posix-cpu-timers: Cleanup and consolidation

@@ -4,11 +4,10 @@
 
 #include <linux/spinlock.h>
 #include <linux/list.h>
-#include <linux/sched.h>
-#include <linux/timex.h>
 #include <linux/alarmtimer.h>
 
-struct siginfo;
+struct kernel_siginfo;
+struct task_struct;
 
 struct cpu_timer_list {
 	struct list_head entry;

@@ -5,7 +5,8 @@
 #include <linux/time.h>
 #include <linux/hrtimer.h>
 #include <linux/timerqueue.h>
-#include <linux/rtc.h>
+
+struct rtc_device;
 
 enum alarmtimer_type {
 	ALARM_REALTIME,

@@ -606,6 +606,19 @@ static int alarm_timer_try_to_cancel(str
 }
 
 /**
+ * alarm_timer_wait_running - Posix timer callback to wait for a timer
+ * @timr:	Pointer to the posixtimer data struct
+ *
+ * Called from the core code when timer cancel detected that the callback
+ * is running. @timr is unlocked and rcu read lock is held to prevent it
+ * from being freed.
+ */
+static void alarm_timer_wait_running(struct k_itimer *timr)
+{
+	hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
+}
+
+/**
  * alarm_timer_arm - Posix timer callback to arm a timer
  * @timr:	Pointer to the posixtimer data struct
  * @expires:	The new expiry time

@@ -834,6 +847,7 @@ const struct k_clock alarm_clock = {
 	.timer_forward		= alarm_timer_forward,
 	.timer_remaining	= alarm_timer_remaining,
 	.timer_try_to_cancel	= alarm_timer_try_to_cancel,
+	.timer_wait_running	= alarm_timer_wait_running,
 	.nsleep			= alarm_timer_nsleep,
 };
 #endif /* CONFIG_POSIX_TIMERS */

@@ -805,7 +805,11 @@ static int common_hrtimer_try_to_cancel(
 	return hrtimer_try_to_cancel(&timr->it.real.timer);
 }
 
-#ifdef CONFIG_PREEMPT_RT
+static void common_timer_wait_running(struct k_itimer *timer)
+{
+	hrtimer_cancel_wait_running(&timer->it.real.timer);
+}
+
 static struct k_itimer *timer_wait_running(struct k_itimer *timer,
 					   unsigned long *flags)
 {

@@ -816,29 +820,13 @@ static struct k_itimer *timer_wait_runni
 	rcu_read_lock();
 	unlock_timer(timer, *flags);
 
-	if (kc->timer_arm == common_hrtimer_arm)
-		hrtimer_cancel_wait_running(&timer->it.real.timer);
-	else if (kc == &alarm_clock)
-		hrtimer_cancel_wait_running(&timer->it.alarm.alarmtimer.timer);
-	else
-		WARN_ON_ONCE(1);
-	rcu_read_unlock();
-
-	/* Relock the timer. It might be not longer hashed. */
-	return lock_timer(timer_id, flags);
-}
-#else
-static struct k_itimer *timer_wait_running(struct k_itimer *timer,
-					   unsigned long *flags)
-{
-	timer_t timer_id = READ_ONCE(timer->it_id);
+	if (!WARN_ON_ONCE(kc->timer_wait_running))
+		kc->timer_wait_running(timer);
 
-	unlock_timer(timer, *flags);
-	cpu_relax();
+	rcu_read_unlock();
 	/* Relock the timer. It might be not longer hashed. */
 	return lock_timer(timer_id, flags);
 }
-#endif
 
 /* Set a POSIX.1b interval timer. */
 int common_timer_set(struct k_itimer *timr, int flags,

@@ -1279,6 +1267,7 @@ static const struct k_clock clock_realti
 	.timer_forward		= common_hrtimer_forward,
 	.timer_remaining	= common_hrtimer_remaining,
 	.timer_try_to_cancel	= common_hrtimer_try_to_cancel,
+	.timer_wait_running	= common_timer_wait_running,
 	.timer_arm		= common_hrtimer_arm,
 };
 

@@ -1294,6 +1283,7 @@ static const struct k_clock clock_monoto
 	.timer_forward		= common_hrtimer_forward,
 	.timer_remaining	= common_hrtimer_remaining,
 	.timer_try_to_cancel	= common_hrtimer_try_to_cancel,
+	.timer_wait_running	= common_timer_wait_running,
 	.timer_arm		= common_hrtimer_arm,
 };
 

@@ -1324,6 +1314,7 @@ static const struct k_clock clock_tai =
 	.timer_forward		= common_hrtimer_forward,
 	.timer_remaining	= common_hrtimer_remaining,
 	.timer_try_to_cancel	= common_hrtimer_try_to_cancel,
+	.timer_wait_running	= common_timer_wait_running,
 	.timer_arm		= common_hrtimer_arm,
 };
 

@@ -1339,6 +1330,7 @@ static const struct k_clock clock_bootti
 	.timer_forward		= common_hrtimer_forward,
 	.timer_remaining	= common_hrtimer_remaining,
 	.timer_try_to_cancel	= common_hrtimer_try_to_cancel,
+	.timer_wait_running	= common_timer_wait_running,
 	.timer_arm		= common_hrtimer_arm,
 };
 

@@ -24,6 +24,7 @@ struct k_clock {
 	int	(*timer_try_to_cancel)(struct k_itimer *timr);
 	void	(*timer_arm)(struct k_itimer *timr, ktime_t expires,
 			     bool absolute, bool sigev_none);
+	void	(*timer_wait_running)(struct k_itimer *timr);
 };
 
 extern const struct k_clock clock_posix_cpu;

@@ -412,9 +412,10 @@ static void cleanup_timers_list(struct l
 }
 
 /*
- * Clean out CPU timers still ticking when a thread exited.  The task
- * pointer is cleared, and the expiry time is replaced with the residual
- * time for later timer_gettime calls to return.
+ * Clean out CPU timers which are still armed when a thread exits. The
+ * timers are only removed from the list. No other updates are done. The
+ * corresponding posix timers are still accessible, but cannot be rearmed.
+ *
  * This must be called with the siglock held.
  */
 static void cleanup_timers(struct list_head *head)

@@ -375,7 +375,8 @@ static int posix_cpu_timer_del(struct k_
 	struct sighand_struct *sighand;
 	struct task_struct *p = timer->it.cpu.task;
 
-	WARN_ON_ONCE(p == NULL);
+	if (WARN_ON_ONCE(!p))
+		return -EINVAL;
 
 	/*
 	 * Protect against sighand release/switch in exit/exec and process/

@@ -581,7 +582,8 @@ static int posix_cpu_timer_set(struct k_
 	u64 old_expires, new_expires, old_incr, val;
 	int ret;
 
-	WARN_ON_ONCE(p == NULL);
+	if (WARN_ON_ONCE(!p))
+		return -EINVAL;
 
 	/*
 	 * Use the to_ktime conversion because that clamps the maximum

@@ -716,10 +718,11 @@ static int posix_cpu_timer_set(struct k_
 
 static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp)
 {
-	u64 now;
 	struct task_struct *p = timer->it.cpu.task;
+	u64 now;
 
-	WARN_ON_ONCE(p == NULL);
+	if (WARN_ON_ONCE(!p))
+		return;
 
 	/*
 	 * Easy part: convert the reload time.

@@ -1001,12 +1004,13 @@ static void check_process_timers(struct
  */
 static void posix_cpu_timer_rearm(struct k_itimer *timer)
 {
+	struct task_struct *p = timer->it.cpu.task;
 	struct sighand_struct *sighand;
 	unsigned long flags;
-	struct task_struct *p = timer->it.cpu.task;
 	u64 now;
 
-	WARN_ON_ONCE(p == NULL);
+	if (WARN_ON_ONCE(!p))
+		return;
 
 	/*
 	 * Fetch the current sample and update the timer's expiry time.

@@ -1203,7 +1207,9 @@ void set_process_cpu_timer(struct task_s
 	u64 now;
 	int ret;
 
-	WARN_ON_ONCE(clock_idx == CPUCLOCK_SCHED);
+	if (WARN_ON_ONCE(clock_idx >= CPUCLOCK_SCHED))
+		return;
+
 	ret = cpu_timer_sample_group(clock_idx, tsk, &now);
 
 	if (oldval && ret != -EINVAL) {

@@ -118,7 +118,7 @@ struct k_itimer {
 	struct rcu_head		rcu;
 };
 
-void run_posix_cpu_timers(struct task_struct *task);
+void run_posix_cpu_timers(void);
 void posix_cpu_timers_exit(struct task_struct *task);
 void posix_cpu_timers_exit_group(struct task_struct *task);
 void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,

@@ -1137,11 +1137,12 @@ static inline int fastpath_timer_check(s
  * already updated our counts.  We need to check if any timers fire now.
  * Interrupts are disabled.
  */
-void run_posix_cpu_timers(struct task_struct *tsk)
+void run_posix_cpu_timers(void)
 {
-	LIST_HEAD(firing);
+	struct task_struct *tsk = current;
 	struct k_itimer *timer, *next;
 	unsigned long flags;
+	LIST_HEAD(firing);
 
 	lockdep_assert_irqs_disabled();
 

@@ -1728,7 +1728,7 @@ void update_process_times(int user_tick)
 #endif
 	scheduler_tick();
 	if (IS_ENABLED(CONFIG_POSIX_TIMERS))
-		run_posix_cpu_timers(p);
+		run_posix_cpu_timers();
 }
 
 /**

@@ -1141,20 +1141,34 @@ void run_posix_cpu_timers(void)
 {
 	struct task_struct *tsk = current;
 	struct k_itimer *timer, *next;
-	unsigned long flags;
 	LIST_HEAD(firing);
 
 	lockdep_assert_irqs_disabled();
 
 	/*
-	 * The fast path checks that there are no expired thread or thread
-	 * group timers.  If that's so, just return.
+	 * Verify that sighand exits. If not, the task is exiting and has
+	 * dropped sighand already. Without sighand, timer expiry is
+	 * pointless.
 	 */
-	if (!fastpath_timer_check(tsk))
+	if (!tsk->sighand)
 		return;
 
-	if (!lock_task_sighand(tsk, &flags))
+	/*
+	 * Now do a fast check for expired task and group timers. If
+	 * no expired timers found, return.
+	 */
+	if(!fastpath_timer_check(tsk))
 		return;
+
+	/*
+	 * The timer interrupt hit current. It's verified that sighand
+	 * exists, so it cannot go away before the timer interrupt returns
+	 * as only current can remove or change its own sighand in exit()
+	 * or exec() with sighand lock held and interrupts disabled. Ergo
+	 * the interrupt can only observe a valid sighand or NULL.
+	 */
+	spin_lock(&tsk->sighand->siglock);
+
 	/*
 	 * Here we take off tsk->signal->cpu_timers[N] and
 	 * tsk->cpu_timers[N] all the timers that are firing, and

@@ -1172,7 +1186,7 @@ void run_posix_cpu_timers(void)
 	 * that gets the timer lock before we do will give it up and
 	 * spin until we've taken care of that timer below.
 	 */
-	unlock_task_sighand(tsk, &flags);
+	spin_unlock(&tsk->sighand->siglock);
 
 	/*
 	 * Now that all the timers on our list have the firing flag,

@@ -35,27 +35,52 @@ void update_rlimit_cpu(struct task_struc
 	spin_unlock_irq(&task->sighand->siglock);
 }
 
-static int check_clock(const clockid_t which_clock)
+/*
+ * Functions for validating access to tasks.
+ */
+static struct task_struct *lookup_task(const pid_t pid, bool thread)
 {
-	int error = 0;
 	struct task_struct *p;
-	const pid_t pid = CPUCLOCK_PID(which_clock);
 
-	if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
-		return -EINVAL;
+	if (!pid)
+		return thread ? current : current->group_leader;
 
-	if (pid == 0)
-		return 0;
+	p = find_task_by_vpid(pid);
+	if (!p || p == current)
+		return p;
+	if (thread)
+		return same_thread_group(p, current) ? p : NULL;
+	if (p == current)
+		return p;
+	return has_group_leader_pid(p) ? p : NULL;
+}
+
+static struct task_struct *__get_task_for_clock(const clockid_t clock,
+						bool getref)
+{
+	const bool thread = !!CPUCLOCK_PERTHREAD(clock);
+	const pid_t pid = CPUCLOCK_PID(clock);
+	struct task_struct *p;
+
+	if (CPUCLOCK_WHICH(clock) >= CPUCLOCK_MAX)
+		return NULL;
 
 	rcu_read_lock();
-	p = find_task_by_vpid(pid);
-	if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
-		   same_thread_group(p, current) : has_group_leader_pid(p))) {
-		error = -EINVAL;
-	}
+	p = lookup_task(pid, thread);
+	if (p && getref)
+		get_task_struct(p);
 	rcu_read_unlock();
+	return p;
+}
 
-	return error;
+static inline struct task_struct *get_task_for_clock(const clockid_t clock)
+{
+	return __get_task_for_clock(clock, true);
+}
+
+static inline int validate_clock_permissions(const clockid_t clock)
+{
+	return __get_task_for_clock(clock, false) ? 0 : -EINVAL;
 }
 
 /*

@@ -125,7 +150,8 @@ static inline u64 virt_ticks(struct task
 static int
 posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 {
-	int error = check_clock(which_clock);
+	int error = validate_clock_permissions(which_clock);
+
 	if (!error) {
 		tp->tv_sec = 0;
 		tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);

@@ -142,20 +168,17 @@ posix_cpu_clock_getres(const clockid_t w
 }
 
 static int
-posix_cpu_clock_set(const clockid_t which_clock, const struct timespec64 *tp)
+posix_cpu_clock_set(const clockid_t clock, const struct timespec64 *tp)
 {
+	int error = validate_clock_permissions(clock);
+
 	/*
 	 * You can never reset a CPU clock, but we check for other errors
 	 * in the call before failing with EPERM.
 	 */
-	int error = check_clock(which_clock);
-	if (error == 0) {
-		error = -EPERM;
-	}
-	return error;
+	return error ? : -EPERM;
 }
 
-
 /*
  * Sample a per-thread clock for the given task.
  */

@@ -289,53 +289,24 @@ static int cpu_clock_sample_group(const
 	return 0;
 }
 
-static int posix_cpu_clock_get_task(struct task_struct *tsk,
-				    const clockid_t which_clock,
-				    struct timespec64 *tp)
+static int posix_cpu_clock_get(const clockid_t clock, struct timespec64 *tp)
 {
-	int err = -EINVAL;
-	u64 rtn;
+	const clockid_t clkid = CPUCLOCK_WHICH(clock);
+	struct task_struct *tsk;
+	u64 t;
+
+	tsk = get_task_for_clock(clock);
+	if (!tsk)
+		return -EINVAL;
+
+	if (CPUCLOCK_PERTHREAD(clock))
+		cpu_clock_sample(clkid, tsk, &t);
+	else
+		cpu_clock_sample_group(clkid, tsk, &t);
+	put_task_struct(tsk);
 
-	if (CPUCLOCK_PERTHREAD(which_clock)) {
-		if (same_thread_group(tsk, current))
-			err = cpu_clock_sample(which_clock, tsk, &rtn);
-	} else {
-		if (tsk == current || thread_group_leader(tsk))
-			err = cpu_clock_sample_group(which_clock, tsk, &rtn);
-	}
-
-	if (!err)
-		*tp = ns_to_timespec64(rtn);
-
-	return err;
-}
-
-
-static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec64 *tp)
-{
-	const pid_t pid = CPUCLOCK_PID(which_clock);
-	int err = -EINVAL;
-
-	if (pid == 0) {
-		/*
-		 * Special case constant value for our own clocks.
-		 * We don't have to do any lookup to find ourselves.
-		 */
-		err = posix_cpu_clock_get_task(current, which_clock, tp);
-	} else {
-		/*
-		 * Find the given PID, and validate that the caller
-		 * should be able to see it.
-		 */
-		struct task_struct *p;
-		rcu_read_lock();
-		p = find_task_by_vpid(pid);
-		if (p)
-			err = posix_cpu_clock_get_task(p, which_clock, tp);
-		rcu_read_unlock();
-	}
-
-	return err;
+	*tp = ns_to_timespec64(t);
+	return 0;
 }
 
 /*

@@ -316,44 +316,15 @@ static int posix_cpu_clock_get(const clo
  */
 static int posix_cpu_timer_create(struct k_itimer *new_timer)
 {
-	int ret = 0;
-	const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
-	struct task_struct *p;
+	struct task_struct *p = get_task_for_clock(new_timer->it_clock);
 
-	if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
+	if (!p)
 		return -EINVAL;
 
 	new_timer->kclock = &clock_posix_cpu;
-
 	INIT_LIST_HEAD(&new_timer->it.cpu.entry);
-
-	rcu_read_lock();
-	if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
-		if (pid == 0) {
-			p = current;
-		} else {
-			p = find_task_by_vpid(pid);
-			if (p && !same_thread_group(p, current))
-				p = NULL;
-		}
-	} else {
-		if (pid == 0) {
-			p = current->group_leader;
-		} else {
-			p = find_task_by_vpid(pid);
-			if (p && !has_group_leader_pid(p))
-				p = NULL;
-		}
-	}
 	new_timer->it.cpu.task = p;
-	if (p) {
-		get_task_struct(p);
-	} else {
-		ret = -EINVAL;
-	}
-	rcu_read_unlock();
-
-	return ret;
+	return 0;
 }
 
 /*

@@ -62,7 +62,7 @@ extern void cputime_adjust(struct task_c
  */
 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times);
 void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times);
-
+void thread_group_sample_cputime(struct task_struct *tsk, struct task_cputime *times);
 
 /*
  * The following are functions that support scheduler-internal time accounting.

@@ -232,6 +232,27 @@ static inline void sample_cputime_atomic
 	times->sum_exec_runtime = atomic64_read(&atomic_times->sum_exec_runtime);
 }
 
+/**
+ * thread_group_sample_cputime - Sample cputime for a given task
+ * @tsk:	Task for which cputime needs to be started
+ * @iimes:	Storage for time samples
+ *
+ * Called from sys_getitimer() to calculate the expiry time of an active
+ * timer. That means group cputime accounting is already active. Called
+ * with task sighand lock held.
+ *
+ * Updates @times with an uptodate sample of the thread group cputimes.
+ */
+void thread_group_sample_cputime(struct task_struct *tsk,
+				struct task_cputime *times)
+{
+	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+
+	WARN_ON_ONCE(!cputimer->running);
+
+	sample_cputime_atomic(times, &cputimer->cputime_atomic);
+}
+
 void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
 {
 	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;

@@ -58,7 +58,7 @@ static void get_cpu_itimer(struct task_s
 		struct task_cputime cputime;
 		u64 t;
 
-		thread_group_cputimer(tsk, &cputime);
+		thread_group_sample_cputime(tsk, &cputime);
 		if (clock_id == CPUCLOCK_PROF)
 			t = cputime.utime + cputime.stime;
 		else

@@ -914,16 +914,17 @@ static void check_process_timers(struct
 	if (!READ_ONCE(tsk->signal->cputimer.running))
 		return;
 
-        /*
+       /*
 	 * Signify that a thread is checking for process timers.
 	 * Write access to this field is protected by the sighand lock.
 	 */
 	sig->cputimer.checking_timer = true;
 
 	/*
-	 * Collect the current process totals.
+	 * Collect the current process totals. Group accounting is active
+	 * so the sample can be taken directly.
 	 */
-	thread_group_cputimer(tsk, &cputime);
+	sample_cputime_atomic(&cputime, &sig->cputimer.cputime_atomic);
 	utime = cputime.utime;
 	ptime = utime + cputime.stime;
 	sum_sched_runtime = cputime.sum_exec_runtime;

@@ -61,7 +61,6 @@ extern void cputime_adjust(struct task_c
  * Thread group CPU time accounting.
  */
 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times);
-void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times);
 void thread_group_sample_cputime(struct task_struct *tsk, struct task_cputime *times);
 
 /*

@@ -253,7 +253,20 @@ void thread_group_sample_cputime(struct
 	sample_cputime_atomic(times, &cputimer->cputime_atomic);
 }
 
-void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
+/**
+ * thread_group_start_cputime - Start cputime and return a sample
+ * @tsk:	Task for which cputime needs to be started
+ * @iimes:	Storage for time samples
+ *
+ * The thread group cputime accouting is avoided when there are no posix
+ * CPU timers armed. Before starting a timer it's required to check whether
+ * the time accounting is active. If not, a full update of the atomic
+ * accounting store needs to be done and the accounting enabled.
+ *
+ * Updates @times with an uptodate sample of the thread group cputimes.
+ */
+static void
+thread_group_start_cputime(struct task_struct *tsk, struct task_cputime *times)
 {
 	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 	struct task_cputime sum;

@@ -536,7 +549,7 @@ static int cpu_timer_sample_group(const
 {
 	struct task_cputime cputime;
 
-	thread_group_cputimer(p, &cputime);
+	thread_group_start_cputime(p, &cputime);
 	switch (CPUCLOCK_WHICH(which_clock)) {
 	default:
 		return -EINVAL;

@@ -294,29 +294,37 @@ thread_group_start_cputime(struct task_s
 }
 
 /*
- * Sample a process (thread group) clock for the given group_leader task.
- * Must be called with task sighand lock held for safe while_each_thread()
- * traversal.
+ * Sample a process (thread group) clock for the given task clkid. If the
+ * groups cputime accounting is already enabled, read the atomic
+ * store. Otherwise a full update is required.  task sighand lock must be
+ * held to protect the task traversal on a full update.
  */
 static int cpu_clock_sample_group(const clockid_t which_clock,
 				  struct task_struct *p,
-				  u64 *sample)
+				  u64 *sample, bool start)
 {
+	struct thread_group_cputimer *cputimer = &p->signal->cputimer;
 	struct task_cputime cputime;
 
+	if (!READ_ONCE(cputimer->running)) {
+		if (start)
+			thread_group_start_cputime(p, &cputime);
+		else
+			thread_group_cputime(p, &cputime);
+	} else {
+		sample_cputime_atomic(&cputime, &cputimer->cputime_atomic);
+	}
+
 	switch (CPUCLOCK_WHICH(which_clock)) {
 	default:
 		return -EINVAL;
 	case CPUCLOCK_PROF:
-		thread_group_cputime(p, &cputime);
 		*sample = cputime.utime + cputime.stime;
 		break;
 	case CPUCLOCK_VIRT:
-		thread_group_cputime(p, &cputime);
 		*sample = cputime.utime;
 		break;
 	case CPUCLOCK_SCHED:
-		thread_group_cputime(p, &cputime);
 		*sample = cputime.sum_exec_runtime;
 		break;
 	}

@@ -336,7 +344,7 @@ static int posix_cpu_clock_get(const clo
 	if (CPUCLOCK_PERTHREAD(clock))
 		cpu_clock_sample(clkid, tsk, &t);
 	else
-		cpu_clock_sample_group(clkid, tsk, &t);
+		cpu_clock_sample_group(clkid, tsk, &t, false);
 	put_task_struct(tsk);
 
 	*tp = ns_to_timespec64(t);

@@ -540,33 +548,6 @@ static void cpu_timer_fire(struct k_itim
 }
 
 /*
- * Sample a process (thread group) timer for the given group_leader task.
- * Must be called with task sighand lock held for safe while_each_thread()
- * traversal.
- */
-static int cpu_timer_sample_group(const clockid_t which_clock,
-				  struct task_struct *p, u64 *sample)
-{
-	struct task_cputime cputime;
-
-	thread_group_start_cputime(p, &cputime);
-	switch (CPUCLOCK_WHICH(which_clock)) {
-	default:
-		return -EINVAL;
-	case CPUCLOCK_PROF:
-		*sample = cputime.utime + cputime.stime;
-		break;
-	case CPUCLOCK_VIRT:
-		*sample = cputime.utime;
-		break;
-	case CPUCLOCK_SCHED:
-		*sample = cputime.sum_exec_runtime;
-		break;
-	}
-	return 0;
-}
-
-/*
  * Guts of sys_timer_settime for CPU timers.
  * This is called with the timer locked and interrupts disabled.
  * If we return TIMER_RETRY, it's necessary to release the timer's lock

@@ -627,7 +608,7 @@ static int posix_cpu_timer_set(struct k_
 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 		cpu_clock_sample(timer->it_clock, p, &val);
 	} else {
-		cpu_timer_sample_group(timer->it_clock, p, &val);
+		cpu_clock_sample_group(timer->it_clock, p, &val, true);
 	}
 
 	if (old) {

@@ -755,7 +736,7 @@ static void posix_cpu_timer_get(struct k
 			timer->it.cpu.expires = 0;
 			return;
 		} else {
-			cpu_timer_sample_group(timer->it_clock, p, &now);
+			cpu_clock_sample_group(timer->it_clock, p, &now, false);
 			unlock_task_sighand(p, &flags);
 		}
 	}

@@ -1042,7 +1023,7 @@ static void posix_cpu_timer_rearm(struct
 			/* If the process is dying, no need to rearm */
 			goto unlock;
 		}
-		cpu_timer_sample_group(timer->it_clock, p, &now);
+		cpu_clock_sample_group(timer->it_clock, p, &now, true);
 		bump_cpu_timer(timer, now);
 		/* Leave the sighand locked for the call below.  */
 	}

@@ -1225,7 +1206,7 @@ void set_process_cpu_timer(struct task_s
 	if (WARN_ON_ONCE(clock_idx >= CPUCLOCK_SCHED))
 		return;
 
-	ret = cpu_timer_sample_group(clock_idx, tsk, &now);
+	ret = cpu_clock_sample_group(clock_idx, tsk, &now, true);
 
 	if (oldval && ret != -EINVAL) {
 		/*

@@ -556,10 +556,11 @@ static void cpu_timer_fire(struct k_itim
 static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
 			       struct itimerspec64 *new, struct itimerspec64 *old)
 {
-	unsigned long flags;
-	struct sighand_struct *sighand;
-	struct task_struct *p = timer->it.cpu.task;
+	clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
 	u64 old_expires, new_expires, old_incr, val;
+	struct task_struct *p = timer->it.cpu.task;
+	struct sighand_struct *sighand;
+	unsigned long flags;
 	int ret;
 
 	if (WARN_ON_ONCE(!p))

@@ -606,9 +607,9 @@ static int posix_cpu_timer_set(struct k_
 	 * check if it's already passed.  In short, we need a sample.
 	 */
 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
-		cpu_clock_sample(timer->it_clock, p, &val);
+		cpu_clock_sample(clkid, p, &val);
 	} else {
-		cpu_clock_sample_group(timer->it_clock, p, &val, true);
+		cpu_clock_sample_group(clkid, p, &val, true);
 	}
 
 	if (old) {

@@ -699,6 +699,7 @@ static int posix_cpu_timer_set(struct k_
 
 static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp)
 {
+	clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
 	struct task_struct *p = timer->it.cpu.task;
 	u64 now;
 

@@ -717,7 +718,7 @@ static void posix_cpu_timer_get(struct k
 	 * Sample the clock to take the difference with the expiry time.
 	 */
 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
-		cpu_clock_sample(timer->it_clock, p, &now);
+		cpu_clock_sample(clkid, p, &now);
 	} else {
 		struct sighand_struct *sighand;
 		unsigned long flags;

@@ -737,7 +738,7 @@ static void posix_cpu_timer_get(struct k
 			timer->it.cpu.expires = 0;
 			return;
 		} else {
-			cpu_clock_sample_group(timer->it_clock, p, &now, false);
+			cpu_clock_sample_group(clkid, p, &now, false);
 			unlock_task_sighand(p, &flags);
 		}
 	}

@@ -987,6 +987,7 @@ static void check_process_timers(struct
  */
 static void posix_cpu_timer_rearm(struct k_itimer *timer)
 {
+	clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
 	struct task_struct *p = timer->it.cpu.task;
 	struct sighand_struct *sighand;
 	unsigned long flags;

@@ -999,7 +1000,7 @@ static void posix_cpu_timer_rearm(struct
 	 * Fetch the current sample and update the timer's expiry time.
 	 */
 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
-		cpu_clock_sample(timer->it_clock, p, &now);
+		cpu_clock_sample(clkid, p, &now);
 		bump_cpu_timer(timer, now);
 		if (unlikely(p->exit_state))
 			return;

@@ -1025,7 +1026,7 @@ static void posix_cpu_timer_rearm(struct
 			/* If the process is dying, no need to rearm */
 			goto unlock;
 		}
-		cpu_clock_sample_group(timer->it_clock, p, &now, true);
+		cpu_clock_sample_group(clkid, p, &now, true);
 		bump_cpu_timer(timer, now);
 		/* Leave the sighand locked for the call below.  */
 	}

@@ -1204,14 +1204,13 @@ void set_process_cpu_timer(struct task_s
 			   u64 *newval, u64 *oldval)
 {
 	u64 now;
-	int ret;
 
 	if (WARN_ON_ONCE(clock_idx >= CPUCLOCK_SCHED))
 		return;
 
-	ret = cpu_clock_sample_group(clock_idx, tsk, &now, true);
+	cpu_clock_sample_group(clock_idx, tsk, &now, true);
 
-	if (oldval && ret != -EINVAL) {
+	if (oldval) {
 		/*
 		 * We are setting itimer. The *oldval is absolute and we update
 		 * it to be relative, *newval argument is relative and we update

@@ -180,14 +180,12 @@ posix_cpu_clock_set(const clockid_t cloc
 }
 
 /*
- * Sample a per-thread clock for the given task.
+ * Sample a per-thread clock for the given task. clkid is validated.
  */
-static int cpu_clock_sample(const clockid_t which_clock,
-			    struct task_struct *p, u64 *sample)
+static void cpu_clock_sample(const clockid_t clkid, struct task_struct *p,
+			     u64 *sample)
 {
-	switch (CPUCLOCK_WHICH(which_clock)) {
-	default:
-		return -EINVAL;
+	switch (clkid) {
 	case CPUCLOCK_PROF:
 		*sample = prof_ticks(p);
 		break;

@@ -197,8 +195,9 @@ static int cpu_clock_sample(const clocki
 	case CPUCLOCK_SCHED:
 		*sample = task_sched_runtime(p);
 		break;
+	default:
+		WARN_ON_ONCE(1);
 	}
-	return 0;
 }
 
 /*

@@ -297,11 +296,11 @@ thread_group_start_cputime(struct task_s
  * Sample a process (thread group) clock for the given task clkid. If the
  * groups cputime accounting is already enabled, read the atomic
  * store. Otherwise a full update is required.  task sighand lock must be
- * held to protect the task traversal on a full update.
+ * held to protect the task traversal on a full update. clkid is already
+ * validated.
  */
-static int cpu_clock_sample_group(const clockid_t which_clock,
-				  struct task_struct *p,
-				  u64 *sample, bool start)
+static void cpu_clock_sample_group(const clockid_t clkid, struct task_struct *p,
+				   u64 *sample, bool start)
 {
 	struct thread_group_cputimer *cputimer = &p->signal->cputimer;
 	struct task_cputime cputime;

@@ -315,9 +314,7 @@ static int cpu_clock_sample_group(const
 		sample_cputime_atomic(&cputime, &cputimer->cputime_atomic);
 	}
 
-	switch (CPUCLOCK_WHICH(which_clock)) {
-	default:
-		return -EINVAL;
+	switch (clkid) {
 	case CPUCLOCK_PROF:
 		*sample = cputime.utime + cputime.stime;
 		break;

@@ -327,8 +324,9 @@ static int cpu_clock_sample_group(const
 	case CPUCLOCK_SCHED:
 		*sample = cputime.sum_exec_runtime;
 		break;
+	default:
+		WARN_ON_ONCE(1);
 	}
-	return 0;
 }
 
 static int posix_cpu_clock_get(const clockid_t clock, struct timespec64 *tp)

@@ -182,22 +182,19 @@ posix_cpu_clock_set(const clockid_t cloc
 /*
  * Sample a per-thread clock for the given task. clkid is validated.
  */
-static void cpu_clock_sample(const clockid_t clkid, struct task_struct *p,
-			     u64 *sample)
+static u64 cpu_clock_sample(const clockid_t clkid, struct task_struct *p)
 {
 	switch (clkid) {
 	case CPUCLOCK_PROF:
-		*sample = prof_ticks(p);
-		break;
+		return prof_ticks(p);
 	case CPUCLOCK_VIRT:
-		*sample = virt_ticks(p);
-		break;
+		return virt_ticks(p);
 	case CPUCLOCK_SCHED:
-		*sample = task_sched_runtime(p);
-		break;
+		return task_sched_runtime(p);
 	default:
 		WARN_ON_ONCE(1);
 	}
+	return 0;
 }
 
 /*

@@ -299,8 +296,8 @@ thread_group_start_cputime(struct task_s
  * held to protect the task traversal on a full update. clkid is already
  * validated.
  */
-static void cpu_clock_sample_group(const clockid_t clkid, struct task_struct *p,
-				   u64 *sample, bool start)
+static u64 cpu_clock_sample_group(const clockid_t clkid, struct task_struct *p,
+				  bool start)
 {
 	struct thread_group_cputimer *cputimer = &p->signal->cputimer;
 	struct task_cputime cputime;

@@ -316,17 +313,15 @@ static void cpu_clock_sample_group(const
 
 	switch (clkid) {
 	case CPUCLOCK_PROF:
-		*sample = cputime.utime + cputime.stime;
-		break;
+		return cputime.utime + cputime.stime;
 	case CPUCLOCK_VIRT:
-		*sample = cputime.utime;
-		break;
+		return cputime.utime;
 	case CPUCLOCK_SCHED:
-		*sample = cputime.sum_exec_runtime;
-		break;
+		return cputime.sum_exec_runtime;
 	default:
 		WARN_ON_ONCE(1);
 	}
+	return 0;
 }
 
 static int posix_cpu_clock_get(const clockid_t clock, struct timespec64 *tp)

@@ -340,9 +335,9 @@ static int posix_cpu_clock_get(const clo
 		return -EINVAL;
 
 	if (CPUCLOCK_PERTHREAD(clock))
-		cpu_clock_sample(clkid, tsk, &t);
+		t = cpu_clock_sample(clkid, tsk);
 	else
-		cpu_clock_sample_group(clkid, tsk, &t, false);
+		t = cpu_clock_sample_group(clkid, tsk, false);
 	put_task_struct(tsk);
 
 	*tp = ns_to_timespec64(t);

@@ -604,11 +599,10 @@ static int posix_cpu_timer_set(struct k_
 	 * times (in arm_timer).  With an absolute time, we must
 	 * check if it's already passed.  In short, we need a sample.
 	 */
-	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
-		cpu_clock_sample(clkid, p, &val);
-	} else {
-		cpu_clock_sample_group(clkid, p, &val, true);
-	}
+	if (CPUCLOCK_PERTHREAD(timer->it_clock))
+		val = cpu_clock_sample(clkid, p);
+	else
+		val = cpu_clock_sample_group(clkid, p, true);
 
 	if (old) {
 		if (old_expires == 0) {

@@ -716,7 +710,7 @@ static void posix_cpu_timer_get(struct k
 	 * Sample the clock to take the difference with the expiry time.
 	 */
 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
-		cpu_clock_sample(clkid, p, &now);
+		now = cpu_clock_sample(clkid, p);
 	} else {
 		struct sighand_struct *sighand;
 		unsigned long flags;

@@ -736,7 +730,7 @@ static void posix_cpu_timer_get(struct k
 			timer->it.cpu.expires = 0;
 			return;
 		} else {
-			cpu_clock_sample_group(clkid, p, &now, false);
+			now = cpu_clock_sample_group(clkid, p, false);
 			unlock_task_sighand(p, &flags);
 		}
 	}

@@ -998,7 +992,7 @@ static void posix_cpu_timer_rearm(struct
 	 * Fetch the current sample and update the timer's expiry time.
 	 */
 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
-		cpu_clock_sample(clkid, p, &now);
+		now = cpu_clock_sample(clkid, p);
 		bump_cpu_timer(timer, now);
 		if (unlikely(p->exit_state))
 			return;

@@ -1024,7 +1018,7 @@ static void posix_cpu_timer_rearm(struct
 			/* If the process is dying, no need to rearm */
 			goto unlock;
 		}
-		cpu_clock_sample_group(clkid, p, &now, true);
+		now = cpu_clock_sample_group(clkid, p, true);
 		bump_cpu_timer(timer, now);
 		/* Leave the sighand locked for the call below.  */
 	}

@@ -1206,7 +1200,7 @@ void set_process_cpu_timer(struct task_s
 	if (WARN_ON_ONCE(clock_idx >= CPUCLOCK_SCHED))
 		return;
 
-	cpu_clock_sample_group(clock_idx, tsk, &now, true);
+	now = cpu_clock_sample_group(clock_idx, tsk, true);
 
 	if (oldval) {
 		/*

@@ -785,9 +785,9 @@ static inline void check_dl_overrun(stru
 static void check_thread_timers(struct task_struct *tsk,
 				struct list_head *firing)
 {
-	struct list_head *timers = tsk->cpu_timers;
 	struct task_cputime *tsk_expires = &tsk->cputime_expires;
-	u64 expires;
+	struct list_head *timers = tsk->cpu_timers;
+	u64 expires, stime, utime;
 	unsigned long soft;
 
 	if (dl_task(tsk))

@@ -800,10 +800,12 @@ static void check_thread_timers(struct t
 	if (task_cputime_zero(&tsk->cputime_expires))
 		return;
 
-	expires = check_timers_list(timers, firing, prof_ticks(tsk));
+	task_cputime(tsk, &utime, &stime);
+
+	expires = check_timers_list(timers, firing, utime + stime);
 	tsk_expires->prof_exp = expires;
 
-	expires = check_timers_list(++timers, firing, virt_ticks(tsk));
+	expires = check_timers_list(++timers, firing, utime);
 	tsk_expires->virt_exp = expires;
 
 	tsk_expires->sched_exp = check_timers_list(++timers, firing,

@@ -130,23 +130,6 @@ static inline int task_cputime_zero(cons
 	return 0;
 }
 
-static inline u64 prof_ticks(struct task_struct *p)
-{
-	u64 utime, stime;
-
-	task_cputime(p, &utime, &stime);
-
-	return utime + stime;
-}
-static inline u64 virt_ticks(struct task_struct *p)
-{
-	u64 utime, stime;
-
-	task_cputime(p, &utime, &stime);
-
-	return utime;
-}
-
 static int
 posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 {

@@ -184,13 +167,18 @@ posix_cpu_clock_set(const clockid_t cloc
  */
 static u64 cpu_clock_sample(const clockid_t clkid, struct task_struct *p)
 {
+	u64 utime, stime;
+
+	if (clkid == CPUCLOCK_SCHED)
+		return task_sched_runtime(p);
+
+	task_cputime(p, &utime, &stime);
+
 	switch (clkid) {
 	case CPUCLOCK_PROF:
-		return prof_ticks(p);
+		return utime + stime;
 	case CPUCLOCK_VIRT:
-		return virt_ticks(p);
-	case CPUCLOCK_SCHED:
-		return task_sched_runtime(p);
+		return utime;
 	default:
 		WARN_ON_ONCE(1);
 	}

@@ -36,17 +36,6 @@ extern struct cred init_cred;
 #define INIT_PREV_CPUTIME(x)
 #endif
 
-#ifdef CONFIG_POSIX_TIMERS
-#define INIT_CPU_TIMERS(s)						\
-	.cpu_timers = {							\
-		LIST_HEAD_INIT(s.cpu_timers[0]),			\
-		LIST_HEAD_INIT(s.cpu_timers[1]),			\
-		LIST_HEAD_INIT(s.cpu_timers[2]),			\
-	},
-#else
-#define INIT_CPU_TIMERS(s)
-#endif
-
 #define INIT_TASK_COMM "swapper"
 
 /* Attach to the init_task data structure for proper alignment */

@@ -62,6 +62,39 @@ static inline int clockid_to_fd(const cl
 	return ~(clk >> 3);
 }
 
+/**
+ * posix_cputimers - Container for posix CPU timer related data
+ * @cpu_timers:		List heads to queue posix CPU timers
+ *
+ * Used in task_struct and signal_struct
+ */
+struct posix_cputimers {
+	struct list_head	cpu_timers[CPUCLOCK_MAX];
+};
+
+static inline void posix_cputimers_init(struct posix_cputimers *pct)
+{
+	INIT_LIST_HEAD(&pct->cpu_timers[0]);
+	INIT_LIST_HEAD(&pct->cpu_timers[1]);
+	INIT_LIST_HEAD(&pct->cpu_timers[2]);
+}
+
+#ifdef CONFIG_POSIX_TIMERS
+/* Init task static initializer */
+#define INIT_CPU_TIMERLISTS(c)	{					\
+	LIST_HEAD_INIT(c.cpu_timers[0]),				\
+	LIST_HEAD_INIT(c.cpu_timers[1]),				\
+	LIST_HEAD_INIT(c.cpu_timers[2]),				\
+}
+
+#define INIT_CPU_TIMERS(s)						\
+	.posix_cputimers = {						\
+		.cpu_timers = INIT_CPU_TIMERLISTS(s.posix_cputimers),	\
+	},
+#else
+#define INIT_CPU_TIMERS(s)
+#endif
+
 #define REQUEUE_PENDING 1
 
 /**

@@ -28,6 +28,7 @@
 #include <linux/signal_types.h>
 #include <linux/mm_types_task.h>
 #include <linux/task_io_accounting.h>
+#include <linux/posix-timers.h>
 #include <linux/rseq.h>
 
 /* task_struct member predeclarations (sorted alphabetically): */

@@ -878,7 +879,7 @@ struct task_struct {
 
 #ifdef CONFIG_POSIX_TIMERS
 	struct task_cputime		cputime_expires;
-	struct list_head		cpu_timers[3];
+	struct posix_cputimers		posix_cputimers;
 #endif
 
 	/* Process credentials: */

@@ -9,6 +9,7 @@
 #include <linux/sched/task.h>
 #include <linux/cred.h>
 #include <linux/refcount.h>
+#include <linux/posix-timers.h>
 
 /*
  * Types defining task->signal and task->sighand and APIs using them:

@@ -151,8 +152,7 @@ struct signal_struct {
 	/* Earliest-expiration cache. */
 	struct task_cputime cputime_expires;
 
-	struct list_head cpu_timers[3];
-
+	struct posix_cputimers posix_cputimers;
 #endif
 
 	/* PID/PID hash table linkage. */

@@ -1523,6 +1523,7 @@ void __cleanup_sighand(struct sighand_st
  */
 static void posix_cpu_timers_init_group(struct signal_struct *sig)
 {
+	struct posix_cputimers *pct = &sig->posix_cputimers;
 	unsigned long cpu_limit;
 
 	cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);

@@ -1531,10 +1532,7 @@ static void posix_cpu_timers_init_group(
 		sig->cputimer.running = true;
 	}
 
-	/* The timer lists. */
-	INIT_LIST_HEAD(&sig->cpu_timers[0]);
-	INIT_LIST_HEAD(&sig->cpu_timers[1]);
-	INIT_LIST_HEAD(&sig->cpu_timers[2]);
+	posix_cputimers_init(pct);
 }
 #else
 static inline void posix_cpu_timers_init_group(struct signal_struct *sig) { }

@@ -1649,9 +1647,8 @@ static void posix_cpu_timers_init(struct
 	tsk->cputime_expires.prof_exp = 0;
 	tsk->cputime_expires.virt_exp = 0;
 	tsk->cputime_expires.sched_exp = 0;
-	INIT_LIST_HEAD(&tsk->cpu_timers[0]);
-	INIT_LIST_HEAD(&tsk->cpu_timers[1]);
-	INIT_LIST_HEAD(&tsk->cpu_timers[2]);
+
+	posix_cputimers_init(&tsk->posix_cputimers);
 }
 #else
 static inline void posix_cpu_timers_init(struct task_struct *tsk) { }

@@ -407,11 +407,11 @@ static void cleanup_timers_list(struct l
  *
  * This must be called with the siglock held.
  */
-static void cleanup_timers(struct list_head *head)
+static void cleanup_timers(struct posix_cputimers *pct)
 {
-	cleanup_timers_list(head);
-	cleanup_timers_list(++head);
-	cleanup_timers_list(++head);
+	cleanup_timers_list(&pct->cpu_timers[CPUCLOCK_PROF]);
+	cleanup_timers_list(&pct->cpu_timers[CPUCLOCK_VIRT]);
+	cleanup_timers_list(&pct->cpu_timers[CPUCLOCK_SCHED]);
 }
 
 /*

@@ -421,11 +421,11 @@ static void cleanup_timers(struct list_h
  */
 void posix_cpu_timers_exit(struct task_struct *tsk)
 {
-	cleanup_timers(tsk->cpu_timers);
+	cleanup_timers(&tsk->posix_cputimers);
 }
 void posix_cpu_timers_exit_group(struct task_struct *tsk)
 {
-	cleanup_timers(tsk->signal->cpu_timers);
+	cleanup_timers(&tsk->signal->posix_cputimers);
 }
 
 static inline int expires_gt(u64 expires, u64 new_exp)

@@ -446,10 +446,10 @@ static void arm_timer(struct k_itimer *t
 	struct cpu_timer_list *next;
 
 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
-		head = p->cpu_timers;
+		head = p->posix_cputimers.cpu_timers;
 		cputime_expires = &p->cputime_expires;
 	} else {
-		head = p->signal->cpu_timers;
+		head = p->signal->posix_cputimers.cpu_timers;
 		cputime_expires = &p->signal->cputime_expires;
 	}
 	head += CPUCLOCK_WHICH(timer->it_clock);

@@ -773,8 +773,8 @@ static inline void check_dl_overrun(stru
 static void check_thread_timers(struct task_struct *tsk,
 				struct list_head *firing)
 {
+	struct list_head *timers = tsk->posix_cputimers.cpu_timers;
 	struct task_cputime *tsk_expires = &tsk->cputime_expires;
-	struct list_head *timers = tsk->cpu_timers;
 	u64 expires, stime, utime;
 	unsigned long soft;
 

@@ -879,9 +879,9 @@ static void check_process_timers(struct
 				 struct list_head *firing)
 {
 	struct signal_struct *const sig = tsk->signal;
+	struct list_head *timers = sig->posix_cputimers.cpu_timers;
 	u64 utime, ptime, virt_expires, prof_expires;
 	u64 sum_sched_runtime, sched_expires;
-	struct list_head *timers = sig->cpu_timers;
 	struct task_cputime cputime;
 	unsigned long soft;
 

@@ -25,6 +25,7 @@
 #include <linux/resource.h>
 #include <linux/latencytop.h>
 #include <linux/sched/prio.h>
+#include <linux/sched/types.h>
 #include <linux/signal_types.h>
 #include <linux/mm_types_task.h>
 #include <linux/task_io_accounting.h>

@@ -245,22 +246,6 @@ struct prev_cputime {
 #endif
 };
 
-/**
- * struct task_cputime - collected CPU time counts
- * @utime:		time spent in user mode, in nanoseconds
- * @stime:		time spent in kernel mode, in nanoseconds
- * @sum_exec_runtime:	total time spent on the CPU, in nanoseconds
- *
- * This structure groups together three kinds of CPU time that are tracked for
- * threads and thread groups.  Most things considering CPU time want to group
- * these counts together and treat all three of them in parallel.
- */
-struct task_cputime {
-	u64				utime;
-	u64				stime;
-	unsigned long long		sum_exec_runtime;
-};
-
 /* Alternate field names when used on cache expirations: */
 #define virt_exp			utime
 #define prof_exp			stime

@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_SCHED_TYPES_H
+#define _LINUX_SCHED_TYPES_H
+
+/**
+ * struct task_cputime - collected CPU time counts
+ * @utime:		time spent in user mode, in nanoseconds
+ * @stime:		time spent in kernel mode, in nanoseconds
+ * @sum_exec_runtime:	total time spent on the CPU, in nanoseconds
+ *
+ * This structure groups together three kinds of CPU time that are tracked for
+ * threads and thread groups.  Most things considering CPU time want to group
+ * these counts together and treat all three of them in parallel.
+ */
+struct task_cputime {
+	u64				utime;
+	u64				stime;
+	unsigned long long		sum_exec_runtime;
+};
+
+#endif

@@ -62,24 +62,49 @@ static inline int clockid_to_fd(const cl
 	return ~(clk >> 3);
 }
 
+/*
+ * Alternate field names for struct task_cputime when used on cache
+ * expirations. Will go away soon.
+ */
+#define virt_exp			utime
+#define prof_exp			stime
+#define sched_exp			sum_exec_runtime
+
+#ifdef CONFIG_POSIX_TIMERS
 /**
  * posix_cputimers - Container for posix CPU timer related data
+ * @cputime_expires:	Earliest-expiration cache
  * @cpu_timers:		List heads to queue posix CPU timers
  *
  * Used in task_struct and signal_struct
  */
 struct posix_cputimers {
+	struct task_cputime	cputime_expires;
 	struct list_head	cpu_timers[CPUCLOCK_MAX];
 };
 
 static inline void posix_cputimers_init(struct posix_cputimers *pct)
 {
+	memset(&pct->cputime_expires, 0, sizeof(pct->cputime_expires));
 	INIT_LIST_HEAD(&pct->cpu_timers[0]);
 	INIT_LIST_HEAD(&pct->cpu_timers[1]);
 	INIT_LIST_HEAD(&pct->cpu_timers[2]);
 }
 
-#ifdef CONFIG_POSIX_TIMERS
+static inline void posix_cputimers_group_init(struct posix_cputimers *pct,
+					      u64 cpu_limit)
+{
+	posix_cputimers_init(pct);
+	if (cpu_limit != RLIM_INFINITY)
+		pct->cputime_expires.prof_exp = cpu_limit * NSEC_PER_SEC;
+}
+
+static inline void posix_cputimers_rt_watchdog(struct posix_cputimers *pct,
+					       u64 runtime)
+{
+	pct->cputime_expires.sched_exp = runtime;
+}
+
 /* Init task static initializer */
 #define INIT_CPU_TIMERLISTS(c)	{					\
 	LIST_HEAD_INIT(c.cpu_timers[0]),				\

@@ -92,7 +117,11 @@ static inline void posix_cputimers_init(
 		.cpu_timers = INIT_CPU_TIMERLISTS(s.posix_cputimers),	\
 	},
 #else
+struct posix_cputimers { };
 #define INIT_CPU_TIMERS(s)
+static inline void posix_cputimers_init(struct posix_cputimers *pct) { }
+static inline void posix_cputimers_group_init(struct posix_cputimers *pct,
+					      u64 cpu_limit) { }
 #endif
 
 #define REQUEUE_PENDING 1

@@ -246,11 +246,6 @@ struct prev_cputime {
 #endif
 };
 
-/* Alternate field names when used on cache expirations: */
-#define virt_exp			utime
-#define prof_exp			stime
-#define sched_exp			sum_exec_runtime
-
 enum vtime_state {
 	/* Task is sleeping or running in a CPU with VTIME inactive: */
 	VTIME_INACTIVE = 0,

@@ -863,7 +858,6 @@ struct task_struct {
 	unsigned long			maj_flt;
 
 #ifdef CONFIG_POSIX_TIMERS
-	struct task_cputime		cputime_expires;
 	struct posix_cputimers		posix_cputimers;
 #endif
 

@@ -149,9 +149,6 @@ struct signal_struct {
 	 */
 	struct thread_group_cputimer cputimer;
 
-	/* Earliest-expiration cache. */
-	struct task_cputime cputime_expires;
-
 	struct posix_cputimers posix_cputimers;
 #endif
 

@@ -1527,12 +1527,9 @@ static void posix_cpu_timers_init_group(
 	unsigned long cpu_limit;
 
 	cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
-	if (cpu_limit != RLIM_INFINITY) {
-		sig->cputime_expires.prof_exp = cpu_limit * NSEC_PER_SEC;
+	posix_cputimers_group_init(pct, cpu_limit);
+	if (cpu_limit != RLIM_INFINITY)
 		sig->cputimer.running = true;
-	}
-
-	posix_cputimers_init(pct);
 }
 #else
 static inline void posix_cpu_timers_init_group(struct signal_struct *sig) { }

@@ -1638,22 +1635,6 @@ static void rt_mutex_init_task(struct ta
 #endif
 }
 
-#ifdef CONFIG_POSIX_TIMERS
-/*
- * Initialize POSIX timer handling for a single task.
- */
-static void posix_cpu_timers_init(struct task_struct *tsk)
-{
-	tsk->cputime_expires.prof_exp = 0;
-	tsk->cputime_expires.virt_exp = 0;
-	tsk->cputime_expires.sched_exp = 0;
-
-	posix_cputimers_init(&tsk->posix_cputimers);
-}
-#else
-static inline void posix_cpu_timers_init(struct task_struct *tsk) { }
-#endif
-
 static inline void init_task_pid_links(struct task_struct *task)
 {
 	enum pid_type type;

@@ -1932,7 +1913,7 @@ static __latent_entropy struct task_stru
 	task_io_accounting_init(&p->ioac);
 	acct_clear_integrals(p);
 
-	posix_cpu_timers_init(p);
+	posix_cputimers_init(&p->posix_cputimers);
 
 	p->io_context = NULL;
 	audit_set_context(p, NULL);

@@ -2305,8 +2305,10 @@ static void watchdog(struct rq *rq, stru
 		}
 
 		next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
-		if (p->rt.timeout > next)
-			p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
+		if (p->rt.timeout > next) {
+			posix_cputimers_rt_watchdog(&p->posix_cputimers,
+						    p->se.sum_exec_runtime);
+		}
 	}
 }
 #else

@@ -22,9 +22,9 @@ static void posix_cpu_timer_rearm(struct
 
 /*
  * Called after updating RLIMIT_CPU to run cpu timer and update
- * tsk->signal->cputime_expires expiration cache if necessary. Needs
- * siglock protection since other code may update expiration cache as
- * well.
+ * tsk->signal->posix_cputimers.cputime_expires expiration cache if
+ * necessary. Needs siglock protection since other code may update
+ * expiration cache as well.
  */
 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
 {

@@ -447,10 +447,10 @@ static void arm_timer(struct k_itimer *t
 
 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 		head = p->posix_cputimers.cpu_timers;
-		cputime_expires = &p->cputime_expires;
+		cputime_expires = &p->posix_cputimers.cputime_expires;
 	} else {
 		head = p->signal->posix_cputimers.cpu_timers;
-		cputime_expires = &p->signal->cputime_expires;
+		cputime_expires = &p->signal->posix_cputimers.cputime_expires;
 	}
 	head += CPUCLOCK_WHICH(timer->it_clock);
 

@@ -774,7 +774,7 @@ static void check_thread_timers(struct t
 				struct list_head *firing)
 {
 	struct list_head *timers = tsk->posix_cputimers.cpu_timers;
-	struct task_cputime *tsk_expires = &tsk->cputime_expires;
+	struct task_cputime *tsk_expires = &tsk->posix_cputimers.cputime_expires;
 	u64 expires, stime, utime;
 	unsigned long soft;
 

@@ -785,7 +785,7 @@ static void check_thread_timers(struct t
 	 * If cputime_expires is zero, then there are no active
 	 * per thread CPU timers.
 	 */
-	if (task_cputime_zero(&tsk->cputime_expires))
+	if (task_cputime_zero(tsk_expires))
 		return;
 
 	task_cputime(tsk, &utime, &stime);

@@ -954,10 +954,10 @@ static void check_process_timers(struct
 			prof_expires = x;
 	}
 
-	sig->cputime_expires.prof_exp = prof_expires;
-	sig->cputime_expires.virt_exp = virt_expires;
-	sig->cputime_expires.sched_exp = sched_expires;
-	if (task_cputime_zero(&sig->cputime_expires))
+	sig->posix_cputimers.cputime_expires.prof_exp = prof_expires;
+	sig->posix_cputimers.cputime_expires.virt_exp = virt_expires;
+	sig->posix_cputimers.cputime_expires.sched_exp = sched_expires;
+	if (task_cputime_zero(&sig->posix_cputimers.cputime_expires))
 		stop_process_timers(sig);
 
 	sig->cputimer.checking_timer = false;

@@ -1058,12 +1058,13 @@ static inline int fastpath_timer_check(s
 {
 	struct signal_struct *sig;
 
-	if (!task_cputime_zero(&tsk->cputime_expires)) {
+	if (!task_cputime_zero(&tsk->posix_cputimers.cputime_expires)) {
 		struct task_cputime task_sample;
 
 		task_cputime(tsk, &task_sample.utime, &task_sample.stime);
 		task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime;
-		if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
+		if (task_cputime_expired(&task_sample,
+					 &tsk->posix_cputimers.cputime_expires))
 			return 1;
 	}
 

@@ -1088,7 +1089,8 @@ static inline int fastpath_timer_check(s
 
 		sample_cputime_atomic(&group_sample, &sig->cputimer.cputime_atomic);
 
-		if (task_cputime_expired(&group_sample, &sig->cputime_expires))
+		if (task_cputime_expired(&group_sample,
+					 &sig->posix_cputimers.cputime_expires))
 			return 1;
 	}
 

@@ -1218,12 +1220,12 @@ void set_process_cpu_timer(struct task_s
 	 */
 	switch (clock_idx) {
 	case CPUCLOCK_PROF:
-		if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
-			tsk->signal->cputime_expires.prof_exp = *newval;
+		if (expires_gt(tsk->signal->posix_cputimers.cputime_expires.prof_exp, *newval))
+			tsk->signal->posix_cputimers.cputime_expires.prof_exp = *newval;
 		break;
 	case CPUCLOCK_VIRT:
-		if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
-			tsk->signal->cputime_expires.virt_exp = *newval;
+		if (expires_gt(tsk->signal->posix_cputimers.cputime_expires.virt_exp, *newval))
+			tsk->signal->posix_cputimers.cputime_expires.virt_exp = *newval;
 		break;
 	}
 

@@ -65,27 +65,39 @@ static inline int clockid_to_fd(const cl
 /*
  * Alternate field names for struct task_cputime when used on cache
  * expirations. Will go away soon.
+ *
+ * stime corresponds to CLOCKCPU_PROF
+ * utime corresponds to CLOCKCPU_VIRT
+ * sum_exex_runtime corresponds to CLOCKCPU_SCHED
+ *
+ * The ordering is currently enforced so struct task_cputime and the
+ * expiries array in struct posix_cputimers are equivalent.
  */
-#define virt_exp			utime
 #define prof_exp			stime
+#define virt_exp			utime
 #define sched_exp			sum_exec_runtime
 
 #ifdef CONFIG_POSIX_TIMERS
 /**
  * posix_cputimers - Container for posix CPU timer related data
- * @cputime_expires:	Earliest-expiration cache
+ * @cputime_expires:	Earliest-expiration cache task_cputime based
+ * @expiries:		Earliest-expiration cache array based
  * @cpu_timers:		List heads to queue posix CPU timers
  *
  * Used in task_struct and signal_struct
  */
 struct posix_cputimers {
-	struct task_cputime	cputime_expires;
-	struct list_head	cpu_timers[CPUCLOCK_MAX];
+	/* Temporary union until all users are cleaned up */
+	union {
+		struct task_cputime	cputime_expires;
+		u64			expiries[CPUCLOCK_MAX];
+	};
+	struct list_head		cpu_timers[CPUCLOCK_MAX];
 };
 
 static inline void posix_cputimers_init(struct posix_cputimers *pct)
 {
-	memset(&pct->cputime_expires, 0, sizeof(pct->cputime_expires));
+	memset(&pct->expiries, 0, sizeof(pct->expiries));
 	INIT_LIST_HEAD(&pct->cpu_timers[0]);
 	INIT_LIST_HEAD(&pct->cpu_timers[1]);
 	INIT_LIST_HEAD(&pct->cpu_timers[2]);

@@ -96,13 +108,13 @@ static inline void posix_cputimers_group
 {
 	posix_cputimers_init(pct);
 	if (cpu_limit != RLIM_INFINITY)
-		pct->cputime_expires.prof_exp = cpu_limit * NSEC_PER_SEC;
+		pct->expiries[CPUCLOCK_PROF] = cpu_limit * NSEC_PER_SEC;
 }
 
 static inline void posix_cputimers_rt_watchdog(struct posix_cputimers *pct,
 					       u64 runtime)
 {
-	pct->cputime_expires.sched_exp = runtime;
+	pct->expiries[CPUCLOCK_SCHED] = runtime;
 }
 
 /* Init task static initializer */

@@ -4,8 +4,8 @@
 
 /**
  * struct task_cputime - collected CPU time counts
- * @utime:		time spent in user mode, in nanoseconds
  * @stime:		time spent in kernel mode, in nanoseconds
+ * @utime:		time spent in user mode, in nanoseconds
  * @sum_exec_runtime:	total time spent on the CPU, in nanoseconds
  *
  * This structure groups together three kinds of CPU time that are tracked for

@@ -13,8 +13,8 @@
  * these counts together and treat all three of them in parallel.
  */
 struct task_cputime {
-	u64				utime;
 	u64				stime;
+	u64				utime;
 	unsigned long long		sum_exec_runtime;
 };
 

@@ -18,6 +18,16 @@
 
 #include "posix-timers.h"
 
+static inline void temporary_check(void)
+{
+	BUILD_BUG_ON(offsetof(struct task_cputime, stime) !=
+		     CPUCLOCK_PROF * sizeof(u64));
+	BUILD_BUG_ON(offsetof(struct task_cputime, utime) !=
+		     CPUCLOCK_VIRT * sizeof(u64));
+	BUILD_BUG_ON(offsetof(struct task_cputime, sum_exec_runtime) !=
+		     CPUCLOCK_SCHED * sizeof(u64));
+}
+
 static void posix_cpu_timer_rearm(struct k_itimer *timer);
 
 /*

@@ -449,20 +449,20 @@ static inline int expires_gt(u64 expires
  */
 static void arm_timer(struct k_itimer *timer)
 {
+	struct cpu_timer_list *const nt = &timer->it.cpu;
+	int clkidx = CPUCLOCK_WHICH(timer->it_clock);
+	u64 *cpuexp, newexp = timer->it.cpu.expires;
 	struct task_struct *p = timer->it.cpu.task;
 	struct list_head *head, *listpos;
-	struct task_cputime *cputime_expires;
-	struct cpu_timer_list *const nt = &timer->it.cpu;
 	struct cpu_timer_list *next;
 
 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
-		head = p->posix_cputimers.cpu_timers;
-		cputime_expires = &p->posix_cputimers.cputime_expires;
+		head = p->posix_cputimers.cpu_timers + clkidx;
+		cpuexp = p->posix_cputimers.expiries + clkidx;
 	} else {
-		head = p->signal->posix_cputimers.cpu_timers;
-		cputime_expires = &p->signal->posix_cputimers.cputime_expires;
+		head = p->signal->posix_cputimers.cpu_timers + clkidx;
+		cpuexp = p->signal->posix_cputimers.expiries + clkidx;
 	}
-	head += CPUCLOCK_WHICH(timer->it_clock);
 
 	listpos = head;
 	list_for_each_entry(next, head, entry) {

@@ -472,35 +472,22 @@ static void arm_timer(struct k_itimer *t
 	}
 	list_add(&nt->entry, listpos);
 
-	if (listpos == head) {
-		u64 exp = nt->expires;
+	if (listpos != head)
+		return;
 
-		/*
-		 * We are the new earliest-expiring POSIX 1.b timer, hence
-		 * need to update expiration cache. Take into account that
-		 * for process timers we share expiration cache with itimers
-		 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
-		 */
-
-		switch (CPUCLOCK_WHICH(timer->it_clock)) {
-		case CPUCLOCK_PROF:
-			if (expires_gt(cputime_expires->prof_exp, exp))
-				cputime_expires->prof_exp = exp;
-			break;
-		case CPUCLOCK_VIRT:
-			if (expires_gt(cputime_expires->virt_exp, exp))
-				cputime_expires->virt_exp = exp;
-			break;
-		case CPUCLOCK_SCHED:
-			if (expires_gt(cputime_expires->sched_exp, exp))
-				cputime_expires->sched_exp = exp;
-			break;
-		}
-		if (CPUCLOCK_PERTHREAD(timer->it_clock))
-			tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
-		else
-			tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);
-	}
+	/*
+	 * We are the new earliest-expiring POSIX 1.b timer, hence
+	 * need to update expiration cache. Take into account that
+	 * for process timers we share expiration cache with itimers
+	 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
+	 */
+	if (expires_gt(*cpuexp, newexp))
+		*cpuexp = newexp;
+
+	if (CPUCLOCK_PERTHREAD(timer->it_clock))
+		tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
+	else
+		tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);
 }
 
 /*

@@ -1181,15 +1181,15 @@ void run_posix_cpu_timers(void)
  * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
  * The tsk->sighand->siglock must be held by the caller.
  */
-void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
+void set_process_cpu_timer(struct task_struct *tsk, unsigned int clkid,
 			   u64 *newval, u64 *oldval)
 {
-	u64 now;
+	u64 now, *expiry = tsk->signal->posix_cputimers.expiries + clkid;
 
-	if (WARN_ON_ONCE(clock_idx >= CPUCLOCK_SCHED))
+	if (WARN_ON_ONCE(clkid >= CPUCLOCK_SCHED))
 		return;
 
-	now = cpu_clock_sample_group(clock_idx, tsk, true);
+	now = cpu_clock_sample_group(clkid, tsk, true);
 
 	if (oldval) {
 		/*

@@ -1212,19 +1212,11 @@ void set_process_cpu_timer(struct task_s
 	}
 
 	/*
-	 * Update expiration cache if we are the earliest timer, or eventually
-	 * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
+	 * Update expiration cache if this is the earliest timer. CPUCLOCK_PROF
+	 * expiry cache is also used by RLIMIT_CPU!.
 	 */
-	switch (clock_idx) {
-	case CPUCLOCK_PROF:
-		if (expires_gt(tsk->signal->posix_cputimers.cputime_expires.prof_exp, *newval))
-			tsk->signal->posix_cputimers.cputime_expires.prof_exp = *newval;
-		break;
-	case CPUCLOCK_VIRT:
-		if (expires_gt(tsk->signal->posix_cputimers.cputime_expires.virt_exp, *newval))
-			tsk->signal->posix_cputimers.cputime_expires.virt_exp = *newval;
-		break;
-	}
+	if (expires_gt(*expiry, *newval))
+		*expiry = *newval;
 
 	tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER);
 }

@@ -771,8 +771,7 @@ static void check_thread_timers(struct t
 				struct list_head *firing)
 {
 	struct list_head *timers = tsk->posix_cputimers.cpu_timers;
-	struct task_cputime *tsk_expires = &tsk->posix_cputimers.cputime_expires;
-	u64 expires, stime, utime;
+	u64 stime, utime, *expires = tsk->posix_cputimers.expiries;
 	unsigned long soft;
 
 	if (dl_task(tsk))

@@ -782,19 +781,14 @@ static void check_thread_timers(struct t
 	 * If cputime_expires is zero, then there are no active
 	 * per thread CPU timers.
 	 */
-	if (task_cputime_zero(tsk_expires))
+	if (task_cputime_zero(&tsk->posix_cputimers.cputime_expires))
 		return;
 
 	task_cputime(tsk, &utime, &stime);
 
-	expires = check_timers_list(timers, firing, utime + stime);
-	tsk_expires->prof_exp = expires;
-
-	expires = check_timers_list(++timers, firing, utime);
-	tsk_expires->virt_exp = expires;
-
-	tsk_expires->sched_exp = check_timers_list(++timers, firing,
-						   tsk->se.sum_exec_runtime);
+	*expires++ = check_timers_list(timers, firing, utime + stime);
+	*expires++ = check_timers_list(++timers, firing, utime);
+	*expires = check_timers_list(++timers, firing, tsk->se.sum_exec_runtime);
 
 	/*
 	 * Check for the special case thread timers.

@@ -832,7 +826,8 @@ static void check_thread_timers(struct t
 			__group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
 		}
 	}
-	if (task_cputime_zero(tsk_expires))
+
+	if (task_cputime_zero(&tsk->posix_cputimers.cputime_expires))
 		tick_dep_clear_task(tsk, TICK_DEP_BIT_POSIX_TIMER);
 }
 

@@ -951,9 +946,10 @@ static void check_process_timers(struct
 			prof_expires = x;
 	}
 
-	sig->posix_cputimers.cputime_expires.prof_exp = prof_expires;
-	sig->posix_cputimers.cputime_expires.virt_exp = virt_expires;
-	sig->posix_cputimers.cputime_expires.sched_exp = sched_expires;
+	sig->posix_cputimers.expiries[CPUCLOCK_PROF] = prof_expires;
+	sig->posix_cputimers.expiries[CPUCLOCK_VIRT] = virt_expires;
+	sig->posix_cputimers.expiries[CPUCLOCK_SCHED] = sched_expires;
+
 	if (task_cputime_zero(&sig->posix_cputimers.cputime_expires))
 		stop_process_timers(sig);
 

@@ -62,21 +62,6 @@ static inline int clockid_to_fd(const cl
 	return ~(clk >> 3);
 }
 
-/*
- * Alternate field names for struct task_cputime when used on cache
- * expirations. Will go away soon.
- *
- * stime corresponds to CLOCKCPU_PROF
- * utime corresponds to CLOCKCPU_VIRT
- * sum_exex_runtime corresponds to CLOCKCPU_SCHED
- *
- * The ordering is currently enforced so struct task_cputime and the
- * expiries array in struct posix_cputimers are equivalent.
- */
-#define prof_exp			stime
-#define virt_exp			utime
-#define sched_exp			sum_exec_runtime
-
 #ifdef CONFIG_POSIX_TIMERS
 /**
  * posix_cputimers - Container for posix CPU timer related data

@@ -195,6 +195,32 @@ static u64 cpu_clock_sample(const clocki
 	return 0;
 }
 
+static inline void store_samples(u64 *samples, u64 stime, u64 utime, u64 rtime)
+{
+	samples[CPUCLOCK_PROF] = stime + utime;
+	samples[CPUCLOCK_VIRT] = utime;
+	samples[CPUCLOCK_SCHED] = rtime;
+}
+
+static void task_sample_cputime(struct task_struct *p, u64 *samples)
+{
+	u64 stime, utime;
+
+	task_cputime(p, &utime, &stime);
+	store_samples(samples, stime, utime, p->se.sum_exec_runtime);
+}
+
+static void proc_sample_cputime_atomic(struct task_cputime_atomic *at,
+				       u64 *samples)
+{
+	u64 stime, utime, rtime;
+
+	utime = atomic64_read(&at->utime);
+	stime = atomic64_read(&at->stime);
+	rtime = atomic64_read(&at->sum_exec_runtime);
+	store_samples(samples, stime, utime, rtime);
+}
+
 /*
  * Set cputime to sum_cputime if sum_cputime > cputime. Use cmpxchg
  * to avoid race conditions with concurrent updates to cputime.

@@ -32,7 +32,7 @@ static void posix_cpu_timer_rearm(struct
 
 /*
  * Called after updating RLIMIT_CPU to run cpu timer and update
- * tsk->signal->posix_cputimers.cputime_expires expiration cache if
+ * tsk->signal->posix_cputimers.expiries expiration cache if
  * necessary. Needs siglock protection since other code may update
  * expiration cache as well.
  */

@@ -125,19 +125,9 @@ static void bump_cpu_timer(struct k_itim
 	}
 }
 
-/**
- * task_cputime_zero - Check a task_cputime struct for all zero fields.
- *
- * @cputime:	The struct to compare.
- *
- * Checks @cputime to see if all fields are zero.  Returns true if all fields
- * are zero, false if any field is nonzero.
- */
-static inline int task_cputime_zero(const struct task_cputime *cputime)
+static inline bool expiry_cache_is_zero(const u64 *ec)
 {
-	if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
-		return 1;
-	return 0;
+	return !(ec[CPUCLOCK_PROF] | ec[CPUCLOCK_VIRT] | ec[CPUCLOCK_SCHED]);
 }
 
 static int

@@ -804,10 +794,10 @@ static void check_thread_timers(struct t
 		check_dl_overrun(tsk);
 
 	/*
-	 * If cputime_expires is zero, then there are no active
-	 * per thread CPU timers.
+	 * If the expiry cache is zero, then there are no active per thread
+	 * CPU timers.
 	 */
-	if (task_cputime_zero(&tsk->posix_cputimers.cputime_expires))
+	if (expiry_cache_is_zero(tsk->posix_cputimers.expiries))
 		return;
 
 	task_cputime(tsk, &utime, &stime);

@@ -853,7 +843,7 @@ static void check_thread_timers(struct t
 		}
 	}
 
-	if (task_cputime_zero(&tsk->posix_cputimers.cputime_expires))
+	if (expiry_cache_is_zero(tsk->posix_cputimers.expiries))
 		tick_dep_clear_task(tsk, TICK_DEP_BIT_POSIX_TIMER);
 }
 

@@ -976,7 +966,7 @@ static void check_process_timers(struct
 	sig->posix_cputimers.expiries[CPUCLOCK_VIRT] = virt_expires;
 	sig->posix_cputimers.expiries[CPUCLOCK_SCHED] = sched_expires;
 
-	if (task_cputime_zero(&sig->posix_cputimers.cputime_expires))
+	if (expiry_cache_is_zero(sig->posix_cputimers.expiries))
 		stop_process_timers(sig);
 
 	sig->cputimer.checking_timer = false;

@@ -1041,26 +1031,23 @@ static void posix_cpu_timer_rearm(struct
 }
 
 /**
- * task_cputime_expired - Compare two task_cputime entities.
+ * task_cputimers_expired - Compare two task_cputime entities.
  *
- * @sample:	The task_cputime structure to be checked for expiration.
- * @expires:	Expiration times, against which @sample will be checked.
+ * @samples:	Array of current samples for the CPUCLOCK clocks
+ * @expiries:	Array of expiry values for the CPUCLOCK clocks
  *
- * Checks @sample against @expires to see if any field of @sample has expired.
- * Returns true if any field of the former is greater than the corresponding
- * field of the latter if the latter field is set.  Otherwise returns false.
+ * Returns true if any mmember of @samples is greater than the corresponding
+ * member of @expiries if that member is non zero. False otherwise
  */
-static inline int task_cputime_expired(const struct task_cputime *sample,
-					const struct task_cputime *expires)
+static inline bool task_cputimers_expired(const u64 *sample, const u64 *expiries)
 {
-	if (expires->utime && sample->utime >= expires->utime)
-		return 1;
-	if (expires->stime && sample->utime + sample->stime >= expires->stime)
-		return 1;
-	if (expires->sum_exec_runtime != 0 &&
-	    sample->sum_exec_runtime >= expires->sum_exec_runtime)
-		return 1;
-	return 0;
+	int i;
+
+	for (i = 0; i < CPUCLOCK_MAX; i++) {
+		if (expiries[i] && sample[i] >= expiries[i])
+			return true;
+	}
+	return false;
 }
 
 /**

@@ -1073,18 +1060,17 @@ static inline int task_cputime_expired(c
  * timers and compare them with the corresponding expiration times.  Return
  * true if a timer has expired, else return false.
  */
-static inline int fastpath_timer_check(struct task_struct *tsk)
+static inline bool fastpath_timer_check(struct task_struct *tsk)
 {
+	u64 *expiries = tsk->posix_cputimers.expiries;
 	struct signal_struct *sig;
 
-	if (!task_cputime_zero(&tsk->posix_cputimers.cputime_expires)) {
-		struct task_cputime task_sample;
+	if (!expiry_cache_is_zero(expiries)) {
+		u64 samples[CPUCLOCK_MAX];
 
-		task_cputime(tsk, &task_sample.utime, &task_sample.stime);
-		task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime;
-		if (task_cputime_expired(&task_sample,
-					 &tsk->posix_cputimers.cputime_expires))
-			return 1;
+		task_sample_cputime(tsk, samples);
+		if (task_cputimers_expired(samples, expiries))
+			return true;
 	}
 
 	sig = tsk->signal;