X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fposix-cpu-timers.c;h=2eae91f954ca2ed98b05e2c145b38c2cb857fbb5;hb=f6a4c8bdb30370991905941ddf85d28dde7370b1;hp=b3f3edc475de16a56b85ef64c45dbcff6805d35b;hpb=e03d13e985d48ac4885382c9e3b1510c78bd047f;p=safe%2Fjmp%2Flinux-2.6

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index b3f3edc..2eae91f 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -7,7 +7,7 @@
 #include <asm/uaccess.h>
 #include <linux/errno.h>
 
-static int check_clock(clockid_t which_clock)
+static int check_clock(const clockid_t which_clock)
 {
 	int error = 0;
 	struct task_struct *p;
@@ -20,9 +20,9 @@ static int check_clock(clockid_t which_clock)
 		return 0;
 
 	read_lock(&tasklist_lock);
-	p = find_task_by_pid(pid);
-	if (!p || (CPUCLOCK_PERTHREAD(which_clock) ?
-		   p->tgid != current->tgid : p->tgid != pid)) {
+	p = find_task_by_vpid(pid);
+	if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
+		   same_thread_group(p, current) : thread_group_leader(p))) {
 		error = -EINVAL;
 	}
 	read_unlock(&tasklist_lock);
@@ -31,19 +31,19 @@ static int check_clock(clockid_t which_clock)
 }
 
 static inline union cpu_time_count
-timespec_to_sample(clockid_t which_clock, const struct timespec *tp)
+timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
 {
 	union cpu_time_count ret;
 	ret.sched = 0;		/* high half always zero when .cpu used */
 	if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
-		ret.sched = tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
+		ret.sched = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
 	} else {
 		ret.cpu = timespec_to_cputime(tp);
 	}
 	return ret;
 }
 
-static void sample_to_timespec(clockid_t which_clock,
+static void sample_to_timespec(const clockid_t which_clock,
 			       union cpu_time_count cpu,
 			       struct timespec *tp)
 {
@@ -55,7 +55,7 @@ static void sample_to_timespec(clockid_t which_clock,
 	}
 }
 
-static inline int cpu_time_before(clockid_t which_clock,
+static inline int cpu_time_before(const clockid_t which_clock,
 				  union cpu_time_count now,
 				  union cpu_time_count then)
 {
@@ -65,7 +65,7 @@ static inline int cpu_time_before(clockid_t which_clock,
 		return cputime_lt(now.cpu, then.cpu);
 	}
 }
-static inline void cpu_time_add(clockid_t which_clock,
+static inline void cpu_time_add(const clockid_t which_clock,
 				union cpu_time_count *acc,
 			        union cpu_time_count val)
 {
@@ -75,7 +75,7 @@ static inline void cpu_time_add(clockid_t which_clock,
 		acc->cpu = cputime_add(acc->cpu, val.cpu);
 	}
 }
-static inline union cpu_time_count cpu_time_sub(clockid_t which_clock,
+static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock,
 						union cpu_time_count a,
 						union cpu_time_count b)
 {
@@ -88,10 +88,23 @@ static inline union cpu_time_count cpu_time_sub(clockid_t which_clock,
 }
 
 /*
+ * Divide and limit the result to res >= 1
+ *
+ * This is necessary to prevent signal delivery starvation, when the result of
+ * the division would be rounded down to 0.
+ */
+static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div)
+{
+	cputime_t res = cputime_div(time, div);
+
+	return max_t(cputime_t, res, 1);
+}
+
+/*
  * Update expiry time from increment, and increase overrun count,
  * given the current clock sample.
  */
-static inline void bump_cpu_timer(struct k_itimer *timer,
+static void bump_cpu_timer(struct k_itimer *timer,
 				  union cpu_time_count now)
 {
 	int i;
@@ -110,7 +123,7 @@ static inline void bump_cpu_timer(struct k_itimer *timer,
 		for (i = 0; incr < delta - incr; i++)
 			incr = incr << 1;
 		for (; i >= 0; incr >>= 1, i--) {
-			if (delta <= incr)
+			if (delta < incr)
 				continue;
 			timer->it.cpu.expires.sched += incr;
 			timer->it_overrun += 1 << i;
@@ -128,7 +141,7 @@ static inline void bump_cpu_timer(struct k_itimer *timer,
 		for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
 			     incr = cputime_add(incr, incr);
 		for (; i >= 0; incr = cputime_halve(incr), i--) {
-			if (cputime_le(delta, incr))
+			if (cputime_lt(delta, incr))
 				continue;
 			timer->it.cpu.expires.cpu =
 				cputime_add(timer->it.cpu.expires.cpu, incr);
@@ -148,10 +161,10 @@ static inline cputime_t virt_ticks(struct task_struct *p)
 }
 static inline unsigned long long sched_ns(struct task_struct *p)
 {
-	return (p == current) ? current_sched_time(p) : p->sched_time;
+	return task_sched_runtime(p);
 }
 
-int posix_cpu_clock_getres(clockid_t which_clock, struct timespec *tp)
+int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
 {
 	int error = check_clock(which_clock);
 	if (!error) {
@@ -169,7 +182,7 @@ int posix_cpu_clock_getres(clockid_t which_clock, struct timespec *tp)
 	return error;
 }
 
-int posix_cpu_clock_set(clockid_t which_clock, const struct timespec *tp)
+int posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
 {
 	/*
 	 * You can never reset a CPU clock, but we check for other errors
@@ -186,7 +199,7 @@ int posix_cpu_clock_set(clockid_t which_clock, const struct timespec *tp)
 /*
  * Sample a per-thread clock for the given task.
  */
-static int cpu_clock_sample(clockid_t which_clock, struct task_struct *p,
+static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
 			    union cpu_time_count *cpu)
 {
 	switch (CPUCLOCK_WHICH(which_clock)) {
@@ -233,23 +246,12 @@ static int cpu_clock_sample_group_locked(unsigned int clock_idx,
 		} while (t != p);
 		break;
 	case CPUCLOCK_SCHED:
-		cpu->sched = p->signal->sched_time;
+		cpu->sched = p->signal->sum_sched_runtime;
 		/* Add in each other live thread.  */
 		while ((t = next_thread(t)) != p) {
-			cpu->sched += t->sched_time;
-		}
-		if (p->tgid == current->tgid) {
-			/*
-			 * We're sampling ourselves, so include the
-			 * cycles not yet banked.  We still omit
-			 * other threads running on other CPUs,
-			 * so the total can always be behind as
-			 * much as max(nthreads-1,ncpus) * (NSEC_PER_SEC/HZ).
-			 */
-			cpu->sched += current_sched_time(current);
-		} else {
-			cpu->sched += p->sched_time;
+			cpu->sched += t->se.sum_exec_runtime;
 		}
+		cpu->sched += sched_ns(p);
 		break;
 	}
 	return 0;
@@ -259,7 +261,7 @@ static int cpu_clock_sample_group_locked(unsigned int clock_idx,
  * Sample a process (thread group) clock for the given group_leader task.
  * Must be called with tasklist_lock held for reading.
  */
-static int cpu_clock_sample_group(clockid_t which_clock,
+static int cpu_clock_sample_group(const clockid_t which_clock,
 				  struct task_struct *p,
 				  union cpu_time_count *cpu)
 {
@@ -273,7 +275,7 @@ static int cpu_clock_sample_group(clockid_t which_clock,
 }
 
 
-int posix_cpu_clock_get(clockid_t which_clock, struct timespec *tp)
+int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
 {
 	const pid_t pid = CPUCLOCK_PID(which_clock);
 	int error = -EINVAL;
@@ -302,20 +304,25 @@ int posix_cpu_clock_get(clockid_t which_clock, struct timespec *tp)
 		 * should be able to see it.
 		 */
 		struct task_struct *p;
-		read_lock(&tasklist_lock);
-		p = find_task_by_pid(pid);
+		rcu_read_lock();
+		p = find_task_by_vpid(pid);
 		if (p) {
 			if (CPUCLOCK_PERTHREAD(which_clock)) {
-				if (p->tgid == current->tgid) {
+				if (same_thread_group(p, current)) {
 					error = cpu_clock_sample(which_clock,
 								 p, &rtn);
 				}
-			} else if (p->tgid == pid && p->signal) {
-				error = cpu_clock_sample_group(which_clock,
-							       p, &rtn);
+			} else {
+				read_lock(&tasklist_lock);
+				if (thread_group_leader(p) && p->signal) {
+					error =
+					    cpu_clock_sample_group(which_clock,
+							           p, &rtn);
+				}
+				read_unlock(&tasklist_lock);
 			}
 		}
-		read_unlock(&tasklist_lock);
+		rcu_read_unlock();
 	}
 
 	if (error)
@@ -347,16 +354,16 @@ int posix_cpu_timer_create(struct k_itimer *new_timer)
 		if (pid == 0) {
 			p = current;
 		} else {
-			p = find_task_by_pid(pid);
-			if (p && p->tgid != current->tgid)
+			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_pid(pid);
-			if (p && p->tgid != pid)
+			p = find_task_by_vpid(pid);
+			if (p && !thread_group_leader(p))
 				p = NULL;
 		}
 	}
@@ -380,28 +387,31 @@ int posix_cpu_timer_create(struct k_itimer *new_timer)
 int posix_cpu_timer_del(struct k_itimer *timer)
 {
 	struct task_struct *p = timer->it.cpu.task;
+	int ret = 0;
 
-	if (timer->it.cpu.firing)
-		return TIMER_RETRY;
-
-	if (unlikely(p == NULL))
-		return 0;
+	if (likely(p != NULL)) {
+		read_lock(&tasklist_lock);
+		if (unlikely(p->signal == NULL)) {
+			/*
+			 * We raced with the reaping of the task.
+			 * The deletion should have cleared us off the list.
+			 */
+			BUG_ON(!list_empty(&timer->it.cpu.entry));
+		} else {
+			spin_lock(&p->sighand->siglock);
+			if (timer->it.cpu.firing)
+				ret = TIMER_RETRY;
+			else
+				list_del(&timer->it.cpu.entry);
+			spin_unlock(&p->sighand->siglock);
+		}
+		read_unlock(&tasklist_lock);
 
-	spin_lock(&p->sighand->siglock);
-	if (!list_empty(&timer->it.cpu.entry)) {
-		/*
-		 * Take us off the task's timer list.  We don't need to
-		 * take tasklist_lock and check for the task being reaped.
-		 * If it was reaped, it already called posix_cpu_timers_exit
-		 * and posix_cpu_timers_exit_group to clear all the timers
-		 * that pointed to it.
-		 */
-		list_del(&timer->it.cpu.entry);
-		put_task_struct(p);
+		if (!ret)
+			put_task_struct(p);
 	}
-	spin_unlock(&p->sighand->siglock);
 
-	return 0;
+	return ret;
 }
 
 /*
@@ -412,14 +422,12 @@ int posix_cpu_timer_del(struct k_itimer *timer)
  */
 static void cleanup_timers(struct list_head *head,
 			   cputime_t utime, cputime_t stime,
-			   unsigned long long sched_time)
+			   unsigned long long sum_exec_runtime)
 {
 	struct cpu_timer_list *timer, *next;
 	cputime_t ptime = cputime_add(utime, stime);
 
 	list_for_each_entry_safe(timer, next, head, entry) {
-		put_task_struct(timer->task);
-		timer->task = NULL;
 		list_del_init(&timer->entry);
 		if (cputime_lt(timer->expires.cpu, ptime)) {
 			timer->expires.cpu = cputime_zero;
@@ -431,8 +439,6 @@ static void cleanup_timers(struct list_head *head,
 
 	++head;
 	list_for_each_entry_safe(timer, next, head, entry) {
-		put_task_struct(timer->task);
-		timer->task = NULL;
 		list_del_init(&timer->entry);
 		if (cputime_lt(timer->expires.cpu, utime)) {
 			timer->expires.cpu = cputime_zero;
@@ -444,13 +450,11 @@ static void cleanup_timers(struct list_head *head,
 
 	++head;
 	list_for_each_entry_safe(timer, next, head, entry) {
-		put_task_struct(timer->task);
-		timer->task = NULL;
 		list_del_init(&timer->entry);
-		if (timer->expires.sched < sched_time) {
+		if (timer->expires.sched < sum_exec_runtime) {
 			timer->expires.sched = 0;
 		} else {
-			timer->expires.sched -= sched_time;
+			timer->expires.sched -= sum_exec_runtime;
 		}
 	}
 }
@@ -463,7 +467,7 @@ static void cleanup_timers(struct list_head *head,
 void posix_cpu_timers_exit(struct task_struct *tsk)
 {
 	cleanup_timers(tsk->cpu_timers,
-		       tsk->utime, tsk->stime, tsk->sched_time);
+		       tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
 
 }
 void posix_cpu_timers_exit_group(struct task_struct *tsk)
@@ -471,7 +475,7 @@ void posix_cpu_timers_exit_group(struct task_struct *tsk)
 	cleanup_timers(tsk->signal->cpu_timers,
 		       cputime_add(tsk->utime, tsk->signal->utime),
 		       cputime_add(tsk->stime, tsk->signal->stime),
-		       tsk->sched_time + tsk->signal->sched_time);
+		     tsk->se.sum_exec_runtime + tsk->signal->sum_sched_runtime);
 }
 
 
@@ -489,15 +493,18 @@ static void process_timer_rebalance(struct task_struct *p,
  	struct task_struct *t = p;
 	unsigned int nthreads = atomic_read(&p->signal->live);
 
+	if (!nthreads)
+		return;
+
 	switch (clock_idx) {
 	default:
 		BUG();
 		break;
 	case CPUCLOCK_PROF:
-		left = cputime_div(cputime_sub(expires.cpu, val.cpu),
-				   nthreads);
+		left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu),
+				       nthreads);
 		do {
-			if (!unlikely(t->exit_state)) {
+			if (likely(!(t->flags & PF_EXITING))) {
 				ticks = cputime_add(prof_ticks(t), left);
 				if (cputime_eq(t->it_prof_expires,
 					       cputime_zero) ||
@@ -509,10 +516,10 @@ static void process_timer_rebalance(struct task_struct *p,
 		} while (t != p);
 		break;
 	case CPUCLOCK_VIRT:
-		left = cputime_div(cputime_sub(expires.cpu, val.cpu),
-				   nthreads);
+		left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu),
+				       nthreads);
 		do {
-			if (!unlikely(t->exit_state)) {
+			if (likely(!(t->flags & PF_EXITING))) {
 				ticks = cputime_add(virt_ticks(t), left);
 				if (cputime_eq(t->it_virt_expires,
 					       cputime_zero) ||
@@ -526,9 +533,10 @@ static void process_timer_rebalance(struct task_struct *p,
 	case CPUCLOCK_SCHED:
 		nsleft = expires.sched - val.sched;
 		do_div(nsleft, nthreads);
+		nsleft = max_t(unsigned long long, nsleft, 1);
 		do {
-			if (!unlikely(t->exit_state)) {
-				ns = t->sched_time + nsleft;
+			if (likely(!(t->flags & PF_EXITING))) {
+				ns = t->se.sum_exec_runtime + nsleft;
 				if (t->it_sched_expires == 0 ||
 				    t->it_sched_expires > ns) {
 					t->it_sched_expires = ns;
@@ -576,17 +584,15 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
 	listpos = head;
 	if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
 		list_for_each_entry(next, head, entry) {
-			if (next->expires.sched > nt->expires.sched) {
-				listpos = &next->entry;
+			if (next->expires.sched > nt->expires.sched)
 				break;
-			}
+			listpos = &next->entry;
 		}
 	} else {
 		list_for_each_entry(next, head, entry) {
-			if (cputime_gt(next->expires.cpu, nt->expires.cpu)) {
-				listpos = &next->entry;
+			if (cputime_gt(next->expires.cpu, nt->expires.cpu))
 				break;
-			}
+			listpos = &next->entry;
 		}
 	}
 	list_add(&nt->entry, listpos);
@@ -730,9 +736,15 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
 	 * Disarm any old timer after extracting its expiry time.
 	 */
 	BUG_ON(!irqs_disabled());
+
+	ret = 0;
 	spin_lock(&p->sighand->siglock);
 	old_expires = timer->it.cpu.expires;
-	list_del_init(&timer->it.cpu.entry);
+	if (unlikely(timer->it.cpu.firing)) {
+		timer->it.cpu.firing = -1;
+		ret = TIMER_RETRY;
+	} else
+		list_del_init(&timer->it.cpu.entry);
 	spin_unlock(&p->sighand->siglock);
 
 	/*
@@ -780,7 +792,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
 		}
 	}
 
-	if (unlikely(timer->it.cpu.firing)) {
+	if (unlikely(ret)) {
 		/*
 		 * We are colliding with the timer actually firing.
 		 * Punt after filling in the timer's old value, and
@@ -788,8 +800,6 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
 		 * it as an overrun (thanks to bump_cpu_timer above).
 		 */
 		read_unlock(&tasklist_lock);
-		timer->it.cpu.firing = -1;
-		ret = TIMER_RETRY;
 		goto out;
 	}
 
@@ -955,14 +965,17 @@ void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
 static void check_thread_timers(struct task_struct *tsk,
 				struct list_head *firing)
 {
+	int maxfire;
 	struct list_head *timers = tsk->cpu_timers;
+	struct signal_struct *const sig = tsk->signal;
 
+	maxfire = 20;
 	tsk->it_prof_expires = cputime_zero;
 	while (!list_empty(timers)) {
-		struct cpu_timer_list *t = list_entry(timers->next,
+		struct cpu_timer_list *t = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
-		if (cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
+		if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
 			tsk->it_prof_expires = t->expires.cpu;
 			break;
 		}
@@ -971,12 +984,13 @@ static void check_thread_timers(struct task_struct *tsk,
 	}
 
 	++timers;
+	maxfire = 20;
 	tsk->it_virt_expires = cputime_zero;
 	while (!list_empty(timers)) {
-		struct cpu_timer_list *t = list_entry(timers->next,
+		struct cpu_timer_list *t = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
-		if (cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
+		if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
 			tsk->it_virt_expires = t->expires.cpu;
 			break;
 		}
@@ -985,18 +999,48 @@ static void check_thread_timers(struct task_struct *tsk,
 	}
 
 	++timers;
+	maxfire = 20;
 	tsk->it_sched_expires = 0;
 	while (!list_empty(timers)) {
-		struct cpu_timer_list *t = list_entry(timers->next,
+		struct cpu_timer_list *t = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
-		if (tsk->sched_time < t->expires.sched) {
+		if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
 			tsk->it_sched_expires = t->expires.sched;
 			break;
 		}
 		t->firing = 1;
 		list_move_tail(&t->entry, firing);
 	}
+
+	/*
+	 * Check for the special case thread timers.
+	 */
+	if (sig->rlim[RLIMIT_RTTIME].rlim_cur != RLIM_INFINITY) {
+		unsigned long hard = sig->rlim[RLIMIT_RTTIME].rlim_max;
+		unsigned long *soft = &sig->rlim[RLIMIT_RTTIME].rlim_cur;
+
+		if (hard != RLIM_INFINITY &&
+		    tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
+			/*
+			 * At the hard limit, we just die.
+			 * No need to calculate anything else now.
+			 */
+			__group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
+			return;
+		}
+		if (tsk->rt.timeout > DIV_ROUND_UP(*soft, USEC_PER_SEC/HZ)) {
+			/*
+			 * At the soft limit, send a SIGXCPU every second.
+			 */
+			if (sig->rlim[RLIMIT_RTTIME].rlim_cur
+			    < sig->rlim[RLIMIT_RTTIME].rlim_max) {
+				sig->rlim[RLIMIT_RTTIME].rlim_cur +=
+								USEC_PER_SEC;
+			}
+			__group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
+		}
+	}
 }
 
 /*
@@ -1007,9 +1051,10 @@ static void check_thread_timers(struct task_struct *tsk,
 static void check_process_timers(struct task_struct *tsk,
 				 struct list_head *firing)
 {
+	int maxfire;
 	struct signal_struct *const sig = tsk->signal;
 	cputime_t utime, stime, ptime, virt_expires, prof_expires;
-	unsigned long long sched_time, sched_expires;
+	unsigned long long sum_sched_runtime, sched_expires;
 	struct task_struct *t;
 	struct list_head *timers = sig->cpu_timers;
 
@@ -1029,22 +1074,23 @@ static void check_process_timers(struct task_struct *tsk,
 	 */
 	utime = sig->utime;
 	stime = sig->stime;
-	sched_time = sig->sched_time;
+	sum_sched_runtime = sig->sum_sched_runtime;
 	t = tsk;
 	do {
 		utime = cputime_add(utime, t->utime);
 		stime = cputime_add(stime, t->stime);
-		sched_time += t->sched_time;
+		sum_sched_runtime += t->se.sum_exec_runtime;
 		t = next_thread(t);
 	} while (t != tsk);
 	ptime = cputime_add(utime, stime);
 
+	maxfire = 20;
 	prof_expires = cputime_zero;
 	while (!list_empty(timers)) {
-		struct cpu_timer_list *t = list_entry(timers->next,
+		struct cpu_timer_list *t = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
-		if (cputime_lt(ptime, t->expires.cpu)) {
+		if (!--maxfire || cputime_lt(ptime, t->expires.cpu)) {
 			prof_expires = t->expires.cpu;
 			break;
 		}
@@ -1053,12 +1099,13 @@ static void check_process_timers(struct task_struct *tsk,
 	}
 
 	++timers;
+	maxfire = 20;
 	virt_expires = cputime_zero;
 	while (!list_empty(timers)) {
-		struct cpu_timer_list *t = list_entry(timers->next,
+		struct cpu_timer_list *t = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
-		if (cputime_lt(utime, t->expires.cpu)) {
+		if (!--maxfire || cputime_lt(utime, t->expires.cpu)) {
 			virt_expires = t->expires.cpu;
 			break;
 		}
@@ -1067,12 +1114,13 @@ static void check_process_timers(struct task_struct *tsk,
 	}
 
 	++timers;
+	maxfire = 20;
 	sched_expires = 0;
 	while (!list_empty(timers)) {
-		struct cpu_timer_list *t = list_entry(timers->next,
+		struct cpu_timer_list *t = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
-		if (sched_time < t->expires.sched) {
+		if (!--maxfire || sum_sched_runtime < t->expires.sched) {
 			sched_expires = t->expires.sched;
 			break;
 		}
@@ -1155,19 +1203,26 @@ static void check_process_timers(struct task_struct *tsk,
 		unsigned long long sched_left, sched;
 		const unsigned int nthreads = atomic_read(&sig->live);
 
+		if (!nthreads)
+			return;
+
 		prof_left = cputime_sub(prof_expires, utime);
 		prof_left = cputime_sub(prof_left, stime);
-		prof_left = cputime_div(prof_left, nthreads);
+		prof_left = cputime_div_non_zero(prof_left, nthreads);
 		virt_left = cputime_sub(virt_expires, utime);
-		virt_left = cputime_div(virt_left, nthreads);
+		virt_left = cputime_div_non_zero(virt_left, nthreads);
 		if (sched_expires) {
-			sched_left = sched_expires - sched_time;
+			sched_left = sched_expires - sum_sched_runtime;
 			do_div(sched_left, nthreads);
+			sched_left = max_t(unsigned long long, sched_left, 1);
 		} else {
 			sched_left = 0;
 		}
 		t = tsk;
 		do {
+			if (unlikely(t->flags & PF_EXITING))
+				continue;
+
 			ticks = cputime_add(cputime_add(t->utime, t->stime),
 					    prof_left);
 			if (!cputime_eq(prof_expires, cputime_zero) &&
@@ -1183,16 +1238,12 @@ static void check_process_timers(struct task_struct *tsk,
 				t->it_virt_expires = ticks;
 			}
 
-			sched = t->sched_time + sched_left;
+			sched = t->se.sum_exec_runtime + sched_left;
 			if (sched_expires && (t->it_sched_expires == 0 ||
 					      t->it_sched_expires > sched)) {
 				t->it_sched_expires = sched;
 			}
-
-			do {
-				t = next_thread(t);
-			} while (unlikely(t->exit_state));
-		} while (t != tsk);
+		} while ((t = next_thread(t)) != tsk);
 	}
 }
 
@@ -1209,7 +1260,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
 		/*
 		 * The task was cleaned up already, no future firings.
 		 */
-		return;
+		goto out;
 
 	/*
 	 * Fetch the current sample and update the timer's expiry time.
@@ -1219,7 +1270,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
 		bump_cpu_timer(timer, now);
 		if (unlikely(p->exit_state)) {
 			clear_dead_task(timer, now);
-			return;
+			goto out;
 		}
 		read_lock(&tasklist_lock); /* arm_timer needs it.  */
 	} else {
@@ -1232,8 +1283,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
 			put_task_struct(p);
 			timer->it.cpu.task = p = NULL;
 			timer->it.cpu.expires.sched = 0;
-			read_unlock(&tasklist_lock);
-			return;
+			goto out_unlock;
 		} else if (unlikely(p->exit_state) && thread_group_empty(p)) {
 			/*
 			 * We've noticed that the thread is dead, but
@@ -1241,8 +1291,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
 			 * drop our task ref.
 			 */
 			clear_dead_task(timer, now);
-			read_unlock(&tasklist_lock);
-			return;
+			goto out_unlock;
 		}
 		cpu_clock_sample_group(timer->it_clock, p, &now);
 		bump_cpu_timer(timer, now);
@@ -1254,7 +1303,13 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
 	 */
 	arm_timer(timer, now);
 
+out_unlock:
 	read_unlock(&tasklist_lock);
+
+out:
+	timer->it_overrun_last = timer->it_overrun;
+	timer->it_overrun = -1;
+	++timer->it_requeue_pending;
 }
 
 /*
@@ -1275,35 +1330,35 @@ void run_posix_cpu_timers(struct task_struct *tsk)
 
 	if (UNEXPIRED(prof) && UNEXPIRED(virt) &&
 	    (tsk->it_sched_expires == 0 ||
-	     tsk->sched_time < tsk->it_sched_expires))
+	     tsk->se.sum_exec_runtime < tsk->it_sched_expires))
 		return;
 
 #undef	UNEXPIRED
 
-	BUG_ON(tsk->exit_state);
-
 	/*
 	 * Double-check with locks held.
 	 */
 	read_lock(&tasklist_lock);
-	spin_lock(&tsk->sighand->siglock);
+	if (likely(tsk->signal != NULL)) {
+		spin_lock(&tsk->sighand->siglock);
 
-	/*
-	 * Here we take off tsk->cpu_timers[N] and tsk->signal->cpu_timers[N]
-	 * all the timers that are firing, and put them on the firing list.
-	 */
-	check_thread_timers(tsk, &firing);
-	check_process_timers(tsk, &firing);
+		/*
+		 * Here we take off tsk->cpu_timers[N] and tsk->signal->cpu_timers[N]
+		 * all the timers that are firing, and put them on the firing list.
+		 */
+		check_thread_timers(tsk, &firing);
+		check_process_timers(tsk, &firing);
 
-	/*
-	 * We must release these locks before taking any timer's lock.
-	 * There is a potential race with timer deletion here, as the
-	 * siglock now protects our private firing list.  We have set
-	 * the firing flag in each timer, so that a deletion attempt
-	 * that gets the timer lock before we do will give it up and
-	 * spin until we've taken care of that timer below.
-	 */
-	spin_unlock(&tsk->sighand->siglock);
+		/*
+		 * We must release these locks before taking any timer's lock.
+		 * There is a potential race with timer deletion here, as the
+		 * siglock now protects our private firing list.  We have set
+		 * the firing flag in each timer, so that a deletion attempt
+		 * that gets the timer lock before we do will give it up and
+		 * spin until we've taken care of that timer below.
+		 */
+		spin_unlock(&tsk->sighand->siglock);
+	}
 	read_unlock(&tasklist_lock);
 
 	/*
@@ -1375,7 +1430,7 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
 	 */
 	head = &tsk->signal->cpu_timers[clock_idx];
 	if (list_empty(head) ||
-	    cputime_ge(list_entry(head->next,
+	    cputime_ge(list_first_entry(head,
 				  struct cpu_timer_list, entry)->expires.cpu,
 		       *newval)) {
 		/*
@@ -1388,25 +1443,13 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
 	}
 }
 
-static long posix_cpu_clock_nanosleep_restart(struct restart_block *);
-
-int posix_cpu_nsleep(clockid_t which_clock, int flags,
-		     struct timespec *rqtp)
+static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
+			    struct timespec *rqtp, struct itimerspec *it)
 {
-	struct restart_block *restart_block =
-	    &current_thread_info()->restart_block;
 	struct k_itimer timer;
 	int error;
 
 	/*
-	 * Diagnose required errors first.
-	 */
-	if (CPUCLOCK_PERTHREAD(which_clock) &&
-	    (CPUCLOCK_PID(which_clock) == 0 ||
-	     CPUCLOCK_PID(which_clock) == current->pid))
-		return -EINVAL;
-
-	/*
 	 * Set up a temporary timer and then wait for it to go off.
 	 */
 	memset(&timer, 0, sizeof timer);
@@ -1416,13 +1459,13 @@ int posix_cpu_nsleep(clockid_t which_clock, int flags,
 	error = posix_cpu_timer_create(&timer);
 	timer.it_process = current;
 	if (!error) {
-		struct timespec __user *rmtp;
 		static struct itimerspec zero_it;
-		struct itimerspec it = { .it_value = *rqtp,
-					 .it_interval = {} };
+
+		memset(it, 0, sizeof *it);
+		it->it_value = *rqtp;
 
 		spin_lock_irq(&timer.it_lock);
-		error = posix_cpu_timer_set(&timer, flags, &it, NULL);
+		error = posix_cpu_timer_set(&timer, flags, it, NULL);
 		if (error) {
 			spin_unlock_irq(&timer.it_lock);
 			return error;
@@ -1450,55 +1493,102 @@ int posix_cpu_nsleep(clockid_t which_clock, int flags,
 		 * We were interrupted by a signal.
 		 */
 		sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
-		posix_cpu_timer_set(&timer, 0, &zero_it, &it);
+		posix_cpu_timer_set(&timer, 0, &zero_it, it);
 		spin_unlock_irq(&timer.it_lock);
 
-		if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) {
+		if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
 			/*
 			 * It actually did fire already.
 			 */
 			return 0;
 		}
 
+		error = -ERESTART_RESTARTBLOCK;
+	}
+
+	return error;
+}
+
+int posix_cpu_nsleep(const clockid_t which_clock, int flags,
+		     struct timespec *rqtp, struct timespec __user *rmtp)
+{
+	struct restart_block *restart_block =
+	    &current_thread_info()->restart_block;
+	struct itimerspec it;
+	int error;
+
+	/*
+	 * Diagnose required errors first.
+	 */
+	if (CPUCLOCK_PERTHREAD(which_clock) &&
+	    (CPUCLOCK_PID(which_clock) == 0 ||
+	     CPUCLOCK_PID(which_clock) == current->pid))
+		return -EINVAL;
+
+	error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
+
+	if (error == -ERESTART_RESTARTBLOCK) {
+
+	       	if (flags & TIMER_ABSTIME)
+			return -ERESTARTNOHAND;
 		/*
-		 * Report back to the user the time still remaining.
-		 */
-		rmtp = (struct timespec __user *) restart_block->arg1;
-		if (rmtp != NULL && !(flags & TIMER_ABSTIME) &&
-		    copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
+	 	 * Report back to the user the time still remaining.
+	 	 */
+		if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
 			return -EFAULT;
 
-		restart_block->fn = posix_cpu_clock_nanosleep_restart;
-		/* Caller already set restart_block->arg1 */
+		restart_block->fn = posix_cpu_nsleep_restart;
 		restart_block->arg0 = which_clock;
+		restart_block->arg1 = (unsigned long) rmtp;
 		restart_block->arg2 = rqtp->tv_sec;
 		restart_block->arg3 = rqtp->tv_nsec;
-
-		error = -ERESTART_RESTARTBLOCK;
 	}
-
 	return error;
 }
 
-static long
-posix_cpu_clock_nanosleep_restart(struct restart_block *restart_block)
+long posix_cpu_nsleep_restart(struct restart_block *restart_block)
 {
 	clockid_t which_clock = restart_block->arg0;
-	struct timespec t = { .tv_sec = restart_block->arg2,
-			      .tv_nsec = restart_block->arg3 };
+	struct timespec __user *rmtp;
+	struct timespec t;
+	struct itimerspec it;
+	int error;
+
+	rmtp = (struct timespec __user *) restart_block->arg1;
+	t.tv_sec = restart_block->arg2;
+	t.tv_nsec = restart_block->arg3;
+
 	restart_block->fn = do_no_restart_syscall;
-	return posix_cpu_nsleep(which_clock, TIMER_ABSTIME, &t);
+	error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
+
+	if (error == -ERESTART_RESTARTBLOCK) {
+		/*
+	 	 * Report back to the user the time still remaining.
+	 	 */
+		if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
+			return -EFAULT;
+
+		restart_block->fn = posix_cpu_nsleep_restart;
+		restart_block->arg0 = which_clock;
+		restart_block->arg1 = (unsigned long) rmtp;
+		restart_block->arg2 = t.tv_sec;
+		restart_block->arg3 = t.tv_nsec;
+	}
+	return error;
+
 }
 
 
 #define PROCESS_CLOCK	MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
 #define THREAD_CLOCK	MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
 
-static int process_cpu_clock_getres(clockid_t which_clock, struct timespec *tp)
+static int process_cpu_clock_getres(const clockid_t which_clock,
+				    struct timespec *tp)
 {
 	return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
 }
-static int process_cpu_clock_get(clockid_t which_clock, struct timespec *tp)
+static int process_cpu_clock_get(const clockid_t which_clock,
+				 struct timespec *tp)
 {
 	return posix_cpu_clock_get(PROCESS_CLOCK, tp);
 }
@@ -1507,16 +1597,23 @@ static int process_cpu_timer_create(struct k_itimer *timer)
 	timer->it_clock = PROCESS_CLOCK;
 	return posix_cpu_timer_create(timer);
 }
-static int process_cpu_nsleep(clockid_t which_clock, int flags,
-			      struct timespec *rqtp)
+static int process_cpu_nsleep(const clockid_t which_clock, int flags,
+			      struct timespec *rqtp,
+			      struct timespec __user *rmtp)
+{
+	return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
+}
+static long process_cpu_nsleep_restart(struct restart_block *restart_block)
 {
-	return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp);
+	return -EINVAL;
 }
-static int thread_cpu_clock_getres(clockid_t which_clock, struct timespec *tp)
+static int thread_cpu_clock_getres(const clockid_t which_clock,
+				   struct timespec *tp)
 {
 	return posix_cpu_clock_getres(THREAD_CLOCK, tp);
 }
-static int thread_cpu_clock_get(clockid_t which_clock, struct timespec *tp)
+static int thread_cpu_clock_get(const clockid_t which_clock,
+				struct timespec *tp)
 {
 	return posix_cpu_clock_get(THREAD_CLOCK, tp);
 }
@@ -1525,8 +1622,12 @@ static int thread_cpu_timer_create(struct k_itimer *timer)
 	timer->it_clock = THREAD_CLOCK;
 	return posix_cpu_timer_create(timer);
 }
-static int thread_cpu_nsleep(clockid_t which_clock, int flags,
-			      struct timespec *rqtp)
+static int thread_cpu_nsleep(const clockid_t which_clock, int flags,
+			      struct timespec *rqtp, struct timespec __user *rmtp)
+{
+	return -EINVAL;
+}
+static long thread_cpu_nsleep_restart(struct restart_block *restart_block)
 {
 	return -EINVAL;
 }
@@ -1539,6 +1640,7 @@ static __init int init_posix_cpu_timers(void)
 		.clock_set = do_posix_clock_nosettime,
 		.timer_create = process_cpu_timer_create,
 		.nsleep = process_cpu_nsleep,
+		.nsleep_restart = process_cpu_nsleep_restart,
 	};
 	struct k_clock thread = {
 		.clock_getres = thread_cpu_clock_getres,
@@ -1546,6 +1648,7 @@ static __init int init_posix_cpu_timers(void)
 		.clock_set = do_posix_clock_nosettime,
 		.timer_create = thread_cpu_timer_create,
 		.nsleep = thread_cpu_nsleep,
+		.nsleep_restart = thread_cpu_nsleep_restart,
 	};
 
 	register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process);