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()
  ...

16 files changed, 283 insertions, 181 deletions

diff --git a/include/linux/alarmtimer.h b/include/linux/alarmtimer.h
index 05e758b8b894..3ffa5341dce2 100644
--- a/include/linux/alarmtimer.h
+++ b/include/linux/alarmtimer.h
@@ -20,12 +20,6 @@ enum alarmtimer_type {
 	ALARM_BOOTTIME_FREEZER,
 };
 
-enum alarmtimer_restart {
-	ALARMTIMER_NORESTART,
-	ALARMTIMER_RESTART,
-};
-
-
 #define ALARMTIMER_STATE_INACTIVE	0x00
 #define ALARMTIMER_STATE_ENQUEUED	0x01
 
@@ -42,14 +36,14 @@ enum alarmtimer_restart {
 struct alarm {
 	struct timerqueue_node	node;
 	struct hrtimer		timer;
-	enum alarmtimer_restart	(*function)(struct alarm *, ktime_t now);
+	void			(*function)(struct alarm *, ktime_t now);
 	enum alarmtimer_type	type;
 	int			state;
 	void			*data;
 };
 
 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
-		enum alarmtimer_restart (*function)(struct alarm *, ktime_t));
+		void (*function)(struct alarm *, ktime_t));
 void alarm_start(struct alarm *alarm, ktime_t start);
 void alarm_start_relative(struct alarm *alarm, ktime_t start);
 void alarm_restart(struct alarm *alarm);
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index d35b677b08fe..ef1b16da6ad5 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -215,7 +215,6 @@ static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift)
 
 extern int clocksource_unregister(struct clocksource*);
 extern void clocksource_touch_watchdog(void);
-extern void clocksource_change_rating(struct clocksource *cs, int rating);
 extern void clocksource_suspend(void);
 extern void clocksource_resume(void);
 extern struct clocksource * __init clocksource_default_clock(void);
diff --git a/include/linux/delay.h b/include/linux/delay.h
index ff9cda975e30..89866bab100d 100644
--- a/include/linux/delay.h
+++ b/include/linux/delay.h
@@ -6,21 +6,12 @@
  * Copyright (C) 1993 Linus Torvalds
  *
  * Delay routines, using a pre-computed "loops_per_jiffy" value.
- *
- * Please note that ndelay(), udelay() and mdelay() may return early for
- * several reasons:
- *  1. computed loops_per_jiffy too low (due to the time taken to
- *     execute the timer interrupt.)
- *  2. cache behaviour affecting the time it takes to execute the
- *     loop function.
- *  3. CPU clock rate changes.
- *
- * Please see this thread:
- *   https://lists.openwall.net/linux-kernel/2011/01/09/56
+ * Sleep routines using timer list timers or hrtimers.
  */
 
 #include <linux/math.h>
 #include <linux/sched.h>
+#include <linux/jiffies.h>
 
 extern unsigned long loops_per_jiffy;
 
@@ -35,12 +26,21 @@ extern unsigned long loops_per_jiffy;
  * The 2nd mdelay() definition ensures GCC will optimize away the 
  * while loop for the common cases where n <= MAX_UDELAY_MS  --  Paul G.
  */
-
 #ifndef MAX_UDELAY_MS
 #define MAX_UDELAY_MS	5
 #endif
 
 #ifndef mdelay
+/**
+ * mdelay - Inserting a delay based on milliseconds with busy waiting
+ * @n:	requested delay in milliseconds
+ *
+ * See udelay() for basic information about mdelay() and it's variants.
+ *
+ * Please double check, whether mdelay() is the right way to go or whether a
+ * refactoring of the code is the better variant to be able to use msleep()
+ * instead.
+ */
 #define mdelay(n) (\
 	(__builtin_constant_p(n) && (n)<=MAX_UDELAY_MS) ? udelay((n)*1000) : \
 	({unsigned long __ms=(n); while (__ms--) udelay(1000);}))
@@ -63,30 +63,75 @@ unsigned long msleep_interruptible(unsigned int msecs);
 void usleep_range_state(unsigned long min, unsigned long max,
 			unsigned int state);
 
+/**
+ * usleep_range - Sleep for an approximate time
+ * @min:	Minimum time in microseconds to sleep
+ * @max:	Maximum time in microseconds to sleep
+ *
+ * For basic information please refere to usleep_range_state().
+ *
+ * The task will be in the state TASK_UNINTERRUPTIBLE during the sleep.
+ */
 static inline void usleep_range(unsigned long min, unsigned long max)
 {
 	usleep_range_state(min, max, TASK_UNINTERRUPTIBLE);
 }
 
-static inline void usleep_idle_range(unsigned long min, unsigned long max)
+/**
+ * usleep_range_idle - Sleep for an approximate time with idle time accounting
+ * @min:	Minimum time in microseconds to sleep
+ * @max:	Maximum time in microseconds to sleep
+ *
+ * For basic information please refere to usleep_range_state().
+ *
+ * The sleeping task has the state TASK_IDLE during the sleep to prevent
+ * contribution to the load avarage.
+ */
+static inline void usleep_range_idle(unsigned long min, unsigned long max)
 {
 	usleep_range_state(min, max, TASK_IDLE);
 }
 
+/**
+ * ssleep - wrapper for seconds around msleep
+ * @seconds:	Requested sleep duration in seconds
+ *
+ * Please refere to msleep() for detailed information.
+ */
 static inline void ssleep(unsigned int seconds)
 {
 	msleep(seconds * 1000);
 }
 
-/* see Documentation/timers/timers-howto.rst for the thresholds */
+static const unsigned int max_slack_shift = 2;
+#define USLEEP_RANGE_UPPER_BOUND	((TICK_NSEC << max_slack_shift) / NSEC_PER_USEC)
+
+/**
+ * fsleep - flexible sleep which autoselects the best mechanism
+ * @usecs:	requested sleep duration in microseconds
+ *
+ * flseep() selects the best mechanism that will provide maximum 25% slack
+ * to the requested sleep duration. Therefore it uses:
+ *
+ * * udelay() loop for sleep durations <= 10 microseconds to avoid hrtimer
+ *   overhead for really short sleep durations.
+ * * usleep_range() for sleep durations which would lead with the usage of
+ *   msleep() to a slack larger than 25%. This depends on the granularity of
+ *   jiffies.
+ * * msleep() for all other sleep durations.
+ *
+ * Note: When %CONFIG_HIGH_RES_TIMERS is not set, all sleeps are processed with
+ * the granularity of jiffies and the slack might exceed 25% especially for
+ * short sleep durations.
+ */
 static inline void fsleep(unsigned long usecs)
 {
 	if (usecs <= 10)
 		udelay(usecs);
-	else if (usecs <= 20000)
-		usleep_range(usecs, 2 * usecs);
+	else if (usecs < USLEEP_RANGE_UPPER_BOUND)
+		usleep_range(usecs, usecs + (usecs >> max_slack_shift));
 	else
-		msleep(DIV_ROUND_UP(usecs, 1000));
+		msleep(DIV_ROUND_UP(usecs, USEC_PER_MSEC));
 }
 
 #endif /* defined(_LINUX_DELAY_H) */
diff --git a/include/linux/dw_apb_timer.h b/include/linux/dw_apb_timer.h
index 82ebf9223948..f8811c46b89e 100644
--- a/include/linux/dw_apb_timer.h
+++ b/include/linux/dw_apb_timer.h
@@ -34,9 +34,6 @@ struct dw_apb_clocksource {
 };
 
 void dw_apb_clockevent_register(struct dw_apb_clock_event_device *dw_ced);
-void dw_apb_clockevent_pause(struct dw_apb_clock_event_device *dw_ced);
-void dw_apb_clockevent_resume(struct dw_apb_clock_event_device *dw_ced);
-void dw_apb_clockevent_stop(struct dw_apb_clock_event_device *dw_ced);
 
 struct dw_apb_clock_event_device *
 dw_apb_clockevent_init(int cpu, const char *name, unsigned rating,
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index aa1e65ccb615..7ef5f7ef31a9 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -228,32 +228,17 @@ static inline void hrtimer_cancel_wait_running(struct hrtimer *timer)
 /* Initialize timers: */
 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 			 enum hrtimer_mode mode);
-extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
-				 enum hrtimer_mode mode);
+extern void hrtimer_setup(struct hrtimer *timer, enum hrtimer_restart (*function)(struct hrtimer *),
+			  clockid_t clock_id, enum hrtimer_mode mode);
+extern void hrtimer_setup_on_stack(struct hrtimer *timer,
+				   enum hrtimer_restart (*function)(struct hrtimer *),
+				   clockid_t clock_id, enum hrtimer_mode mode);
+extern void hrtimer_setup_sleeper_on_stack(struct hrtimer_sleeper *sl, clockid_t clock_id,
+					   enum hrtimer_mode mode);
 
 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
-extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
-				  enum hrtimer_mode mode);
-extern void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
-					  clockid_t clock_id,
-					  enum hrtimer_mode mode);
-
 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
 #else
-static inline void hrtimer_init_on_stack(struct hrtimer *timer,
-					 clockid_t which_clock,
-					 enum hrtimer_mode mode)
-{
-	hrtimer_init(timer, which_clock, mode);
-}
-
-static inline void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
-						 clockid_t clock_id,
-						 enum hrtimer_mode mode)
-{
-	hrtimer_init_sleeper(sl, clock_id, mode);
-}
-
 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
 #endif
 
@@ -337,6 +322,28 @@ static inline int hrtimer_callback_running(struct hrtimer *timer)
 	return timer->base->running == timer;
 }
 
+/**
+ * hrtimer_update_function - Update the timer's callback function
+ * @timer:	Timer to update
+ * @function:	New callback function
+ *
+ * Only safe to call if the timer is not enqueued. Can be called in the callback function if the
+ * timer is not enqueued at the same time (see the comments above HRTIMER_STATE_ENQUEUED).
+ */
+static inline void hrtimer_update_function(struct hrtimer *timer,
+					   enum hrtimer_restart (*function)(struct hrtimer *))
+{
+	guard(raw_spinlock_irqsave)(&timer->base->cpu_base->lock);
+
+	if (WARN_ON_ONCE(hrtimer_is_queued(timer)))
+		return;
+
+	if (WARN_ON_ONCE(!function))
+		return;
+
+	timer->function = function;
+}
+
 /* Forward a hrtimer so it expires after now: */
 extern u64
 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h
index 19a7b00baff4..91324c331a4b 100644
--- a/include/linux/iopoll.h
+++ b/include/linux/iopoll.h
@@ -19,19 +19,19 @@
  * @op: accessor function (takes @args as its arguments)
  * @val: Variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @sleep_us: Maximum time to sleep between reads in us (0
- *            tight-loops).  Should be less than ~20ms since usleep_range
- *            is used (see Documentation/timers/timers-howto.rst).
+ * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please
+ *            read usleep_range() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  * @sleep_before_read: if it is true, sleep @sleep_us before read.
  * @args: arguments for @op poll
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
- * case, the last read value at @args is stored in @val. Must not
- * be called from atomic context if sleep_us or timeout_us are used.
- *
  * When available, you'll probably want to use one of the specialized
  * macros defined below rather than this macro directly.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either
+ * case, the last read value at @args is stored in @val. Must not
+ * be called from atomic context if sleep_us or timeout_us are used.
  */
 #define read_poll_timeout(op, val, cond, sleep_us, timeout_us, \
 				sleep_before_read, args...) \
@@ -64,22 +64,22 @@
  * @op: accessor function (takes @args as its arguments)
  * @val: Variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @delay_us: Time to udelay between reads in us (0 tight-loops).  Should
- *            be less than ~10us since udelay is used (see
- *            Documentation/timers/timers-howto.rst).
+ * @delay_us: Time to udelay between reads in us (0 tight-loops). Please
+ *            read udelay() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  * @delay_before_read: if it is true, delay @delay_us before read.
  * @args: arguments for @op poll
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
- * case, the last read value at @args is stored in @val.
- *
  * This macro does not rely on timekeeping.  Hence it is safe to call even when
  * timekeeping is suspended, at the expense of an underestimation of wall clock
  * time, which is rather minimal with a non-zero delay_us.
  *
  * When available, you'll probably want to use one of the specialized
  * macros defined below rather than this macro directly.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either
+ * case, the last read value at @args is stored in @val.
  */
 #define read_poll_timeout_atomic(op, val, cond, delay_us, timeout_us, \
 					delay_before_read, args...) \
@@ -119,17 +119,17 @@
  * @addr: Address to poll
  * @val: Variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @sleep_us: Maximum time to sleep between reads in us (0
- *            tight-loops).  Should be less than ~20ms since usleep_range
- *            is used (see Documentation/timers/timers-howto.rst).
+ * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please
+ *            read usleep_range() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
- * case, the last read value at @addr is stored in @val. Must not
- * be called from atomic context if sleep_us or timeout_us are used.
- *
  * When available, you'll probably want to use one of the specialized
  * macros defined below rather than this macro directly.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either
+ * case, the last read value at @addr is stored in @val. Must not
+ * be called from atomic context if sleep_us or timeout_us are used.
  */
 #define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us)	\
 	read_poll_timeout(op, val, cond, sleep_us, timeout_us, false, addr)
@@ -140,16 +140,16 @@
  * @addr: Address to poll
  * @val: Variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @delay_us: Time to udelay between reads in us (0 tight-loops).  Should
- *            be less than ~10us since udelay is used (see
- *            Documentation/timers/timers-howto.rst).
+ * @delay_us: Time to udelay between reads in us (0 tight-loops). Please
+ *            read udelay() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
- * case, the last read value at @addr is stored in @val.
- *
  * When available, you'll probably want to use one of the specialized
  * macros defined below rather than this macro directly.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either
+ * case, the last read value at @addr is stored in @val.
  */
 #define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \
 	read_poll_timeout_atomic(op, val, cond, delay_us, timeout_us, false, addr)
diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
index 1220f0fbe5bf..ed945f42e064 100644
--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h
@@ -502,7 +502,7 @@ static inline unsigned long _msecs_to_jiffies(const unsigned int m)
  * - all other values are converted to jiffies by either multiplying
  *   the input value by a factor or dividing it with a factor and
  *   handling any 32-bit overflows.
- *   for the details see __msecs_to_jiffies()
+ *   for the details see _msecs_to_jiffies()
  *
  * msecs_to_jiffies() checks for the passed in value being a constant
  * via __builtin_constant_p() allowing gcc to eliminate most of the
@@ -526,6 +526,19 @@ static __always_inline unsigned long msecs_to_jiffies(const unsigned int m)
 	}
 }
 
+/**
+ * secs_to_jiffies: - convert seconds to jiffies
+ * @_secs: time in seconds
+ *
+ * Conversion is done by simple multiplication with HZ
+ *
+ * secs_to_jiffies() is defined as a macro rather than a static inline
+ * function so it can be used in static initializers.
+ *
+ * Return: jiffies value
+ */
+#define secs_to_jiffies(_secs) ((_secs) * HZ)
+
 extern unsigned long __usecs_to_jiffies(const unsigned int u);
 #if !(USEC_PER_SEC % HZ)
 static inline unsigned long _usecs_to_jiffies(const unsigned int u)
diff --git a/include/linux/phy.h b/include/linux/phy.h
index a98bc91a0cde..504766d4b2d5 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -1378,12 +1378,13 @@ int phy_read_mmd(struct phy_device *phydev, int devad, u32 regnum);
  * @regnum: The register on the MMD to read
  * @val: Variable to read the register into
  * @cond: Break condition (usually involving @val)
- * @sleep_us: Maximum time to sleep between reads in us (0
- *            tight-loops).  Should be less than ~20ms since usleep_range
- *            is used (see Documentation/timers/timers-howto.rst).
+ * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please
+ *            read usleep_range() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  * @sleep_before_read: if it is true, sleep @sleep_us before read.
- * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either
  * case, the last read value at @args is stored in @val. Must not
  * be called from atomic context if sleep_us or timeout_us are used.
  */
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index 453691710839..f11f10c97bd9 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -5,12 +5,16 @@
 #include <linux/alarmtimer.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/pid.h>
 #include <linux/posix-timers_types.h>
+#include <linux/rcuref.h>
 #include <linux/spinlock.h>
 #include <linux/timerqueue.h>
 
 struct kernel_siginfo;
 struct task_struct;
+struct sigqueue;
+struct k_itimer;
 
 static inline clockid_t make_process_cpuclock(const unsigned int pid,
 		const clockid_t clock)
@@ -35,6 +39,8 @@ static inline int clockid_to_fd(const clockid_t clk)
 
 #ifdef CONFIG_POSIX_TIMERS
 
+#include <linux/signal_types.h>
+
 /**
  * cpu_timer - Posix CPU timer representation for k_itimer
  * @node:	timerqueue node to queue in the task/sig
@@ -42,6 +48,7 @@ static inline int clockid_to_fd(const clockid_t clk)
  * @pid:	Pointer to target task PID
  * @elist:	List head for the expiry list
  * @firing:	Timer is currently firing
+ * @nanosleep:	Timer is used for nanosleep and is not a regular posix-timer
  * @handling:	Pointer to the task which handles expiry
  */
 struct cpu_timer {
@@ -49,7 +56,8 @@ struct cpu_timer {
 	struct timerqueue_head		*head;
 	struct pid			*pid;
 	struct list_head		elist;
-	int				firing;
+	bool				firing;
+	bool				nanosleep;
 	struct task_struct __rcu	*handling;
 };
 
@@ -101,6 +109,12 @@ static inline void posix_cputimers_rt_watchdog(struct posix_cputimers *pct,
 	pct->bases[CPUCLOCK_SCHED].nextevt = runtime;
 }
 
+void posixtimer_rearm_itimer(struct task_struct *p);
+bool posixtimer_init_sigqueue(struct sigqueue *q);
+void posixtimer_send_sigqueue(struct k_itimer *tmr);
+bool posixtimer_deliver_signal(struct kernel_siginfo *info, struct sigqueue *timer_sigq);
+void posixtimer_free_timer(struct k_itimer *timer);
+
 /* Init task static initializer */
 #define INIT_CPU_TIMERBASE(b) {						\
 	.nextevt	= U64_MAX,					\
@@ -122,6 +136,10 @@ struct cpu_timer { };
 static inline void posix_cputimers_init(struct posix_cputimers *pct) { }
 static inline void posix_cputimers_group_init(struct posix_cputimers *pct,
 					      u64 cpu_limit) { }
+static inline void posixtimer_rearm_itimer(struct task_struct *p) { }
+static inline bool posixtimer_deliver_signal(struct kernel_siginfo *info,
+					     struct sigqueue *timer_sigq) { return false; }
+static inline void posixtimer_free_timer(struct k_itimer *timer) { }
 #endif
 
 #ifdef CONFIG_POSIX_CPU_TIMERS_TASK_WORK
@@ -132,50 +150,56 @@ static inline void clear_posix_cputimers_work(struct task_struct *p) { }
 static inline void posix_cputimers_init_work(void) { }
 #endif
 
-#define REQUEUE_PENDING 1
-
 /**
  * struct k_itimer - POSIX.1b interval timer structure.
- * @list:		List head for binding the timer to signals->posix_timers
+ * @list:		List node for binding the timer to tsk::signal::posix_timers
+ * @ignored_list:	List node for tracking ignored timers in tsk::signal::ignored_posix_timers
  * @t_hash:		Entry in the posix timer hash table
  * @it_lock:		Lock protecting the timer
  * @kclock:		Pointer to the k_clock struct handling this timer
  * @it_clock:		The posix timer clock id
  * @it_id:		The posix timer id for identifying the timer
- * @it_active:		Marker that timer is active
+ * @it_status:		The status of the timer
+ * @it_sig_periodic:	The periodic status at signal delivery
  * @it_overrun:		The overrun counter for pending signals
  * @it_overrun_last:	The overrun at the time of the last delivered signal
- * @it_requeue_pending:	Indicator that timer waits for being requeued on
- *			signal delivery
+ * @it_signal_seq:	Sequence count to control signal delivery
+ * @it_sigqueue_seq:	The sequence count at the point where the signal was queued
  * @it_sigev_notify:	The notify word of sigevent struct for signal delivery
  * @it_interval:	The interval for periodic timers
  * @it_signal:		Pointer to the creators signal struct
  * @it_pid:		The pid of the process/task targeted by the signal
  * @it_process:		The task to wakeup on clock_nanosleep (CPU timers)
- * @sigq:		Pointer to preallocated sigqueue
+ * @rcuref:		Reference count for life time management
+ * @sigq:		Embedded sigqueue
  * @it:			Union representing the various posix timer type
  *			internals.
  * @rcu:		RCU head for freeing the timer.
  */
 struct k_itimer {
 	struct hlist_node	list;
+	struct hlist_node	ignored_list;
 	struct hlist_node	t_hash;
 	spinlock_t		it_lock;
 	const struct k_clock	*kclock;
 	clockid_t		it_clock;
 	timer_t			it_id;
-	int			it_active;
+	int			it_status;
+	bool			it_sig_periodic;
 	s64			it_overrun;
 	s64			it_overrun_last;
-	int			it_requeue_pending;
+	unsigned int		it_signal_seq;
+	unsigned int		it_sigqueue_seq;
 	int			it_sigev_notify;
+	enum pid_type		it_pid_type;
 	ktime_t			it_interval;
 	struct signal_struct	*it_signal;
 	union {
 		struct pid		*it_pid;
 		struct task_struct	*it_process;
 	};
-	struct sigqueue		*sigq;
+	struct sigqueue		sigq;
+	rcuref_t		rcuref;
 	union {
 		struct {
 			struct hrtimer	timer;
@@ -196,5 +220,29 @@ void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,
 
 int update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new);
 
-void posixtimer_rearm(struct kernel_siginfo *info);
+#ifdef CONFIG_POSIX_TIMERS
+static inline void posixtimer_putref(struct k_itimer *tmr)
+{
+	if (rcuref_put(&tmr->rcuref))
+		posixtimer_free_timer(tmr);
+}
+
+static inline void posixtimer_sigqueue_getref(struct sigqueue *q)
+{
+	struct k_itimer *tmr = container_of(q, struct k_itimer, sigq);
+
+	WARN_ON_ONCE(!rcuref_get(&tmr->rcuref));
+}
+
+static inline void posixtimer_sigqueue_putref(struct sigqueue *q)
+{
+	struct k_itimer *tmr = container_of(q, struct k_itimer, sigq);
+
+	posixtimer_putref(tmr);
+}
+#else  /* CONFIG_POSIX_TIMERS */
+static inline void posixtimer_sigqueue_getref(struct sigqueue *q) { }
+static inline void posixtimer_sigqueue_putref(struct sigqueue *q) { }
+#endif /* !CONFIG_POSIX_TIMERS */
+
 #endif
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index f9ccad32fc5c..75f162b60ba1 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -106,17 +106,17 @@ struct reg_sequence {
  * @addr: Address to poll
  * @val: Unsigned integer variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @sleep_us: Maximum time to sleep between reads in us (0
- *            tight-loops).  Should be less than ~20ms since usleep_range
- *            is used (see Documentation/timers/timers-howto.rst).
+ * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please
+ *            read usleep_range() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout or the regmap_read
+ * This is modelled after the readx_poll_timeout macros in linux/iopoll.h.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout or the regmap_read
  * error return value in case of a error read. In the two former cases,
  * the last read value at @addr is stored in @val. Must not be called
  * from atomic context if sleep_us or timeout_us are used.
- *
- * This is modelled after the readx_poll_timeout macros in linux/iopoll.h.
  */
 #define regmap_read_poll_timeout(map, addr, val, cond, sleep_us, timeout_us) \
 ({ \
@@ -133,20 +133,20 @@ struct reg_sequence {
  * @addr: Address to poll
  * @val: Unsigned integer variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @delay_us: Time to udelay between reads in us (0 tight-loops).
- *            Should be less than ~10us since udelay is used
- *            (see Documentation/timers/timers-howto.rst).
+ * @delay_us: Time to udelay between reads in us (0 tight-loops). Please
+ *            read udelay() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout or the regmap_read
- * error return value in case of a error read. In the two former cases,
- * the last read value at @addr is stored in @val.
- *
  * This is modelled after the readx_poll_timeout_atomic macros in linux/iopoll.h.
  *
  * Note: In general regmap cannot be used in atomic context. If you want to use
  * this macro then first setup your regmap for atomic use (flat or no cache
  * and MMIO regmap).
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout or the regmap_read
+ * error return value in case of a error read. In the two former cases,
+ * the last read value at @addr is stored in @val.
  */
 #define regmap_read_poll_timeout_atomic(map, addr, val, cond, delay_us, timeout_us) \
 ({ \
@@ -177,17 +177,17 @@ struct reg_sequence {
  * @field: Regmap field to read from
  * @val: Unsigned integer variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @sleep_us: Maximum time to sleep between reads in us (0
- *            tight-loops).  Should be less than ~20ms since usleep_range
- *            is used (see Documentation/timers/timers-howto.rst).
+ * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please
+ *            read usleep_range() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout or the regmap_field_read
+ * This is modelled after the readx_poll_timeout macros in linux/iopoll.h.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout or the regmap_field_read
  * error return value in case of a error read. In the two former cases,
  * the last read value at @addr is stored in @val. Must not be called
  * from atomic context if sleep_us or timeout_us are used.
- *
- * This is modelled after the readx_poll_timeout macros in linux/iopoll.h.
  */
 #define regmap_field_read_poll_timeout(field, val, cond, sleep_us, timeout_us) \
 ({ \
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index c8ed09ac29ac..d5d03d919df8 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -138,6 +138,7 @@ struct signal_struct {
 	/* POSIX.1b Interval Timers */
 	unsigned int		next_posix_timer_id;
 	struct hlist_head	posix_timers;
+	struct hlist_head	ignored_posix_timers;
 
 	/* ITIMER_REAL timer for the process */
 	struct hrtimer real_timer;
@@ -338,9 +339,6 @@ extern void force_fatal_sig(int);
 extern void force_exit_sig(int);
 extern int send_sig(int, struct task_struct *, int);
 extern int zap_other_threads(struct task_struct *p);
-extern struct sigqueue *sigqueue_alloc(void);
-extern void sigqueue_free(struct sigqueue *);
-extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type);
 extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
 
 static inline void clear_notify_signal(void)
diff --git a/include/linux/tick.h b/include/linux/tick.h
index 99c9c5a7252a..b8ddc8e631a3 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -20,12 +20,10 @@ extern void __init tick_init(void);
 extern void tick_suspend_local(void);
 /* Should be core only, but XEN resume magic and ARM BL switcher require it */
 extern void tick_resume_local(void);
-extern void tick_cleanup_dead_cpu(int cpu);
 #else /* CONFIG_GENERIC_CLOCKEVENTS */
 static inline void tick_init(void) { }
 static inline void tick_suspend_local(void) { }
 static inline void tick_resume_local(void) { }
-static inline void tick_cleanup_dead_cpu(int cpu) { }
 #endif /* !CONFIG_GENERIC_CLOCKEVENTS */
 
 #if defined(CONFIG_GENERIC_CLOCKEVENTS) && defined(CONFIG_HOTPLUG_CPU)
diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h
index 902c20ef495a..e39d4d563b19 100644
--- a/include/linux/timekeeper_internal.h
+++ b/include/linux/timekeeper_internal.h
@@ -26,7 +26,7 @@
  * occupies a single 64byte cache line.
  *
  * The struct is separate from struct timekeeper as it is also used
- * for a fast NMI safe accessors.
+ * for the fast NMI safe accessors.
  *
  * @base_real is for the fast NMI safe accessor to allow reading clock
  * realtime from any context.
@@ -44,33 +44,38 @@ struct tk_read_base {
 
 /**
  * struct timekeeper - Structure holding internal timekeeping values.
- * @tkr_mono:		The readout base structure for CLOCK_MONOTONIC
- * @tkr_raw:		The readout base structure for CLOCK_MONOTONIC_RAW
- * @xtime_sec:		Current CLOCK_REALTIME time in seconds
- * @ktime_sec:		Current CLOCK_MONOTONIC time in seconds
- * @wall_to_monotonic:	CLOCK_REALTIME to CLOCK_MONOTONIC offset
- * @offs_real:		Offset clock monotonic -> clock realtime
- * @offs_boot:		Offset clock monotonic -> clock boottime
- * @offs_tai:		Offset clock monotonic -> clock tai
- * @tai_offset:		The current UTC to TAI offset in seconds
- * @clock_was_set_seq:	The sequence number of clock was set events
- * @cs_was_changed_seq:	The sequence number of clocksource change events
- * @next_leap_ktime:	CLOCK_MONOTONIC time value of a pending leap-second
- * @raw_sec:		CLOCK_MONOTONIC_RAW  time in seconds
- * @monotonic_to_boot:	CLOCK_MONOTONIC to CLOCK_BOOTTIME offset
- * @cycle_interval:	Number of clock cycles in one NTP interval
- * @xtime_interval:	Number of clock shifted nano seconds in one NTP
- *			interval.
- * @xtime_remainder:	Shifted nano seconds left over when rounding
- *			@cycle_interval
- * @raw_interval:	Shifted raw nano seconds accumulated per NTP interval.
- * @ntp_error:		Difference between accumulated time and NTP time in ntp
- *			shifted nano seconds.
- * @ntp_error_shift:	Shift conversion between clock shifted nano seconds and
- *			ntp shifted nano seconds.
- * @last_warning:	Warning ratelimiter (DEBUG_TIMEKEEPING)
- * @underflow_seen:	Underflow warning flag (DEBUG_TIMEKEEPING)
- * @overflow_seen:	Overflow warning flag (DEBUG_TIMEKEEPING)
+ * @tkr_mono:			The readout base structure for CLOCK_MONOTONIC
+ * @xtime_sec:			Current CLOCK_REALTIME time in seconds
+ * @ktime_sec:			Current CLOCK_MONOTONIC time in seconds
+ * @wall_to_monotonic:		CLOCK_REALTIME to CLOCK_MONOTONIC offset
+ * @offs_real:			Offset clock monotonic -> clock realtime
+ * @offs_boot:			Offset clock monotonic -> clock boottime
+ * @offs_tai:			Offset clock monotonic -> clock tai
+ * @tai_offset:			The current UTC to TAI offset in seconds
+ * @tkr_raw:			The readout base structure for CLOCK_MONOTONIC_RAW
+ * @raw_sec:			CLOCK_MONOTONIC_RAW  time in seconds
+ * @clock_was_set_seq:		The sequence number of clock was set events
+ * @cs_was_changed_seq:		The sequence number of clocksource change events
+ * @monotonic_to_boot:		CLOCK_MONOTONIC to CLOCK_BOOTTIME offset
+ * @cycle_interval:		Number of clock cycles in one NTP interval
+ * @xtime_interval:		Number of clock shifted nano seconds in one NTP
+ *				interval.
+ * @xtime_remainder:		Shifted nano seconds left over when rounding
+ *				@cycle_interval
+ * @raw_interval:		Shifted raw nano seconds accumulated per NTP interval.
+ * @next_leap_ktime:		CLOCK_MONOTONIC time value of a pending leap-second
+ * @ntp_tick:			The ntp_tick_length() value currently being
+ *				used. This cached copy ensures we consistently
+ *				apply the tick length for an entire tick, as
+ *				ntp_tick_length may change mid-tick, and we don't
+ *				want to apply that new value to the tick in
+ *				progress.
+ * @ntp_error:			Difference between accumulated time and NTP time in ntp
+ *				shifted nano seconds.
+ * @ntp_error_shift:		Shift conversion between clock shifted nano seconds and
+ *				ntp shifted nano seconds.
+ * @ntp_err_mult:		Multiplication factor for scaled math conversion
+ * @skip_second_overflow:	Flag used to avoid updating NTP twice with same second
  *
  * Note: For timespec(64) based interfaces wall_to_monotonic is what
  * we need to add to xtime (or xtime corrected for sub jiffy times)
@@ -88,10 +93,28 @@ struct tk_read_base {
  *
  * @monotonic_to_boottime is a timespec64 representation of @offs_boot to
  * accelerate the VDSO update for CLOCK_BOOTTIME.
+ *
+ * The cacheline ordering of the structure is optimized for in kernel usage of
+ * the ktime_get() and ktime_get_ts64() family of time accessors. Struct
+ * timekeeper is prepended in the core timekeeping code with a sequence count,
+ * which results in the following cacheline layout:
+ *
+ * 0:	seqcount, tkr_mono
+ * 1:	xtime_sec ... tai_offset
+ * 2:	tkr_raw, raw_sec
+ * 3,4: Internal variables
+ *
+ * Cacheline 0,1 contain the data which is used for accessing
+ * CLOCK_MONOTONIC/REALTIME/BOOTTIME/TAI, while cacheline 2 contains the
+ * data for accessing CLOCK_MONOTONIC_RAW.  Cacheline 3,4 are internal
+ * variables which are only accessed during timekeeper updates once per
+ * tick.
  */
 struct timekeeper {
+	/* Cacheline 0 (together with prepended seqcount of timekeeper core): */
 	struct tk_read_base	tkr_mono;
-	struct tk_read_base	tkr_raw;
+
+	/* Cacheline 1: */
 	u64			xtime_sec;
 	unsigned long		ktime_sec;
 	struct timespec64	wall_to_monotonic;
@@ -99,43 +122,28 @@ struct timekeeper {
 	ktime_t			offs_boot;
 	ktime_t			offs_tai;
 	s32			tai_offset;
+
+	/* Cacheline 2: */
+	struct tk_read_base	tkr_raw;
+	u64			raw_sec;
+
+	/* Cachline 3 and 4 (timekeeping internal variables): */
 	unsigned int		clock_was_set_seq;
 	u8			cs_was_changed_seq;
-	ktime_t			next_leap_ktime;
-	u64			raw_sec;
+
 	struct timespec64	monotonic_to_boot;
 
-	/* The following members are for timekeeping internal use */
 	u64			cycle_interval;
 	u64			xtime_interval;
 	s64			xtime_remainder;
 	u64			raw_interval;
-	/* The ntp_tick_length() value currently being used.
-	 * This cached copy ensures we consistently apply the tick
-	 * length for an entire tick, as ntp_tick_length may change
-	 * mid-tick, and we don't want to apply that new value to
-	 * the tick in progress.
-	 */
+
+	ktime_t			next_leap_ktime;
 	u64			ntp_tick;
-	/* Difference between accumulated time and NTP time in ntp
-	 * shifted nano seconds. */
 	s64			ntp_error;
 	u32			ntp_error_shift;
 	u32			ntp_err_mult;
-	/* Flag used to avoid updating NTP twice with same second */
 	u32			skip_second_overflow;
-#ifdef CONFIG_DEBUG_TIMEKEEPING
-	long			last_warning;
-	/*
-	 * These simple flag variables are managed
-	 * without locks, which is racy, but they are
-	 * ok since we don't really care about being
-	 * super precise about how many events were
-	 * seen, just that a problem was observed.
-	 */
-	int			underflow_seen;
-	int			overflow_seen;
-#endif
 };
 
 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 84a035e86ac8..0e035f675efe 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -280,6 +280,7 @@ struct ktime_timestamps {
  *				 counter value
  * @cycles:	Clocksource counter value to produce the system times
  * @real:	Realtime system time
+ * @boot:	Boot time
  * @raw:	Monotonic raw system time
  * @cs_id:	Clocksource ID
  * @clock_was_set_seq:	The sequence number of clock-was-set events
@@ -288,6 +289,7 @@ struct ktime_timestamps {
 struct system_time_snapshot {
 	u64			cycles;
 	ktime_t			real;
+	ktime_t			boot;
 	ktime_t			raw;
 	enum clocksource_ids	cs_id;
 	unsigned int		clock_was_set_seq;
diff --git a/include/linux/timex.h b/include/linux/timex.h
index 3871b06bd302..4ee32eff3f22 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -139,14 +139,6 @@ unsigned long random_get_entropy_fallback(void);
 #define MAXSEC 2048		/* max interval between updates (s) */
 #define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_USEC) << 5) /* beyond max. dispersion */
 
-/*
- * kernel variables
- * Note: maximum error = NTP sync distance = dispersion + delay / 2;
- * estimated error = NTP dispersion.
- */
-extern unsigned long tick_usec;		/* USER_HZ period (usec) */
-extern unsigned long tick_nsec;		/* SHIFTED_HZ period (nsec) */
-
 /* Required to safely shift negative values */
 #define shift_right(x, s) ({	\
 	__typeof__(x) __x = (x);	\
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 2b322a9b88a2..6d90ad974408 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -542,8 +542,8 @@ do {										\
 	int __ret = 0;								\
 	struct hrtimer_sleeper __t;						\
 										\
-	hrtimer_init_sleeper_on_stack(&__t, CLOCK_MONOTONIC,			\
-				      HRTIMER_MODE_REL);			\
+	hrtimer_setup_sleeper_on_stack(&__t, CLOCK_MONOTONIC,			\
+				       HRTIMER_MODE_REL);			\
 	if ((timeout) != KTIME_MAX) {						\
 		hrtimer_set_expires_range_ns(&__t.timer, timeout,		\
 					current->timer_slack_ns);		\