1 files changed, 124 insertions, 91 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index da0bf6fe9ecd..5555e49c4e12 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -873,15 +873,11 @@ static inline void hrtick_rq_init(struct rq *rq)
 	({								\
 		typeof(ptr) _ptr = (ptr);				\
 		typeof(mask) _mask = (mask);				\
-		typeof(*_ptr) _old, _val = *_ptr;			\
+		typeof(*_ptr) _val = *_ptr;				\
 									\
-		for (;;) {						\
-			_old = cmpxchg(_ptr, _val, _val | _mask);	\
-			if (_old == _val)				\
-				break;					\
-			_val = _old;					\
-		}							\
-	_old;								\
+		do {							\
+		} while (!try_cmpxchg(_ptr, &_val, _val | _mask));	\
+	_val;								\
 })
 
 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
@@ -890,7 +886,7 @@ static inline void hrtick_rq_init(struct rq *rq)
  * this avoids any races wrt polling state changes and thereby avoids
  * spurious IPIs.
  */
-static bool set_nr_and_not_polling(struct task_struct *p)
+static inline bool set_nr_and_not_polling(struct task_struct *p)
 {
 	struct thread_info *ti = task_thread_info(p);
 	return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
@@ -905,30 +901,28 @@ static bool set_nr_and_not_polling(struct task_struct *p)
 static bool set_nr_if_polling(struct task_struct *p)
 {
 	struct thread_info *ti = task_thread_info(p);
-	typeof(ti->flags) old, val = READ_ONCE(ti->flags);
+	typeof(ti->flags) val = READ_ONCE(ti->flags);
 
 	for (;;) {
 		if (!(val & _TIF_POLLING_NRFLAG))
 			return false;
 		if (val & _TIF_NEED_RESCHED)
 			return true;
-		old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
-		if (old == val)
+		if (try_cmpxchg(&ti->flags, &val, val | _TIF_NEED_RESCHED))
 			break;
-		val = old;
 	}
 	return true;
 }
 
 #else
-static bool set_nr_and_not_polling(struct task_struct *p)
+static inline bool set_nr_and_not_polling(struct task_struct *p)
 {
 	set_tsk_need_resched(p);
 	return true;
 }
 
 #ifdef CONFIG_SMP
-static bool set_nr_if_polling(struct task_struct *p)
+static inline bool set_nr_if_polling(struct task_struct *p)
 {
 	return false;
 }
@@ -3808,7 +3802,7 @@ bool cpus_share_cache(int this_cpu, int that_cpu)
 	return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
 }
 
-static inline bool ttwu_queue_cond(int cpu, int wake_flags)
+static inline bool ttwu_queue_cond(int cpu)
 {
 	/*
 	 * Do not complicate things with the async wake_list while the CPU is
@@ -3824,13 +3818,21 @@ static inline bool ttwu_queue_cond(int cpu, int wake_flags)
 	if (!cpus_share_cache(smp_processor_id(), cpu))
 		return true;
 
+	if (cpu == smp_processor_id())
+		return false;
+
 	/*
-	 * If the task is descheduling and the only running task on the
-	 * CPU then use the wakelist to offload the task activation to
-	 * the soon-to-be-idle CPU as the current CPU is likely busy.
-	 * nr_running is checked to avoid unnecessary task stacking.
+	 * If the wakee cpu is idle, or the task is descheduling and the
+	 * only running task on the CPU, then use the wakelist to offload
+	 * the task activation to the idle (or soon-to-be-idle) CPU as
+	 * the current CPU is likely busy. nr_running is checked to
+	 * avoid unnecessary task stacking.
+	 *
+	 * Note that we can only get here with (wakee) p->on_rq=0,
+	 * p->on_cpu can be whatever, we've done the dequeue, so
+	 * the wakee has been accounted out of ->nr_running.
 	 */
-	if ((wake_flags & WF_ON_CPU) && cpu_rq(cpu)->nr_running <= 1)
+	if (!cpu_rq(cpu)->nr_running)
 		return true;
 
 	return false;
@@ -3838,10 +3840,7 @@ static inline bool ttwu_queue_cond(int cpu, int wake_flags)
 
 static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
 {
-	if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu, wake_flags)) {
-		if (WARN_ON_ONCE(cpu == smp_processor_id()))
-			return false;
-
+	if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu)) {
 		sched_clock_cpu(cpu); /* Sync clocks across CPUs */
 		__ttwu_queue_wakelist(p, cpu, wake_flags);
 		return true;
@@ -4163,7 +4162,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
 	 * scheduling.
 	 */
 	if (smp_load_acquire(&p->on_cpu) &&
-	    ttwu_queue_wakelist(p, task_cpu(p), wake_flags | WF_ON_CPU))
+	    ttwu_queue_wakelist(p, task_cpu(p), wake_flags))
 		goto unlock;
 
 	/*
@@ -4753,7 +4752,8 @@ static inline void prepare_task(struct task_struct *next)
 	 * Claim the task as running, we do this before switching to it
 	 * such that any running task will have this set.
 	 *
-	 * See the ttwu() WF_ON_CPU case and its ordering comment.
+	 * See the smp_load_acquire(&p->on_cpu) case in ttwu() and
+	 * its ordering comment.
 	 */
 	WRITE_ONCE(next->on_cpu, 1);
 #endif
@@ -6500,8 +6500,12 @@ static inline void sched_submit_work(struct task_struct *tsk)
 			io_wq_worker_sleeping(tsk);
 	}
 
-	if (tsk_is_pi_blocked(tsk))
-		return;
+	/*
+	 * spinlock and rwlock must not flush block requests.  This will
+	 * deadlock if the callback attempts to acquire a lock which is
+	 * already acquired.
+	 */
+	SCHED_WARN_ON(current->__state & TASK_RTLOCK_WAIT);
 
 	/*
 	 * If we are going to sleep and we have plugged IO queued,
@@ -6998,17 +7002,29 @@ out_unlock:
 EXPORT_SYMBOL(set_user_nice);
 
 /*
- * can_nice - check if a task can reduce its nice value
+ * is_nice_reduction - check if nice value is an actual reduction
+ *
+ * Similar to can_nice() but does not perform a capability check.
+ *
  * @p: task
  * @nice: nice value
  */
-int can_nice(const struct task_struct *p, const int nice)
+static bool is_nice_reduction(const struct task_struct *p, const int nice)
 {
 	/* Convert nice value [19,-20] to rlimit style value [1,40]: */
 	int nice_rlim = nice_to_rlimit(nice);
 
-	return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
-		capable(CAP_SYS_NICE));
+	return (nice_rlim <= task_rlimit(p, RLIMIT_NICE));
+}
+
+/*
+ * can_nice - check if a task can reduce its nice value
+ * @p: task
+ * @nice: nice value
+ */
+int can_nice(const struct task_struct *p, const int nice)
+{
+	return is_nice_reduction(p, nice) || capable(CAP_SYS_NICE);
 }
 
 #ifdef __ARCH_WANT_SYS_NICE
@@ -7137,12 +7153,14 @@ struct task_struct *idle_task(int cpu)
  * required to meet deadlines.
  */
 unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
-				 unsigned long max, enum cpu_util_type type,
+				 enum cpu_util_type type,
 				 struct task_struct *p)
 {
-	unsigned long dl_util, util, irq;
+	unsigned long dl_util, util, irq, max;
 	struct rq *rq = cpu_rq(cpu);
 
+	max = arch_scale_cpu_capacity(cpu);
+
 	if (!uclamp_is_used() &&
 	    type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
 		return max;
@@ -7222,10 +7240,9 @@ unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
 	return min(max, util);
 }
 
-unsigned long sched_cpu_util(int cpu, unsigned long max)
+unsigned long sched_cpu_util(int cpu)
 {
-	return effective_cpu_util(cpu, cpu_util_cfs(cpu), max,
-				  ENERGY_UTIL, NULL);
+	return effective_cpu_util(cpu, cpu_util_cfs(cpu), ENERGY_UTIL, NULL);
 }
 #endif /* CONFIG_SMP */
 
@@ -7287,6 +7304,69 @@ static bool check_same_owner(struct task_struct *p)
 	return match;
 }
 
+/*
+ * Allow unprivileged RT tasks to decrease priority.
+ * Only issue a capable test if needed and only once to avoid an audit
+ * event on permitted non-privileged operations:
+ */
+static int user_check_sched_setscheduler(struct task_struct *p,
+					 const struct sched_attr *attr,
+					 int policy, int reset_on_fork)
+{
+	if (fair_policy(policy)) {
+		if (attr->sched_nice < task_nice(p) &&
+		    !is_nice_reduction(p, attr->sched_nice))
+			goto req_priv;
+	}
+
+	if (rt_policy(policy)) {
+		unsigned long rlim_rtprio = task_rlimit(p, RLIMIT_RTPRIO);
+
+		/* Can't set/change the rt policy: */
+		if (policy != p->policy && !rlim_rtprio)
+			goto req_priv;
+
+		/* Can't increase priority: */
+		if (attr->sched_priority > p->rt_priority &&
+		    attr->sched_priority > rlim_rtprio)
+			goto req_priv;
+	}
+
+	/*
+	 * Can't set/change SCHED_DEADLINE policy at all for now
+	 * (safest behavior); in the future we would like to allow
+	 * unprivileged DL tasks to increase their relative deadline
+	 * or reduce their runtime (both ways reducing utilization)
+	 */
+	if (dl_policy(policy))
+		goto req_priv;
+
+	/*
+	 * Treat SCHED_IDLE as nice 20. Only allow a switch to
+	 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
+	 */
+	if (task_has_idle_policy(p) && !idle_policy(policy)) {
+		if (!is_nice_reduction(p, task_nice(p)))
+			goto req_priv;
+	}
+
+	/* Can't change other user's priorities: */
+	if (!check_same_owner(p))
+		goto req_priv;
+
+	/* Normal users shall not reset the sched_reset_on_fork flag: */
+	if (p->sched_reset_on_fork && !reset_on_fork)
+		goto req_priv;
+
+	return 0;
+
+req_priv:
+	if (!capable(CAP_SYS_NICE))
+		return -EPERM;
+
+	return 0;
+}
+
 static int __sched_setscheduler(struct task_struct *p,
 				const struct sched_attr *attr,
 				bool user, bool pi)
@@ -7328,58 +7408,11 @@ recheck:
 	    (rt_policy(policy) != (attr->sched_priority != 0)))
 		return -EINVAL;
 
-	/*
-	 * Allow unprivileged RT tasks to decrease priority:
-	 */
-	if (user && !capable(CAP_SYS_NICE)) {
-		if (fair_policy(policy)) {
-			if (attr->sched_nice < task_nice(p) &&
-			    !can_nice(p, attr->sched_nice))
-				return -EPERM;
-		}
-
-		if (rt_policy(policy)) {
-			unsigned long rlim_rtprio =
-					task_rlimit(p, RLIMIT_RTPRIO);
-
-			/* Can't set/change the rt policy: */
-			if (policy != p->policy && !rlim_rtprio)
-				return -EPERM;
-
-			/* Can't increase priority: */
-			if (attr->sched_priority > p->rt_priority &&
-			    attr->sched_priority > rlim_rtprio)
-				return -EPERM;
-		}
-
-		 /*
-		  * Can't set/change SCHED_DEADLINE policy at all for now
-		  * (safest behavior); in the future we would like to allow
-		  * unprivileged DL tasks to increase their relative deadline
-		  * or reduce their runtime (both ways reducing utilization)
-		  */
-		if (dl_policy(policy))
-			return -EPERM;
-
-		/*
-		 * Treat SCHED_IDLE as nice 20. Only allow a switch to
-		 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
-		 */
-		if (task_has_idle_policy(p) && !idle_policy(policy)) {
-			if (!can_nice(p, task_nice(p)))
-				return -EPERM;
-		}
-
-		/* Can't change other user's priorities: */
-		if (!check_same_owner(p))
-			return -EPERM;
-
-		/* Normal users shall not reset the sched_reset_on_fork flag: */
-		if (p->sched_reset_on_fork && !reset_on_fork)
-			return -EPERM;
-	}
-
 	if (user) {
+		retval = user_check_sched_setscheduler(p, attr, policy, reset_on_fork);
+		if (retval)
+			return retval;
+
 		if (attr->sched_flags & SCHED_FLAG_SUGOV)
 			return -EINVAL;
 
@@ -9531,7 +9564,7 @@ static struct kmem_cache *task_group_cache __read_mostly;
 #endif
 
 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
-DECLARE_PER_CPU(cpumask_var_t, select_idle_mask);
+DECLARE_PER_CPU(cpumask_var_t, select_rq_mask);
 
 void __init sched_init(void)
 {
@@ -9580,7 +9613,7 @@ void __init sched_init(void)
 	for_each_possible_cpu(i) {
 		per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
 			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
-		per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node(
+		per_cpu(select_rq_mask, i) = (cpumask_var_t)kzalloc_node(
 			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
 	}
 #endif /* CONFIG_CPUMASK_OFFSTACK */