Adding debian version 4.19.249-2.debian/4.19.249-2debian

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 650 insertions, 0 deletions

diff --git a/debian/patches-rt/0271-timers-Redo-the-notification-of-canceling-timers-on-.patch b/debian/patches-rt/0271-timers-Redo-the-notification-of-canceling-timers-on-.patch
new file mode 100644
index 000000000..46b7ac22c
--- /dev/null
+++ b/debian/patches-rt/0271-timers-Redo-the-notification-of-canceling-timers-on-.patch
@@ -0,0 +1,650 @@
+From abca2e3959b31be6e2cbc9d1e8d6ddebf31df3ea Mon Sep 17 00:00:00 2001
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Mon, 24 Jun 2019 19:39:06 +0200
+Subject: [PATCH 271/347] timers: Redo the notification of canceling timers on
+ -RT
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz
+
+[ Upstream commit c71273154c2ad12e13333aada340ff30e826a11b ]
+
+Rework of the hrtimer, timer and posix-timer cancelation interface
+on -RT. Instead of the swait/schedule interface we now have locks
+which are taken while timer is active. During the cancellation of an
+active timer the lock is acquired. The lock will then either
+PI-boost the timer or block and wait until the timer completed.
+The new code looks simpler and does not trigger a warning from
+rcu_note_context_switch() anymore like reported by Grygorii Strashko
+and Daniel Wagner.
+The patches were contributed by Anna-Maria Gleixner.
+
+This is an all in one commit of the following patches:
+| [PATCH] timers: Introduce expiry spin lock
+| [PATCH] timers: Drop expiry lock after each timer invocation
+| [PATCH] hrtimer: Introduce expiry spin lock
+| [PATCH] posix-timers: move rcu out of union
+| [PATCH] posix-timers: Add expiry lock
+
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+---
+ fs/timerfd.c                   |  5 +-
+ include/linux/hrtimer.h        | 17 ++----
+ include/linux/posix-timers.h   |  1 +
+ kernel/time/alarmtimer.c       |  2 +-
+ kernel/time/hrtimer.c          | 36 ++++---------
+ kernel/time/itimer.c           |  2 +-
+ kernel/time/posix-cpu-timers.c | 23 ++++++++
+ kernel/time/posix-timers.c     | 69 ++++++++++--------------
+ kernel/time/posix-timers.h     |  2 +
+ kernel/time/timer.c            | 96 ++++++++++++++++------------------
+ 10 files changed, 118 insertions(+), 135 deletions(-)
+
+diff --git a/fs/timerfd.c b/fs/timerfd.c
+index 82d0f52414a6..f845093466be 100644
+--- a/fs/timerfd.c
++++ b/fs/timerfd.c
+@@ -471,10 +471,11 @@ static int do_timerfd_settime(int ufd, int flags,
+ 				break;
+ 		}
+ 		spin_unlock_irq(&ctx->wqh.lock);
++
+ 		if (isalarm(ctx))
+-			hrtimer_wait_for_timer(&ctx->t.alarm.timer);
++			hrtimer_grab_expiry_lock(&ctx->t.alarm.timer);
+ 		else
+-			hrtimer_wait_for_timer(&ctx->t.tmr);
++			hrtimer_grab_expiry_lock(&ctx->t.tmr);
+ 	}
+ 
+ 	/*
+diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
+index 082147c07831..aee31b1f0cc3 100644
+--- a/include/linux/hrtimer.h
++++ b/include/linux/hrtimer.h
+@@ -22,7 +22,6 @@
+ #include <linux/percpu.h>
+ #include <linux/timer.h>
+ #include <linux/timerqueue.h>
+-#include <linux/wait.h>
+ 
+ struct hrtimer_clock_base;
+ struct hrtimer_cpu_base;
+@@ -193,6 +192,8 @@ enum  hrtimer_base_type {
+  * @nr_retries:		Total number of hrtimer interrupt retries
+  * @nr_hangs:		Total number of hrtimer interrupt hangs
+  * @max_hang_time:	Maximum time spent in hrtimer_interrupt
++ * @softirq_expiry_lock: Lock which is taken while softirq based hrtimer are
++ *			 expired
+  * @expires_next:	absolute time of the next event, is required for remote
+  *			hrtimer enqueue; it is the total first expiry time (hard
+  *			and soft hrtimer are taken into account)
+@@ -220,12 +221,10 @@ struct hrtimer_cpu_base {
+ 	unsigned short			nr_hangs;
+ 	unsigned int			max_hang_time;
+ #endif
++	spinlock_t			softirq_expiry_lock;
+ 	ktime_t				expires_next;
+ 	struct hrtimer			*next_timer;
+ 	ktime_t				softirq_expires_next;
+-#ifdef CONFIG_PREEMPT_RT_BASE
+-	wait_queue_head_t		wait;
+-#endif
+ 	struct hrtimer			*softirq_next_timer;
+ 	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];
+ } ____cacheline_aligned;
+@@ -426,6 +425,7 @@ static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
+ 
+ extern int hrtimer_cancel(struct hrtimer *timer);
+ extern int hrtimer_try_to_cancel(struct hrtimer *timer);
++extern void hrtimer_grab_expiry_lock(const struct hrtimer *timer);
+ 
+ static inline void hrtimer_start_expires(struct hrtimer *timer,
+ 					 enum hrtimer_mode mode)
+@@ -443,13 +443,6 @@ static inline void hrtimer_restart(struct hrtimer *timer)
+ 	hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
+ }
+ 
+-/* Softirq preemption could deadlock timer removal */
+-#ifdef CONFIG_PREEMPT_RT_BASE
+-  extern void hrtimer_wait_for_timer(const struct hrtimer *timer);
+-#else
+-# define hrtimer_wait_for_timer(timer)	do { cpu_relax(); } while (0)
+-#endif
+-
+ /* Query timers: */
+ extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);
+ 
+@@ -481,7 +474,7 @@ static inline bool hrtimer_is_queued(struct hrtimer *timer)
+  * Helper function to check, whether the timer is running the callback
+  * function
+  */
+-static inline int hrtimer_callback_running(const struct hrtimer *timer)
++static inline int hrtimer_callback_running(struct hrtimer *timer)
+ {
+ 	return timer->base->running == timer;
+ }
+diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
+index 0571b498db73..3e6c91bdf2ef 100644
+--- a/include/linux/posix-timers.h
++++ b/include/linux/posix-timers.h
+@@ -15,6 +15,7 @@ struct cpu_timer_list {
+ 	u64 expires, incr;
+ 	struct task_struct *task;
+ 	int firing;
++	int firing_cpu;
+ };
+ 
+ /*
+diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
+index f4c8cfde00b0..e7b983df6996 100644
+--- a/kernel/time/alarmtimer.c
++++ b/kernel/time/alarmtimer.c
+@@ -438,7 +438,7 @@ int alarm_cancel(struct alarm *alarm)
+ 		int ret = alarm_try_to_cancel(alarm);
+ 		if (ret >= 0)
+ 			return ret;
+-		hrtimer_wait_for_timer(&alarm->timer);
++		hrtimer_grab_expiry_lock(&alarm->timer);
+ 	}
+ }
+ EXPORT_SYMBOL_GPL(alarm_cancel);
+diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
+index aa8f3177580a..bbc408f24f5d 100644
+--- a/kernel/time/hrtimer.c
++++ b/kernel/time/hrtimer.c
+@@ -981,33 +981,16 @@ u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
+ }
+ EXPORT_SYMBOL_GPL(hrtimer_forward);
+ 
+-#ifdef CONFIG_PREEMPT_RT_BASE
+-# define wake_up_timer_waiters(b)	wake_up(&(b)->wait)
+-
+-/**
+- * hrtimer_wait_for_timer - Wait for a running timer
+- *
+- * @timer:	timer to wait for
+- *
+- * The function waits in case the timers callback function is
+- * currently executed on the waitqueue of the timer base. The
+- * waitqueue is woken up after the timer callback function has
+- * finished execution.
+- */
+-void hrtimer_wait_for_timer(const struct hrtimer *timer)
++void hrtimer_grab_expiry_lock(const struct hrtimer *timer)
+ {
+ 	struct hrtimer_clock_base *base = timer->base;
+ 
+-	if (base && base->cpu_base &&
+-	    base->index >= HRTIMER_BASE_MONOTONIC_SOFT)
+-		wait_event(base->cpu_base->wait,
+-				!(hrtimer_callback_running(timer)));
++	if (base && base->cpu_base) {
++		spin_lock(&base->cpu_base->softirq_expiry_lock);
++		spin_unlock(&base->cpu_base->softirq_expiry_lock);
++	}
+ }
+ 
+-#else
+-# define wake_up_timer_waiters(b)	do { } while (0)
+-#endif
+-
+ /*
+  * enqueue_hrtimer - internal function to (re)start a timer
+  *
+@@ -1291,7 +1274,7 @@ int hrtimer_cancel(struct hrtimer *timer)
+ 
+ 		if (ret >= 0)
+ 			return ret;
+-		hrtimer_wait_for_timer(timer);
++		hrtimer_grab_expiry_lock(timer);
+ 	}
+ }
+ EXPORT_SYMBOL_GPL(hrtimer_cancel);
+@@ -1595,6 +1578,7 @@ static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
+ 	unsigned long flags;
+ 	ktime_t now;
+ 
++	spin_lock(&cpu_base->softirq_expiry_lock);
+ 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
+ 
+ 	now = hrtimer_update_base(cpu_base);
+@@ -1604,7 +1588,7 @@ static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
+ 	hrtimer_update_softirq_timer(cpu_base, true);
+ 
+ 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+-	wake_up_timer_waiters(cpu_base);
++	spin_unlock(&cpu_base->softirq_expiry_lock);
+ }
+ 
+ #ifdef CONFIG_HIGH_RES_TIMERS
+@@ -2014,9 +1998,7 @@ int hrtimers_prepare_cpu(unsigned int cpu)
+ 	cpu_base->softirq_next_timer = NULL;
+ 	cpu_base->expires_next = KTIME_MAX;
+ 	cpu_base->softirq_expires_next = KTIME_MAX;
+-#ifdef CONFIG_PREEMPT_RT_BASE
+-	init_waitqueue_head(&cpu_base->wait);
+-#endif
++	spin_lock_init(&cpu_base->softirq_expiry_lock);
+ 	return 0;
+ }
+ 
+diff --git a/kernel/time/itimer.c b/kernel/time/itimer.c
+index 7650ee736964..48d977f947d9 100644
+--- a/kernel/time/itimer.c
++++ b/kernel/time/itimer.c
+@@ -211,7 +211,7 @@ int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
+ 		/* We are sharing ->siglock with it_real_fn() */
+ 		if (hrtimer_try_to_cancel(timer) < 0) {
+ 			spin_unlock_irq(&tsk->sighand->siglock);
+-			hrtimer_wait_for_timer(&tsk->signal->real_timer);
++			hrtimer_grab_expiry_lock(timer);
+ 			goto again;
+ 		}
+ 		expires = timeval_to_ktime(value->it_value);
+diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
+index 2d29b269dc83..54632ed51c65 100644
+--- a/kernel/time/posix-cpu-timers.c
++++ b/kernel/time/posix-cpu-timers.c
+@@ -792,6 +792,7 @@ check_timers_list(struct list_head *timers,
+ 			return t->expires;
+ 
+ 		t->firing = 1;
++		t->firing_cpu = smp_processor_id();
+ 		list_move_tail(&t->entry, firing);
+ 	}
+ 
+@@ -1138,6 +1139,20 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
+ 	return 0;
+ }
+ 
++static DEFINE_PER_CPU(spinlock_t, cpu_timer_expiry_lock) = __SPIN_LOCK_UNLOCKED(cpu_timer_expiry_lock);
++
++void cpu_timers_grab_expiry_lock(struct k_itimer *timer)
++{
++	int cpu = timer->it.cpu.firing_cpu;
++
++	if (cpu >= 0) {
++		spinlock_t *expiry_lock = per_cpu_ptr(&cpu_timer_expiry_lock, cpu);
++
++		spin_lock_irq(expiry_lock);
++		spin_unlock_irq(expiry_lock);
++	}
++}
++
+ /*
+  * This is called from the timer interrupt handler.  The irq handler has
+  * already updated our counts.  We need to check if any timers fire now.
+@@ -1148,6 +1163,7 @@ static void __run_posix_cpu_timers(struct task_struct *tsk)
+ 	LIST_HEAD(firing);
+ 	struct k_itimer *timer, *next;
+ 	unsigned long flags;
++	spinlock_t *expiry_lock;
+ 
+ 	/*
+ 	 * The fast path checks that there are no expired thread or thread
+@@ -1156,6 +1172,9 @@ static void __run_posix_cpu_timers(struct task_struct *tsk)
+ 	if (!fastpath_timer_check(tsk))
+ 		return;
+ 
++	expiry_lock = this_cpu_ptr(&cpu_timer_expiry_lock);
++	spin_lock(expiry_lock);
++
+ 	if (!lock_task_sighand(tsk, &flags))
+ 		return;
+ 	/*
+@@ -1190,6 +1209,7 @@ static void __run_posix_cpu_timers(struct task_struct *tsk)
+ 		list_del_init(&timer->it.cpu.entry);
+ 		cpu_firing = timer->it.cpu.firing;
+ 		timer->it.cpu.firing = 0;
++		timer->it.cpu.firing_cpu = -1;
+ 		/*
+ 		 * The firing flag is -1 if we collided with a reset
+ 		 * of the timer, which already reported this
+@@ -1199,6 +1219,7 @@ static void __run_posix_cpu_timers(struct task_struct *tsk)
+ 			cpu_timer_fire(timer);
+ 		spin_unlock(&timer->it_lock);
+ 	}
++	spin_unlock(expiry_lock);
+ }
+ 
+ #ifdef CONFIG_PREEMPT_RT_BASE
+@@ -1466,6 +1487,8 @@ static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
+ 		spin_unlock_irq(&timer.it_lock);
+ 
+ 		while (error == TIMER_RETRY) {
++
++			cpu_timers_grab_expiry_lock(&timer);
+ 			/*
+ 			 * We need to handle case when timer was or is in the
+ 			 * middle of firing. In other cases we already freed
+diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
+index 2cf5aa704106..3fd433d2a767 100644
+--- a/kernel/time/posix-timers.c
++++ b/kernel/time/posix-timers.c
+@@ -821,25 +821,20 @@ static void common_hrtimer_arm(struct k_itimer *timr, ktime_t expires,
+ 		hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
+ }
+ 
+-/*
+- * Protected by RCU!
+- */
+-static void timer_wait_for_callback(const struct k_clock *kc, struct k_itimer *timr)
++static int common_hrtimer_try_to_cancel(struct k_itimer *timr)
+ {
+-#ifdef CONFIG_PREEMPT_RT_FULL
+-	if (kc->timer_arm == common_hrtimer_arm)
+-		hrtimer_wait_for_timer(&timr->it.real.timer);
+-	else if (kc == &alarm_clock)
+-		hrtimer_wait_for_timer(&timr->it.alarm.alarmtimer.timer);
+-	else
+-		/* FIXME: Whacky hack for posix-cpu-timers */
+-		schedule_timeout(1);
+-#endif
++	return hrtimer_try_to_cancel(&timr->it.real.timer);
+ }
+ 
+-static int common_hrtimer_try_to_cancel(struct k_itimer *timr)
++static void timer_wait_for_callback(const struct k_clock *kc, struct k_itimer *timer)
+ {
+-	return hrtimer_try_to_cancel(&timr->it.real.timer);
++	if (kc->timer_arm == common_hrtimer_arm)
++		hrtimer_grab_expiry_lock(&timer->it.real.timer);
++	else if (kc == &alarm_clock)
++		hrtimer_grab_expiry_lock(&timer->it.alarm.alarmtimer.timer);
++	else
++		/* posix-cpu-timers */
++		cpu_timers_grab_expiry_lock(timer);
+ }
+ 
+ /* Set a POSIX.1b interval timer. */
+@@ -901,21 +896,21 @@ static int do_timer_settime(timer_t timer_id, int flags,
+ 	if (!timr)
+ 		return -EINVAL;
+ 
+-	rcu_read_lock();
+ 	kc = timr->kclock;
+ 	if (WARN_ON_ONCE(!kc || !kc->timer_set))
+ 		error = -EINVAL;
+ 	else
+ 		error = kc->timer_set(timr, flags, new_spec64, old_spec64);
+ 
+-	unlock_timer(timr, flag);
+ 	if (error == TIMER_RETRY) {
++		rcu_read_lock();
++		unlock_timer(timr, flag);
+ 		timer_wait_for_callback(kc, timr);
+-		old_spec64 = NULL;	// We already got the old time...
+ 		rcu_read_unlock();
++		old_spec64 = NULL;	// We already got the old time...
+ 		goto retry;
+ 	}
+-	rcu_read_unlock();
++	unlock_timer(timr, flag);
+ 
+ 	return error;
+ }
+@@ -977,13 +972,21 @@ int common_timer_del(struct k_itimer *timer)
+ 	return 0;
+ }
+ 
+-static inline int timer_delete_hook(struct k_itimer *timer)
++static int timer_delete_hook(struct k_itimer *timer)
+ {
+ 	const struct k_clock *kc = timer->kclock;
++	int ret;
+ 
+ 	if (WARN_ON_ONCE(!kc || !kc->timer_del))
+ 		return -EINVAL;
+-	return kc->timer_del(timer);
++	ret = kc->timer_del(timer);
++	if (ret == TIMER_RETRY) {
++		rcu_read_lock();
++		spin_unlock_irq(&timer->it_lock);
++		timer_wait_for_callback(kc, timer);
++		rcu_read_unlock();
++	}
++	return ret;
+ }
+ 
+ /* Delete a POSIX.1b interval timer. */
+@@ -997,15 +1000,8 @@ SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
+ 	if (!timer)
+ 		return -EINVAL;
+ 
+-	rcu_read_lock();
+-	if (timer_delete_hook(timer) == TIMER_RETRY) {
+-		unlock_timer(timer, flags);
+-		timer_wait_for_callback(clockid_to_kclock(timer->it_clock),
+-					timer);
+-		rcu_read_unlock();
++	if (timer_delete_hook(timer) == TIMER_RETRY)
+ 		goto retry_delete;
+-	}
+-	rcu_read_unlock();
+ 
+ 	spin_lock(&current->sighand->siglock);
+ 	list_del(&timer->list);
+@@ -1031,20 +1027,9 @@ static void itimer_delete(struct k_itimer *timer)
+ retry_delete:
+ 	spin_lock_irqsave(&timer->it_lock, flags);
+ 
+-	/* On RT we can race with a deletion */
+-	if (!timer->it_signal) {
+-		unlock_timer(timer, flags);
+-		return;
+-	}
+-
+-	if (timer_delete_hook(timer) == TIMER_RETRY) {
+-		rcu_read_lock();
+-		unlock_timer(timer, flags);
+-		timer_wait_for_callback(clockid_to_kclock(timer->it_clock),
+-					timer);
+-		rcu_read_unlock();
++	if (timer_delete_hook(timer) == TIMER_RETRY)
+ 		goto retry_delete;
+-	}
++
+ 	list_del(&timer->list);
+ 	/*
+ 	 * This keeps any tasks waiting on the spin lock from thinking
+diff --git a/kernel/time/posix-timers.h b/kernel/time/posix-timers.h
+index ddb21145211a..725bd230a8db 100644
+--- a/kernel/time/posix-timers.h
++++ b/kernel/time/posix-timers.h
+@@ -32,6 +32,8 @@ extern const struct k_clock clock_process;
+ extern const struct k_clock clock_thread;
+ extern const struct k_clock alarm_clock;
+ 
++extern void cpu_timers_grab_expiry_lock(struct k_itimer *timer);
++
+ int posix_timer_event(struct k_itimer *timr, int si_private);
+ 
+ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting);
+diff --git a/kernel/time/timer.c b/kernel/time/timer.c
+index c7bd68db6f63..a2be2277506d 100644
+--- a/kernel/time/timer.c
++++ b/kernel/time/timer.c
+@@ -45,7 +45,6 @@
+ #include <linux/slab.h>
+ #include <linux/compat.h>
+ #include <linux/random.h>
+-#include <linux/swait.h>
+ 
+ #include <linux/uaccess.h>
+ #include <asm/unistd.h>
+@@ -199,9 +198,7 @@ EXPORT_SYMBOL(jiffies_64);
+ struct timer_base {
+ 	raw_spinlock_t		lock;
+ 	struct timer_list	*running_timer;
+-#ifdef CONFIG_PREEMPT_RT_FULL
+-	struct swait_queue_head	wait_for_running_timer;
+-#endif
++	spinlock_t		expiry_lock;
+ 	unsigned long		clk;
+ 	unsigned long		next_expiry;
+ 	unsigned int		cpu;
+@@ -1201,33 +1198,6 @@ void add_timer_on(struct timer_list *timer, int cpu)
+ }
+ EXPORT_SYMBOL_GPL(add_timer_on);
+ 
+-#ifdef CONFIG_PREEMPT_RT_FULL
+-/*
+- * Wait for a running timer
+- */
+-static void wait_for_running_timer(struct timer_list *timer)
+-{
+-	struct timer_base *base;
+-	u32 tf = timer->flags;
+-
+-	if (tf & TIMER_MIGRATING)
+-		return;
+-
+-	base = get_timer_base(tf);
+-	swait_event_exclusive(base->wait_for_running_timer,
+-			      base->running_timer != timer);
+-}
+-
+-# define wakeup_timer_waiters(b)	swake_up_all(&(b)->wait_for_running_timer)
+-#else
+-static inline void wait_for_running_timer(struct timer_list *timer)
+-{
+-	cpu_relax();
+-}
+-
+-# define wakeup_timer_waiters(b)	do { } while (0)
+-#endif
+-
+ /**
+  * del_timer - deactivate a timer.
+  * @timer: the timer to be deactivated
+@@ -1257,14 +1227,8 @@ int del_timer(struct timer_list *timer)
+ }
+ EXPORT_SYMBOL(del_timer);
+ 
+-/**
+- * try_to_del_timer_sync - Try to deactivate a timer
+- * @timer: timer to delete
+- *
+- * This function tries to deactivate a timer. Upon successful (ret >= 0)
+- * exit the timer is not queued and the handler is not running on any CPU.
+- */
+-int try_to_del_timer_sync(struct timer_list *timer)
++static int __try_to_del_timer_sync(struct timer_list *timer,
++				   struct timer_base **basep)
+ {
+ 	struct timer_base *base;
+ 	unsigned long flags;
+@@ -1272,7 +1236,7 @@ int try_to_del_timer_sync(struct timer_list *timer)
+ 
+ 	debug_assert_init(timer);
+ 
+-	base = lock_timer_base(timer, &flags);
++	*basep = base = lock_timer_base(timer, &flags);
+ 
+ 	if (base->running_timer != timer)
+ 		ret = detach_if_pending(timer, base, true);
+@@ -1281,9 +1245,42 @@ int try_to_del_timer_sync(struct timer_list *timer)
+ 
+ 	return ret;
+ }
++
++/**
++ * try_to_del_timer_sync - Try to deactivate a timer
++ * @timer: timer to delete
++ *
++ * This function tries to deactivate a timer. Upon successful (ret >= 0)
++ * exit the timer is not queued and the handler is not running on any CPU.
++ */
++int try_to_del_timer_sync(struct timer_list *timer)
++{
++	struct timer_base *base;
++
++	return __try_to_del_timer_sync(timer, &base);
++}
+ EXPORT_SYMBOL(try_to_del_timer_sync);
+ 
+ #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT_FULL)
++static int __del_timer_sync(struct timer_list *timer)
++{
++	struct timer_base *base;
++	int ret;
++
++	for (;;) {
++		ret = __try_to_del_timer_sync(timer, &base);
++		if (ret >= 0)
++			return ret;
++
++		/*
++		 * When accessing the lock, timers of base are no longer expired
++		 * and so timer is no longer running.
++		 */
++		spin_lock(&base->expiry_lock);
++		spin_unlock(&base->expiry_lock);
++	}
++}
++
+ /**
+  * del_timer_sync - deactivate a timer and wait for the handler to finish.
+  * @timer: the timer to be deactivated
+@@ -1339,12 +1336,8 @@ int del_timer_sync(struct timer_list *timer)
+ 	 * could lead to deadlock.
+ 	 */
+ 	WARN_ON(in_irq() && !(timer->flags & TIMER_IRQSAFE));
+-	for (;;) {
+-		int ret = try_to_del_timer_sync(timer);
+-		if (ret >= 0)
+-			return ret;
+-		wait_for_running_timer(timer);
+-	}
++
++	return __del_timer_sync(timer);
+ }
+ EXPORT_SYMBOL(del_timer_sync);
+ #endif
+@@ -1409,11 +1402,15 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head)
+ 			raw_spin_unlock(&base->lock);
+ 			call_timer_fn(timer, fn);
+ 			base->running_timer = NULL;
++			spin_unlock(&base->expiry_lock);
++			spin_lock(&base->expiry_lock);
+ 			raw_spin_lock(&base->lock);
+ 		} else {
+ 			raw_spin_unlock_irq(&base->lock);
+ 			call_timer_fn(timer, fn);
+ 			base->running_timer = NULL;
++			spin_unlock(&base->expiry_lock);
++			spin_lock(&base->expiry_lock);
+ 			raw_spin_lock_irq(&base->lock);
+ 		}
+ 	}
+@@ -1710,6 +1707,7 @@ static inline void __run_timers(struct timer_base *base)
+ 	if (!time_after_eq(jiffies, base->clk))
+ 		return;
+ 
++	spin_lock(&base->expiry_lock);
+ 	raw_spin_lock_irq(&base->lock);
+ 
+ 	/*
+@@ -1737,7 +1735,7 @@ static inline void __run_timers(struct timer_base *base)
+ 			expire_timers(base, heads + levels);
+ 	}
+ 	raw_spin_unlock_irq(&base->lock);
+-	wakeup_timer_waiters(base);
++	spin_unlock(&base->expiry_lock);
+ }
+ 
+ /*
+@@ -1984,9 +1982,7 @@ static void __init init_timer_cpu(int cpu)
+ 		base->cpu = cpu;
+ 		raw_spin_lock_init(&base->lock);
+ 		base->clk = jiffies;
+-#ifdef CONFIG_PREEMPT_RT_FULL
+-		init_swait_queue_head(&base->wait_for_running_timer);
+-#endif
++		spin_lock_init(&base->expiry_lock);
+ 	}
+ }
+ 
+-- 
+2.36.1
+