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- The final step to get rid of auto-rearming posix-timers
posix-timers are currently auto-rearmed by the kernel when the signal
of the timer is ignored so that the timer signal can be delivered once
the corresponding signal is unignored.
This requires to throttle the timer to prevent a DoS by small intervals
and keeps the system pointlessly out of low power states for no value.
This is a long standing non-trivial problem due to the lock order of
posix-timer lock and the sighand lock along with life time issues as
the timer and the sigqueue have different life time rules.
Cure this by:
* Embedding the sigqueue into the timer struct to have the same life
time rules. Aside of that this also avoids the lookup of the timer
in the signal delivery and rearm path as it's just a always valid
container_of() now.
* Queuing ignored timer signals onto a seperate ignored list.
* Moving queued timer signals onto the ignored list when the signal is
switched to SIG_IGN before it could be delivered.
* Walking the ignored list when SIG_IGN is lifted and requeue the
signals to the actual signal lists. This allows the signal delivery
code to rearm the timer.
This also required to consolidate the signal delivery rules so they are
consistent across all situations. With that all self test scenarios
finally succeed.
- Core infrastructure for VFS multigrain timestamping
This is required to allow the kernel to use coarse grained time stamps
by default and switch to fine grained time stamps when inode attributes
are actively observed via getattr().
These changes have been provided to the VFS tree as well, so that the
VFS specific infrastructure could be built on top.
- Cleanup and consolidation of the sleep() infrastructure
* Move all sleep and timeout functions into one file
* Rework udelay() and ndelay() into proper documented inline functions
and replace the hardcoded magic numbers by proper defines.
* Rework the fsleep() implementation to take the reality of the timer
wheel granularity on different HZ values into account. Right now the
boundaries are hard coded time ranges which fail to provide the
requested accuracy on different HZ settings.
* Update documentation for all sleep/timeout related functions and fix
up stale documentation links all over the place
* Fixup a few usage sites
- Rework of timekeeping and adjtimex(2) to prepare for multiple PTP clocks
A system can have multiple PTP clocks which are participating in
seperate and independent PTP clock domains. So far the kernel only
considers the PTP clock which is based on CLOCK TAI relevant as that's
the clock which drives the timekeeping adjustments via the various user
space daemons through adjtimex(2).
The non TAI based clock domains are accessible via the file descriptor
based posix clocks, but their usability is very limited. They can't be
accessed fast as they always go all the way out to the hardware and
they cannot be utilized in the kernel itself.
As Time Sensitive Networking (TSN) gains traction it is required to
provide fast user and kernel space access to these clocks.
The approach taken is to utilize the timekeeping and adjtimex(2)
infrastructure to provide this access in a similar way how the kernel
provides access to clock MONOTONIC, REALTIME etc.
Instead of creating a duplicated infrastructure this rework converts
timekeeping and adjtimex(2) into generic functionality which operates
on pointers to data structures instead of using static variables.
This allows to provide time accessors and adjtimex(2) functionality for
the independent PTP clocks in a subsequent step.
- Consolidate hrtimer initialization
hrtimers are set up by initializing the data structure and then
seperately setting the callback function for historical reasons.
That's an extra unnecessary step and makes Rust support less straight
forward than it should be.
Provide a new set of hrtimer_setup*() functions and convert the core
code and a few usage sites of the less frequently used interfaces over.
The bulk of the htimer_init() to hrtimer_setup() conversion is already
prepared and scheduled for the next merge window.
- Drivers:
* Ensure that the global timekeeping clocksource is utilizing the
cluster 0 timer on MIPS multi-cluster systems.
Otherwise CPUs on different clusters use their cluster specific
clocksource which is not guaranteed to be synchronized with other
clusters.
* Mostly boring cleanups, fixes, improvements and code movement
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Merge tag 'timers-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
"A rather large update for timekeeping and timers:
- The final step to get rid of auto-rearming posix-timers
posix-timers are currently auto-rearmed by the kernel when the
signal of the timer is ignored so that the timer signal can be
delivered once the corresponding signal is unignored.
This requires to throttle the timer to prevent a DoS by small
intervals and keeps the system pointlessly out of low power states
for no value. This is a long standing non-trivial problem due to
the lock order of posix-timer lock and the sighand lock along with
life time issues as the timer and the sigqueue have different life
time rules.
Cure this by:
- Embedding the sigqueue into the timer struct to have the same
life time rules. Aside of that this also avoids the lookup of
the timer in the signal delivery and rearm path as it's just a
always valid container_of() now.
- Queuing ignored timer signals onto a seperate ignored list.
- Moving queued timer signals onto the ignored list when the
signal is switched to SIG_IGN before it could be delivered.
- Walking the ignored list when SIG_IGN is lifted and requeue the
signals to the actual signal lists. This allows the signal
delivery code to rearm the timer.
This also required to consolidate the signal delivery rules so they
are consistent across all situations. With that all self test
scenarios finally succeed.
- Core infrastructure for VFS multigrain timestamping
This is required to allow the kernel to use coarse grained time
stamps by default and switch to fine grained time stamps when inode
attributes are actively observed via getattr().
These changes have been provided to the VFS tree as well, so that
the VFS specific infrastructure could be built on top.
- Cleanup and consolidation of the sleep() infrastructure
- Move all sleep and timeout functions into one file
- Rework udelay() and ndelay() into proper documented inline
functions and replace the hardcoded magic numbers by proper
defines.
- Rework the fsleep() implementation to take the reality of the
timer wheel granularity on different HZ values into account.
Right now the boundaries are hard coded time ranges which fail
to provide the requested accuracy on different HZ settings.
- Update documentation for all sleep/timeout related functions
and fix up stale documentation links all over the place
- Fixup a few usage sites
- Rework of timekeeping and adjtimex(2) to prepare for multiple PTP
clocks
A system can have multiple PTP clocks which are participating in
seperate and independent PTP clock domains. So far the kernel only
considers the PTP clock which is based on CLOCK TAI relevant as
that's the clock which drives the timekeeping adjustments via the
various user space daemons through adjtimex(2).
The non TAI based clock domains are accessible via the file
descriptor based posix clocks, but their usability is very limited.
They can't be accessed fast as they always go all the way out to
the hardware and they cannot be utilized in the kernel itself.
As Time Sensitive Networking (TSN) gains traction it is required to
provide fast user and kernel space access to these clocks.
The approach taken is to utilize the timekeeping and adjtimex(2)
infrastructure to provide this access in a similar way how the
kernel provides access to clock MONOTONIC, REALTIME etc.
Instead of creating a duplicated infrastructure this rework
converts timekeeping and adjtimex(2) into generic functionality
which operates on pointers to data structures instead of using
static variables.
This allows to provide time accessors and adjtimex(2) functionality
for the independent PTP clocks in a subsequent step.
- Consolidate hrtimer initialization
hrtimers are set up by initializing the data structure and then
seperately setting the callback function for historical reasons.
That's an extra unnecessary step and makes Rust support less
straight forward than it should be.
Provide a new set of hrtimer_setup*() functions and convert the
core code and a few usage sites of the less frequently used
interfaces over.
The bulk of the htimer_init() to hrtimer_setup() conversion is
already prepared and scheduled for the next merge window.
- Drivers:
- Ensure that the global timekeeping clocksource is utilizing the
cluster 0 timer on MIPS multi-cluster systems.
Otherwise CPUs on different clusters use their cluster specific
clocksource which is not guaranteed to be synchronized with
other clusters.
- Mostly boring cleanups, fixes, improvements and code movement"
* tag 'timers-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (140 commits)
posix-timers: Fix spurious warning on double enqueue versus do_exit()
clocksource/drivers/arm_arch_timer: Use of_property_present() for non-boolean properties
clocksource/drivers/gpx: Remove redundant casts
clocksource/drivers/timer-ti-dm: Fix child node refcount handling
dt-bindings: timer: actions,owl-timer: convert to YAML
clocksource/drivers/ralink: Add Ralink System Tick Counter driver
clocksource/drivers/mips-gic-timer: Always use cluster 0 counter as clocksource
clocksource/drivers/timer-ti-dm: Don't fail probe if int not found
clocksource/drivers:sp804: Make user selectable
clocksource/drivers/dw_apb: Remove unused dw_apb_clockevent functions
hrtimers: Delete hrtimer_init_on_stack()
alarmtimer: Switch to use hrtimer_setup() and hrtimer_setup_on_stack()
io_uring: Switch to use hrtimer_setup_on_stack()
sched/idle: Switch to use hrtimer_setup_on_stack()
hrtimers: Delete hrtimer_init_sleeper_on_stack()
wait: Switch to use hrtimer_setup_sleeper_on_stack()
timers: Switch to use hrtimer_setup_sleeper_on_stack()
net: pktgen: Switch to use hrtimer_setup_sleeper_on_stack()
futex: Switch to use hrtimer_setup_sleeper_on_stack()
fs/aio: Switch to use hrtimer_setup_sleeper_on_stack()
...
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| .. | ||
| 32-bit.config | ||
| 64-bit.config | ||
| defconfig | ||
| nommu_k210_defconfig | ||
| nommu_k210_sdcard_defconfig | ||
| nommu_virt_defconfig | ||