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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /kernel/time/hrtimer.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'kernel/time/hrtimer.c')
-rw-r--r--kernel/time/hrtimer.c2391
1 files changed, 2391 insertions, 0 deletions
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
new file mode 100644
index 0000000000..760793998c
--- /dev/null
+++ b/kernel/time/hrtimer.c
@@ -0,0 +1,2391 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
+ * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
+ * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner
+ *
+ * High-resolution kernel timers
+ *
+ * In contrast to the low-resolution timeout API, aka timer wheel,
+ * hrtimers provide finer resolution and accuracy depending on system
+ * configuration and capabilities.
+ *
+ * Started by: Thomas Gleixner and Ingo Molnar
+ *
+ * Credits:
+ * Based on the original timer wheel code
+ *
+ * Help, testing, suggestions, bugfixes, improvements were
+ * provided by:
+ *
+ * George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
+ * et. al.
+ */
+
+#include <linux/cpu.h>
+#include <linux/export.h>
+#include <linux/percpu.h>
+#include <linux/hrtimer.h>
+#include <linux/notifier.h>
+#include <linux/syscalls.h>
+#include <linux/interrupt.h>
+#include <linux/tick.h>
+#include <linux/err.h>
+#include <linux/debugobjects.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/sysctl.h>
+#include <linux/sched/rt.h>
+#include <linux/sched/deadline.h>
+#include <linux/sched/nohz.h>
+#include <linux/sched/debug.h>
+#include <linux/timer.h>
+#include <linux/freezer.h>
+#include <linux/compat.h>
+
+#include <linux/uaccess.h>
+
+#include <trace/events/timer.h>
+
+#include "tick-internal.h"
+
+/*
+ * Masks for selecting the soft and hard context timers from
+ * cpu_base->active
+ */
+#define MASK_SHIFT (HRTIMER_BASE_MONOTONIC_SOFT)
+#define HRTIMER_ACTIVE_HARD ((1U << MASK_SHIFT) - 1)
+#define HRTIMER_ACTIVE_SOFT (HRTIMER_ACTIVE_HARD << MASK_SHIFT)
+#define HRTIMER_ACTIVE_ALL (HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
+
+/*
+ * The timer bases:
+ *
+ * There are more clockids than hrtimer bases. Thus, we index
+ * into the timer bases by the hrtimer_base_type enum. When trying
+ * to reach a base using a clockid, hrtimer_clockid_to_base()
+ * is used to convert from clockid to the proper hrtimer_base_type.
+ */
+DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
+{
+ .lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
+ .clock_base =
+ {
+ {
+ .index = HRTIMER_BASE_MONOTONIC,
+ .clockid = CLOCK_MONOTONIC,
+ .get_time = &ktime_get,
+ },
+ {
+ .index = HRTIMER_BASE_REALTIME,
+ .clockid = CLOCK_REALTIME,
+ .get_time = &ktime_get_real,
+ },
+ {
+ .index = HRTIMER_BASE_BOOTTIME,
+ .clockid = CLOCK_BOOTTIME,
+ .get_time = &ktime_get_boottime,
+ },
+ {
+ .index = HRTIMER_BASE_TAI,
+ .clockid = CLOCK_TAI,
+ .get_time = &ktime_get_clocktai,
+ },
+ {
+ .index = HRTIMER_BASE_MONOTONIC_SOFT,
+ .clockid = CLOCK_MONOTONIC,
+ .get_time = &ktime_get,
+ },
+ {
+ .index = HRTIMER_BASE_REALTIME_SOFT,
+ .clockid = CLOCK_REALTIME,
+ .get_time = &ktime_get_real,
+ },
+ {
+ .index = HRTIMER_BASE_BOOTTIME_SOFT,
+ .clockid = CLOCK_BOOTTIME,
+ .get_time = &ktime_get_boottime,
+ },
+ {
+ .index = HRTIMER_BASE_TAI_SOFT,
+ .clockid = CLOCK_TAI,
+ .get_time = &ktime_get_clocktai,
+ },
+ }
+};
+
+static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
+ /* Make sure we catch unsupported clockids */
+ [0 ... MAX_CLOCKS - 1] = HRTIMER_MAX_CLOCK_BASES,
+
+ [CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
+ [CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
+ [CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
+ [CLOCK_TAI] = HRTIMER_BASE_TAI,
+};
+
+/*
+ * Functions and macros which are different for UP/SMP systems are kept in a
+ * single place
+ */
+#ifdef CONFIG_SMP
+
+/*
+ * We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base()
+ * such that hrtimer_callback_running() can unconditionally dereference
+ * timer->base->cpu_base
+ */
+static struct hrtimer_cpu_base migration_cpu_base = {
+ .clock_base = { {
+ .cpu_base = &migration_cpu_base,
+ .seq = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq,
+ &migration_cpu_base.lock),
+ }, },
+};
+
+#define migration_base migration_cpu_base.clock_base[0]
+
+static inline bool is_migration_base(struct hrtimer_clock_base *base)
+{
+ return base == &migration_base;
+}
+
+/*
+ * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
+ * means that all timers which are tied to this base via timer->base are
+ * locked, and the base itself is locked too.
+ *
+ * So __run_timers/migrate_timers can safely modify all timers which could
+ * be found on the lists/queues.
+ *
+ * When the timer's base is locked, and the timer removed from list, it is
+ * possible to set timer->base = &migration_base and drop the lock: the timer
+ * remains locked.
+ */
+static
+struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
+ unsigned long *flags)
+ __acquires(&timer->base->lock)
+{
+ struct hrtimer_clock_base *base;
+
+ for (;;) {
+ base = READ_ONCE(timer->base);
+ if (likely(base != &migration_base)) {
+ raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
+ if (likely(base == timer->base))
+ return base;
+ /* The timer has migrated to another CPU: */
+ raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
+ }
+ cpu_relax();
+ }
+}
+
+/*
+ * We do not migrate the timer when it is expiring before the next
+ * event on the target cpu. When high resolution is enabled, we cannot
+ * reprogram the target cpu hardware and we would cause it to fire
+ * late. To keep it simple, we handle the high resolution enabled and
+ * disabled case similar.
+ *
+ * Called with cpu_base->lock of target cpu held.
+ */
+static int
+hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
+{
+ ktime_t expires;
+
+ expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
+ return expires < new_base->cpu_base->expires_next;
+}
+
+static inline
+struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
+ int pinned)
+{
+#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
+ if (static_branch_likely(&timers_migration_enabled) && !pinned)
+ return &per_cpu(hrtimer_bases, get_nohz_timer_target());
+#endif
+ return base;
+}
+
+/*
+ * We switch the timer base to a power-optimized selected CPU target,
+ * if:
+ * - NO_HZ_COMMON is enabled
+ * - timer migration is enabled
+ * - the timer callback is not running
+ * - the timer is not the first expiring timer on the new target
+ *
+ * If one of the above requirements is not fulfilled we move the timer
+ * to the current CPU or leave it on the previously assigned CPU if
+ * the timer callback is currently running.
+ */
+static inline struct hrtimer_clock_base *
+switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
+ int pinned)
+{
+ struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
+ struct hrtimer_clock_base *new_base;
+ int basenum = base->index;
+
+ this_cpu_base = this_cpu_ptr(&hrtimer_bases);
+ new_cpu_base = get_target_base(this_cpu_base, pinned);
+again:
+ new_base = &new_cpu_base->clock_base[basenum];
+
+ if (base != new_base) {
+ /*
+ * We are trying to move timer to new_base.
+ * However we can't change timer's base while it is running,
+ * so we keep it on the same CPU. No hassle vs. reprogramming
+ * the event source in the high resolution case. The softirq
+ * code will take care of this when the timer function has
+ * completed. There is no conflict as we hold the lock until
+ * the timer is enqueued.
+ */
+ if (unlikely(hrtimer_callback_running(timer)))
+ return base;
+
+ /* See the comment in lock_hrtimer_base() */
+ WRITE_ONCE(timer->base, &migration_base);
+ raw_spin_unlock(&base->cpu_base->lock);
+ raw_spin_lock(&new_base->cpu_base->lock);
+
+ if (new_cpu_base != this_cpu_base &&
+ hrtimer_check_target(timer, new_base)) {
+ raw_spin_unlock(&new_base->cpu_base->lock);
+ raw_spin_lock(&base->cpu_base->lock);
+ new_cpu_base = this_cpu_base;
+ WRITE_ONCE(timer->base, base);
+ goto again;
+ }
+ WRITE_ONCE(timer->base, new_base);
+ } else {
+ if (new_cpu_base != this_cpu_base &&
+ hrtimer_check_target(timer, new_base)) {
+ new_cpu_base = this_cpu_base;
+ goto again;
+ }
+ }
+ return new_base;
+}
+
+#else /* CONFIG_SMP */
+
+static inline bool is_migration_base(struct hrtimer_clock_base *base)
+{
+ return false;
+}
+
+static inline struct hrtimer_clock_base *
+lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
+ __acquires(&timer->base->cpu_base->lock)
+{
+ struct hrtimer_clock_base *base = timer->base;
+
+ raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
+
+ return base;
+}
+
+# define switch_hrtimer_base(t, b, p) (b)
+
+#endif /* !CONFIG_SMP */
+
+/*
+ * Functions for the union type storage format of ktime_t which are
+ * too large for inlining:
+ */
+#if BITS_PER_LONG < 64
+/*
+ * Divide a ktime value by a nanosecond value
+ */
+s64 __ktime_divns(const ktime_t kt, s64 div)
+{
+ int sft = 0;
+ s64 dclc;
+ u64 tmp;
+
+ dclc = ktime_to_ns(kt);
+ tmp = dclc < 0 ? -dclc : dclc;
+
+ /* Make sure the divisor is less than 2^32: */
+ while (div >> 32) {
+ sft++;
+ div >>= 1;
+ }
+ tmp >>= sft;
+ do_div(tmp, (u32) div);
+ return dclc < 0 ? -tmp : tmp;
+}
+EXPORT_SYMBOL_GPL(__ktime_divns);
+#endif /* BITS_PER_LONG >= 64 */
+
+/*
+ * Add two ktime values and do a safety check for overflow:
+ */
+ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
+{
+ ktime_t res = ktime_add_unsafe(lhs, rhs);
+
+ /*
+ * We use KTIME_SEC_MAX here, the maximum timeout which we can
+ * return to user space in a timespec:
+ */
+ if (res < 0 || res < lhs || res < rhs)
+ res = ktime_set(KTIME_SEC_MAX, 0);
+
+ return res;
+}
+
+EXPORT_SYMBOL_GPL(ktime_add_safe);
+
+#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
+
+static const struct debug_obj_descr hrtimer_debug_descr;
+
+static void *hrtimer_debug_hint(void *addr)
+{
+ return ((struct hrtimer *) addr)->function;
+}
+
+/*
+ * fixup_init is called when:
+ * - an active object is initialized
+ */
+static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state)
+{
+ struct hrtimer *timer = addr;
+
+ switch (state) {
+ case ODEBUG_STATE_ACTIVE:
+ hrtimer_cancel(timer);
+ debug_object_init(timer, &hrtimer_debug_descr);
+ return true;
+ default:
+ return false;
+ }
+}
+
+/*
+ * fixup_activate is called when:
+ * - an active object is activated
+ * - an unknown non-static object is activated
+ */
+static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
+{
+ switch (state) {
+ case ODEBUG_STATE_ACTIVE:
+ WARN_ON(1);
+ fallthrough;
+ default:
+ return false;
+ }
+}
+
+/*
+ * fixup_free is called when:
+ * - an active object is freed
+ */
+static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
+{
+ struct hrtimer *timer = addr;
+
+ switch (state) {
+ case ODEBUG_STATE_ACTIVE:
+ hrtimer_cancel(timer);
+ debug_object_free(timer, &hrtimer_debug_descr);
+ return true;
+ default:
+ return false;
+ }
+}
+
+static const struct debug_obj_descr hrtimer_debug_descr = {
+ .name = "hrtimer",
+ .debug_hint = hrtimer_debug_hint,
+ .fixup_init = hrtimer_fixup_init,
+ .fixup_activate = hrtimer_fixup_activate,
+ .fixup_free = hrtimer_fixup_free,
+};
+
+static inline void debug_hrtimer_init(struct hrtimer *timer)
+{
+ debug_object_init(timer, &hrtimer_debug_descr);
+}
+
+static inline void debug_hrtimer_activate(struct hrtimer *timer,
+ enum hrtimer_mode mode)
+{
+ debug_object_activate(timer, &hrtimer_debug_descr);
+}
+
+static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
+{
+ debug_object_deactivate(timer, &hrtimer_debug_descr);
+}
+
+static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
+ enum hrtimer_mode mode);
+
+void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
+ enum hrtimer_mode mode)
+{
+ debug_object_init_on_stack(timer, &hrtimer_debug_descr);
+ __hrtimer_init(timer, clock_id, mode);
+}
+EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
+
+static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
+ clockid_t clock_id, enum hrtimer_mode mode);
+
+void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
+ clockid_t clock_id, enum hrtimer_mode mode)
+{
+ debug_object_init_on_stack(&sl->timer, &hrtimer_debug_descr);
+ __hrtimer_init_sleeper(sl, clock_id, mode);
+}
+EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack);
+
+void destroy_hrtimer_on_stack(struct hrtimer *timer)
+{
+ debug_object_free(timer, &hrtimer_debug_descr);
+}
+EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
+
+#else
+
+static inline void debug_hrtimer_init(struct hrtimer *timer) { }
+static inline void debug_hrtimer_activate(struct hrtimer *timer,
+ enum hrtimer_mode mode) { }
+static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
+#endif
+
+static inline void
+debug_init(struct hrtimer *timer, clockid_t clockid,
+ enum hrtimer_mode mode)
+{
+ debug_hrtimer_init(timer);
+ trace_hrtimer_init(timer, clockid, mode);
+}
+
+static inline void debug_activate(struct hrtimer *timer,
+ enum hrtimer_mode mode)
+{
+ debug_hrtimer_activate(timer, mode);
+ trace_hrtimer_start(timer, mode);
+}
+
+static inline void debug_deactivate(struct hrtimer *timer)
+{
+ debug_hrtimer_deactivate(timer);
+ trace_hrtimer_cancel(timer);
+}
+
+static struct hrtimer_clock_base *
+__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
+{
+ unsigned int idx;
+
+ if (!*active)
+ return NULL;
+
+ idx = __ffs(*active);
+ *active &= ~(1U << idx);
+
+ return &cpu_base->clock_base[idx];
+}
+
+#define for_each_active_base(base, cpu_base, active) \
+ while ((base = __next_base((cpu_base), &(active))))
+
+static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
+ const struct hrtimer *exclude,
+ unsigned int active,
+ ktime_t expires_next)
+{
+ struct hrtimer_clock_base *base;
+ ktime_t expires;
+
+ for_each_active_base(base, cpu_base, active) {
+ struct timerqueue_node *next;
+ struct hrtimer *timer;
+
+ next = timerqueue_getnext(&base->active);
+ timer = container_of(next, struct hrtimer, node);
+ if (timer == exclude) {
+ /* Get to the next timer in the queue. */
+ next = timerqueue_iterate_next(next);
+ if (!next)
+ continue;
+
+ timer = container_of(next, struct hrtimer, node);
+ }
+ expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
+ if (expires < expires_next) {
+ expires_next = expires;
+
+ /* Skip cpu_base update if a timer is being excluded. */
+ if (exclude)
+ continue;
+
+ if (timer->is_soft)
+ cpu_base->softirq_next_timer = timer;
+ else
+ cpu_base->next_timer = timer;
+ }
+ }
+ /*
+ * clock_was_set() might have changed base->offset of any of
+ * the clock bases so the result might be negative. Fix it up
+ * to prevent a false positive in clockevents_program_event().
+ */
+ if (expires_next < 0)
+ expires_next = 0;
+ return expires_next;
+}
+
+/*
+ * Recomputes cpu_base::*next_timer and returns the earliest expires_next
+ * but does not set cpu_base::*expires_next, that is done by
+ * hrtimer[_force]_reprogram and hrtimer_interrupt only. When updating
+ * cpu_base::*expires_next right away, reprogramming logic would no longer
+ * work.
+ *
+ * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
+ * those timers will get run whenever the softirq gets handled, at the end of
+ * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
+ *
+ * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
+ * The !softirq values are the minima across HRTIMER_ACTIVE_ALL, unless an actual
+ * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
+ *
+ * @active_mask must be one of:
+ * - HRTIMER_ACTIVE_ALL,
+ * - HRTIMER_ACTIVE_SOFT, or
+ * - HRTIMER_ACTIVE_HARD.
+ */
+static ktime_t
+__hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
+{
+ unsigned int active;
+ struct hrtimer *next_timer = NULL;
+ ktime_t expires_next = KTIME_MAX;
+
+ if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
+ active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
+ cpu_base->softirq_next_timer = NULL;
+ expires_next = __hrtimer_next_event_base(cpu_base, NULL,
+ active, KTIME_MAX);
+
+ next_timer = cpu_base->softirq_next_timer;
+ }
+
+ if (active_mask & HRTIMER_ACTIVE_HARD) {
+ active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
+ cpu_base->next_timer = next_timer;
+ expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
+ expires_next);
+ }
+
+ return expires_next;
+}
+
+static ktime_t hrtimer_update_next_event(struct hrtimer_cpu_base *cpu_base)
+{
+ ktime_t expires_next, soft = KTIME_MAX;
+
+ /*
+ * If the soft interrupt has already been activated, ignore the
+ * soft bases. They will be handled in the already raised soft
+ * interrupt.
+ */
+ if (!cpu_base->softirq_activated) {
+ soft = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
+ /*
+ * Update the soft expiry time. clock_settime() might have
+ * affected it.
+ */
+ cpu_base->softirq_expires_next = soft;
+ }
+
+ expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
+ /*
+ * If a softirq timer is expiring first, update cpu_base->next_timer
+ * and program the hardware with the soft expiry time.
+ */
+ if (expires_next > soft) {
+ cpu_base->next_timer = cpu_base->softirq_next_timer;
+ expires_next = soft;
+ }
+
+ return expires_next;
+}
+
+static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
+{
+ ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
+ ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
+ ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
+
+ ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
+ offs_real, offs_boot, offs_tai);
+
+ base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
+ base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
+ base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
+
+ return now;
+}
+
+/*
+ * Is the high resolution mode active ?
+ */
+static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
+{
+ return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
+ cpu_base->hres_active : 0;
+}
+
+static inline int hrtimer_hres_active(void)
+{
+ return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
+}
+
+static void __hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base,
+ struct hrtimer *next_timer,
+ ktime_t expires_next)
+{
+ cpu_base->expires_next = expires_next;
+
+ /*
+ * If hres is not active, hardware does not have to be
+ * reprogrammed yet.
+ *
+ * If a hang was detected in the last timer interrupt then we
+ * leave the hang delay active in the hardware. We want the
+ * system to make progress. That also prevents the following
+ * scenario:
+ * T1 expires 50ms from now
+ * T2 expires 5s from now
+ *
+ * T1 is removed, so this code is called and would reprogram
+ * the hardware to 5s from now. Any hrtimer_start after that
+ * will not reprogram the hardware due to hang_detected being
+ * set. So we'd effectively block all timers until the T2 event
+ * fires.
+ */
+ if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
+ return;
+
+ tick_program_event(expires_next, 1);
+}
+
+/*
+ * Reprogram the event source with checking both queues for the
+ * next event
+ * Called with interrupts disabled and base->lock held
+ */
+static void
+hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
+{
+ ktime_t expires_next;
+
+ expires_next = hrtimer_update_next_event(cpu_base);
+
+ if (skip_equal && expires_next == cpu_base->expires_next)
+ return;
+
+ __hrtimer_reprogram(cpu_base, cpu_base->next_timer, expires_next);
+}
+
+/* High resolution timer related functions */
+#ifdef CONFIG_HIGH_RES_TIMERS
+
+/*
+ * High resolution timer enabled ?
+ */
+static bool hrtimer_hres_enabled __read_mostly = true;
+unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
+EXPORT_SYMBOL_GPL(hrtimer_resolution);
+
+/*
+ * Enable / Disable high resolution mode
+ */
+static int __init setup_hrtimer_hres(char *str)
+{
+ return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
+}
+
+__setup("highres=", setup_hrtimer_hres);
+
+/*
+ * hrtimer_high_res_enabled - query, if the highres mode is enabled
+ */
+static inline int hrtimer_is_hres_enabled(void)
+{
+ return hrtimer_hres_enabled;
+}
+
+static void retrigger_next_event(void *arg);
+
+/*
+ * Switch to high resolution mode
+ */
+static void hrtimer_switch_to_hres(void)
+{
+ struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
+
+ if (tick_init_highres()) {
+ pr_warn("Could not switch to high resolution mode on CPU %u\n",
+ base->cpu);
+ return;
+ }
+ base->hres_active = 1;
+ hrtimer_resolution = HIGH_RES_NSEC;
+
+ tick_setup_sched_timer();
+ /* "Retrigger" the interrupt to get things going */
+ retrigger_next_event(NULL);
+}
+
+#else
+
+static inline int hrtimer_is_hres_enabled(void) { return 0; }
+static inline void hrtimer_switch_to_hres(void) { }
+
+#endif /* CONFIG_HIGH_RES_TIMERS */
+/*
+ * Retrigger next event is called after clock was set with interrupts
+ * disabled through an SMP function call or directly from low level
+ * resume code.
+ *
+ * This is only invoked when:
+ * - CONFIG_HIGH_RES_TIMERS is enabled.
+ * - CONFIG_NOHZ_COMMON is enabled
+ *
+ * For the other cases this function is empty and because the call sites
+ * are optimized out it vanishes as well, i.e. no need for lots of
+ * #ifdeffery.
+ */
+static void retrigger_next_event(void *arg)
+{
+ struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
+
+ /*
+ * When high resolution mode or nohz is active, then the offsets of
+ * CLOCK_REALTIME/TAI/BOOTTIME have to be updated. Otherwise the
+ * next tick will take care of that.
+ *
+ * If high resolution mode is active then the next expiring timer
+ * must be reevaluated and the clock event device reprogrammed if
+ * necessary.
+ *
+ * In the NOHZ case the update of the offset and the reevaluation
+ * of the next expiring timer is enough. The return from the SMP
+ * function call will take care of the reprogramming in case the
+ * CPU was in a NOHZ idle sleep.
+ */
+ if (!__hrtimer_hres_active(base) && !tick_nohz_active)
+ return;
+
+ raw_spin_lock(&base->lock);
+ hrtimer_update_base(base);
+ if (__hrtimer_hres_active(base))
+ hrtimer_force_reprogram(base, 0);
+ else
+ hrtimer_update_next_event(base);
+ raw_spin_unlock(&base->lock);
+}
+
+/*
+ * When a timer is enqueued and expires earlier than the already enqueued
+ * timers, we have to check, whether it expires earlier than the timer for
+ * which the clock event device was armed.
+ *
+ * Called with interrupts disabled and base->cpu_base.lock held
+ */
+static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram)
+{
+ struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+ struct hrtimer_clock_base *base = timer->base;
+ ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
+
+ WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
+
+ /*
+ * CLOCK_REALTIME timer might be requested with an absolute
+ * expiry time which is less than base->offset. Set it to 0.
+ */
+ if (expires < 0)
+ expires = 0;
+
+ if (timer->is_soft) {
+ /*
+ * soft hrtimer could be started on a remote CPU. In this
+ * case softirq_expires_next needs to be updated on the
+ * remote CPU. The soft hrtimer will not expire before the
+ * first hard hrtimer on the remote CPU -
+ * hrtimer_check_target() prevents this case.
+ */
+ struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
+
+ if (timer_cpu_base->softirq_activated)
+ return;
+
+ if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
+ return;
+
+ timer_cpu_base->softirq_next_timer = timer;
+ timer_cpu_base->softirq_expires_next = expires;
+
+ if (!ktime_before(expires, timer_cpu_base->expires_next) ||
+ !reprogram)
+ return;
+ }
+
+ /*
+ * If the timer is not on the current cpu, we cannot reprogram
+ * the other cpus clock event device.
+ */
+ if (base->cpu_base != cpu_base)
+ return;
+
+ if (expires >= cpu_base->expires_next)
+ return;
+
+ /*
+ * If the hrtimer interrupt is running, then it will reevaluate the
+ * clock bases and reprogram the clock event device.
+ */
+ if (cpu_base->in_hrtirq)
+ return;
+
+ cpu_base->next_timer = timer;
+
+ __hrtimer_reprogram(cpu_base, timer, expires);
+}
+
+static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base,
+ unsigned int active)
+{
+ struct hrtimer_clock_base *base;
+ unsigned int seq;
+ ktime_t expires;
+
+ /*
+ * Update the base offsets unconditionally so the following
+ * checks whether the SMP function call is required works.
+ *
+ * The update is safe even when the remote CPU is in the hrtimer
+ * interrupt or the hrtimer soft interrupt and expiring affected
+ * bases. Either it will see the update before handling a base or
+ * it will see it when it finishes the processing and reevaluates
+ * the next expiring timer.
+ */
+ seq = cpu_base->clock_was_set_seq;
+ hrtimer_update_base(cpu_base);
+
+ /*
+ * If the sequence did not change over the update then the
+ * remote CPU already handled it.
+ */
+ if (seq == cpu_base->clock_was_set_seq)
+ return false;
+
+ /*
+ * If the remote CPU is currently handling an hrtimer interrupt, it
+ * will reevaluate the first expiring timer of all clock bases
+ * before reprogramming. Nothing to do here.
+ */
+ if (cpu_base->in_hrtirq)
+ return false;
+
+ /*
+ * Walk the affected clock bases and check whether the first expiring
+ * timer in a clock base is moving ahead of the first expiring timer of
+ * @cpu_base. If so, the IPI must be invoked because per CPU clock
+ * event devices cannot be remotely reprogrammed.
+ */
+ active &= cpu_base->active_bases;
+
+ for_each_active_base(base, cpu_base, active) {
+ struct timerqueue_node *next;
+
+ next = timerqueue_getnext(&base->active);
+ expires = ktime_sub(next->expires, base->offset);
+ if (expires < cpu_base->expires_next)
+ return true;
+
+ /* Extra check for softirq clock bases */
+ if (base->clockid < HRTIMER_BASE_MONOTONIC_SOFT)
+ continue;
+ if (cpu_base->softirq_activated)
+ continue;
+ if (expires < cpu_base->softirq_expires_next)
+ return true;
+ }
+ return false;
+}
+
+/*
+ * Clock was set. This might affect CLOCK_REALTIME, CLOCK_TAI and
+ * CLOCK_BOOTTIME (for late sleep time injection).
+ *
+ * This requires to update the offsets for these clocks
+ * vs. CLOCK_MONOTONIC. When high resolution timers are enabled, then this
+ * also requires to eventually reprogram the per CPU clock event devices
+ * when the change moves an affected timer ahead of the first expiring
+ * timer on that CPU. Obviously remote per CPU clock event devices cannot
+ * be reprogrammed. The other reason why an IPI has to be sent is when the
+ * system is in !HIGH_RES and NOHZ mode. The NOHZ mode updates the offsets
+ * in the tick, which obviously might be stopped, so this has to bring out
+ * the remote CPU which might sleep in idle to get this sorted.
+ */
+void clock_was_set(unsigned int bases)
+{
+ struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases);
+ cpumask_var_t mask;
+ int cpu;
+
+ if (!__hrtimer_hres_active(cpu_base) && !tick_nohz_active)
+ goto out_timerfd;
+
+ if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
+ on_each_cpu(retrigger_next_event, NULL, 1);
+ goto out_timerfd;
+ }
+
+ /* Avoid interrupting CPUs if possible */
+ cpus_read_lock();
+ for_each_online_cpu(cpu) {
+ unsigned long flags;
+
+ cpu_base = &per_cpu(hrtimer_bases, cpu);
+ raw_spin_lock_irqsave(&cpu_base->lock, flags);
+
+ if (update_needs_ipi(cpu_base, bases))
+ cpumask_set_cpu(cpu, mask);
+
+ raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+ }
+
+ preempt_disable();
+ smp_call_function_many(mask, retrigger_next_event, NULL, 1);
+ preempt_enable();
+ cpus_read_unlock();
+ free_cpumask_var(mask);
+
+out_timerfd:
+ timerfd_clock_was_set();
+}
+
+static void clock_was_set_work(struct work_struct *work)
+{
+ clock_was_set(CLOCK_SET_WALL);
+}
+
+static DECLARE_WORK(hrtimer_work, clock_was_set_work);
+
+/*
+ * Called from timekeeping code to reprogram the hrtimer interrupt device
+ * on all cpus and to notify timerfd.
+ */
+void clock_was_set_delayed(void)
+{
+ schedule_work(&hrtimer_work);
+}
+
+/*
+ * Called during resume either directly from via timekeeping_resume()
+ * or in the case of s2idle from tick_unfreeze() to ensure that the
+ * hrtimers are up to date.
+ */
+void hrtimers_resume_local(void)
+{
+ lockdep_assert_irqs_disabled();
+ /* Retrigger on the local CPU */
+ retrigger_next_event(NULL);
+}
+
+/*
+ * Counterpart to lock_hrtimer_base above:
+ */
+static inline
+void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
+ __releases(&timer->base->cpu_base->lock)
+{
+ raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
+}
+
+/**
+ * hrtimer_forward - forward the timer expiry
+ * @timer: hrtimer to forward
+ * @now: forward past this time
+ * @interval: the interval to forward
+ *
+ * Forward the timer expiry so it will expire in the future.
+ * Returns the number of overruns.
+ *
+ * Can be safely called from the callback function of @timer. If
+ * called from other contexts @timer must neither be enqueued nor
+ * running the callback and the caller needs to take care of
+ * serialization.
+ *
+ * Note: This only updates the timer expiry value and does not requeue
+ * the timer.
+ */
+u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
+{
+ u64 orun = 1;
+ ktime_t delta;
+
+ delta = ktime_sub(now, hrtimer_get_expires(timer));
+
+ if (delta < 0)
+ return 0;
+
+ if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
+ return 0;
+
+ if (interval < hrtimer_resolution)
+ interval = hrtimer_resolution;
+
+ if (unlikely(delta >= interval)) {
+ s64 incr = ktime_to_ns(interval);
+
+ orun = ktime_divns(delta, incr);
+ hrtimer_add_expires_ns(timer, incr * orun);
+ if (hrtimer_get_expires_tv64(timer) > now)
+ return orun;
+ /*
+ * This (and the ktime_add() below) is the
+ * correction for exact:
+ */
+ orun++;
+ }
+ hrtimer_add_expires(timer, interval);
+
+ return orun;
+}
+EXPORT_SYMBOL_GPL(hrtimer_forward);
+
+/*
+ * enqueue_hrtimer - internal function to (re)start a timer
+ *
+ * The timer is inserted in expiry order. Insertion into the
+ * red black tree is O(log(n)). Must hold the base lock.
+ *
+ * Returns 1 when the new timer is the leftmost timer in the tree.
+ */
+static int enqueue_hrtimer(struct hrtimer *timer,
+ struct hrtimer_clock_base *base,
+ enum hrtimer_mode mode)
+{
+ debug_activate(timer, mode);
+
+ base->cpu_base->active_bases |= 1 << base->index;
+
+ /* Pairs with the lockless read in hrtimer_is_queued() */
+ WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
+
+ return timerqueue_add(&base->active, &timer->node);
+}
+
+/*
+ * __remove_hrtimer - internal function to remove a timer
+ *
+ * Caller must hold the base lock.
+ *
+ * High resolution timer mode reprograms the clock event device when the
+ * timer is the one which expires next. The caller can disable this by setting
+ * reprogram to zero. This is useful, when the context does a reprogramming
+ * anyway (e.g. timer interrupt)
+ */
+static void __remove_hrtimer(struct hrtimer *timer,
+ struct hrtimer_clock_base *base,
+ u8 newstate, int reprogram)
+{
+ struct hrtimer_cpu_base *cpu_base = base->cpu_base;
+ u8 state = timer->state;
+
+ /* Pairs with the lockless read in hrtimer_is_queued() */
+ WRITE_ONCE(timer->state, newstate);
+ if (!(state & HRTIMER_STATE_ENQUEUED))
+ return;
+
+ if (!timerqueue_del(&base->active, &timer->node))
+ cpu_base->active_bases &= ~(1 << base->index);
+
+ /*
+ * Note: If reprogram is false we do not update
+ * cpu_base->next_timer. This happens when we remove the first
+ * timer on a remote cpu. No harm as we never dereference
+ * cpu_base->next_timer. So the worst thing what can happen is
+ * an superfluous call to hrtimer_force_reprogram() on the
+ * remote cpu later on if the same timer gets enqueued again.
+ */
+ if (reprogram && timer == cpu_base->next_timer)
+ hrtimer_force_reprogram(cpu_base, 1);
+}
+
+/*
+ * remove hrtimer, called with base lock held
+ */
+static inline int
+remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base,
+ bool restart, bool keep_local)
+{
+ u8 state = timer->state;
+
+ if (state & HRTIMER_STATE_ENQUEUED) {
+ bool reprogram;
+
+ /*
+ * Remove the timer and force reprogramming when high
+ * resolution mode is active and the timer is on the current
+ * CPU. If we remove a timer on another CPU, reprogramming is
+ * skipped. The interrupt event on this CPU is fired and
+ * reprogramming happens in the interrupt handler. This is a
+ * rare case and less expensive than a smp call.
+ */
+ debug_deactivate(timer);
+ reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
+
+ /*
+ * If the timer is not restarted then reprogramming is
+ * required if the timer is local. If it is local and about
+ * to be restarted, avoid programming it twice (on removal
+ * and a moment later when it's requeued).
+ */
+ if (!restart)
+ state = HRTIMER_STATE_INACTIVE;
+ else
+ reprogram &= !keep_local;
+
+ __remove_hrtimer(timer, base, state, reprogram);
+ return 1;
+ }
+ return 0;
+}
+
+static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
+ const enum hrtimer_mode mode)
+{
+#ifdef CONFIG_TIME_LOW_RES
+ /*
+ * CONFIG_TIME_LOW_RES indicates that the system has no way to return
+ * granular time values. For relative timers we add hrtimer_resolution
+ * (i.e. one jiffie) to prevent short timeouts.
+ */
+ timer->is_rel = mode & HRTIMER_MODE_REL;
+ if (timer->is_rel)
+ tim = ktime_add_safe(tim, hrtimer_resolution);
+#endif
+ return tim;
+}
+
+static void
+hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
+{
+ ktime_t expires;
+
+ /*
+ * Find the next SOFT expiration.
+ */
+ expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
+
+ /*
+ * reprogramming needs to be triggered, even if the next soft
+ * hrtimer expires at the same time than the next hard
+ * hrtimer. cpu_base->softirq_expires_next needs to be updated!
+ */
+ if (expires == KTIME_MAX)
+ return;
+
+ /*
+ * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
+ * cpu_base->*expires_next is only set by hrtimer_reprogram()
+ */
+ hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
+}
+
+static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
+ u64 delta_ns, const enum hrtimer_mode mode,
+ struct hrtimer_clock_base *base)
+{
+ struct hrtimer_clock_base *new_base;
+ bool force_local, first;
+
+ /*
+ * If the timer is on the local cpu base and is the first expiring
+ * timer then this might end up reprogramming the hardware twice
+ * (on removal and on enqueue). To avoid that by prevent the
+ * reprogram on removal, keep the timer local to the current CPU
+ * and enforce reprogramming after it is queued no matter whether
+ * it is the new first expiring timer again or not.
+ */
+ force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
+ force_local &= base->cpu_base->next_timer == timer;
+
+ /*
+ * Remove an active timer from the queue. In case it is not queued
+ * on the current CPU, make sure that remove_hrtimer() updates the
+ * remote data correctly.
+ *
+ * If it's on the current CPU and the first expiring timer, then
+ * skip reprogramming, keep the timer local and enforce
+ * reprogramming later if it was the first expiring timer. This
+ * avoids programming the underlying clock event twice (once at
+ * removal and once after enqueue).
+ */
+ remove_hrtimer(timer, base, true, force_local);
+
+ if (mode & HRTIMER_MODE_REL)
+ tim = ktime_add_safe(tim, base->get_time());
+
+ tim = hrtimer_update_lowres(timer, tim, mode);
+
+ hrtimer_set_expires_range_ns(timer, tim, delta_ns);
+
+ /* Switch the timer base, if necessary: */
+ if (!force_local) {
+ new_base = switch_hrtimer_base(timer, base,
+ mode & HRTIMER_MODE_PINNED);
+ } else {
+ new_base = base;
+ }
+
+ first = enqueue_hrtimer(timer, new_base, mode);
+ if (!force_local)
+ return first;
+
+ /*
+ * Timer was forced to stay on the current CPU to avoid
+ * reprogramming on removal and enqueue. Force reprogram the
+ * hardware by evaluating the new first expiring timer.
+ */
+ hrtimer_force_reprogram(new_base->cpu_base, 1);
+ return 0;
+}
+
+/**
+ * hrtimer_start_range_ns - (re)start an hrtimer
+ * @timer: the timer to be added
+ * @tim: expiry time
+ * @delta_ns: "slack" range for the timer
+ * @mode: timer mode: absolute (HRTIMER_MODE_ABS) or
+ * relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
+ * softirq based mode is considered for debug purpose only!
+ */
+void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
+ u64 delta_ns, const enum hrtimer_mode mode)
+{
+ struct hrtimer_clock_base *base;
+ unsigned long flags;
+
+ /*
+ * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
+ * match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard
+ * expiry mode because unmarked timers are moved to softirq expiry.
+ */
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+ WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
+ else
+ WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard);
+
+ base = lock_hrtimer_base(timer, &flags);
+
+ if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
+ hrtimer_reprogram(timer, true);
+
+ unlock_hrtimer_base(timer, &flags);
+}
+EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
+
+/**
+ * hrtimer_try_to_cancel - try to deactivate a timer
+ * @timer: hrtimer to stop
+ *
+ * Returns:
+ *
+ * * 0 when the timer was not active
+ * * 1 when the timer was active
+ * * -1 when the timer is currently executing the callback function and
+ * cannot be stopped
+ */
+int hrtimer_try_to_cancel(struct hrtimer *timer)
+{
+ struct hrtimer_clock_base *base;
+ unsigned long flags;
+ int ret = -1;
+
+ /*
+ * Check lockless first. If the timer is not active (neither
+ * enqueued nor running the callback, nothing to do here. The
+ * base lock does not serialize against a concurrent enqueue,
+ * so we can avoid taking it.
+ */
+ if (!hrtimer_active(timer))
+ return 0;
+
+ base = lock_hrtimer_base(timer, &flags);
+
+ if (!hrtimer_callback_running(timer))
+ ret = remove_hrtimer(timer, base, false, false);
+
+ unlock_hrtimer_base(timer, &flags);
+
+ return ret;
+
+}
+EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
+
+#ifdef CONFIG_PREEMPT_RT
+static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
+{
+ spin_lock_init(&base->softirq_expiry_lock);
+}
+
+static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
+{
+ spin_lock(&base->softirq_expiry_lock);
+}
+
+static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
+{
+ spin_unlock(&base->softirq_expiry_lock);
+}
+
+/*
+ * The counterpart to hrtimer_cancel_wait_running().
+ *
+ * If there is a waiter for cpu_base->expiry_lock, then it was waiting for
+ * the timer callback to finish. Drop expiry_lock and reacquire it. That
+ * allows the waiter to acquire the lock and make progress.
+ */
+static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
+ unsigned long flags)
+{
+ if (atomic_read(&cpu_base->timer_waiters)) {
+ raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+ spin_unlock(&cpu_base->softirq_expiry_lock);
+ spin_lock(&cpu_base->softirq_expiry_lock);
+ raw_spin_lock_irq(&cpu_base->lock);
+ }
+}
+
+/*
+ * This function is called on PREEMPT_RT kernels when the fast path
+ * deletion of a timer failed because the timer callback function was
+ * running.
+ *
+ * This prevents priority inversion: if the soft irq thread is preempted
+ * in the middle of a timer callback, then calling del_timer_sync() can
+ * lead to two issues:
+ *
+ * - If the caller is on a remote CPU then it has to spin wait for the timer
+ * handler to complete. This can result in unbound priority inversion.
+ *
+ * - If the caller originates from the task which preempted the timer
+ * handler on the same CPU, then spin waiting for the timer handler to
+ * complete is never going to end.
+ */
+void hrtimer_cancel_wait_running(const struct hrtimer *timer)
+{
+ /* Lockless read. Prevent the compiler from reloading it below */
+ struct hrtimer_clock_base *base = READ_ONCE(timer->base);
+
+ /*
+ * Just relax if the timer expires in hard interrupt context or if
+ * it is currently on the migration base.
+ */
+ if (!timer->is_soft || is_migration_base(base)) {
+ cpu_relax();
+ return;
+ }
+
+ /*
+ * Mark the base as contended and grab the expiry lock, which is
+ * held by the softirq across the timer callback. Drop the lock
+ * immediately so the softirq can expire the next timer. In theory
+ * the timer could already be running again, but that's more than
+ * unlikely and just causes another wait loop.
+ */
+ atomic_inc(&base->cpu_base->timer_waiters);
+ spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
+ atomic_dec(&base->cpu_base->timer_waiters);
+ spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
+}
+#else
+static inline void
+hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
+static inline void
+hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
+static inline void
+hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
+static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
+ unsigned long flags) { }
+#endif
+
+/**
+ * hrtimer_cancel - cancel a timer and wait for the handler to finish.
+ * @timer: the timer to be cancelled
+ *
+ * Returns:
+ * 0 when the timer was not active
+ * 1 when the timer was active
+ */
+int hrtimer_cancel(struct hrtimer *timer)
+{
+ int ret;
+
+ do {
+ ret = hrtimer_try_to_cancel(timer);
+
+ if (ret < 0)
+ hrtimer_cancel_wait_running(timer);
+ } while (ret < 0);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(hrtimer_cancel);
+
+/**
+ * __hrtimer_get_remaining - get remaining time for the timer
+ * @timer: the timer to read
+ * @adjust: adjust relative timers when CONFIG_TIME_LOW_RES=y
+ */
+ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
+{
+ unsigned long flags;
+ ktime_t rem;
+
+ lock_hrtimer_base(timer, &flags);
+ if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
+ rem = hrtimer_expires_remaining_adjusted(timer);
+ else
+ rem = hrtimer_expires_remaining(timer);
+ unlock_hrtimer_base(timer, &flags);
+
+ return rem;
+}
+EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
+
+#ifdef CONFIG_NO_HZ_COMMON
+/**
+ * hrtimer_get_next_event - get the time until next expiry event
+ *
+ * Returns the next expiry time or KTIME_MAX if no timer is pending.
+ */
+u64 hrtimer_get_next_event(void)
+{
+ struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+ u64 expires = KTIME_MAX;
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&cpu_base->lock, flags);
+
+ if (!__hrtimer_hres_active(cpu_base))
+ expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
+
+ raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+
+ return expires;
+}
+
+/**
+ * hrtimer_next_event_without - time until next expiry event w/o one timer
+ * @exclude: timer to exclude
+ *
+ * Returns the next expiry time over all timers except for the @exclude one or
+ * KTIME_MAX if none of them is pending.
+ */
+u64 hrtimer_next_event_without(const struct hrtimer *exclude)
+{
+ struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+ u64 expires = KTIME_MAX;
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&cpu_base->lock, flags);
+
+ if (__hrtimer_hres_active(cpu_base)) {
+ unsigned int active;
+
+ if (!cpu_base->softirq_activated) {
+ active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
+ expires = __hrtimer_next_event_base(cpu_base, exclude,
+ active, KTIME_MAX);
+ }
+ active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
+ expires = __hrtimer_next_event_base(cpu_base, exclude, active,
+ expires);
+ }
+
+ raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+
+ return expires;
+}
+#endif
+
+static inline int hrtimer_clockid_to_base(clockid_t clock_id)
+{
+ if (likely(clock_id < MAX_CLOCKS)) {
+ int base = hrtimer_clock_to_base_table[clock_id];
+
+ if (likely(base != HRTIMER_MAX_CLOCK_BASES))
+ return base;
+ }
+ WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
+ return HRTIMER_BASE_MONOTONIC;
+}
+
+static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
+ enum hrtimer_mode mode)
+{
+ bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
+ struct hrtimer_cpu_base *cpu_base;
+ int base;
+
+ /*
+ * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
+ * marked for hard interrupt expiry mode are moved into soft
+ * interrupt context for latency reasons and because the callbacks
+ * can invoke functions which might sleep on RT, e.g. spin_lock().
+ */
+ if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
+ softtimer = true;
+
+ memset(timer, 0, sizeof(struct hrtimer));
+
+ cpu_base = raw_cpu_ptr(&hrtimer_bases);
+
+ /*
+ * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
+ * clock modifications, so they needs to become CLOCK_MONOTONIC to
+ * ensure POSIX compliance.
+ */
+ if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
+ clock_id = CLOCK_MONOTONIC;
+
+ base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
+ base += hrtimer_clockid_to_base(clock_id);
+ timer->is_soft = softtimer;
+ timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
+ timer->base = &cpu_base->clock_base[base];
+ timerqueue_init(&timer->node);
+}
+
+/**
+ * hrtimer_init - initialize a timer to the given clock
+ * @timer: the timer to be initialized
+ * @clock_id: the clock to be used
+ * @mode: The modes which are relevant for initialization:
+ * HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
+ * HRTIMER_MODE_REL_SOFT
+ *
+ * The PINNED variants of the above can be handed in,
+ * but the PINNED bit is ignored as pinning happens
+ * when the hrtimer is started
+ */
+void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
+ enum hrtimer_mode mode)
+{
+ debug_init(timer, clock_id, mode);
+ __hrtimer_init(timer, clock_id, mode);
+}
+EXPORT_SYMBOL_GPL(hrtimer_init);
+
+/*
+ * A timer is active, when it is enqueued into the rbtree or the
+ * callback function is running or it's in the state of being migrated
+ * to another cpu.
+ *
+ * It is important for this function to not return a false negative.
+ */
+bool hrtimer_active(const struct hrtimer *timer)
+{
+ struct hrtimer_clock_base *base;
+ unsigned int seq;
+
+ do {
+ base = READ_ONCE(timer->base);
+ seq = raw_read_seqcount_begin(&base->seq);
+
+ if (timer->state != HRTIMER_STATE_INACTIVE ||
+ base->running == timer)
+ return true;
+
+ } while (read_seqcount_retry(&base->seq, seq) ||
+ base != READ_ONCE(timer->base));
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(hrtimer_active);
+
+/*
+ * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
+ * distinct sections:
+ *
+ * - queued: the timer is queued
+ * - callback: the timer is being ran
+ * - post: the timer is inactive or (re)queued
+ *
+ * On the read side we ensure we observe timer->state and cpu_base->running
+ * from the same section, if anything changed while we looked at it, we retry.
+ * This includes timer->base changing because sequence numbers alone are
+ * insufficient for that.
+ *
+ * The sequence numbers are required because otherwise we could still observe
+ * a false negative if the read side got smeared over multiple consecutive
+ * __run_hrtimer() invocations.
+ */
+
+static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
+ struct hrtimer_clock_base *base,
+ struct hrtimer *timer, ktime_t *now,
+ unsigned long flags) __must_hold(&cpu_base->lock)
+{
+ enum hrtimer_restart (*fn)(struct hrtimer *);
+ bool expires_in_hardirq;
+ int restart;
+
+ lockdep_assert_held(&cpu_base->lock);
+
+ debug_deactivate(timer);
+ base->running = timer;
+
+ /*
+ * Separate the ->running assignment from the ->state assignment.
+ *
+ * As with a regular write barrier, this ensures the read side in
+ * hrtimer_active() cannot observe base->running == NULL &&
+ * timer->state == INACTIVE.
+ */
+ raw_write_seqcount_barrier(&base->seq);
+
+ __remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
+ fn = timer->function;
+
+ /*
+ * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
+ * timer is restarted with a period then it becomes an absolute
+ * timer. If its not restarted it does not matter.
+ */
+ if (IS_ENABLED(CONFIG_TIME_LOW_RES))
+ timer->is_rel = false;
+
+ /*
+ * The timer is marked as running in the CPU base, so it is
+ * protected against migration to a different CPU even if the lock
+ * is dropped.
+ */
+ raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+ trace_hrtimer_expire_entry(timer, now);
+ expires_in_hardirq = lockdep_hrtimer_enter(timer);
+
+ restart = fn(timer);
+
+ lockdep_hrtimer_exit(expires_in_hardirq);
+ trace_hrtimer_expire_exit(timer);
+ raw_spin_lock_irq(&cpu_base->lock);
+
+ /*
+ * Note: We clear the running state after enqueue_hrtimer and
+ * we do not reprogram the event hardware. Happens either in
+ * hrtimer_start_range_ns() or in hrtimer_interrupt()
+ *
+ * Note: Because we dropped the cpu_base->lock above,
+ * hrtimer_start_range_ns() can have popped in and enqueued the timer
+ * for us already.
+ */
+ if (restart != HRTIMER_NORESTART &&
+ !(timer->state & HRTIMER_STATE_ENQUEUED))
+ enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
+
+ /*
+ * Separate the ->running assignment from the ->state assignment.
+ *
+ * As with a regular write barrier, this ensures the read side in
+ * hrtimer_active() cannot observe base->running.timer == NULL &&
+ * timer->state == INACTIVE.
+ */
+ raw_write_seqcount_barrier(&base->seq);
+
+ WARN_ON_ONCE(base->running != timer);
+ base->running = NULL;
+}
+
+static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
+ unsigned long flags, unsigned int active_mask)
+{
+ struct hrtimer_clock_base *base;
+ unsigned int active = cpu_base->active_bases & active_mask;
+
+ for_each_active_base(base, cpu_base, active) {
+ struct timerqueue_node *node;
+ ktime_t basenow;
+
+ basenow = ktime_add(now, base->offset);
+
+ while ((node = timerqueue_getnext(&base->active))) {
+ struct hrtimer *timer;
+
+ timer = container_of(node, struct hrtimer, node);
+
+ /*
+ * The immediate goal for using the softexpires is
+ * minimizing wakeups, not running timers at the
+ * earliest interrupt after their soft expiration.
+ * This allows us to avoid using a Priority Search
+ * Tree, which can answer a stabbing query for
+ * overlapping intervals and instead use the simple
+ * BST we already have.
+ * We don't add extra wakeups by delaying timers that
+ * are right-of a not yet expired timer, because that
+ * timer will have to trigger a wakeup anyway.
+ */
+ if (basenow < hrtimer_get_softexpires_tv64(timer))
+ break;
+
+ __run_hrtimer(cpu_base, base, timer, &basenow, flags);
+ if (active_mask == HRTIMER_ACTIVE_SOFT)
+ hrtimer_sync_wait_running(cpu_base, flags);
+ }
+ }
+}
+
+static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
+{
+ struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+ unsigned long flags;
+ ktime_t now;
+
+ hrtimer_cpu_base_lock_expiry(cpu_base);
+ raw_spin_lock_irqsave(&cpu_base->lock, flags);
+
+ now = hrtimer_update_base(cpu_base);
+ __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
+
+ cpu_base->softirq_activated = 0;
+ hrtimer_update_softirq_timer(cpu_base, true);
+
+ raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+ hrtimer_cpu_base_unlock_expiry(cpu_base);
+}
+
+#ifdef CONFIG_HIGH_RES_TIMERS
+
+/*
+ * High resolution timer interrupt
+ * Called with interrupts disabled
+ */
+void hrtimer_interrupt(struct clock_event_device *dev)
+{
+ struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+ ktime_t expires_next, now, entry_time, delta;
+ unsigned long flags;
+ int retries = 0;
+
+ BUG_ON(!cpu_base->hres_active);
+ cpu_base->nr_events++;
+ dev->next_event = KTIME_MAX;
+
+ raw_spin_lock_irqsave(&cpu_base->lock, flags);
+ entry_time = now = hrtimer_update_base(cpu_base);
+retry:
+ cpu_base->in_hrtirq = 1;
+ /*
+ * We set expires_next to KTIME_MAX here with cpu_base->lock
+ * held to prevent that a timer is enqueued in our queue via
+ * the migration code. This does not affect enqueueing of
+ * timers which run their callback and need to be requeued on
+ * this CPU.
+ */
+ cpu_base->expires_next = KTIME_MAX;
+
+ if (!ktime_before(now, cpu_base->softirq_expires_next)) {
+ cpu_base->softirq_expires_next = KTIME_MAX;
+ cpu_base->softirq_activated = 1;
+ raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+ }
+
+ __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
+
+ /* Reevaluate the clock bases for the [soft] next expiry */
+ expires_next = hrtimer_update_next_event(cpu_base);
+ /*
+ * Store the new expiry value so the migration code can verify
+ * against it.
+ */
+ cpu_base->expires_next = expires_next;
+ cpu_base->in_hrtirq = 0;
+ raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+
+ /* Reprogramming necessary ? */
+ if (!tick_program_event(expires_next, 0)) {
+ cpu_base->hang_detected = 0;
+ return;
+ }
+
+ /*
+ * The next timer was already expired due to:
+ * - tracing
+ * - long lasting callbacks
+ * - being scheduled away when running in a VM
+ *
+ * We need to prevent that we loop forever in the hrtimer
+ * interrupt routine. We give it 3 attempts to avoid
+ * overreacting on some spurious event.
+ *
+ * Acquire base lock for updating the offsets and retrieving
+ * the current time.
+ */
+ raw_spin_lock_irqsave(&cpu_base->lock, flags);
+ now = hrtimer_update_base(cpu_base);
+ cpu_base->nr_retries++;
+ if (++retries < 3)
+ goto retry;
+ /*
+ * Give the system a chance to do something else than looping
+ * here. We stored the entry time, so we know exactly how long
+ * we spent here. We schedule the next event this amount of
+ * time away.
+ */
+ cpu_base->nr_hangs++;
+ cpu_base->hang_detected = 1;
+ raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+
+ delta = ktime_sub(now, entry_time);
+ if ((unsigned int)delta > cpu_base->max_hang_time)
+ cpu_base->max_hang_time = (unsigned int) delta;
+ /*
+ * Limit it to a sensible value as we enforce a longer
+ * delay. Give the CPU at least 100ms to catch up.
+ */
+ if (delta > 100 * NSEC_PER_MSEC)
+ expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
+ else
+ expires_next = ktime_add(now, delta);
+ tick_program_event(expires_next, 1);
+ pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta));
+}
+
+/* called with interrupts disabled */
+static inline void __hrtimer_peek_ahead_timers(void)
+{
+ struct tick_device *td;
+
+ if (!hrtimer_hres_active())
+ return;
+
+ td = this_cpu_ptr(&tick_cpu_device);
+ if (td && td->evtdev)
+ hrtimer_interrupt(td->evtdev);
+}
+
+#else /* CONFIG_HIGH_RES_TIMERS */
+
+static inline void __hrtimer_peek_ahead_timers(void) { }
+
+#endif /* !CONFIG_HIGH_RES_TIMERS */
+
+/*
+ * Called from run_local_timers in hardirq context every jiffy
+ */
+void hrtimer_run_queues(void)
+{
+ struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+ unsigned long flags;
+ ktime_t now;
+
+ if (__hrtimer_hres_active(cpu_base))
+ return;
+
+ /*
+ * This _is_ ugly: We have to check periodically, whether we
+ * can switch to highres and / or nohz mode. The clocksource
+ * switch happens with xtime_lock held. Notification from
+ * there only sets the check bit in the tick_oneshot code,
+ * otherwise we might deadlock vs. xtime_lock.
+ */
+ if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
+ hrtimer_switch_to_hres();
+ return;
+ }
+
+ raw_spin_lock_irqsave(&cpu_base->lock, flags);
+ now = hrtimer_update_base(cpu_base);
+
+ if (!ktime_before(now, cpu_base->softirq_expires_next)) {
+ cpu_base->softirq_expires_next = KTIME_MAX;
+ cpu_base->softirq_activated = 1;
+ raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+ }
+
+ __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
+ raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+}
+
+/*
+ * Sleep related functions:
+ */
+static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
+{
+ struct hrtimer_sleeper *t =
+ container_of(timer, struct hrtimer_sleeper, timer);
+ struct task_struct *task = t->task;
+
+ t->task = NULL;
+ if (task)
+ wake_up_process(task);
+
+ return HRTIMER_NORESTART;
+}
+
+/**
+ * hrtimer_sleeper_start_expires - Start a hrtimer sleeper timer
+ * @sl: sleeper to be started
+ * @mode: timer mode abs/rel
+ *
+ * Wrapper around hrtimer_start_expires() for hrtimer_sleeper based timers
+ * to allow PREEMPT_RT to tweak the delivery mode (soft/hardirq context)
+ */
+void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
+ enum hrtimer_mode mode)
+{
+ /*
+ * Make the enqueue delivery mode check work on RT. If the sleeper
+ * was initialized for hard interrupt delivery, force the mode bit.
+ * This is a special case for hrtimer_sleepers because
+ * hrtimer_init_sleeper() determines the delivery mode on RT so the
+ * fiddling with this decision is avoided at the call sites.
+ */
+ if (IS_ENABLED(CONFIG_PREEMPT_RT) && sl->timer.is_hard)
+ mode |= HRTIMER_MODE_HARD;
+
+ hrtimer_start_expires(&sl->timer, mode);
+}
+EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
+
+static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
+ clockid_t clock_id, enum hrtimer_mode mode)
+{
+ /*
+ * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
+ * marked for hard interrupt expiry mode are moved into soft
+ * interrupt context either for latency reasons or because the
+ * hrtimer callback takes regular spinlocks or invokes other
+ * functions which are not suitable for hard interrupt context on
+ * PREEMPT_RT.
+ *
+ * The hrtimer_sleeper callback is RT compatible in hard interrupt
+ * context, but there is a latency concern: Untrusted userspace can
+ * spawn many threads which arm timers for the same expiry time on
+ * the same CPU. That causes a latency spike due to the wakeup of
+ * a gazillion threads.
+ *
+ * OTOH, privileged real-time user space applications rely on the
+ * low latency of hard interrupt wakeups. If the current task is in
+ * a real-time scheduling class, mark the mode for hard interrupt
+ * expiry.
+ */
+ if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
+ if (task_is_realtime(current) && !(mode & HRTIMER_MODE_SOFT))
+ mode |= HRTIMER_MODE_HARD;
+ }
+
+ __hrtimer_init(&sl->timer, clock_id, mode);
+ sl->timer.function = hrtimer_wakeup;
+ sl->task = current;
+}
+
+/**
+ * hrtimer_init_sleeper - initialize sleeper to the given clock
+ * @sl: sleeper to be initialized
+ * @clock_id: the clock to be used
+ * @mode: timer mode abs/rel
+ */
+void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
+ enum hrtimer_mode mode)
+{
+ debug_init(&sl->timer, clock_id, mode);
+ __hrtimer_init_sleeper(sl, clock_id, mode);
+
+}
+EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
+
+int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
+{
+ switch(restart->nanosleep.type) {
+#ifdef CONFIG_COMPAT_32BIT_TIME
+ case TT_COMPAT:
+ if (put_old_timespec32(ts, restart->nanosleep.compat_rmtp))
+ return -EFAULT;
+ break;
+#endif
+ case TT_NATIVE:
+ if (put_timespec64(ts, restart->nanosleep.rmtp))
+ return -EFAULT;
+ break;
+ default:
+ BUG();
+ }
+ return -ERESTART_RESTARTBLOCK;
+}
+
+static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
+{
+ struct restart_block *restart;
+
+ do {
+ set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
+ hrtimer_sleeper_start_expires(t, mode);
+
+ if (likely(t->task))
+ schedule();
+
+ hrtimer_cancel(&t->timer);
+ mode = HRTIMER_MODE_ABS;
+
+ } while (t->task && !signal_pending(current));
+
+ __set_current_state(TASK_RUNNING);
+
+ if (!t->task)
+ return 0;
+
+ restart = &current->restart_block;
+ if (restart->nanosleep.type != TT_NONE) {
+ ktime_t rem = hrtimer_expires_remaining(&t->timer);
+ struct timespec64 rmt;
+
+ if (rem <= 0)
+ return 0;
+ rmt = ktime_to_timespec64(rem);
+
+ return nanosleep_copyout(restart, &rmt);
+ }
+ return -ERESTART_RESTARTBLOCK;
+}
+
+static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
+{
+ struct hrtimer_sleeper t;
+ int ret;
+
+ hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid,
+ HRTIMER_MODE_ABS);
+ hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
+ ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
+ destroy_hrtimer_on_stack(&t.timer);
+ return ret;
+}
+
+long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
+ const clockid_t clockid)
+{
+ struct restart_block *restart;
+ struct hrtimer_sleeper t;
+ int ret = 0;
+ u64 slack;
+
+ slack = current->timer_slack_ns;
+ if (rt_task(current))
+ slack = 0;
+
+ hrtimer_init_sleeper_on_stack(&t, clockid, mode);
+ hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
+ ret = do_nanosleep(&t, mode);
+ if (ret != -ERESTART_RESTARTBLOCK)
+ goto out;
+
+ /* Absolute timers do not update the rmtp value and restart: */
+ if (mode == HRTIMER_MODE_ABS) {
+ ret = -ERESTARTNOHAND;
+ goto out;
+ }
+
+ restart = &current->restart_block;
+ restart->nanosleep.clockid = t.timer.base->clockid;
+ restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
+ set_restart_fn(restart, hrtimer_nanosleep_restart);
+out:
+ destroy_hrtimer_on_stack(&t.timer);
+ return ret;
+}
+
+#ifdef CONFIG_64BIT
+
+SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
+ struct __kernel_timespec __user *, rmtp)
+{
+ struct timespec64 tu;
+
+ if (get_timespec64(&tu, rqtp))
+ return -EFAULT;
+
+ if (!timespec64_valid(&tu))
+ return -EINVAL;
+
+ current->restart_block.fn = do_no_restart_syscall;
+ current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
+ current->restart_block.nanosleep.rmtp = rmtp;
+ return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
+ CLOCK_MONOTONIC);
+}
+
+#endif
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
+
+SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
+ struct old_timespec32 __user *, rmtp)
+{
+ struct timespec64 tu;
+
+ if (get_old_timespec32(&tu, rqtp))
+ return -EFAULT;
+
+ if (!timespec64_valid(&tu))
+ return -EINVAL;
+
+ current->restart_block.fn = do_no_restart_syscall;
+ current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
+ current->restart_block.nanosleep.compat_rmtp = rmtp;
+ return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
+ CLOCK_MONOTONIC);
+}
+#endif
+
+/*
+ * Functions related to boot-time initialization:
+ */
+int hrtimers_prepare_cpu(unsigned int cpu)
+{
+ struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
+ int i;
+
+ for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
+ struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i];
+
+ clock_b->cpu_base = cpu_base;
+ seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock);
+ timerqueue_init_head(&clock_b->active);
+ }
+
+ cpu_base->cpu = cpu;
+ cpu_base->active_bases = 0;
+ cpu_base->hres_active = 0;
+ cpu_base->hang_detected = 0;
+ cpu_base->next_timer = NULL;
+ cpu_base->softirq_next_timer = NULL;
+ cpu_base->expires_next = KTIME_MAX;
+ cpu_base->softirq_expires_next = KTIME_MAX;
+ hrtimer_cpu_base_init_expiry_lock(cpu_base);
+ return 0;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
+ struct hrtimer_clock_base *new_base)
+{
+ struct hrtimer *timer;
+ struct timerqueue_node *node;
+
+ while ((node = timerqueue_getnext(&old_base->active))) {
+ timer = container_of(node, struct hrtimer, node);
+ BUG_ON(hrtimer_callback_running(timer));
+ debug_deactivate(timer);
+
+ /*
+ * Mark it as ENQUEUED not INACTIVE otherwise the
+ * timer could be seen as !active and just vanish away
+ * under us on another CPU
+ */
+ __remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
+ timer->base = new_base;
+ /*
+ * Enqueue the timers on the new cpu. This does not
+ * reprogram the event device in case the timer
+ * expires before the earliest on this CPU, but we run
+ * hrtimer_interrupt after we migrated everything to
+ * sort out already expired timers and reprogram the
+ * event device.
+ */
+ enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
+ }
+}
+
+int hrtimers_cpu_dying(unsigned int dying_cpu)
+{
+ struct hrtimer_cpu_base *old_base, *new_base;
+ int i, ncpu = cpumask_first(cpu_active_mask);
+
+ tick_cancel_sched_timer(dying_cpu);
+
+ old_base = this_cpu_ptr(&hrtimer_bases);
+ new_base = &per_cpu(hrtimer_bases, ncpu);
+
+ /*
+ * The caller is globally serialized and nobody else
+ * takes two locks at once, deadlock is not possible.
+ */
+ raw_spin_lock(&old_base->lock);
+ raw_spin_lock_nested(&new_base->lock, SINGLE_DEPTH_NESTING);
+
+ for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
+ migrate_hrtimer_list(&old_base->clock_base[i],
+ &new_base->clock_base[i]);
+ }
+
+ /*
+ * The migration might have changed the first expiring softirq
+ * timer on this CPU. Update it.
+ */
+ __hrtimer_get_next_event(new_base, HRTIMER_ACTIVE_SOFT);
+ /* Tell the other CPU to retrigger the next event */
+ smp_call_function_single(ncpu, retrigger_next_event, NULL, 0);
+
+ raw_spin_unlock(&new_base->lock);
+ raw_spin_unlock(&old_base->lock);
+
+ return 0;
+}
+
+#endif /* CONFIG_HOTPLUG_CPU */
+
+void __init hrtimers_init(void)
+{
+ hrtimers_prepare_cpu(smp_processor_id());
+ open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
+}
+
+/**
+ * schedule_hrtimeout_range_clock - sleep until timeout
+ * @expires: timeout value (ktime_t)
+ * @delta: slack in expires timeout (ktime_t) for SCHED_OTHER tasks
+ * @mode: timer mode
+ * @clock_id: timer clock to be used
+ */
+int __sched
+schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
+ const enum hrtimer_mode mode, clockid_t clock_id)
+{
+ struct hrtimer_sleeper t;
+
+ /*
+ * Optimize when a zero timeout value is given. It does not
+ * matter whether this is an absolute or a relative time.
+ */
+ if (expires && *expires == 0) {
+ __set_current_state(TASK_RUNNING);
+ return 0;
+ }
+
+ /*
+ * A NULL parameter means "infinite"
+ */
+ if (!expires) {
+ schedule();
+ return -EINTR;
+ }
+
+ /*
+ * Override any slack passed by the user if under
+ * rt contraints.
+ */
+ if (rt_task(current))
+ delta = 0;
+
+ hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
+ hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
+ hrtimer_sleeper_start_expires(&t, mode);
+
+ if (likely(t.task))
+ schedule();
+
+ hrtimer_cancel(&t.timer);
+ destroy_hrtimer_on_stack(&t.timer);
+
+ __set_current_state(TASK_RUNNING);
+
+ return !t.task ? 0 : -EINTR;
+}
+EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
+
+/**
+ * schedule_hrtimeout_range - sleep until timeout
+ * @expires: timeout value (ktime_t)
+ * @delta: slack in expires timeout (ktime_t) for SCHED_OTHER tasks
+ * @mode: timer mode
+ *
+ * Make the current task sleep until the given expiry time has
+ * elapsed. The routine will return immediately unless
+ * the current task state has been set (see set_current_state()).
+ *
+ * The @delta argument gives the kernel the freedom to schedule the
+ * actual wakeup to a time that is both power and performance friendly
+ * for regular (non RT/DL) tasks.
+ * The kernel give the normal best effort behavior for "@expires+@delta",
+ * but may decide to fire the timer earlier, but no earlier than @expires.
+ *
+ * You can set the task state as follows -
+ *
+ * %TASK_UNINTERRUPTIBLE - at least @timeout time is 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.
+ *
+ * Returns 0 when the timer has expired. If the task was woken before the
+ * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
+ * by an explicit wakeup, it returns -EINTR.
+ */
+int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
+ const enum hrtimer_mode mode)
+{
+ return schedule_hrtimeout_range_clock(expires, delta, mode,
+ CLOCK_MONOTONIC);
+}
+EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
+
+/**
+ * schedule_hrtimeout - sleep until timeout
+ * @expires: timeout value (ktime_t)
+ * @mode: timer mode
+ *
+ * Make the current task sleep until the given expiry time has
+ * elapsed. The routine will return immediately unless
+ * the current task state has been set (see set_current_state()).
+ *
+ * You can set the task state as follows -
+ *
+ * %TASK_UNINTERRUPTIBLE - at least @timeout time is 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.
+ *
+ * Returns 0 when the timer has expired. If the task was woken before the
+ * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
+ * by an explicit wakeup, it returns -EINTR.
+ */
+int __sched schedule_hrtimeout(ktime_t *expires,
+ const enum hrtimer_mode mode)
+{
+ return schedule_hrtimeout_range(expires, 0, mode);
+}
+EXPORT_SYMBOL_GPL(schedule_hrtimeout);