alarmtimer: Switch to use hrtimer_setup() and hrtimer_setup_on_stack()

hrtimer_setup() and hrtimer_setup_on_stack() take the callback function
pointer as argument and initialize the timer completely

alarmtimer: Switch to use hrtimer_setup() and hrtimer_setup_on_stack()

hrtimer_setup() and hrtimer_setup_on_stack() take the callback function
pointer as argument and initialize the timer completely.

Replace the hrtimer_init*() variants and the open coded initialization of
hrtimer::function with the new setup mechanism.

Switch to use the new functions.

Signed-off-by: Nam Cao <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/2bae912336103405adcdab96b88d3ea0353b4228.1730386209.git.namcao@linutronix.de

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alarmtimers: Remove return value from alarm functions

Now that the SIG_IGN problem is solved in the core code, the alarmtimer
callbacks do not require a return value anymore.

Signed-off-by: Thomas

alarmtimers: Remove return value from alarm functions

Now that the SIG_IGN problem is solved in the core code, the alarmtimer
callbacks do not require a return value anymore.

Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Frederic Weisbecker <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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alarmtimers: Remove the throttle mechanism from alarm_forward_now()

Now that ignored posix timer signals are requeued and the timers are
rearmed on signal delivery the workaround to keep such timers

alarmtimers: Remove the throttle mechanism from alarm_forward_now()

Now that ignored posix timer signals are requeued and the timers are
rearmed on signal delivery the workaround to keep such timers alive and
self rearm them is not longer required.

Remove the unused alarm timer parts.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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posix-timers: Cleanup SIG_IGN workaround leftovers

Now that ignored posix timer signals are requeued and the timers are
rearmed on signal delivery the workaround to keep such timers alive and
self r

posix-timers: Cleanup SIG_IGN workaround leftovers

Now that ignored posix timer signals are requeued and the timers are
rearmed on signal delivery the workaround to keep such timers alive and
self rearm them is not longer required.

Remove the relevant hacks and the not longer required return values from
the related functions. The alarm timer workarounds will be cleaned up in a
separate step.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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posix-timers: Add proper state tracking

Right now the state tracking is done by two struct members:

- it_active:
A boolean which tracks armed/disarmed state

- it_signal_seq:
A sequence

posix-timers: Add proper state tracking

Right now the state tracking is done by two struct members:

- it_active:
A boolean which tracks armed/disarmed state

- it_signal_seq:
A sequence counter which is used to invalidate settings
and prevent rearming

Replace it_active with it_status and keep properly track about the states
in one place.

This allows to reuse it_signal_seq to track reprogramming, disarm and
delete operations in order to drop signals which are related to the state
previous of those operations.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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posix-timers: Rename k_itimer:: It_requeue_pending

Prepare for using this struct member to do a proper reprogramming and
deletion accounting so that stale signals can be dropped.

No functional chan

posix-timers: Rename k_itimer:: It_requeue_pending

Prepare for using this struct member to do a proper reprogramming and
deletion accounting so that stale signals can be dropped.

No functional change.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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treewide: Fix wrong singular form of jiffies in comments

There are several comments all over the place, which uses a wrong singular
form of jiffies.

Replace 'jiffie' by 'jiffy'. No functional chang

treewide: Fix wrong singular form of jiffies in comments

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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Geert Uytterhoeven <[email protected]> # m68k
Link: https://lore.kernel.org/all/20240904-devel-anna-maria-b4-timers-flseep-v1-3-e98760256370@linutronix.de

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posix-timers: Consolidate signal queueing

Rename posix_timer_event() to posix_timer_queue_signal() as this is what
the function is about.

Consolidate the requeue pending and deactivation updates in

posix-timers: Consolidate signal queueing

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 <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>

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rtc: class: make rtc_class constant

Since commit 43a7206b0963 ("driver core: class: make class_register() take
a const *"), the driver core allows for struct class to be in read-only
memory, so move

rtc: class: make rtc_class constant

Since commit 43a7206b0963 ("driver core: class: make class_register() take
a const *"), the driver core allows for struct class to be in read-only
memory, so move the rtc_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at boot time.

Cc: Greg Kroah-Hartman <[email protected]>
Suggested-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Ricardo B. Marliere <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexandre Belloni <[email protected]>

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alarmtimer: Use maximum alarm time for suspend

Some userspace applications use timerfd_create() to request wakeups after
a long period of time. For example, a backup application may request a
wakeup

alarmtimer: Use maximum alarm time for suspend

Some userspace applications use timerfd_create() to request wakeups after
a long period of time. For example, a backup application may request a
wakeup once per week. This is perfectly fine as long as the system does
not try to suspend. However, if the system tries to suspend and the
system's RTC does not support the required alarm timeout, the suspend
operation will fail with an error such as

rtc_cmos 00:01: Alarms can be up to one day in the future
PM: dpm_run_callback(): platform_pm_suspend+0x0/0x4a returns -22
alarmtimer alarmtimer.4.auto: platform_pm_suspend+0x0/0x4a returned -22 after 117 usecs
PM: Device alarmtimer.4.auto failed to suspend: error -22

This results in a refusal to suspend the system, causing substantial
battery drain on affected systems.

To fix the problem, use the maximum alarm time offset as reported by RTC
drivers to set the maximum alarm time. While this may result in early
wakeups from suspend, it is still much better than not suspending at all.

Standardize system behavior if the requested alarm timeout is larger than
the alarm timeout supported by the rtc chip. Currently, in this situation,
the RTC driver will do one of the following:

- It may return an error.
- It may limit the alarm timeout to the maximum supported by the rtc chip.
- It may mask the timeout by the maximum alarm timeout supported by the RTC
chip (i.e. a requested timeout of 1 day + 1 minute may result in a 1
minute timeout).

With this in place, if the RTC driver reports the maximum alarm timeout
supported by the RTC chip, the system will always limit the alarm timeout
to the maximum supported by the RTC chip.

Signed-off-by: Guenter Roeck <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: John Stultz <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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alarmtimer: Remove unnecessary (void *) cast

Pointers of type void * do not require a type cast when they are assigned
to a real pointer.

Signed-off-by: Li zeming <[email protected]>
Signed-off-b

alarmtimer: Remove unnecessary (void *) cast

Pointers of type void * do not require a type cast when they are assigned
to a real pointer.

Signed-off-by: Li zeming <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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alarmtimer: Remove unnecessary initialization of variable 'ret'

ret is assigned before checked, so it does not need to initialize the
variable

Signed-off-by: Li zeming <[email protected]>
Signed-

alarmtimer: Remove unnecessary initialization of variable 'ret'

ret is assigned before checked, so it does not need to initialize the
variable

Signed-off-by: Li zeming <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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driver core: class: remove struct class_interface * from callbacks

The add_dev and remove_dev callbacks in struct class_interface currently
pass in a pointer back to the class_interface structure th

driver core: class: remove struct class_interface * from callbacks

The add_dev and remove_dev callbacks in struct class_interface currently
pass in a pointer back to the class_interface structure that is calling
them, but none of the callback implementations actually use this pointer
as it is pointless (the structure is known, the driver passed it in in
the first place if it is really needed again.)

So clean this up and just remove the pointer from the callbacks and fix
up all callback functions.

Cc: Jean Delvare <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: Kurt Schwemmer <[email protected]>
Cc: Jon Mason <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: Allen Hubbe <[email protected]>
Cc: Dominik Brodowski <[email protected]>
Cc: Matt Porter <[email protected]>
Cc: Alexandre Bounine <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: "Martin K. Petersen" <[email protected]>
Cc: Doug Gilbert <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Stephen Boyd <[email protected]>
Cc: Hans de Goede <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Wang Weiyang <[email protected]>
Cc: Yang Yingliang <[email protected]>
Cc: Jakob Koschel <[email protected]>
Cc: Cai Xinchen <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
Acked-by: Logan Gunthorpe <[email protected]>
Link: https://lore.kernel.org/r/2023040250-pushover-platter-509c@gregkh
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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alarmtimer: Prevent starvation by small intervals and SIG_IGN

syzbot reported a RCU stall which is caused by setting up an alarmtimer
with a very small interval and ignoring the signal. The reproduc

alarmtimer: Prevent starvation by small intervals and SIG_IGN

syzbot reported a RCU stall which is caused by setting up an alarmtimer
with a very small interval and ignoring the signal. The reproducer arms the
alarm timer with a relative expiry of 8ns and an interval of 9ns. Not a
problem per se, but that's an issue when the signal is ignored because then
the timer is immediately rearmed because there is no way to delay that
rearming to the signal delivery path. See posix_timer_fn() and commit
58229a189942 ("posix-timers: Prevent softirq starvation by small intervals
and SIG_IGN") for details.

The reproducer does not set SIG_IGN explicitely, but it sets up the timers
signal with SIGCONT. That has the same effect as explicitely setting
SIG_IGN for a signal as SIGCONT is ignored if there is no handler set and
the task is not ptraced.

The log clearly shows that:

[pid 5102] --- SIGCONT {si_signo=SIGCONT, si_code=SI_TIMER, si_timerid=0, si_overrun=316014, si_int=0, si_ptr=NULL} ---

It works because the tasks are traced and therefore the signal is queued so
the tracer can see it, which delays the restart of the timer to the signal
delivery path. But then the tracer is killed:

[pid 5087] kill(-5102, SIGKILL <unfinished ...>
...
./strace-static-x86_64: Process 5107 detached

and after it's gone the stall can be observed:

syzkaller login: [ 79.439102][ C0] hrtimer: interrupt took 68471 ns
[ 184.460538][ C1] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
...
[ 184.658237][ C1] rcu: Stack dump where RCU GP kthread last ran:
[ 184.664574][ C1] Sending NMI from CPU 1 to CPUs 0:
[ 184.669821][ C0] NMI backtrace for cpu 0
[ 184.669831][ C0] CPU: 0 PID: 5108 Comm: syz-executor192 Not tainted 6.2.0-rc6-next-20230203-syzkaller #0
...
[ 184.670036][ C0] Call Trace:
[ 184.670041][ C0] <IRQ>
[ 184.670045][ C0] alarmtimer_fired+0x327/0x670

posix_timer_fn() prevents that by checking whether the interval for
timers which have the signal ignored is smaller than a jiffie and
artifically delay it by shifting the next expiry out by a jiffie. That's
accurate vs. the overrun accounting, but slightly inaccurate
vs. timer_gettimer(2).

The comment in that function says what needs to be done and there was a fix
available for the regular userspace induced SIG_IGN mechanism, but that did
not work due to the implicit ignore for SIGCONT and similar signals. This
needs to be worked on, but for now the only available workaround is to do
exactly what posix_timer_fn() does:

Increase the interval of self-rearming timers, which have their signal
ignored, to at least a jiffie.

Interestingly this has been fixed before via commit ff86bf0c65f1
("alarmtimer: Rate limit periodic intervals") already, but that fix got
lost in a later rework.

Reported-by: [email protected]
Fixes: f2c45807d399 ("alarmtimer: Switch over to generic set/get/rearm routine")
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: John Stultz <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/87k00q1no2.ffs@tglx

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alarmtimer: Check RTC features instead of ops

RTC drivers used to leave .set_alarm() NULL in order to signal the RTC
device doesn't support alarms. The drivers are now clearing the
RTC_FEATURE_ALARM

alarmtimer: Check RTC features instead of ops

RTC drivers used to leave .set_alarm() NULL in order to signal the RTC
device doesn't support alarms. The drivers are now clearing the
RTC_FEATURE_ALARM bit for that purpose in order to keep the rtc_class_ops
structure const. So now, .set_alarm() is set unconditionally and this
possibly causes the alarmtimer code to select an RTC device that doesn't
support alarms.

Test RTC_FEATURE_ALARM instead of relying on ops->set_alarm to determine
whether alarms are available.

Fixes: 7ae41220ef58 ("rtc: introduce features bitfield")
Signed-off-by: Alexandre Belloni <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]

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timekeeping, clocksource: Fix various typos in comments

Fix ~56 single-word typos in timekeeping & clocksource code comments.

Signed-off-by: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <tglx

timekeeping, clocksource: Fix various typos in comments

Fix ~56 single-word typos in timekeeping & clocksource code comments.

Signed-off-by: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Stephen Boyd <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: [email protected]

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kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data()

Preparation for fixing get_nr_restart_syscall() on X86 for COMPAT.

Add a new helper which sets restart_block->fn and calls

kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data()

Preparation for fixing get_nr_restart_syscall() on X86 for COMPAT.

Add a new helper which sets restart_block->fn and calls a dummy
arch_set_restart_data() helper.

Fixes: 609c19a385c8 ("x86/ptrace: Stop setting TS_COMPAT in ptrace code")
Signed-off-by: Oleg Nesterov <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]

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alarmtimer: Update kerneldoc

Update kerneldoc comments to reflect the actual arguments and return values
of the documented functions.

Signed-off-by: Alexandre Belloni <[email protected]

alarmtimer: Update kerneldoc

Update kerneldoc comments to reflect the actual arguments and return values
of the documented functions.

Signed-off-by: Alexandre Belloni <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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alarmtimer: Convert comma to semicolon

Replace a comma between expression statements by a semicolon.

Signed-off-by: Xu Wang <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
R

alarmtimer: Convert comma to semicolon

Replace a comma between expression statements by a semicolon.

Signed-off-by: Xu Wang <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Stephen Boyd <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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time: Delete repeated words in comments

Drop repeated words in kernel/time/. {when, one, into}

Signed-off-by: Randy Dunlap <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]

time: Delete repeated words in comments

Drop repeated words in kernel/time/. {when, one, into}

Signed-off-by: Randy Dunlap <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: John Stultz <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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alarmtimer: Make alarmtimer_get_rtcdev() a stub when CONFIG_RTC_CLASS=n

The stubbed version of alarmtimer_get_rtcdev() is not exported.
so this won't work if this function is used in a module when
C

alarmtimer: Make alarmtimer_get_rtcdev() a stub when CONFIG_RTC_CLASS=n

The stubbed version of alarmtimer_get_rtcdev() is not exported.
so this won't work if this function is used in a module when
CONFIG_RTC_CLASS=n.

Move the stub function to the header file and make it inline so that
callers don't have to worry about linking against this symbol.

rtcdev isn't used outside of this ifdef so it's not required to be
redefined to NULL. Drop that while touching this area.

Signed-off-by: Stephen Boyd <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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alarmtimer: Use wakeup source from alarmtimer platform device

Use the wakeup source that can be associated with the 'alarmtimer'
platform device instead of registering another one by hand.

Signed-o

alarmtimer: Use wakeup source from alarmtimer platform device

Use the wakeup source that can be associated with the 'alarmtimer'
platform device instead of registering another one by hand.

Signed-off-by: Stephen Boyd <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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alarmtimer: Make alarmtimer platform device child of RTC device

The alarmtimer_suspend() function will fail if an RTC device is on a bus
such as SPI or i2c and that RTC device registers and probes a

alarmtimer: Make alarmtimer platform device child of RTC device

The alarmtimer_suspend() function will fail if an RTC device is on a bus
such as SPI or i2c and that RTC device registers and probes after
alarmtimer_init() registers and probes the 'alarmtimer' platform device.

This is because system wide suspend suspends devices in the reverse order
of their probe. When alarmtimer_suspend() attempts to program the RTC for a
wakeup it will try to program an RTC device on a bus that has already been
suspended.

Move the alarmtimer device registration to happen when the RTC which is
used for wakeup is registered. Register the 'alarmtimer' platform device as
a child of the RTC device too, so that it can be guaranteed that the RTC
device won't be suspended when alarmtimer_suspend() is called.

Reported-by: Douglas Anderson <[email protected]>
Signed-off-by: Stephen Boyd <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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alarmtimer: Update alarmtimer_get_rtcdev() docs to reflect reality

This function doesn't do anything like this comment says when an RTC device
hasn't been chosen. It looks like we used to do somethi

alarmtimer: Update alarmtimer_get_rtcdev() docs to reflect reality

This function doesn't do anything like this comment says when an RTC device
hasn't been chosen. It looks like we used to do something like that before
commit 8bc0dafb5cf3 ("alarmtimers: Rework RTC device selection using class
interface") but that's long gone now. Remove this sentence to avoid
confusing the reader.

Signed-off-by: Stephen Boyd <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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alarmtimer: Unregister wakeup source when module get fails

The alarmtimer_rtc_add_device() function creates a wakeup source and then
tries to grab a module reference. If that fails the function retu

alarmtimer: Unregister wakeup source when module get fails

The alarmtimer_rtc_add_device() function creates a wakeup source and then
tries to grab a module reference. If that fails the function returns early
with an error code, but fails to remove the wakeup source.

Cleanup this exit path so there is no dangling wakeup source, which is
named 'alarmtime' left allocated which will conflict with another RTC
device that may be registered later.

Fixes: 51218298a25e ("alarmtimer: Ensure RTC module is not unloaded")
Signed-off-by: Stephen Boyd <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]

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