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Merge tag 'vfs-6.13.mgtime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs multigrain timestamps from Christian Brauner:
"This is another try at implementing multigrain timestamps. This time
with significant help from the timekeeping maintainers to reduce the
performance impact.
Thomas provided a base branch that contains the required timekeeping
interfaces for the VFS. It serves as the base for the multi-grain
timestamp work:
- Multigrain timestamps allow the kernel to use fine-grained
timestamps when an inode's attributes is being actively observed
via ->getattr(). With this support, it's possible for a file to get
a fine-grained timestamp, and another modified after it to get a
coarse-grained stamp that is earlier than the fine-grained time. If
this happens then the files can appear to have been modified in
reverse order, which breaks VFS ordering guarantees.
To prevent this, a floor value is maintained for multigrain
timestamps. Whenever a fine-grained timestamp is handed out, record
it, and when later coarse-grained stamps are handed out, ensure
they are not earlier than that value. If the coarse-grained
timestamp is earlier than the fine-grained floor, return the floor
value instead.
The timekeeper changes add a static singleton atomic64_t into
timekeeper.c that is used to keep track of the latest fine-grained
time ever handed out. This is tracked as a monotonic ktime_t value
to ensure that it isn't affected by clock jumps. Because it is
updated at different times than the rest of the timekeeper object,
the floor value is managed independently of the timekeeper via a
cmpxchg() operation, and sits on its own cacheline.
Two new public timekeeper interfaces are added:
(1) ktime_get_coarse_real_ts64_mg() fills a timespec64 with the
later of the coarse-grained clock and the floor time
(2) ktime_get_real_ts64_mg() gets the fine-grained clock value,
and tries to swap it into the floor. A timespec64 is filled
with the result.
- The VFS has always used coarse-grained timestamps when updating the
ctime and mtime after a change. This has the benefit of allowing
filesystems to optimize away a lot metadata updates, down to around
1 per jiffy, even when a file is under heavy writes.
Unfortunately, this has always been an issue when we're exporting
via NFSv3, which relies on timestamps to validate caches. A lot of
changes can happen in a jiffy, so timestamps aren't sufficient to
help the client decide when to invalidate the cache. Even with
NFSv4, a lot of exported filesystems don't properly support a
change attribute and are subject to the same problems with
timestamp granularity. Other applications have similar issues with
timestamps (e.g backup applications).
If we were to always use fine-grained timestamps, that would
improve the situation, but that becomes rather expensive, as the
underlying filesystem would have to log a lot more metadata
updates.
This adds a way to only use fine-grained timestamps when they are
being actively queried. Use the (unused) top bit in
inode->i_ctime_nsec as a flag that indicates whether the current
timestamps have been queried via stat() or the like. When it's set,
we allow the kernel to use a fine-grained timestamp iff it's
necessary to make the ctime show a different value.
This solves the problem of being able to distinguish the timestamp
between updates, but introduces a new problem: it's now possible
for a file being changed to get a fine-grained timestamp. A file
that is altered just a bit later can then get a coarse-grained one
that appears older than the earlier fine-grained time. This
violates timestamp ordering guarantees.
This is where the earlier mentioned timkeeping interfaces help. A
global monotonic atomic64_t value is kept that acts as a timestamp
floor. When we go to stamp a file, we first get the latter of the
current floor value and the current coarse-grained time. If the
inode ctime hasn't been queried then we just attempt to stamp it
with that value.
If it has been queried, then first see whether the current coarse
time is later than the existing ctime. If it is, then we accept
that value. If it isn't, then we get a fine-grained time and try to
swap that into the global floor. Whether that succeeds or fails, we
take the resulting floor time, convert it to realtime and try to
swap that into the ctime.
We take the result of the ctime swap whether it succeeds or fails,
since either is just as valid.
Filesystems can opt into this by setting the FS_MGTIME fstype flag.
Others should be unaffected (other than being subject to the same
floor value as multigrain filesystems)"
* tag 'vfs-6.13.mgtime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: reduce pointer chasing in is_mgtime() test
tmpfs: add support for multigrain timestamps
btrfs: convert to multigrain timestamps
ext4: switch to multigrain timestamps
xfs: switch to multigrain timestamps
Documentation: add a new file documenting multigrain timestamps
fs: add percpu counters for significant multigrain timestamp events
fs: tracepoints around multigrain timestamp events
fs: handle delegated timestamps in setattr_copy_mgtime
timekeeping: Add percpu counter for tracking floor swap events
timekeeping: Add interfaces for handling timestamps with a floor value
fs: have setattr_copy handle multigrain timestamps appropriately
fs: add infrastructure for multigrain timestamps
Current release - regressions:
- posix-clock: Fix unbalanced locking in pc_clock_settime()
- netfilter: fix typo causing some targets not to load on IPv6
Current release - new code bugs:
- xfrm: policy: remove last remnants of pernet inexact list
Previous releases - regressions:
- core: fix races in netdev_tx_sent_queue()/dev_watchdog()
- bluetooth: fix UAF on sco_sock_timeout
- eth: hv_netvsc: fix VF namespace also in synthetic NIC NETDEV_REGISTER event
- eth: usbnet: fix name regression
- eth: be2net: fix potential memory leak in be_xmit()
- eth: plip: fix transmit path breakage
Previous releases - always broken:
- sched: deny mismatched skip_sw/skip_hw flags for actions created by classifiers
- netfilter: bpf: must hold reference on net namespace
- eth: virtio_net: fix integer overflow in stats
- eth: bnxt_en: replace ptp_lock with irqsave variant
- eth: octeon_ep: add SKB allocation failures handling in __octep_oq_process_rx()
Misc:
- MAINTAINERS: add Simon as an official reviewer
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Merge tag 'net-6.12-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Pull networking fixes from Paolo Abeni:
"Including fixes from netfiler, xfrm and bluetooth.
Oddly this includes a fix for a posix clock regression; in our
previous PR we included a change there as a pre-requisite for
networking one. That fix proved to be buggy and requires the follow-up
included here. Thomas suggested we should send it, given we sent the
buggy patch.
Current release - regressions:
- posix-clock: Fix unbalanced locking in pc_clock_settime()
- netfilter: fix typo causing some targets not to load on IPv6
Current release - new code bugs:
- xfrm: policy: remove last remnants of pernet inexact list
Previous releases - regressions:
- core: fix races in netdev_tx_sent_queue()/dev_watchdog()
- bluetooth: fix UAF on sco_sock_timeout
- eth: hv_netvsc: fix VF namespace also in synthetic NIC
NETDEV_REGISTER event
- eth: usbnet: fix name regression
- eth: be2net: fix potential memory leak in be_xmit()
- eth: plip: fix transmit path breakage
Previous releases - always broken:
- sched: deny mismatched skip_sw/skip_hw flags for actions created by
classifiers
- netfilter: bpf: must hold reference on net namespace
- eth: virtio_net: fix integer overflow in stats
- eth: bnxt_en: replace ptp_lock with irqsave variant
- eth: octeon_ep: add SKB allocation failures handling in
__octep_oq_process_rx()
Misc:
- MAINTAINERS: add Simon as an official reviewer"
* tag 'net-6.12-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (40 commits)
net: dsa: mv88e6xxx: support 4000ps cycle counter period
net: dsa: mv88e6xxx: read cycle counter period from hardware
net: dsa: mv88e6xxx: group cycle counter coefficients
net: usb: qmi_wwan: add Fibocom FG132 0x0112 composition
hv_netvsc: Fix VF namespace also in synthetic NIC NETDEV_REGISTER event
net: dsa: microchip: disable EEE for KSZ879x/KSZ877x/KSZ876x
Bluetooth: ISO: Fix UAF on iso_sock_timeout
Bluetooth: SCO: Fix UAF on sco_sock_timeout
Bluetooth: hci_core: Disable works on hci_unregister_dev
posix-clock: posix-clock: Fix unbalanced locking in pc_clock_settime()
r8169: avoid unsolicited interrupts
net: sched: use RCU read-side critical section in taprio_dump()
net: sched: fix use-after-free in taprio_change()
net/sched: act_api: deny mismatched skip_sw/skip_hw flags for actions created by classifiers
net: usb: usbnet: fix name regression
mlxsw: spectrum_router: fix xa_store() error checking
virtio_net: fix integer overflow in stats
net: fix races in netdev_tx_sent_queue()/dev_watchdog()
net: wwan: fix global oob in wwan_rtnl_policy
netfilter: xtables: fix typo causing some targets not to load on IPv6
...
If get_clock_desc() succeeds, it calls fget() for the clockid's fd,
and get the clk->rwsem read lock, so the error path should release
the lock to make the lock balance and fput the clockid's fd to make
the refcount balance and release the fd related resource.
However the below commit left the error path locked behind resulting in
unbalanced locking. Check timespec64_valid_strict() before
get_clock_desc() to fix it, because the "ts" is not changed
after that.
Fixes: d8794ac20a ("posix-clock: Fix missing timespec64 check in pc_clock_settime()")
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Acked-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
[pabeni@redhat.com: fixed commit message typo]
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
- Fix another aspect of delayed dequeued tasks wrt determining their state,
i.e., whether they're runnable or blocked
- Handle delayed dequeued tasks and their migration wrt PSI properly
- Fix the situation where a delayed dequeue task gets enqueued into a new
class, which should not happen
- Fix a case where memory allocation would happen while the runqueue lock is
held, which is a no-no
- Do not over-schedule when tasks with shorter slices preempt the currently
running task
- Make sure delayed to deque entities are properly handled before unthrottling
- Other smaller cleanups and improvements
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Merge tag 'sched_urgent_for_v6.12_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduling fixes from Borislav Petkov:
- Add PREEMPT_RT maintainers
- Fix another aspect of delayed dequeued tasks wrt determining their
state, i.e., whether they're runnable or blocked
- Handle delayed dequeued tasks and their migration wrt PSI properly
- Fix the situation where a delayed dequeue task gets enqueued into a
new class, which should not happen
- Fix a case where memory allocation would happen while the runqueue
lock is held, which is a no-no
- Do not over-schedule when tasks with shorter slices preempt the
currently running task
- Make sure delayed to deque entities are properly handled before
unthrottling
- Other smaller cleanups and improvements
* tag 'sched_urgent_for_v6.12_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
MAINTAINERS: Add an entry for PREEMPT_RT.
sched/fair: Fix external p->on_rq users
sched/psi: Fix mistaken CPU pressure indication after corrupted task state bug
sched/core: Dequeue PSI signals for blocked tasks that are delayed
sched: Fix delayed_dequeue vs switched_from_fair()
sched/core: Disable page allocation in task_tick_mm_cid()
sched/deadline: Use hrtick_enabled_dl() before start_hrtick_dl()
sched/eevdf: Fix wakeup-preempt by checking cfs_rq->nr_running
sched: Fix sched_delayed vs cfs_bandwidth
As Andrew pointed out, it will make sense that the PTP core
checked timespec64 struct's tv_sec and tv_nsec range before calling
ptp->info->settime64().
As the man manual of clock_settime() said, if tp.tv_sec is negative or
tp.tv_nsec is outside the range [0..999,999,999], it should return EINVAL,
which include dynamic clocks which handles PTP clock, and the condition is
consistent with timespec64_valid(). As Thomas suggested, timespec64_valid()
only check the timespec is valid, but not ensure that the time is
in a valid range, so check it ahead using timespec64_valid_strict()
in pc_clock_settime() and return -EINVAL if not valid.
There are some drivers that use tp->tv_sec and tp->tv_nsec directly to
write registers without validity checks and assume that the higher layer
has checked it, which is dangerous and will benefit from this, such as
hclge_ptp_settime(), igb_ptp_settime_i210(), _rcar_gen4_ptp_settime(),
and some drivers can remove the checks of itself.
Cc: stable@vger.kernel.org
Fixes: 0606f422b4 ("posix clocks: Introduce dynamic clocks")
Acked-by: Richard Cochran <richardcochran@gmail.com>
Suggested-by: Andrew Lunn <andrew@lunn.ch>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20241009072302.1754567-2-ruanjinjie@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Sean noted that ever since commit 152e11f6df ("sched/fair: Implement
delayed dequeue") KVM's preemption notifiers have started
mis-classifying preemption vs blocking.
Notably p->on_rq is no longer sufficient to determine if a task is
runnable or blocked -- the aforementioned commit introduces tasks that
remain on the runqueue even through they will not run again, and
should be considered blocked for many cases.
Add the task_is_runnable() helper to classify things and audit all
external users of the p->on_rq state. Also add a few comments.
Fixes: 152e11f6df ("sched/fair: Implement delayed dequeue")
Reported-by: Sean Christopherson <seanjc@google.com>
Tested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20241010091843.GK33184@noisy.programming.kicks-ass.net
The mgtime_floor value is a global variable for tracking the latest
fine-grained timestamp handed out. Because it's a global, track the
number of times that a new floor value is assigned.
Add a new percpu counter to the timekeeping code to track the number of
floor swap events that have occurred. A later patch will add a debugfs
file to display this counter alongside other stats involving multigrain
timestamps.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Link: https://lore.kernel.org/all/20241002-mgtime-v10-2-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Multigrain timestamps allow the kernel to use fine-grained timestamps when
an inode's attributes is being actively observed via ->getattr(). With
this support, it's possible for a file to get a fine-grained timestamp, and
another modified after it to get a coarse-grained stamp that is earlier
than the fine-grained time. If this happens then the files can appear to
have been modified in reverse order, which breaks VFS ordering guarantees
[1].
To prevent this, maintain a floor value for multigrain timestamps.
Whenever a fine-grained timestamp is handed out, record it, and when later
coarse-grained stamps are handed out, ensure they are not earlier than that
value. If the coarse-grained timestamp is earlier than the fine-grained
floor, return the floor value instead.
Add a static singleton atomic64_t into timekeeper.c that is used to keep
track of the latest fine-grained time ever handed out. This is tracked as a
monotonic ktime_t value to ensure that it isn't affected by clock
jumps. Because it is updated at different times than the rest of the
timekeeper object, the floor value is managed independently of the
timekeeper via a cmpxchg() operation, and sits on its own cacheline.
Add two new public interfaces:
- ktime_get_coarse_real_ts64_mg() fills a timespec64 with the later of the
coarse-grained clock and the floor time
- ktime_get_real_ts64_mg() gets the fine-grained clock value, and tries
to swap it into the floor. A timespec64 is filled with the result.
The floor value is global and updated via a single try_cmpxchg(). If
that fails then the operation raced with a concurrent update. Any
concurrent update must be later than the existing floor value, so any
racing tasks can accept any resulting floor value without retrying.
[1]: POSIX requires that files be stamped with realtime clock values, and
makes no provision for dealing with backward clock jumps. If a backward
realtime clock jump occurs, then files can appear to have been modified
in reverse order.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20241002-mgtime-v10-1-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
no_llseek had been defined to NULL two years ago, in commit 868941b144
("fs: remove no_llseek")
To quote that commit,
At -rc1 we'll need do a mechanical removal of no_llseek -
git grep -l -w no_llseek | grep -v porting.rst | while read i; do
sed -i '/\<no_llseek\>/d' $i
done
would do it.
Unfortunately, that hadn't been done. Linus, could you do that now, so
that we could finally put that thing to rest? All instances are of the
form
.llseek = no_llseek,
so it's obviously safe.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Implement the SCHED_DEADLINE server infrastructure - Daniel Bristot de Oliveira's
last major contribution to the kernel:
"SCHED_DEADLINE servers can help fixing starvation issues of low priority
tasks (e.g., SCHED_OTHER) when higher priority tasks monopolize CPU
cycles. Today we have RT Throttling; DEADLINE servers should be able to
replace and improve that."
(Daniel Bristot de Oliveira, Peter Zijlstra, Joel Fernandes,
Youssef Esmat, Huang Shijie)
- Preparatory changes for sched_ext integration:
- Use set_next_task(.first) where required
- Fix up set_next_task() implementations
- Clean up DL server vs. core sched
- Split up put_prev_task_balance()
- Rework pick_next_task()
- Combine the last put_prev_task() and the first set_next_task()
- Rework dl_server
- Add put_prev_task(.next)
(Peter Zijlstra, with a fix by Tejun Heo)
- Complete the EEVDF transition and refine EEVDF scheduling:
- Implement delayed dequeue
- Allow shorter slices to wakeup-preempt
- Use sched_attr::sched_runtime to set request/slice suggestion
- Document the new feature flags
- Remove unused and duplicate-functionality fields
- Simplify & unify pick_next_task_fair()
- Misc debuggability enhancements
(Peter Zijlstra, with fixes/cleanups by Dietmar Eggemann,
Valentin Schneider and Chuyi Zhou)
- Initialize the vruntime of a new task when it is first enqueued,
resulting in significant decrease in latency of newly woken tasks.
(Zhang Qiao)
- Introduce SM_IDLE and an idle re-entry fast-path in __schedule()
(K Prateek Nayak, Peter Zijlstra)
- Clean up and clarify the usage of Clean up usage of rt_task()
(Qais Yousef)
- Preempt SCHED_IDLE entities in strict cgroup hierarchies
(Tianchen Ding)
- Clarify the documentation of time units for deadline scheduler
parameters. (Christian Loehle)
- Remove the HZ_BW chicken-bit feature flag introduced a year ago,
the original change seems to be working fine.
(Phil Auld)
- Misc fixes and cleanups (Chen Yu, Dan Carpenter, Huang Shijie,
Peilin He, Qais Yousefm and Vincent Guittot)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2024-09-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Implement the SCHED_DEADLINE server infrastructure - Daniel Bristot
de Oliveira's last major contribution to the kernel:
"SCHED_DEADLINE servers can help fixing starvation issues of low
priority tasks (e.g., SCHED_OTHER) when higher priority tasks
monopolize CPU cycles. Today we have RT Throttling; DEADLINE
servers should be able to replace and improve that."
(Daniel Bristot de Oliveira, Peter Zijlstra, Joel Fernandes, Youssef
Esmat, Huang Shijie)
- Preparatory changes for sched_ext integration:
- Use set_next_task(.first) where required
- Fix up set_next_task() implementations
- Clean up DL server vs. core sched
- Split up put_prev_task_balance()
- Rework pick_next_task()
- Combine the last put_prev_task() and the first set_next_task()
- Rework dl_server
- Add put_prev_task(.next)
(Peter Zijlstra, with a fix by Tejun Heo)
- Complete the EEVDF transition and refine EEVDF scheduling:
- Implement delayed dequeue
- Allow shorter slices to wakeup-preempt
- Use sched_attr::sched_runtime to set request/slice suggestion
- Document the new feature flags
- Remove unused and duplicate-functionality fields
- Simplify & unify pick_next_task_fair()
- Misc debuggability enhancements
(Peter Zijlstra, with fixes/cleanups by Dietmar Eggemann, Valentin
Schneider and Chuyi Zhou)
- Initialize the vruntime of a new task when it is first enqueued,
resulting in significant decrease in latency of newly woken tasks
(Zhang Qiao)
- Introduce SM_IDLE and an idle re-entry fast-path in __schedule()
(K Prateek Nayak, Peter Zijlstra)
- Clean up and clarify the usage of Clean up usage of rt_task()
(Qais Yousef)
- Preempt SCHED_IDLE entities in strict cgroup hierarchies
(Tianchen Ding)
- Clarify the documentation of time units for deadline scheduler
parameters (Christian Loehle)
- Remove the HZ_BW chicken-bit feature flag introduced a year ago,
the original change seems to be working fine (Phil Auld)
- Misc fixes and cleanups (Chen Yu, Dan Carpenter, Huang Shijie,
Peilin He, Qais Yousefm and Vincent Guittot)
* tag 'sched-core-2024-09-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits)
sched/cpufreq: Use NSEC_PER_MSEC for deadline task
cpufreq/cppc: Use NSEC_PER_MSEC for deadline task
sched/deadline: Clarify nanoseconds in uapi
sched/deadline: Convert schedtool example to chrt
sched/debug: Fix the runnable tasks output
sched: Fix sched_delayed vs sched_core
kernel/sched: Fix util_est accounting for DELAY_DEQUEUE
kthread: Fix task state in kthread worker if being frozen
sched/pelt: Use rq_clock_task() for hw_pressure
sched/fair: Move effective_cpu_util() and effective_cpu_util() in fair.c
sched/core: Introduce SM_IDLE and an idle re-entry fast-path in __schedule()
sched: Add put_prev_task(.next)
sched: Rework dl_server
sched: Combine the last put_prev_task() and the first set_next_task()
sched: Rework pick_next_task()
sched: Split up put_prev_task_balance()
sched: Clean up DL server vs core sched
sched: Fixup set_next_task() implementations
sched: Use set_next_task(.first) where required
sched/fair: Properly deactivate sched_delayed task upon class change
...
- Core:
- Overhaul of posix-timers in preparation of removing the
workaround for periodic timers which have signal delivery
ignored.
- Remove the historical extra jiffie in msleep()
msleep() adds an extra jiffie to the timeout value to ensure
minimal sleep time. The timer wheel ensures minimal sleep
time since the large rewrite to a non-cascading wheel, but the
extra jiffie in msleep() remained unnoticed. Remove it.
- Make the timer slack handling correct for realtime tasks.
The procfs interface is inconsistent and does neither reflect
reality nor conforms to the man page. Show the correct 0 slack
for real time tasks and enforce it at the core level instead of
having inconsistent individual checks in various timer setup
functions.
- The usual set of updates and enhancements all over the place.
- Drivers:
- Allow the ACPI PM timer to be turned off during suspend
- No new drivers
- The usual updates and enhancements in various drivers
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Merge tag 'timers-core-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
"Core:
- Overhaul of posix-timers in preparation of removing the workaround
for periodic timers which have signal delivery ignored.
- Remove the historical extra jiffie in msleep()
msleep() adds an extra jiffie to the timeout value to ensure
minimal sleep time. The timer wheel ensures minimal sleep time
since the large rewrite to a non-cascading wheel, but the extra
jiffie in msleep() remained unnoticed. Remove it.
- Make the timer slack handling correct for realtime tasks.
The procfs interface is inconsistent and does neither reflect
reality nor conforms to the man page. Show the correct 0 slack for
real time tasks and enforce it at the core level instead of having
inconsistent individual checks in various timer setup functions.
- The usual set of updates and enhancements all over the place.
Drivers:
- Allow the ACPI PM timer to be turned off during suspend
- No new drivers
- The usual updates and enhancements in various drivers"
* tag 'timers-core-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
ntp: Make sure RTC is synchronized when time goes backwards
treewide: Fix wrong singular form of jiffies in comments
cpu: Use already existing usleep_range()
timers: Rename next_expiry_recalc() to be unique
platform/x86:intel/pmc: Fix comment for the pmc_core_acpi_pm_timer_suspend_resume function
clocksource/drivers/jcore: Use request_percpu_irq()
clocksource/drivers/cadence-ttc: Add missing clk_disable_unprepare in ttc_setup_clockevent
clocksource/drivers/asm9260: Add missing clk_disable_unprepare in asm9260_timer_init
clocksource/drivers/qcom: Add missing iounmap() on errors in msm_dt_timer_init()
clocksource/drivers/ingenic: Use devm_clk_get_enabled() helpers
platform/x86:intel/pmc: Enable the ACPI PM Timer to be turned off when suspended
clocksource: acpi_pm: Add external callback for suspend/resume
clocksource/drivers/arm_arch_timer: Using for_each_available_child_of_node_scoped()
dt-bindings: timer: rockchip: Add rk3576 compatible
timers: Annotate possible non critical data race of next_expiry
timers: Remove historical extra jiffie for timeout in msleep()
hrtimer: Use and report correct timerslack values for realtime tasks
hrtimer: Annotate hrtimer_cpu_base_.*_expiry() for sparse.
timers: Add sparse annotation for timer_sync_wait_running().
signal: Replace BUG_ON()s
...
- Core:
- Remove a global lock in the affinity setting code
The lock protects a cpumask for intermediate results and the lock
causes a bottleneck on simultaneous start of multiple virtual
machines. Replace the lock and the static cpumask with a per CPU
cpumask which is nicely serialized by raw spinlock held when
executing this code.
- Provide support for giving a suffix to interrupt domain names.
That's required to support devices with subfunctions so that the
domain names are distinct even if they originate from the same
device node.
- The usual set of cleanups and enhancements all over the place
- Drivers:
- Support for longarch AVEC interrupt chip
- Refurbishment of the Armada driver so it can be extended for new
variants.
- The usual set of cleanups and enhancements all over the place
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Merge tag 'irq-core-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq updates from Thomas Gleixner:
"Core:
- Remove a global lock in the affinity setting code
The lock protects a cpumask for intermediate results and the lock
causes a bottleneck on simultaneous start of multiple virtual
machines. Replace the lock and the static cpumask with a per CPU
cpumask which is nicely serialized by raw spinlock held when
executing this code.
- Provide support for giving a suffix to interrupt domain names.
That's required to support devices with subfunctions so that the
domain names are distinct even if they originate from the same
device node.
- The usual set of cleanups and enhancements all over the place
Drivers:
- Support for longarch AVEC interrupt chip
- Refurbishment of the Armada driver so it can be extended for new
variants.
- The usual set of cleanups and enhancements all over the place"
* tag 'irq-core-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (73 commits)
genirq: Use cpumask_intersects()
genirq/cpuhotplug: Use cpumask_intersects()
irqchip/apple-aic: Only access system registers on SoCs which provide them
irqchip/apple-aic: Add a new "Global fast IPIs only" feature level
irqchip/apple-aic: Skip unnecessary enabling of use_fast_ipi
dt-bindings: apple,aic: Document A7-A11 compatibles
irqdomain: Use IS_ERR_OR_NULL() in irq_domain_trim_hierarchy()
genirq/msi: Use kmemdup_array() instead of kmemdup()
genirq/proc: Change the return value for set affinity permission error
genirq/proc: Use irq_move_pending() in show_irq_affinity()
genirq/proc: Correctly set file permissions for affinity control files
genirq: Get rid of global lock in irq_do_set_affinity()
genirq: Fix typo in struct comment
irqchip/loongarch-avec: Add AVEC irqchip support
irqchip/loongson-pch-msi: Prepare get_pch_msi_handle() for AVECINTC
irqchip/loongson-eiointc: Rename CPUHP_AP_IRQ_LOONGARCH_STARTING
LoongArch: Architectural preparation for AVEC irqchip
LoongArch: Move irqchip function prototypes to irq-loongson.h
irqchip/loongson-pch-msi: Switch to MSI parent domains
softirq: Remove unused 'action' parameter from action callback
...
- Make the uncertainty margin handling more robust to prevent false
positives
- Clarify comments
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Merge tag 'timers-clocksource-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull clocksource watchdog updates from Thomas Gleixner:
- Make the uncertainty margin handling more robust to prevent false
positives
- Clarify comments
* tag 'timers-clocksource-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clocksource: Set cs_watchdog_read() checks based on .uncertainty_margin
clocksource: Fix comments on WATCHDOG_THRESHOLD & WATCHDOG_MAX_SKEW
clocksource: Improve comments for watchdog skew bounds
sync_hw_clock() is normally called every 11 minutes when time is
synchronized. This issue is that this periodic timer uses the REALTIME
clock, so when time moves backwards (the NTP server jumps into the past),
the timer expires late.
If the timer expires late, which can be days later, the RTC will no longer
be updated, which is an issue if the device is abruptly powered OFF during
this period. When the device will restart (when powered ON), it will have
the date prior to the ADJ_SETOFFSET call.
A normal NTP server should not jump in the past like that, but it is
possible... Another way of reproducing this issue is to use phc2sys to
synchronize the REALTIME clock with, for example, an IRIG timecode with
the source always starting at the same date (not synchronized).
Also, if the time jump in the future by less than 11 minutes, the RTC may
not be updated immediately (minor issue). Consider the following scenario:
- Time is synchronized, and sync_hw_clock() was just called (the timer
expires in 11 minutes).
- A time jump is realized in the future by a couple of minutes.
- The time is synchronized again.
- Users may expect that RTC to be updated as soon as possible, and not
after 11 minutes (for the same reason, if a power loss occurs in this
period).
Cancel periodic timer on any time jump (ADJ_SETOFFSET) greater than or
equal to 1s. The timer will be relaunched at the end of do_adjtimex() if
NTP is still considered synced. Otherwise the timer will be relaunched
later when NTP is synced. This way, when the time is synchronized again,
the RTC is updated after less than 2 seconds.
Signed-off-by: Benjamin ROBIN <dev@benjarobin.fr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240908140836.203911-1-dev@benjarobin.fr
There are several comments all over the place, which uses a wrong singular
form of jiffies.
Replace 'jiffie' by 'jiffy'. No functional change.
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
Link: https://lore.kernel.org/all/20240904-devel-anna-maria-b4-timers-flseep-v1-3-e98760256370@linutronix.de
next_expiry_recalc is the name of a function as well as the name of a
struct member of struct timer_base. This might lead to confusion.
Rename next_expiry_recalc() to timer_recalc_next_expiry(). No functional
change.
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/all/20240904-devel-anna-maria-b4-timers-flseep-v1-1-e98760256370@linutronix.de
Global timers could be expired remotely when the target CPU is idle. After
a remote timer expiry, the remote timer_base->next_expiry value is updated
while holding the timer_base->lock. When the formerly idle CPU becomes
active at the same time and checks whether timers need to expire, this
check is done lockless as it is on the local CPU. This could lead to a data
race, which was reported by sysbot:
https://lore.kernel.org/r/000000000000916e55061f969e14@google.com
When the value is read lockless but changed by the remote CPU, only two non
critical scenarios could happen:
1) The already update value is read -> everything is perfect
2) The old value is read -> a superfluous timer soft interrupt is raised
The same situation could happen when enqueueing a new first pinned timer by
a remote CPU also with non critical scenarios:
1) The already update value is read -> everything is perfect
2) The old value is read -> when the CPU is idle, an IPI is executed
nevertheless and when the CPU isn't idle, the updated value will be visible
on the next tick and the timer might be late one jiffie.
As this is very unlikely to happen, the overhead of doing the check under
the lock is a way more effort, than a superfluous timer soft interrupt or a
possible 1 jiffie delay of the timer.
Document and annotate this non critical behavior in the code by using
READ/WRITE_ONCE() pair when accessing timer_base->next_expiry.
Reported-by: syzbot+bf285fcc0a048e028118@syzkaller.appspotmail.com
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/all/20240829154305.19259-1-anna-maria@linutronix.de
Closes: https://lore.kernel.org/lkml/000000000000916e55061f969e14@google.com
msleep() and msleep_interruptible() add a jiffie to the requested timeout.
This extra jiffie was introduced to ensure that the timeout will not happen
earlier than specified.
Since the rework of the timer wheel, the enqueue path already takes care of
this. So the extra jiffie added by msleep*() is pointless now.
Remove this extra jiffie in msleep() and msleep_interruptible().
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/all/20240829074133.4547-1-anna-maria@linutronix.de
The timerslack_ns setting is used to specify how much the hardware
timers should be delayed, to potentially dispatch multiple timers in a
single interrupt. This is a performance optimization. Timers of
realtime tasks (having a realtime scheduling policy) should not be
delayed.
This logic was inconsitently applied to the hrtimers, leading to delays
of realtime tasks which used timed waits for events (e.g. condition
variables). Due to the downstream override of the slack for rt tasks,
the procfs reported incorrect (non-zero) timerslack_ns values.
This is changed by setting the timer_slack_ns task attribute to 0 for
all tasks with a rt policy. By that, downstream users do not need to
specially handle rt tasks (w.r.t. the slack), and the procfs entry
shows the correct value of "0". Setting non-zero slack values (either
via procfs or PR_SET_TIMERSLACK) on tasks with a rt policy is ignored,
as stated in "man 2 PR_SET_TIMERSLACK":
Timer slack is not applied to threads that are scheduled under a
real-time scheduling policy (see sched_setscheduler(2)).
The special handling of timerslack on rt tasks in downstream users
is removed as well.
Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240814121032.368444-2-felix.moessbauer@siemens.com
When soft interrupt actions are called, they are passed a pointer to the
struct softirq action which contains the action's function pointer.
This pointer isn't useful, as the action callback already knows what
function it is. And since each callback handles a specific soft interrupt,
the callback also knows which soft interrupt number is running.
No soft interrupt action callback actually uses this parameter, so remove
it from the function pointer signature. This clarifies that soft interrupt
actions are global routines and makes it slightly cheaper to call them.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/all/20240815171549.3260003-1-csander@purestorage.com
The two hrtimer_cpu_base_.*_expiry() functions are wrappers around the
locking functions and sparse complains about the missing counterpart.
Add sparse annotation to denote that this bevaviour is expected.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240812105326.2240000-3-bigeasy@linutronix.de
timer_sync_wait_running() first releases two locks and then acquires
them again. This is unexpected and sparse complains about it.
Add sparse annotation for timer_sync_wait_running() to note that the
locking is expected.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240812105326.2240000-2-bigeasy@linutronix.de
Some find the name realtime overloaded. Use rt_or_dl() as an
alternative, hopefully better, name.
Suggested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Qais Yousef <qyousef@layalina.io>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240610192018.1567075-4-qyousef@layalina.io
rt_task() checks if a task has RT priority. But depends on your
dictionary, this could mean it belongs to RT class, or is a 'realtime'
task, which includes RT and DL classes.
Since this has caused some confusion already on discussion [1], it
seemed a clean up is due.
I define the usage of rt_task() to be tasks that belong to RT class.
Make sure that it returns true only for RT class and audit the users and
replace the ones required the old behavior with the new realtime_task()
which returns true for RT and DL classes. Introduce similar
realtime_prio() to create similar distinction to rt_prio() and update
the users that required the old behavior to use the new function.
Move MAX_DL_PRIO to prio.h so it can be used in the new definitions.
Document the functions to make it more obvious what is the difference
between them. PI-boosted tasks is a factor that must be taken into
account when choosing which function to use.
Rename task_is_realtime() to realtime_task_policy() as the old name is
confusing against the new realtime_task().
No functional changes were intended.
[1] https://lore.kernel.org/lkml/20240506100509.GL40213@noisy.programming.kicks-ass.net/
Signed-off-by: Qais Yousef <qyousef@layalina.io>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240610192018.1567075-2-qyousef@layalina.io
The addition of the bases argument to clock_was_set() fixed up all call
sites correctly except for do_adjtimex(). This uses CLOCK_REALTIME
instead of CLOCK_SET_WALL as argument. CLOCK_REALTIME is 0.
As a result the effect of that clock_was_set() notification is incomplete
and might result in timers expiring late because the hrtimer code does
not re-evaluate the affected clock bases.
Use CLOCK_SET_WALL instead of CLOCK_REALTIME to tell the hrtimers code
which clock bases need to be re-evaluated.
Fixes: 17a1b8826b ("hrtimer: Add bases argument to clock_was_set()")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/877ccx7igo.ffs@tglx
Using syzkaller with the recently reintroduced signed integer overflow
sanitizer produces this UBSAN report:
UBSAN: signed-integer-overflow in ../kernel/time/ntp.c:738:18
9223372036854775806 + 4 cannot be represented in type 'long'
Call Trace:
handle_overflow+0x171/0x1b0
__do_adjtimex+0x1236/0x1440
do_adjtimex+0x2be/0x740
The user supplied time_constant value is incremented by four and then
clamped to the operating range.
Before commit eea83d896e ("ntp: NTP4 user space bits update") the user
supplied value was sanity checked to be in the operating range. That change
removed the sanity check and relied on clamping after incrementing which
does not work correctly when the user supplied value is in the overflow
zone of the '+ 4' operation.
The operation requires CAP_SYS_TIME and the side effect of the overflow is
NTP getting out of sync.
Similar to the fixups for time_maxerror and time_esterror, clamp the user
space supplied value to the operating range.
[ tglx: Switch to clamping ]
Fixes: eea83d896e ("ntp: NTP4 user space bits update")
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240517-b4-sio-ntp-c-v2-1-f3a80096f36f@google.com
Closes: https://github.com/KSPP/linux/issues/352
Using syzkaller alongside the newly reintroduced signed integer overflow
sanitizer spits out this report:
UBSAN: signed-integer-overflow in ../kernel/time/ntp.c:461:16
9223372036854775807 + 500 cannot be represented in type 'long'
Call Trace:
handle_overflow+0x171/0x1b0
second_overflow+0x2d6/0x500
accumulate_nsecs_to_secs+0x60/0x160
timekeeping_advance+0x1fe/0x890
update_wall_time+0x10/0x30
time_maxerror is unconditionally incremented and the result is checked
against NTP_PHASE_LIMIT, but the increment itself can overflow, resulting
in wrap-around to negative space.
Before commit eea83d896e ("ntp: NTP4 user space bits update") the user
supplied value was sanity checked to be in the operating range. That change
removed the sanity check and relied on clamping in handle_overflow() which
does not work correctly when the user supplied value is in the overflow
zone of the '+ 500' operation.
The operation requires CAP_SYS_TIME and the side effect of the overflow is
NTP getting out of sync.
Miroslav confirmed that the input value should be clamped to the operating
range and the same applies to time_esterror. The latter is not used by the
kernel, but the value still should be in the operating range as it was
before the sanity check got removed.
Clamp them to the operating range.
[ tglx: Changed it to clamping and included time_esterror ]
Fixes: eea83d896e ("ntp: NTP4 user space bits update")
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Link: https://lore.kernel.org/all/20240517-b4-sio-ntp-usec-v2-1-d539180f2b79@google.com
Closes: https://github.com/KSPP/linux/issues/354
Right now, cs_watchdog_read() does clocksource sanity checks based
on WATCHDOG_MAX_SKEW, which sets a floor on any clocksource's
.uncertainty_margin. These sanity checks can therefore act
inappropriately for clocksources with large uncertainty margins.
One reason for a clocksource to have a large .uncertainty_margin is when
that clocksource has long read-out latency, given that it does not make
sense for the .uncertainty_margin to be smaller than the read-out latency.
With the current checks, cs_watchdog_read() could reject all normal
reads from a clocksource with long read-out latencies, such as those
from legacy clocksources that are no longer implemented in hardware.
Therefore, recast the cs_watchdog_read() checks in terms of the
.uncertainty_margin values of the clocksources involved in the timespan in
question. The first covers two watchdog reads and one cs read, so use
twice the watchdog .uncertainty_margin plus that of the cs. The second
covers only a pair of watchdog reads, so use twice the watchdog
.uncertainty_margin.
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240802154618.4149953-4-paulmck@kernel.org
The WATCHDOG_THRESHOLD macro is no longer used to supply a default value
for ->uncertainty_margin, but WATCHDOG_MAX_SKEW now is.
Therefore, update the comments to reflect this change.
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/all/20240802154618.4149953-3-paulmck@kernel.org
Add more detail on the rationale for bounding the clocksource
->uncertainty_margin below at about 500ppm.
Signed-off-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240802154618.4149953-1-paulmck@kernel.org
The current "nretries > 1 || nretries >= max_retries" check in
cs_watchdog_read() will always evaluate to true, and thus pr_warn(), if
nretries is greater than 1. The intent is instead to never warn on the
first try, but otherwise warn if the successful retry was the last retry.
Therefore, change that "||" to "&&".
Fixes: db3a34e174 ("clocksource: Retry clock read if long delays detected")
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240802154618.4149953-2-paulmck@kernel.org
The recent fix for making the take over of the broadcast timer more
reliable retrieves a per CPU pointer in preemptible context.
This went unnoticed as compilers hoist the access into the non-preemptible
region where the pointer is actually used. But of course it's valid that
the compiler keeps it at the place where the code puts it which rightfully
triggers:
BUG: using smp_processor_id() in preemptible [00000000] code:
caller is hotplug_cpu__broadcast_tick_pull+0x1c/0xc0
Move it to the actual usage site which is in a non-preemptible region.
Fixes: f7d43dd206 ("tick/broadcast: Make takeover of broadcast hrtimer reliable")
Reported-by: David Wang <00107082@163.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Yu Liao <liaoyu15@huawei.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/87ttg56ers.ffs@tglx
Rename posix_timer_event() to posix_timer_queue_signal() as this is what
the function is about.
Consolidate the requeue pending and deactivation updates into that function
as there is no point in doing this in all incarnations of posix timers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Posix CPU timers are not updating k_itimer::it_active which makes it
impossible to base decisions in the common posix timer code on it.
Update it when queueing or dequeueing posix CPU timers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
hrtimer based and CPU timers have their own way to install the new interval
and to reset overrun and signal handling related data.
Create a helper function and do the same operation for all variants.
This also makes the handling of the interval consistent. It's only stored
when the timer is actually armed, i.e. timer->it_value != 0. Before that it
was stored unconditionally for posix CPU timers and conditionally for the
other posix timers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
No requirement for a real list. Spare a few bytes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Keeping the overrun count of the previous setup around is just wrong. The
new setting has nothing to do with the previous one and has to start from a
clean slate.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
No point in doing this all over the place.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Avoid the late sighand lock/unlock dance when a timer is not armed to
enforce reevaluation of the timer base so that the process wide CPU timer
sampling can be disabled.
Do it right at the point where the arming decision is made which already
has sighand locked.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
A leftover from historical code which describes fiction.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
posix_cpu_timer_set() uses @val as variable for the current time. That's
confusing at best.
Use @now as anywhere else and rewrite the confusing comment about clock
sampling.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
There is no point in arming SIGEV_NONE timers as they never deliver a
signal. timer_gettime() is handling the expiry time correctly and that's
all SIGEV_NONE timers care about.
Prevent arming them and remove the expiry handler code which just disarms
them.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reuse the split out __posix_cpu_timer_get() function which does already the
right thing.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Expired SIGEV_NONE oneshot timers must return 0 nsec for the expiry time in
timer_get(), but the posix CPU timer implementation returns 1 nsec.
Add the missing conditional.
This will be cleaned up in a follow up patch.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Expired SIGEV_NONE oneshot timers must return 0 nsec for the expiry time in
timer_get(), but the posix CPU timer implementation returns 1 nsec.
Add the missing conditional.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
timer_gettime() must return the remaining time to the next expiry of a
timer or 0 if the timer is not armed and no signal pending, but posix CPU
timers fail to forward a timer which is already expired.
Add the required logic to address that.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
There is no point to return the interval for timers which have been
disarmed.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
In preparation for addressing issues in the timer_get() and timer_set()
functions of posix CPU timers.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
- Stop testing the group->parent pointer as it is not guaranteed to be
stable over a chain of operations by design. This includes a warning
which would be nice to have but it produces false positives due to
the racy nature of the check.
- Plug a race between CPUs going in and out of idle and a CPU hotplug
operation. The latter can create and connect a new hierarchy level
which is missed in the concurrent updates of CPUs which go into idle.
As a result the events of such a CPU might not be processed and
timers go stale.
Cure it by splitting the hotplug operation into a prepare and online
callback. The prepare callback is guaranteed to run on an online and
therefore active CPU. This CPU updates the hierarchy and being online
ensures that there is always at least one migrator active which
handles the modified hierarchy correctly when going idle. The online
callback which runs on the incoming CPU then just marks the CPU
active and brings it into operation.
- Improve tracing and polish the code further so it is more obvious
what's going on.
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Merge tag 'timers-urgent-2024-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer migration updates from Thomas Gleixner:
"Fixes and minor updates for the timer migration code:
- Stop testing the group->parent pointer as it is not guaranteed to
be stable over a chain of operations by design.
This includes a warning which would be nice to have but it produces
false positives due to the racy nature of the check.
- Plug a race between CPUs going in and out of idle and a CPU hotplug
operation. The latter can create and connect a new hierarchy level
which is missed in the concurrent updates of CPUs which go into
idle. As a result the events of such a CPU might not be processed
and timers go stale.
Cure it by splitting the hotplug operation into a prepare and
online callback. The prepare callback is guaranteed to run on an
online and therefore active CPU. This CPU updates the hierarchy and
being online ensures that there is always at least one migrator
active which handles the modified hierarchy correctly when going
idle. The online callback which runs on the incoming CPU then just
marks the CPU active and brings it into operation.
- Improve tracing and polish the code further so it is more obvious
what's going on"
* tag 'timers-urgent-2024-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timers/migration: Fix grammar in comment
timers/migration: Spare write when nothing changed
timers/migration: Rename childmask by groupmask to make naming more obvious
timers/migration: Read childmask and parent pointer in a single place
timers/migration: Use a single struct for hierarchy walk data
timers/migration: Improve tracing
timers/migration: Move hierarchy setup into cpuhotplug prepare callback
timers/migration: Do not rely always on group->parent
