.c to use struct snd_pcm_status_64.
---

Arnd Bergmann (3):
ALSA: move snd_pcm_ioctl_sync_ptr_compat into pcm_native.c
ALSA: add new 32-bit layout for snd_pcm_mmap_status/control
ALSA: bump uapi version numbers

Baolin Wang (6):
ALSA: Replace timespec with timespec64
ALSA: Avoid using timespec for struct snd_timer_status
ALSA: Avoid using timespec for struct snd_ctl_elem_value
ALSA: Avoid using timespec for struct snd_pcm_status
ALSA: Avoid using timespec for struct snd_rawmidi_status
ALSA: Avoid using timespec for struct snd_timer_tread

include/sound/pcm.h | 74 ++++++--
include/sound/soc-component.h | 4 +-
include/sound/timer.h | 4 +-
include/uapi/sound/asound.h | 145 +++++++++++++--
sound/core/pcm.c | 12 +-
sound/core/pcm_compat.c | 282 ++++++++----------------------
sound/core/pcm_lib.c | 38 ++--
sound/core/pcm_native.c | 226 +++++++++++++++++++++---
sound/core/rawmidi.c | 132 +++++++++++---
sound/core/rawmidi_compat.c | 87 +++------
sound/core/timer.c | 229 ++++++++++++++++++------
sound/core/timer_compat.c | 62 +------
sound/drivers/aloop.c | 2 +-
sound/pci/hda/hda_controller.c | 10 +-
sound/soc/intel/skylake/skl-pcm.c | 4 +-
15 files changed, 817 insertions(+), 494 deletions(-)

--
2.20.0

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