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()
  ...

1 files changed, 2 insertions, 193 deletions

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 06f0bc1db6d9..a5860bf6d16f 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -37,7 +37,6 @@
 #include <linux/tick.h>
 #include <linux/kallsyms.h>
 #include <linux/irq_work.h>
-#include <linux/sched/signal.h>
 #include <linux/sched/sysctl.h>
 #include <linux/sched/nohz.h>
 #include <linux/sched/debug.h>
@@ -2422,7 +2421,8 @@ static inline void __run_timers(struct timer_base *base)
 
 static void __run_timer_base(struct timer_base *base)
 {
-	if (time_before(jiffies, base->next_expiry))
+	/* Can race against a remote CPU updating next_expiry under the lock */
+	if (time_before(jiffies, READ_ONCE(base->next_expiry)))
 		return;
 
 	timer_base_lock_expiry(base);
@@ -2526,141 +2526,6 @@ void update_process_times(int user_tick)
 		run_posix_cpu_timers();
 }
 
-/*
- * Since schedule_timeout()'s timer is defined on the stack, it must store
- * the target task on the stack as well.
- */
-struct process_timer {
-	struct timer_list timer;
-	struct task_struct *task;
-};
-
-static void process_timeout(struct timer_list *t)
-{
-	struct process_timer *timeout = from_timer(timeout, t, timer);
-
-	wake_up_process(timeout->task);
-}
-
-/**
- * schedule_timeout - sleep until timeout
- * @timeout: timeout value in jiffies
- *
- * Make the current task sleep until @timeout jiffies have elapsed.
- * The function behavior depends on the current task state
- * (see also set_current_state() description):
- *
- * %TASK_RUNNING - the scheduler is called, but the task does not sleep
- * at all. That happens because sched_submit_work() does nothing for
- * tasks in %TASK_RUNNING state.
- *
- * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
- * pass before the routine returns unless the current task is explicitly
- * woken up, (e.g. by wake_up_process()).
- *
- * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
- * delivered to the current task or the current task is explicitly woken
- * up.
- *
- * The current task state is guaranteed to be %TASK_RUNNING when this
- * routine returns.
- *
- * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
- * the CPU away without a bound on the timeout. In this case the return
- * value will be %MAX_SCHEDULE_TIMEOUT.
- *
- * Returns 0 when the timer has expired otherwise the remaining time in
- * jiffies will be returned. In all cases the return value is guaranteed
- * to be non-negative.
- */
-signed long __sched schedule_timeout(signed long timeout)
-{
-	struct process_timer timer;
-	unsigned long expire;
-
-	switch (timeout)
-	{
-	case MAX_SCHEDULE_TIMEOUT:
-		/*
-		 * These two special cases are useful to be comfortable
-		 * in the caller. Nothing more. We could take
-		 * MAX_SCHEDULE_TIMEOUT from one of the negative value
-		 * but I' d like to return a valid offset (>=0) to allow
-		 * the caller to do everything it want with the retval.
-		 */
-		schedule();
-		goto out;
-	default:
-		/*
-		 * Another bit of PARANOID. Note that the retval will be
-		 * 0 since no piece of kernel is supposed to do a check
-		 * for a negative retval of schedule_timeout() (since it
-		 * should never happens anyway). You just have the printk()
-		 * that will tell you if something is gone wrong and where.
-		 */
-		if (timeout < 0) {
-			printk(KERN_ERR "schedule_timeout: wrong timeout "
-				"value %lx\n", timeout);
-			dump_stack();
-			__set_current_state(TASK_RUNNING);
-			goto out;
-		}
-	}
-
-	expire = timeout + jiffies;
-
-	timer.task = current;
-	timer_setup_on_stack(&timer.timer, process_timeout, 0);
-	__mod_timer(&timer.timer, expire, MOD_TIMER_NOTPENDING);
-	schedule();
-	del_timer_sync(&timer.timer);
-
-	/* Remove the timer from the object tracker */
-	destroy_timer_on_stack(&timer.timer);
-
-	timeout = expire - jiffies;
-
- out:
-	return timeout < 0 ? 0 : timeout;
-}
-EXPORT_SYMBOL(schedule_timeout);
-
-/*
- * We can use __set_current_state() here because schedule_timeout() calls
- * schedule() unconditionally.
- */
-signed long __sched schedule_timeout_interruptible(signed long timeout)
-{
-	__set_current_state(TASK_INTERRUPTIBLE);
-	return schedule_timeout(timeout);
-}
-EXPORT_SYMBOL(schedule_timeout_interruptible);
-
-signed long __sched schedule_timeout_killable(signed long timeout)
-{
-	__set_current_state(TASK_KILLABLE);
-	return schedule_timeout(timeout);
-}
-EXPORT_SYMBOL(schedule_timeout_killable);
-
-signed long __sched schedule_timeout_uninterruptible(signed long timeout)
-{
-	__set_current_state(TASK_UNINTERRUPTIBLE);
-	return schedule_timeout(timeout);
-}
-EXPORT_SYMBOL(schedule_timeout_uninterruptible);
-
-/*
- * Like schedule_timeout_uninterruptible(), except this task will not contribute
- * to load average.
- */
-signed long __sched schedule_timeout_idle(signed long timeout)
-{
-	__set_current_state(TASK_IDLE);
-	return schedule_timeout(timeout);
-}
-EXPORT_SYMBOL(schedule_timeout_idle);
-
 #ifdef CONFIG_HOTPLUG_CPU
 static void migrate_timer_list(struct timer_base *new_base, struct hlist_head *head)
 {
@@ -2757,59 +2622,3 @@ void __init init_timers(void)
 	posix_cputimers_init_work();
 	open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
 }
-
-/**
- * msleep - sleep safely even with waitqueue interruptions
- * @msecs: Time in milliseconds to sleep for
- */
-void msleep(unsigned int msecs)
-{
-	unsigned long timeout = msecs_to_jiffies(msecs);
-
-	while (timeout)
-		timeout = schedule_timeout_uninterruptible(timeout);
-}
-
-EXPORT_SYMBOL(msleep);
-
-/**
- * msleep_interruptible - sleep waiting for signals
- * @msecs: Time in milliseconds to sleep for
- */
-unsigned long msleep_interruptible(unsigned int msecs)
-{
-	unsigned long timeout = msecs_to_jiffies(msecs);
-
-	while (timeout && !signal_pending(current))
-		timeout = schedule_timeout_interruptible(timeout);
-	return jiffies_to_msecs(timeout);
-}
-
-EXPORT_SYMBOL(msleep_interruptible);
-
-/**
- * usleep_range_state - Sleep for an approximate time in a given state
- * @min:	Minimum time in usecs to sleep
- * @max:	Maximum time in usecs to sleep
- * @state:	State of the current task that will be while sleeping
- *
- * In non-atomic context where the exact wakeup time is flexible, use
- * usleep_range_state() instead of udelay().  The sleep improves responsiveness
- * by avoiding the CPU-hogging busy-wait of udelay(), and the range reduces
- * power usage by allowing hrtimers to take advantage of an already-
- * scheduled interrupt instead of scheduling a new one just for this sleep.
- */
-void __sched usleep_range_state(unsigned long min, unsigned long max,
-				unsigned int state)
-{
-	ktime_t exp = ktime_add_us(ktime_get(), min);
-	u64 delta = (u64)(max - min) * NSEC_PER_USEC;
-
-	for (;;) {
-		__set_current_state(state);
-		/* Do not return before the requested sleep time has elapsed */
-		if (!schedule_hrtimeout_range(&exp, delta, HRTIMER_MODE_ABS))
-			break;
-	}
-}
-EXPORT_SYMBOL(usleep_range_state);