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authorDavid S. Miller <davem@davemloft.net>2011-05-20 13:10:22 -0700
committerDavid S. Miller <davem@davemloft.net>2011-05-20 13:10:22 -0700
commit90d3ac15e5c637d45849e83c828ed78c62886737 (patch)
treec5568365f32386559d2710e8981ed41e5fe0eb12 /kernel/sched.c
parent9fafbd806198eb690c9a9f9fe35a879db93a1b8d (diff)
parent317f394160e9beb97d19a84c39b7e5eb3d7815a8 (diff)
Merge commit '317f394160e9beb97d19a84c39b7e5eb3d7815a8'
Conflicts: arch/sparc/kernel/smp_32.c With merge conflict help from Daniel Hellstrom. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c627
1 files changed, 349 insertions, 278 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 312f8b95c2d..8c9d804dc07 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -312,6 +312,9 @@ struct cfs_rq {
u64 exec_clock;
u64 min_vruntime;
+#ifndef CONFIG_64BIT
+ u64 min_vruntime_copy;
+#endif
struct rb_root tasks_timeline;
struct rb_node *rb_leftmost;
@@ -553,6 +556,10 @@ struct rq {
unsigned int ttwu_count;
unsigned int ttwu_local;
#endif
+
+#ifdef CONFIG_SMP
+ struct task_struct *wake_list;
+#endif
};
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
@@ -596,7 +603,7 @@ static inline int cpu_of(struct rq *rq)
* Return the group to which this tasks belongs.
*
* We use task_subsys_state_check() and extend the RCU verification
- * with lockdep_is_held(&task_rq(p)->lock) because cpu_cgroup_attach()
+ * with lockdep_is_held(&p->pi_lock) because cpu_cgroup_attach()
* holds that lock for each task it moves into the cgroup. Therefore
* by holding that lock, we pin the task to the current cgroup.
*/
@@ -606,7 +613,7 @@ static inline struct task_group *task_group(struct task_struct *p)
struct cgroup_subsys_state *css;
css = task_subsys_state_check(p, cpu_cgroup_subsys_id,
- lockdep_is_held(&task_rq(p)->lock));
+ lockdep_is_held(&p->pi_lock));
tg = container_of(css, struct task_group, css);
return autogroup_task_group(p, tg);
@@ -838,18 +845,39 @@ static inline int task_current(struct rq *rq, struct task_struct *p)
return rq->curr == p;
}
-#ifndef __ARCH_WANT_UNLOCKED_CTXSW
static inline int task_running(struct rq *rq, struct task_struct *p)
{
+#ifdef CONFIG_SMP
+ return p->on_cpu;
+#else
return task_current(rq, p);
+#endif
}
+#ifndef __ARCH_WANT_UNLOCKED_CTXSW
static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
{
+#ifdef CONFIG_SMP
+ /*
+ * We can optimise this out completely for !SMP, because the
+ * SMP rebalancing from interrupt is the only thing that cares
+ * here.
+ */
+ next->on_cpu = 1;
+#endif
}
static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
{
+#ifdef CONFIG_SMP
+ /*
+ * After ->on_cpu is cleared, the task can be moved to a different CPU.
+ * We must ensure this doesn't happen until the switch is completely
+ * finished.
+ */
+ smp_wmb();
+ prev->on_cpu = 0;
+#endif
#ifdef CONFIG_DEBUG_SPINLOCK
/* this is a valid case when another task releases the spinlock */
rq->lock.owner = current;
@@ -865,15 +893,6 @@ static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
}
#else /* __ARCH_WANT_UNLOCKED_CTXSW */
-static inline int task_running(struct rq *rq, struct task_struct *p)
-{
-#ifdef CONFIG_SMP
- return p->oncpu;
-#else
- return task_current(rq, p);
-#endif
-}
-
static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
{
#ifdef CONFIG_SMP
@@ -882,7 +901,7 @@ static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
* SMP rebalancing from interrupt is the only thing that cares
* here.
*/
- next->oncpu = 1;
+ next->on_cpu = 1;
#endif
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
raw_spin_unlock_irq(&rq->lock);
@@ -895,12 +914,12 @@ static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
{
#ifdef CONFIG_SMP
/*
- * After ->oncpu is cleared, the task can be moved to a different CPU.
+ * After ->on_cpu is cleared, the task can be moved to a different CPU.
* We must ensure this doesn't happen until the switch is completely
* finished.
*/
smp_wmb();
- prev->oncpu = 0;
+ prev->on_cpu = 0;
#endif
#ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
local_irq_enable();
@@ -909,23 +928,15 @@ static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
#endif /* __ARCH_WANT_UNLOCKED_CTXSW */
/*
- * Check whether the task is waking, we use this to synchronize ->cpus_allowed
- * against ttwu().
- */
-static inline int task_is_waking(struct task_struct *p)
-{
- return unlikely(p->state == TASK_WAKING);
-}
-
-/*
- * __task_rq_lock - lock the runqueue a given task resides on.
- * Must be called interrupts disabled.
+ * __task_rq_lock - lock the rq @p resides on.
*/
static inline struct rq *__task_rq_lock(struct task_struct *p)
__acquires(rq->lock)
{
struct rq *rq;
+ lockdep_assert_held(&p->pi_lock);
+
for (;;) {
rq = task_rq(p);
raw_spin_lock(&rq->lock);
@@ -936,22 +947,22 @@ static inline struct rq *__task_rq_lock(struct task_struct *p)
}
/*
- * task_rq_lock - lock the runqueue a given task resides on and disable
- * interrupts. Note the ordering: we can safely lookup the task_rq without
- * explicitly disabling preemption.
+ * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
*/
static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
+ __acquires(p->pi_lock)
__acquires(rq->lock)
{
struct rq *rq;
for (;;) {
- local_irq_save(*flags);
+ raw_spin_lock_irqsave(&p->pi_lock, *flags);
rq = task_rq(p);
raw_spin_lock(&rq->lock);
if (likely(rq == task_rq(p)))
return rq;
- raw_spin_unlock_irqrestore(&rq->lock, *flags);
+ raw_spin_unlock(&rq->lock);
+ raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
}
}
@@ -961,10 +972,13 @@ static void __task_rq_unlock(struct rq *rq)
raw_spin_unlock(&rq->lock);
}
-static inline void task_rq_unlock(struct rq *rq, unsigned long *flags)
+static inline void
+task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
__releases(rq->lock)
+ __releases(p->pi_lock)
{
- raw_spin_unlock_irqrestore(&rq->lock, *flags);
+ raw_spin_unlock(&rq->lock);
+ raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
}
/*
@@ -1773,7 +1787,6 @@ static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
update_rq_clock(rq);
sched_info_queued(p);
p->sched_class->enqueue_task(rq, p, flags);
- p->se.on_rq = 1;
}
static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
@@ -1781,7 +1794,6 @@ static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
update_rq_clock(rq);
sched_info_dequeued(p);
p->sched_class->dequeue_task(rq, p, flags);
- p->se.on_rq = 0;
}
/*
@@ -2116,7 +2128,7 @@ static void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
* A queue event has occurred, and we're going to schedule. In
* this case, we can save a useless back to back clock update.
*/
- if (rq->curr->se.on_rq && test_tsk_need_resched(rq->curr))
+ if (rq->curr->on_rq && test_tsk_need_resched(rq->curr))
rq->skip_clock_update = 1;
}
@@ -2162,6 +2174,11 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
*/
WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
!(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
+
+#ifdef CONFIG_LOCKDEP
+ WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
+ lockdep_is_held(&task_rq(p)->lock)));
+#endif
#endif
trace_sched_migrate_task(p, new_cpu);
@@ -2185,13 +2202,15 @@ static int migration_cpu_stop(void *data);
* The task's runqueue lock must be held.
* Returns true if you have to wait for migration thread.
*/
-static bool migrate_task(struct task_struct *p, struct rq *rq)
+static bool need_migrate_task(struct task_struct *p)
{
/*
* If the task is not on a runqueue (and not running), then
* the next wake-up will properly place the task.
*/
- return p->se.on_rq || task_running(rq, p);
+ bool running = p->on_rq || p->on_cpu;
+ smp_rmb(); /* finish_lock_switch() */
+ return running;
}
/*
@@ -2251,11 +2270,11 @@ unsigned long wait_task_inactive(struct task_struct *p, long match_state)
rq = task_rq_lock(p, &flags);
trace_sched_wait_task(p);
running = task_running(rq, p);
- on_rq = p->se.on_rq;
+ on_rq = p->on_rq;
ncsw = 0;
if (!match_state || p->state == match_state)
ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
- task_rq_unlock(rq, &flags);
+ task_rq_unlock(rq, p, &flags);
/*
* If it changed from the expected state, bail out now.
@@ -2330,7 +2349,7 @@ EXPORT_SYMBOL_GPL(kick_process);
#ifdef CONFIG_SMP
/*
- * ->cpus_allowed is protected by either TASK_WAKING or rq->lock held.
+ * ->cpus_allowed is protected by both rq->lock and p->pi_lock
*/
static int select_fallback_rq(int cpu, struct task_struct *p)
{
@@ -2363,12 +2382,12 @@ static int select_fallback_rq(int cpu, struct task_struct *p)
}
/*
- * The caller (fork, wakeup) owns TASK_WAKING, ->cpus_allowed is stable.
+ * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
*/
static inline
-int select_task_rq(struct rq *rq, struct task_struct *p, int sd_flags, int wake_flags)
+int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
{
- int cpu = p->sched_class->select_task_rq(rq, p, sd_flags, wake_flags);
+ int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags);
/*
* In order not to call set_task_cpu() on a blocking task we need
@@ -2394,27 +2413,60 @@ static void update_avg(u64 *avg, u64 sample)
}
#endif
-static inline void ttwu_activate(struct task_struct *p, struct rq *rq,
- bool is_sync, bool is_migrate, bool is_local,
- unsigned long en_flags)
+static void
+ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
{
+#ifdef CONFIG_SCHEDSTATS
+ struct rq *rq = this_rq();
+
+#ifdef CONFIG_SMP
+ int this_cpu = smp_processor_id();
+
+ if (cpu == this_cpu) {
+ schedstat_inc(rq, ttwu_local);
+ schedstat_inc(p, se.statistics.nr_wakeups_local);
+ } else {
+ struct sched_domain *sd;
+
+ schedstat_inc(p, se.statistics.nr_wakeups_remote);
+ for_each_domain(this_cpu, sd) {
+ if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
+ schedstat_inc(sd, ttwu_wake_remote);
+ break;
+ }
+ }
+ }
+#endif /* CONFIG_SMP */
+
+ schedstat_inc(rq, ttwu_count);
schedstat_inc(p, se.statistics.nr_wakeups);
- if (is_sync)
+
+ if (wake_flags & WF_SYNC)
schedstat_inc(p, se.statistics.nr_wakeups_sync);
- if (is_migrate)
+
+ if (cpu != task_cpu(p))
schedstat_inc(p, se.statistics.nr_wakeups_migrate);
- if (is_local)
- schedstat_inc(p, se.statistics.nr_wakeups_local);
- else
- schedstat_inc(p, se.statistics.nr_wakeups_remote);
+#endif /* CONFIG_SCHEDSTATS */
+}
+
+static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
+{
activate_task(rq, p, en_flags);
+ p->on_rq = 1;
+
+ /* if a worker is waking up, notify workqueue */
+ if (p->flags & PF_WQ_WORKER)
+ wq_worker_waking_up(p, cpu_of(rq));
}
-static inline void ttwu_post_activation(struct task_struct *p, struct rq *rq,
- int wake_flags, bool success)
+/*
+ * Mark the task runnable and perform wakeup-preemption.
+ */
+static void
+ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
{
- trace_sched_wakeup(p, success);
+ trace_sched_wakeup(p, true);
check_preempt_curr(rq, p, wake_flags);
p->state = TASK_RUNNING;
@@ -2433,9 +2485,99 @@ static inline void ttwu_post_activation(struct task_struct *p, struct rq *rq,
rq->idle_stamp = 0;
}
#endif
- /* if a worker is waking up, notify workqueue */
- if ((p->flags & PF_WQ_WORKER) && success)
- wq_worker_waking_up(p, cpu_of(rq));
+}
+
+static void
+ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
+{
+#ifdef CONFIG_SMP
+ if (p->sched_contributes_to_load)
+ rq->nr_uninterruptible--;
+#endif
+
+ ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
+ ttwu_do_wakeup(rq, p, wake_flags);
+}
+
+/*
+ * Called in case the task @p isn't fully descheduled from its runqueue,
+ * in this case we must do a remote wakeup. Its a 'light' wakeup though,
+ * since all we need to do is flip p->state to TASK_RUNNING, since
+ * the task is still ->on_rq.
+ */
+static int ttwu_remote(struct task_struct *p, int wake_flags)
+{
+ struct rq *rq;
+ int ret = 0;
+
+ rq = __task_rq_lock(p);
+ if (p->on_rq) {
+ ttwu_do_wakeup(rq, p, wake_flags);
+ ret = 1;
+ }
+ __task_rq_unlock(rq);
+
+ return ret;
+}
+
+#ifdef CONFIG_SMP
+static void sched_ttwu_pending(void)
+{
+ struct rq *rq = this_rq();
+ struct task_struct *list = xchg(&rq->wake_list, NULL);
+
+ if (!list)
+ return;
+
+ raw_spin_lock(&rq->lock);
+
+ while (list) {
+ struct task_struct *p = list;
+ list = list->wake_entry;
+ ttwu_do_activate(rq, p, 0);
+ }
+
+ raw_spin_unlock(&rq->lock);
+}
+
+void scheduler_ipi(void)
+{
+ sched_ttwu_pending();
+}
+
+static void ttwu_queue_remote(struct task_struct *p, int cpu)
+{
+ struct rq *rq = cpu_rq(cpu);
+ struct task_struct *next = rq->wake_list;
+
+ for (;;) {
+ struct task_struct *old = next;
+
+ p->wake_entry = next;
+ next = cmpxchg(&rq->wake_list, old, p);
+ if (next == old)
+ break;
+ }
+
+ if (!next)
+ smp_send_reschedule(cpu);
+}
+#endif
+
+static void ttwu_queue(struct task_struct *p, int cpu)
+{
+ struct rq *rq = cpu_rq(cpu);
+
+#if defined(CONFIG_SMP) && defined(CONFIG_SCHED_TTWU_QUEUE)
+ if (sched_feat(TTWU_QUEUE) && cpu != smp_processor_id()) {
+ ttwu_queue_remote(p, cpu);
+ return;
+ }
+#endif
+
+ raw_spin_lock(&rq->lock);
+ ttwu_do_activate(rq, p, 0);
+ raw_spin_unlock(&rq->lock);
}
/**
@@ -2453,92 +2595,64 @@ static inline void ttwu_post_activation(struct task_struct *p, struct rq *rq,
* Returns %true if @p was woken up, %false if it was already running
* or @state didn't match @p's state.
*/
-static int try_to_wake_up(struct task_struct *p, unsigned int state,
- int wake_flags)
+static int
+try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
{
- int cpu, orig_cpu, this_cpu, success = 0;
unsigned long flags;
- unsigned long en_flags = ENQUEUE_WAKEUP;
- struct rq *rq;
-
- this_cpu = get_cpu();
+ int cpu, success = 0;
smp_wmb();
- rq = task_rq_lock(p, &flags);
+ raw_spin_lock_irqsave(&p->pi_lock, flags);
if (!(p->state & state))
goto out;
- if (p->se.on_rq)
- goto out_running;
-
+ success = 1; /* we're going to change ->state */
cpu = task_cpu(p);
- orig_cpu = cpu;
-#ifdef CONFIG_SMP
- if (unlikely(task_running(rq, p)))
- goto out_activate;
+ if (p->on_rq && ttwu_remote(p, wake_flags))
+ goto stat;
+#ifdef CONFIG_SMP
/*
- * In order to handle concurrent wakeups and release the rq->lock
- * we put the task in TASK_WAKING state.
- *
- * First fix up the nr_uninterruptible count:
+ * If the owning (remote) cpu is still in the middle of schedule() with
+ * this task as prev, wait until its done referencing the task.
*/
- if (task_contributes_to_load(p)) {
- if (likely(cpu_online(orig_cpu)))
- rq->nr_uninterruptible--;
- else
- this_rq()->nr_uninterruptible--;
- }
- p->state = TASK_WAKING;
-
- if (p->sched_class->task_waking) {
- p->sched_class->task_waking(rq, p);
- en_flags |= ENQUEUE_WAKING;
+ while (p->on_cpu) {
+#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
+ /*
+ * If called from interrupt context we could have landed in the
+ * middle of schedule(), in this case we should take care not
+ * to spin on ->on_cpu if p is current, since that would
+ * deadlock.
+ */
+ if (p == current) {
+ ttwu_queue(p, cpu);
+ goto stat;
+ }
+#endif
+ cpu_relax();
}
-
- cpu = select_task_rq(rq, p, SD_BALANCE_WAKE, wake_flags);
- if (cpu != orig_cpu)
- set_task_cpu(p, cpu);
- __task_rq_unlock(rq);
-
- rq = cpu_rq(cpu);
- raw_spin_lock(&rq->lock);
-
/*
- * We migrated the task without holding either rq->lock, however
- * since the task is not on the task list itself, nobody else
- * will try and migrate the task, hence the rq should match the
- * cpu we just moved it to.
+ * Pairs with the smp_wmb() in finish_lock_switch().
*/
- WARN_ON(task_cpu(p) != cpu);
- WARN_ON(p->state != TASK_WAKING);
+ smp_rmb();
-#ifdef CONFIG_SCHEDSTATS
- schedstat_inc(rq, ttwu_count);
- if (cpu == this_cpu)
- schedstat_inc(rq, ttwu_local);
- else {
- struct sched_domain *sd;
- for_each_domain(this_cpu, sd) {
- if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
- schedstat_inc(sd, ttwu_wake_remote);
- break;
- }
- }
- }
-#endif /* CONFIG_SCHEDSTATS */
+ p->sched_contributes_to_load = !!task_contributes_to_load(p);
+ p->state = TASK_WAKING;
+
+ if (p->sched_class->task_waking)
+ p->sched_class->task_waking(p);
-out_activate:
+ cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
+ if (task_cpu(p) != cpu)
+ set_task_cpu(p, cpu);
#endif /* CONFIG_SMP */
- ttwu_activate(p, rq, wake_flags & WF_SYNC, orig_cpu != cpu,
- cpu == this_cpu, en_flags);
- success = 1;
-out_running:
- ttwu_post_activation(p, rq, wake_flags, success);
+
+ ttwu_queue(p, cpu);
+stat:
+ ttwu_stat(p, cpu, wake_flags);
out:
- task_rq_unlock(rq, &flags);
- put_cpu();
+ raw_spin_unlock_irqrestore(&p->pi_lock, flags);
return success;
}
@@ -2547,31 +2661,34 @@ out:
* try_to_wake_up_local - try to wake up a local task with rq lock held
* @p: the thread to be awakened
*
- * Put @p on the run-queue if it's not already there. The caller must
+ * Put @p on the run-queue if it's not already there. The caller must
* ensure that this_rq() is locked, @p is bound to this_rq() and not
- * the current task. this_rq() stays locked over invocation.
+ * the current task.
*/
static void try_to_wake_up_local(struct task_struct *p)
{
struct rq *rq = task_rq(p);
- bool success = false;
BUG_ON(rq != this_rq());
BUG_ON(p == current);
lockdep_assert_held(&rq->lock);
+ if (!raw_spin_trylock(&p->pi_lock)) {
+ raw_spin_unlock(&rq->lock);
+ raw_spin_lock(&p->pi_lock);
+ raw_spin_lock(&rq->lock);
+ }
+
if (!(p->state & TASK_NORMAL))
- return;
+ goto out;
- if (!p->se.on_rq) {
- if (likely(!task_running(rq, p))) {
- schedstat_inc(rq, ttwu_count);
- schedstat_inc(rq, ttwu_local);
- }
- ttwu_activate(p, rq, false, false, true, ENQUEUE_WAKEUP);
- success = true;
- }
- ttwu_post_activation(p, rq, 0, success);
+ if (!p->on_rq)
+ ttwu_activate(rq, p, ENQUEUE_WAKEUP);
+
+ ttwu_do_wakeup(rq, p, 0);
+ ttwu_stat(p, smp_processor_id(), 0);
+out:
+ raw_spin_unlock(&p->pi_lock);
}
/**
@@ -2604,19 +2721,21 @@ int wake_up_state(struct task_struct *p, unsigned int state)
*/
static void __sched_fork(struct task_struct *p)
{
+ p->on_rq = 0;
+
+ p->se.on_rq = 0;
p->se.exec_start = 0;
p->se.sum_exec_runtime = 0;
p->se.prev_sum_exec_runtime = 0;
p->se.nr_migrations = 0;
p->se.vruntime = 0;
+ INIT_LIST_HEAD(&p->se.group_node);
#ifdef CONFIG_SCHEDSTATS
memset(&p->se.statistics, 0, sizeof(p->se.statistics));
#endif
INIT_LIST_HEAD(&p->rt.run_list);
- p->se.on_rq = 0;
- INIT_LIST_HEAD(&p->se.group_node);
#ifdef CONFIG_PREEMPT_NOTIFIERS
INIT_HLIST_HEAD(&p->preempt_notifiers);
@@ -2628,6 +2747,7 @@ static void __sched_fork(struct task_struct *p)
*/
void sched_fork(struct task_struct *p, int clone_flags)
{
+ unsigned long flags;
int cpu = get_cpu();
__sched_fork(p);
@@ -2678,16 +2798,16 @@ void sched_fork(struct task_struct *p, int clone_flags)
*
* Silence PROVE_RCU.
*/
- rcu_read_lock();
+ raw_spin_lock_irqsave(&p->pi_lock, flags);
set_task_cpu(p, cpu);
- rcu_read_unlock();
+ raw_spin_unlock_irqrestore(&p->pi_lock, flags);
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
if (likely(sched_info_on()))
memset(&p->sched_info, 0, sizeof(p->sched_info));
#endif
-#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
- p->oncpu = 0;
+#if defined(CONFIG_SMP)
+ p->on_cpu = 0;
#endif
#ifdef CONFIG_PREEMPT
/* Want to start with kernel preemption disabled. */
@@ -2711,37 +2831,27 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
{
unsigned long flags;
struct rq *rq;
- int cpu __maybe_unused = get_cpu();
+ raw_spin_lock_irqsave(&p->pi_lock, flags);
#ifdef CONFIG_SMP
- rq = task_rq_lock(p, &flags);
- p->state = TASK_WAKING;
-
/*
* Fork balancing, do it here and not earlier because:
* - cpus_allowed can change in the fork path
* - any previously selected cpu might disappear through hotplug
- *
- * We set TASK_WAKING so that select_task_rq() can drop rq->lock
- * without people poking at ->cpus_allowed.
*/
- cpu = select_task_rq(rq, p, SD_BALANCE_FORK, 0);
- set_task_cpu(p, cpu);
-
- p->state = TASK_RUNNING;
- task_rq_unlock(rq, &flags);
+ set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0));
#endif
- rq = task_rq_lock(p, &flags);
+ rq = __task_rq_lock(p);
activate_task(rq, p, 0);
- trace_sched_wakeup_new(p, 1);
+ p->on_rq = 1;
+ trace_sched_wakeup_new(p, true);
check_preempt_curr(rq, p, WF_FORK);
#ifdef CONFIG_SMP
if (p->sched_class->task_woken)
p->sched_class->task_woken(rq, p);
#endif
- task_rq_unlock(rq, &flags);
- put_cpu();
+ task_rq_unlock(rq, p, &flags);
}
#ifdef CONFIG_PREEMPT_NOTIFIERS
@@ -3450,27 +3560,22 @@ void sched_exec(void)
{
struct task_struct *p = current;
unsigned long flags;
- struct rq *rq;
int dest_cpu;
- rq = task_rq_lock(p, &flags);
- dest_cpu = p->sched_class->select_task_rq(rq, p, SD_BALANCE_EXEC, 0);
+ raw_spin_lock_irqsave(&p->pi_lock, flags);
+ dest_cpu = p->sched_class->select_task_rq(p, SD_BALANCE_EXEC, 0);
if (dest_cpu == smp_processor_id())
goto unlock;
- /*
- * select_task_rq() can race against ->cpus_allowed
- */
- if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed) &&
- likely(cpu_active(dest_cpu)) && migrate_task(p, rq)) {
+ if (likely(cpu_active(dest_cpu))) {
struct migration_arg arg = { p, dest_cpu };
- task_rq_unlock(rq, &flags);
- stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
+ raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+ stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
return;
}
unlock:
- task_rq_unlock(rq, &flags);
+ raw_spin_unlock_irqrestore(&p->pi_lock, flags);
}
#endif
@@ -3507,7 +3612,7 @@ unsigned long long task_delta_exec(struct task_struct *p)
rq = task_rq_lock(p, &flags);
ns = do_task_delta_exec(p, rq);
- task_rq_unlock(rq, &flags);
+ task_rq_unlock(rq, p, &flags);
return ns;
}
@@ -3525,7 +3630,7 @@ unsigned long long task_sched_runtime(struct task_struct *p)
rq = task_rq_lock(p, &flags);
ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
- task_rq_unlock(rq, &flags);
+ task_rq_unlock(rq, p, &flags);
return ns;
}
@@ -3549,7 +3654,7 @@ unsigned long long thread_group_sched_runtime(struct task_struct *p)
rq = task_rq_lock(p, &flags);
thread_group_cputime(p, &totals);
ns = totals.sum_exec_runtime + do_task_delta_exec(p, rq);
- task_rq_unlock(rq, &flags);
+ task_rq_unlock(rq, p, &flags);
return ns;
}
@@ -4035,7 +4140,7 @@ static inline void schedule_debug(struct task_struct *prev)
static void put_prev_task(struct rq *rq, struct task_struct *prev)
{
- if (prev->se.on_rq)
+ if (prev->on_rq)
update_rq_clock(rq);
prev->sched_class->put_prev_task(rq, prev);
}
@@ -4097,11 +4202,13 @@ need_resched:
if (unlikely(signal_pending_state(prev->state, prev))) {
prev->state = TASK_RUNNING;
} else {
+ deactivate_task(rq, prev, DEQUEUE_SLEEP);
+ prev->on_rq = 0;
+
/*
- * If a worker is going to sleep, notify and
- * ask workqueue whether it wants to wake up a
- * task to maintain concurrency. If so, wake
- * up the task.
+ * If a worker went to sleep, notify and ask workqueue
+ * whether it wants to wake up a task to maintain
+ * concurrency.
*/
if (prev->flags & PF_WQ_WORKER) {
struct task_struct *to_wakeup;
@@ -4110,11 +4217,10 @@ need_resched:
if (to_wakeup)
try_to_wake_up_local(to_wakeup);
}
- deactivate_task(rq, prev, DEQUEUE_SLEEP);
/*
- * If we are going to sleep and we have plugged IO queued, make
- * sure to submit it to avoid deadlocks.
+ * If we are going to sleep and we have plugged IO
+ * queued, make sure to submit it to avoid deadlocks.
*/
if (blk_needs_flush_plug(prev)) {
raw_spin_unlock(&rq->lock);
@@ -4161,70 +4267,53 @@ need_resched:
EXPORT_SYMBOL(schedule);
#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
-/*
- * Look out! "owner" is an entirely speculative pointer
- * access and not reliable.
- */
-int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
-{
- unsigned int cpu;
- struct rq *rq;
- if (!sched_feat(OWNER_SPIN))
- return 0;
+static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
+{
+ bool ret = false;
-#ifdef CONFIG_DEBUG_PAGEALLOC
- /*
- * Need to access the cpu field knowing that
- * DEBUG_PAGEALLOC could have unmapped it if
- * the mutex owner just released it and exited.
- */
- if (probe_kernel_address(&owner->cpu, cpu))
- return 0;
-#else
- cpu = owner->cpu;
-#endif
+ rcu_read_lock();
+ if (lock->owner != owner)
+ goto fail;
/*
- * Even if the access succeeded (likely case),
- * the cpu field may no longer be valid.
+ * Ensure we emit the owner->on_cpu, dereference _after_ checking
+ * lock->owner still matches owner, if that fails, owner might
+ * point to free()d memory, if it still matches, the rcu_read_lock()
+ * ensures the memory stays valid.
*/
- if (cpu >= nr_cpumask_bits)
- return 0;
+ barrier();
- /*
- * We need to validate that we can do a
- * get_cpu() and that we have the percpu area.
- */
- if (!cpu_online(cpu))
- return 0;
+ ret = owner->on_cpu;
+fail:
+ rcu_read_unlock();
- rq = cpu_rq(cpu);
+ return ret;
+}
- for (;;) {
- /*
- * Owner changed, break to re-assess state.
- */
- if (lock->owner != owner) {
- /*
- * If the lock has switched to a different owner,
- * we likely have heavy contention. Return 0 to quit
- * optimistic spinning and not contend further:
- */
- if (lock->owner)
- return 0;
- break;
- }
+/*
+ * Look out! "owner" is an entirely speculative pointer
+ * access and not reliable.
+ */
+int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
+{
+ if (!sched_feat(OWNER_SPIN))
+ return 0;
- /*
- * Is that owner really running on that cpu?
- */
- if (task_thread_info(rq->curr) != owner || need_resched())
+ while (owner_running(lock, owner)) {
+ if (need_resched())
return 0;
arch_mutex_cpu_relax();
}
+ /*
+ * If the owner changed to another task there is likely
+ * heavy contention, stop spinning.
+ */
+ if (lock->owner)
+ return 0;
+
return 1;
}
#endif
@@ -4684,19 +4773,18 @@ EXPORT_SYMBOL(sleep_on_timeout);
*/
void rt_mutex_setprio(struct task_struct *p, int prio)
{
- unsigned long flags;
int oldprio, on_rq, running;
struct rq *rq;
const struct sched_class *prev_class;
BUG_ON(prio < 0 || prio > MAX_PRIO);
- rq = task_rq_lock(p, &flags);
+ rq = __task_rq_lock(p);
trace_sched_pi_setprio(p, prio);
oldprio = p->prio;
prev_class = p->sched_class;
- on_rq = p->se.on_rq;
+ on_rq = p->on_rq;
running = task_current(rq, p);
if (on_rq)
dequeue_task(rq, p, 0);
@@ -4716,7 +4804,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0);
check_class_changed(rq, p, prev_class, oldprio);
- task_rq_unlock(rq, &flags);
+ __task_rq_unlock(rq);
}
#endif
@@ -4744,7 +4832,7 @@ void set_user_nice(struct task_struct *p, long nice)
p->static_prio = NICE_TO_PRIO(nice);
goto out_unlock;
}
- on_rq = p->se.on_rq;
+ on_rq = p->on_rq;
if (on_rq)
dequeue_task(rq, p, 0);
@@ -4764,7 +4852,7 @@ void set_user_nice(struct task_struct *p, long nice)
resched_task(rq->curr);
}
out_unlock:
- task_rq_unlock(rq, &flags);
+ task_rq_unlock(rq, p, &flags);
}
EXPORT_SYMBOL(set_user_nice);
@@ -4878,8 +4966,6 @@ static struct task_struct *find_process_by_pid(pid_t pid)
static void
__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
{
- BUG_ON(p->se.on_rq);
-
p->policy = policy;
p->rt_priority = prio;
p->normal_prio = normal_prio(p);
@@ -4994,20 +5080,17 @@ recheck:
/*
* make sure no PI-waiters arrive (or leave) while we are
* changing the priority of the task:
- */
- raw_spin_lock_irqsave(&p->pi_lock, flags);
- /*
+ *
* To be able to change p->policy safely, the appropriate
* runqueue lock must be held.
*/
- rq = __task_rq_lock(p);
+ rq = task_rq_lock(p, &flags);
/*
* Changing the policy of the stop threads its a very bad idea
*/
if (p == rq->stop) {
- __task_rq_unlock(rq);
- raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+ task_rq_unlock(rq, p, &flags);
return -EINVAL;
}
@@ -5031,8 +5114,7 @@ recheck:
if (rt_bandwidth_enabled() && rt_policy(policy) &&
task_group(p)->rt_bandwidth.rt_runtime == 0 &&
!task_group_is_autogroup(task_group(p))) {
- __task_rq_unlock(rq);
- raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+ task_rq_unlock(rq, p, &flags);
return -EPERM;
}
}
@@ -5041,11 +5123,10 @@ recheck:
/* recheck policy now with rq lock held */
if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
policy = oldpolicy = -1;
- __task_rq_unlock(rq);
- raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+ task_rq_unlock(rq, p, &flags);
goto recheck;
}
- on_rq = p->se.on_rq;
+ on_rq = p->on_rq;
running = task_current(rq, p);
if (on_rq)
deactivate_task(rq, p, 0);
@@ -5064,8 +5145,7 @@ recheck:
activate_task(rq, p, 0);
check_class_changed(rq, p, prev_class, oldprio);
- __task_rq_unlock(rq);
- raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+ task_rq_unlock(rq, p, &flags);
rt_mutex_adjust_pi(p);
@@ -5316,7 +5396,6 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask)
{
struct task_struct *p;
unsigned long flags;
- struct rq *rq;
int retval;
get_online_cpus();
@@ -5331,9 +5410,9 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask)
if (retval)
goto out_unlock;
- rq = task_rq_lock(p, &flags);
+ raw_spin_lock_irqsave(&p->pi_lock, flags);
cpumask_and(mask, &p->cpus_allowed, cpu_online_mask);
- task_rq_unlock(rq, &flags);
+ raw_spin_unlock_irqrestore(&p->pi_lock, flags);
out_unlock:
rcu_read_unlock();
@@ -5658,7 +5737,7 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
rq = task_rq_lock(p, &flags);
time_slice = p->sched_class->get_rr_interval(rq, p);
- task_rq_unlock(rq, &flags);
+ task_rq_unlock(rq, p, &flags);
rcu_read_unlock();
jiffies_to_timespec(time_slice, &t);
@@ -5776,8 +5855,8 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
rcu_read_unlock();
rq->curr = rq->idle = idle;
-#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
- idle->oncpu = 1;
+#if defined(CONFIG_SMP)
+ idle->on_cpu = 1;
#endif
raw_spin_unlock_irqrestore(&rq->lock, flags);
@@ -5881,18 +5960,7 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
unsigned int dest_cpu;
int ret = 0;
- /*
- * Serialize against TASK_WAKING so that ttwu() and wunt() can
- * drop the rq->lock and still rely on ->cpus_allowed.
- */
-again:
- while (task_is_waking(p))
- cpu_relax();
rq = task_rq_lock(p, &flags);
- if (task_is_waking(p)) {
- task_rq_unlock(rq, &flags);
- goto again;
- }
if (!cpumask_intersects(new_mask, cpu_active_mask)) {
ret = -EINVAL;
@@ -5917,16 +5985,16 @@ again:
goto out;
dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
- if (migrate_task(p, rq)) {
+ if (need_migrate_task(p)) {
struct migration_arg arg = { p, dest_cpu };
/* Need help from migration thread: drop lock and wait. */
- task_rq_unlock(rq, &flags);
+ task_rq_unlock(rq, p, &flags);
stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
tlb_migrate_finish(p->mm);
return 0;
}
out:
- task_rq_unlock(rq, &flags);
+ task_rq_unlock(rq, p, &flags);
return ret;
}
@@ -5954,6 +6022,7 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
rq_src = cpu_rq(src_cpu);
rq_dest = cpu_rq(dest_cpu);
+ raw_spin_lock(&p->pi_lock);
double_rq_lock(rq_src, rq_dest);
/* Already moved. */
if (task_cpu(p) != src_cpu)
@@ -5966,7 +6035,7 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
* If we're not on a rq, the next wake-up will ensure we're
* placed properly.
*/
- if (p->se.on_rq) {
+ if (p->on_rq) {
deactivate_task(rq_src, p, 0);
set_task_cpu(p, dest_cpu);
activate_task(rq_dest, p, 0);
@@ -5976,6 +6045,7 @@ done:
ret = 1;
fail:
double_rq_unlock(rq_src, rq_dest);
+ raw_spin_unlock(&p->pi_lock);
return ret;
}
@@ -6316,6 +6386,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DYING:
+ sched_ttwu_pending();
/* Update our root-domain */
raw_spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) {
@@ -8340,7 +8411,7 @@ static void normalize_task(struct rq *rq, struct task_struct *p)
int old_prio = p->prio;
int on_rq;
- on_rq = p->se.on_rq;
+ on_rq = p->on_rq;
if (on_rq)
deactivate_task(rq, p, 0);
__setscheduler(rq, p, SCHED_NORMAL, 0);
@@ -8683,7 +8754,7 @@ void sched_move_task(struct task_struct *tsk)
rq = task_rq_lock(tsk, &flags);
running = task_current(rq, tsk);
- on_rq = tsk->se.on_rq;
+ on_rq = tsk->on_rq;
if (on_rq)
dequeue_task(rq, tsk, 0);
@@ -8702,7 +8773,7 @@ void sched_move_task(struct task_struct *tsk)
if (on_rq)
enqueue_task(rq, tsk, 0);
- task_rq_unlock(rq, &flags);
+ task_rq_unlock(rq, tsk, &flags);
}
#endif /* CONFIG_CGROUP_SCHED */