v4.19.13 snapshot.
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
new file mode 100644
index 0000000..d503d1a
--- /dev/null
+++ b/kernel/cgroup/rstat.c
@@ -0,0 +1,416 @@
+#include "cgroup-internal.h"
+
+#include <linux/sched/cputime.h>
+
+static DEFINE_SPINLOCK(cgroup_rstat_lock);
+static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock);
+
+static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu);
+
+static struct cgroup_rstat_cpu *cgroup_rstat_cpu(struct cgroup *cgrp, int cpu)
+{
+ return per_cpu_ptr(cgrp->rstat_cpu, cpu);
+}
+
+/**
+ * cgroup_rstat_updated - keep track of updated rstat_cpu
+ * @cgrp: target cgroup
+ * @cpu: cpu on which rstat_cpu was updated
+ *
+ * @cgrp's rstat_cpu on @cpu was updated. Put it on the parent's matching
+ * rstat_cpu->updated_children list. See the comment on top of
+ * cgroup_rstat_cpu definition for details.
+ */
+void cgroup_rstat_updated(struct cgroup *cgrp, int cpu)
+{
+ raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu);
+ struct cgroup *parent;
+ unsigned long flags;
+
+ /* nothing to do for root */
+ if (!cgroup_parent(cgrp))
+ return;
+
+ /*
+ * Paired with the one in cgroup_rstat_cpu_pop_upated(). Either we
+ * see NULL updated_next or they see our updated stat.
+ */
+ smp_mb();
+
+ /*
+ * Because @parent's updated_children is terminated with @parent
+ * instead of NULL, we can tell whether @cgrp is on the list by
+ * testing the next pointer for NULL.
+ */
+ if (cgroup_rstat_cpu(cgrp, cpu)->updated_next)
+ return;
+
+ raw_spin_lock_irqsave(cpu_lock, flags);
+
+ /* put @cgrp and all ancestors on the corresponding updated lists */
+ for (parent = cgroup_parent(cgrp); parent;
+ cgrp = parent, parent = cgroup_parent(cgrp)) {
+ struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
+ struct cgroup_rstat_cpu *prstatc = cgroup_rstat_cpu(parent, cpu);
+
+ /*
+ * Both additions and removals are bottom-up. If a cgroup
+ * is already in the tree, all ancestors are.
+ */
+ if (rstatc->updated_next)
+ break;
+
+ rstatc->updated_next = prstatc->updated_children;
+ prstatc->updated_children = cgrp;
+ }
+
+ raw_spin_unlock_irqrestore(cpu_lock, flags);
+}
+EXPORT_SYMBOL_GPL(cgroup_rstat_updated);
+
+/**
+ * cgroup_rstat_cpu_pop_updated - iterate and dismantle rstat_cpu updated tree
+ * @pos: current position
+ * @root: root of the tree to traversal
+ * @cpu: target cpu
+ *
+ * Walks the udpated rstat_cpu tree on @cpu from @root. %NULL @pos starts
+ * the traversal and %NULL return indicates the end. During traversal,
+ * each returned cgroup is unlinked from the tree. Must be called with the
+ * matching cgroup_rstat_cpu_lock held.
+ *
+ * The only ordering guarantee is that, for a parent and a child pair
+ * covered by a given traversal, if a child is visited, its parent is
+ * guaranteed to be visited afterwards.
+ */
+static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos,
+ struct cgroup *root, int cpu)
+{
+ struct cgroup_rstat_cpu *rstatc;
+ struct cgroup *parent;
+
+ if (pos == root)
+ return NULL;
+
+ /*
+ * We're gonna walk down to the first leaf and visit/remove it. We
+ * can pick whatever unvisited node as the starting point.
+ */
+ if (!pos)
+ pos = root;
+ else
+ pos = cgroup_parent(pos);
+
+ /* walk down to the first leaf */
+ while (true) {
+ rstatc = cgroup_rstat_cpu(pos, cpu);
+ if (rstatc->updated_children == pos)
+ break;
+ pos = rstatc->updated_children;
+ }
+
+ /*
+ * Unlink @pos from the tree. As the updated_children list is
+ * singly linked, we have to walk it to find the removal point.
+ * However, due to the way we traverse, @pos will be the first
+ * child in most cases. The only exception is @root.
+ */
+ parent = cgroup_parent(pos);
+ if (parent && rstatc->updated_next) {
+ struct cgroup_rstat_cpu *prstatc = cgroup_rstat_cpu(parent, cpu);
+ struct cgroup_rstat_cpu *nrstatc;
+ struct cgroup **nextp;
+
+ nextp = &prstatc->updated_children;
+ while (true) {
+ nrstatc = cgroup_rstat_cpu(*nextp, cpu);
+ if (*nextp == pos)
+ break;
+
+ WARN_ON_ONCE(*nextp == parent);
+ nextp = &nrstatc->updated_next;
+ }
+
+ *nextp = rstatc->updated_next;
+ rstatc->updated_next = NULL;
+
+ /*
+ * Paired with the one in cgroup_rstat_cpu_updated().
+ * Either they see NULL updated_next or we see their
+ * updated stat.
+ */
+ smp_mb();
+ }
+
+ return pos;
+}
+
+/* see cgroup_rstat_flush() */
+static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
+ __releases(&cgroup_rstat_lock) __acquires(&cgroup_rstat_lock)
+{
+ int cpu;
+
+ lockdep_assert_held(&cgroup_rstat_lock);
+
+ for_each_possible_cpu(cpu) {
+ raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock,
+ cpu);
+ struct cgroup *pos = NULL;
+
+ raw_spin_lock(cpu_lock);
+ while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu))) {
+ struct cgroup_subsys_state *css;
+
+ cgroup_base_stat_flush(pos, cpu);
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(css, &pos->rstat_css_list,
+ rstat_css_node)
+ css->ss->css_rstat_flush(css, cpu);
+ rcu_read_unlock();
+ }
+ raw_spin_unlock(cpu_lock);
+
+ /* if @may_sleep, play nice and yield if necessary */
+ if (may_sleep && (need_resched() ||
+ spin_needbreak(&cgroup_rstat_lock))) {
+ spin_unlock_irq(&cgroup_rstat_lock);
+ if (!cond_resched())
+ cpu_relax();
+ spin_lock_irq(&cgroup_rstat_lock);
+ }
+ }
+}
+
+/**
+ * cgroup_rstat_flush - flush stats in @cgrp's subtree
+ * @cgrp: target cgroup
+ *
+ * Collect all per-cpu stats in @cgrp's subtree into the global counters
+ * and propagate them upwards. After this function returns, all cgroups in
+ * the subtree have up-to-date ->stat.
+ *
+ * This also gets all cgroups in the subtree including @cgrp off the
+ * ->updated_children lists.
+ *
+ * This function may block.
+ */
+void cgroup_rstat_flush(struct cgroup *cgrp)
+{
+ might_sleep();
+
+ spin_lock_irq(&cgroup_rstat_lock);
+ cgroup_rstat_flush_locked(cgrp, true);
+ spin_unlock_irq(&cgroup_rstat_lock);
+}
+
+/**
+ * cgroup_rstat_flush_irqsafe - irqsafe version of cgroup_rstat_flush()
+ * @cgrp: target cgroup
+ *
+ * This function can be called from any context.
+ */
+void cgroup_rstat_flush_irqsafe(struct cgroup *cgrp)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&cgroup_rstat_lock, flags);
+ cgroup_rstat_flush_locked(cgrp, false);
+ spin_unlock_irqrestore(&cgroup_rstat_lock, flags);
+}
+
+/**
+ * cgroup_rstat_flush_begin - flush stats in @cgrp's subtree and hold
+ * @cgrp: target cgroup
+ *
+ * Flush stats in @cgrp's subtree and prevent further flushes. Must be
+ * paired with cgroup_rstat_flush_release().
+ *
+ * This function may block.
+ */
+void cgroup_rstat_flush_hold(struct cgroup *cgrp)
+ __acquires(&cgroup_rstat_lock)
+{
+ might_sleep();
+ spin_lock_irq(&cgroup_rstat_lock);
+ cgroup_rstat_flush_locked(cgrp, true);
+}
+
+/**
+ * cgroup_rstat_flush_release - release cgroup_rstat_flush_hold()
+ */
+void cgroup_rstat_flush_release(void)
+ __releases(&cgroup_rstat_lock)
+{
+ spin_unlock_irq(&cgroup_rstat_lock);
+}
+
+int cgroup_rstat_init(struct cgroup *cgrp)
+{
+ int cpu;
+
+ /* the root cgrp has rstat_cpu preallocated */
+ if (!cgrp->rstat_cpu) {
+ cgrp->rstat_cpu = alloc_percpu(struct cgroup_rstat_cpu);
+ if (!cgrp->rstat_cpu)
+ return -ENOMEM;
+ }
+
+ /* ->updated_children list is self terminated */
+ for_each_possible_cpu(cpu) {
+ struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
+
+ rstatc->updated_children = cgrp;
+ u64_stats_init(&rstatc->bsync);
+ }
+
+ return 0;
+}
+
+void cgroup_rstat_exit(struct cgroup *cgrp)
+{
+ int cpu;
+
+ cgroup_rstat_flush(cgrp);
+
+ /* sanity check */
+ for_each_possible_cpu(cpu) {
+ struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
+
+ if (WARN_ON_ONCE(rstatc->updated_children != cgrp) ||
+ WARN_ON_ONCE(rstatc->updated_next))
+ return;
+ }
+
+ free_percpu(cgrp->rstat_cpu);
+ cgrp->rstat_cpu = NULL;
+}
+
+void __init cgroup_rstat_boot(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ raw_spin_lock_init(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu));
+
+ BUG_ON(cgroup_rstat_init(&cgrp_dfl_root.cgrp));
+}
+
+/*
+ * Functions for cgroup basic resource statistics implemented on top of
+ * rstat.
+ */
+static void cgroup_base_stat_accumulate(struct cgroup_base_stat *dst_bstat,
+ struct cgroup_base_stat *src_bstat)
+{
+ dst_bstat->cputime.utime += src_bstat->cputime.utime;
+ dst_bstat->cputime.stime += src_bstat->cputime.stime;
+ dst_bstat->cputime.sum_exec_runtime += src_bstat->cputime.sum_exec_runtime;
+}
+
+static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+ struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
+ struct task_cputime *last_cputime = &rstatc->last_bstat.cputime;
+ struct task_cputime cputime;
+ struct cgroup_base_stat delta;
+ unsigned seq;
+
+ /* fetch the current per-cpu values */
+ do {
+ seq = __u64_stats_fetch_begin(&rstatc->bsync);
+ cputime = rstatc->bstat.cputime;
+ } while (__u64_stats_fetch_retry(&rstatc->bsync, seq));
+
+ /* calculate the delta to propgate */
+ delta.cputime.utime = cputime.utime - last_cputime->utime;
+ delta.cputime.stime = cputime.stime - last_cputime->stime;
+ delta.cputime.sum_exec_runtime = cputime.sum_exec_runtime -
+ last_cputime->sum_exec_runtime;
+ *last_cputime = cputime;
+
+ /* transfer the pending stat into delta */
+ cgroup_base_stat_accumulate(&delta, &cgrp->pending_bstat);
+ memset(&cgrp->pending_bstat, 0, sizeof(cgrp->pending_bstat));
+
+ /* propagate delta into the global stat and the parent's pending */
+ cgroup_base_stat_accumulate(&cgrp->bstat, &delta);
+ if (parent)
+ cgroup_base_stat_accumulate(&parent->pending_bstat, &delta);
+}
+
+static struct cgroup_rstat_cpu *
+cgroup_base_stat_cputime_account_begin(struct cgroup *cgrp)
+{
+ struct cgroup_rstat_cpu *rstatc;
+
+ rstatc = get_cpu_ptr(cgrp->rstat_cpu);
+ u64_stats_update_begin(&rstatc->bsync);
+ return rstatc;
+}
+
+static void cgroup_base_stat_cputime_account_end(struct cgroup *cgrp,
+ struct cgroup_rstat_cpu *rstatc)
+{
+ u64_stats_update_end(&rstatc->bsync);
+ cgroup_rstat_updated(cgrp, smp_processor_id());
+ put_cpu_ptr(rstatc);
+}
+
+void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec)
+{
+ struct cgroup_rstat_cpu *rstatc;
+
+ rstatc = cgroup_base_stat_cputime_account_begin(cgrp);
+ rstatc->bstat.cputime.sum_exec_runtime += delta_exec;
+ cgroup_base_stat_cputime_account_end(cgrp, rstatc);
+}
+
+void __cgroup_account_cputime_field(struct cgroup *cgrp,
+ enum cpu_usage_stat index, u64 delta_exec)
+{
+ struct cgroup_rstat_cpu *rstatc;
+
+ rstatc = cgroup_base_stat_cputime_account_begin(cgrp);
+
+ switch (index) {
+ case CPUTIME_USER:
+ case CPUTIME_NICE:
+ rstatc->bstat.cputime.utime += delta_exec;
+ break;
+ case CPUTIME_SYSTEM:
+ case CPUTIME_IRQ:
+ case CPUTIME_SOFTIRQ:
+ rstatc->bstat.cputime.stime += delta_exec;
+ break;
+ default:
+ break;
+ }
+
+ cgroup_base_stat_cputime_account_end(cgrp, rstatc);
+}
+
+void cgroup_base_stat_cputime_show(struct seq_file *seq)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ u64 usage, utime, stime;
+
+ if (!cgroup_parent(cgrp))
+ return;
+
+ cgroup_rstat_flush_hold(cgrp);
+ usage = cgrp->bstat.cputime.sum_exec_runtime;
+ cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime, &utime, &stime);
+ cgroup_rstat_flush_release();
+
+ do_div(usage, NSEC_PER_USEC);
+ do_div(utime, NSEC_PER_USEC);
+ do_div(stime, NSEC_PER_USEC);
+
+ seq_printf(seq, "usage_usec %llu\n"
+ "user_usec %llu\n"
+ "system_usec %llu\n",
+ usage, utime, stime);
+}