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 would like to propose merging this into the alsa tree after the v5.5 merge window for inclusion into v5.6, to allow a good amount of testing, in particular for the header changes that may cause problems for user space applications.
A git branch with the same contents is available for testing at [1].
Please review and test!
Arnd
[1] https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git y2038-alsa [2] https://lore.kernel.org/lkml/CAK8P3a2Os66+iwQYf97qh05W2JP8rmWao8zmKoHiXqVHvy...
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 (2): ALSA: move snd_pcm_ioctl_sync_ptr_compat into pcm_native.c ALSA: add new 32-bit layout for snd_pcm_mmap_status/control
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/timer.h | 4 +- include/uapi/sound/asound.h | 132 ++++++++++++-- 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/pci/hda/hda_controller.c | 10 +- sound/soc/intel/skylake/skl-pcm.c | 4 +- 13 files changed, 804 insertions(+), 488 deletions(-)