382 lines
8.2 KiB
C
382 lines
8.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Debug controller
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*
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* WARNING: This controller is for cgroup core debugging only.
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* Its interfaces are unstable and subject to changes at any time.
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*/
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#include <linux/ctype.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include "cgroup-internal.h"
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static struct cgroup_subsys_state *
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debug_css_alloc(struct cgroup_subsys_state *parent_css)
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{
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struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
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if (!css)
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return ERR_PTR(-ENOMEM);
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return css;
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}
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static void debug_css_free(struct cgroup_subsys_state *css)
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{
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kfree(css);
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}
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/*
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* debug_taskcount_read - return the number of tasks in a cgroup.
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* @cgrp: the cgroup in question
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*/
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static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
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struct cftype *cft)
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{
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return cgroup_task_count(css->cgroup);
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}
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static int current_css_set_read(struct seq_file *seq, void *v)
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{
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struct kernfs_open_file *of = seq->private;
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struct css_set *cset;
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struct cgroup_subsys *ss;
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struct cgroup_subsys_state *css;
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int i, refcnt;
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if (!cgroup_kn_lock_live(of->kn, false))
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return -ENODEV;
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spin_lock_irq(&css_set_lock);
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rcu_read_lock();
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cset = task_css_set(current);
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refcnt = refcount_read(&cset->refcount);
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seq_printf(seq, "css_set %pK %d", cset, refcnt);
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if (refcnt > cset->nr_tasks)
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seq_printf(seq, " +%d", refcnt - cset->nr_tasks);
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seq_puts(seq, "\n");
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/*
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* Print the css'es stored in the current css_set.
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*/
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for_each_subsys(ss, i) {
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css = cset->subsys[ss->id];
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if (!css)
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continue;
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seq_printf(seq, "%2d: %-4s\t- %p[%d]\n", ss->id, ss->name,
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css, css->id);
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}
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rcu_read_unlock();
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spin_unlock_irq(&css_set_lock);
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cgroup_kn_unlock(of->kn);
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return 0;
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}
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static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
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struct cftype *cft)
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{
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u64 count;
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rcu_read_lock();
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count = refcount_read(&task_css_set(current)->refcount);
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rcu_read_unlock();
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return count;
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}
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static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
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{
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struct cgrp_cset_link *link;
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struct css_set *cset;
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char *name_buf;
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name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
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if (!name_buf)
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return -ENOMEM;
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spin_lock_irq(&css_set_lock);
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rcu_read_lock();
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cset = task_css_set(current);
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list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
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struct cgroup *c = link->cgrp;
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cgroup_name(c, name_buf, NAME_MAX + 1);
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seq_printf(seq, "Root %d group %s\n",
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c->root->hierarchy_id, name_buf);
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}
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rcu_read_unlock();
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spin_unlock_irq(&css_set_lock);
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kfree(name_buf);
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return 0;
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}
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#define MAX_TASKS_SHOWN_PER_CSS 25
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static int cgroup_css_links_read(struct seq_file *seq, void *v)
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{
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struct cgroup_subsys_state *css = seq_css(seq);
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struct cgrp_cset_link *link;
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int dead_cnt = 0, extra_refs = 0, threaded_csets = 0;
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spin_lock_irq(&css_set_lock);
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list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
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struct css_set *cset = link->cset;
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struct task_struct *task;
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int count = 0;
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int refcnt = refcount_read(&cset->refcount);
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/*
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* Print out the proc_cset and threaded_cset relationship
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* and highlight difference between refcount and task_count.
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*/
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seq_printf(seq, "css_set %pK", cset);
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if (rcu_dereference_protected(cset->dom_cset, 1) != cset) {
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threaded_csets++;
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seq_printf(seq, "=>%pK", cset->dom_cset);
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}
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if (!list_empty(&cset->threaded_csets)) {
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struct css_set *tcset;
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int idx = 0;
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list_for_each_entry(tcset, &cset->threaded_csets,
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threaded_csets_node) {
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seq_puts(seq, idx ? "," : "<=");
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seq_printf(seq, "%pK", tcset);
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idx++;
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}
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} else {
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seq_printf(seq, " %d", refcnt);
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if (refcnt - cset->nr_tasks > 0) {
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int extra = refcnt - cset->nr_tasks;
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seq_printf(seq, " +%d", extra);
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/*
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* Take out the one additional reference in
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* init_css_set.
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*/
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if (cset == &init_css_set)
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extra--;
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extra_refs += extra;
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}
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}
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seq_puts(seq, "\n");
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list_for_each_entry(task, &cset->tasks, cg_list) {
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if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
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seq_printf(seq, " task %d\n",
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task_pid_vnr(task));
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}
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list_for_each_entry(task, &cset->mg_tasks, cg_list) {
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if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
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seq_printf(seq, " task %d\n",
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task_pid_vnr(task));
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}
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/* show # of overflowed tasks */
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if (count > MAX_TASKS_SHOWN_PER_CSS)
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seq_printf(seq, " ... (%d)\n",
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count - MAX_TASKS_SHOWN_PER_CSS);
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if (cset->dead) {
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seq_puts(seq, " [dead]\n");
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dead_cnt++;
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}
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WARN_ON(count != cset->nr_tasks);
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}
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spin_unlock_irq(&css_set_lock);
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if (!dead_cnt && !extra_refs && !threaded_csets)
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return 0;
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seq_puts(seq, "\n");
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if (threaded_csets)
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seq_printf(seq, "threaded css_sets = %d\n", threaded_csets);
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if (extra_refs)
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seq_printf(seq, "extra references = %d\n", extra_refs);
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if (dead_cnt)
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seq_printf(seq, "dead css_sets = %d\n", dead_cnt);
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return 0;
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}
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static int cgroup_subsys_states_read(struct seq_file *seq, void *v)
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{
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struct kernfs_open_file *of = seq->private;
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struct cgroup *cgrp;
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struct cgroup_subsys *ss;
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struct cgroup_subsys_state *css;
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char pbuf[16];
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int i;
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cgrp = cgroup_kn_lock_live(of->kn, false);
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if (!cgrp)
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return -ENODEV;
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for_each_subsys(ss, i) {
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css = rcu_dereference_check(cgrp->subsys[ss->id], true);
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if (!css)
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continue;
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pbuf[0] = '\0';
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/* Show the parent CSS if applicable*/
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if (css->parent)
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snprintf(pbuf, sizeof(pbuf) - 1, " P=%d",
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css->parent->id);
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seq_printf(seq, "%2d: %-4s\t- %p[%d] %d%s\n", ss->id, ss->name,
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css, css->id,
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atomic_read(&css->online_cnt), pbuf);
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}
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cgroup_kn_unlock(of->kn);
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return 0;
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}
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static void cgroup_masks_read_one(struct seq_file *seq, const char *name,
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u16 mask)
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{
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struct cgroup_subsys *ss;
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int ssid;
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bool first = true;
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seq_printf(seq, "%-17s: ", name);
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for_each_subsys(ss, ssid) {
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if (!(mask & (1 << ssid)))
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continue;
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if (!first)
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seq_puts(seq, ", ");
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seq_puts(seq, ss->name);
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first = false;
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}
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seq_putc(seq, '\n');
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}
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static int cgroup_masks_read(struct seq_file *seq, void *v)
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{
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struct kernfs_open_file *of = seq->private;
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struct cgroup *cgrp;
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cgrp = cgroup_kn_lock_live(of->kn, false);
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if (!cgrp)
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return -ENODEV;
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cgroup_masks_read_one(seq, "subtree_control", cgrp->subtree_control);
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cgroup_masks_read_one(seq, "subtree_ss_mask", cgrp->subtree_ss_mask);
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cgroup_kn_unlock(of->kn);
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return 0;
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}
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static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
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{
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return (!cgroup_is_populated(css->cgroup) &&
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!css_has_online_children(&css->cgroup->self));
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}
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static struct cftype debug_legacy_files[] = {
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{
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.name = "taskcount",
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.read_u64 = debug_taskcount_read,
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},
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{
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.name = "current_css_set",
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.seq_show = current_css_set_read,
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.flags = CFTYPE_ONLY_ON_ROOT,
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},
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{
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.name = "current_css_set_refcount",
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.read_u64 = current_css_set_refcount_read,
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.flags = CFTYPE_ONLY_ON_ROOT,
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},
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{
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.name = "current_css_set_cg_links",
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.seq_show = current_css_set_cg_links_read,
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.flags = CFTYPE_ONLY_ON_ROOT,
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},
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{
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.name = "cgroup_css_links",
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.seq_show = cgroup_css_links_read,
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},
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{
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.name = "cgroup_subsys_states",
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.seq_show = cgroup_subsys_states_read,
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},
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{
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.name = "cgroup_masks",
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.seq_show = cgroup_masks_read,
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},
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{
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.name = "releasable",
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.read_u64 = releasable_read,
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},
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{ } /* terminate */
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};
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static struct cftype debug_files[] = {
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{
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.name = "taskcount",
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.read_u64 = debug_taskcount_read,
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},
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{
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.name = "current_css_set",
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.seq_show = current_css_set_read,
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.flags = CFTYPE_ONLY_ON_ROOT,
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},
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{
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.name = "current_css_set_refcount",
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.read_u64 = current_css_set_refcount_read,
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.flags = CFTYPE_ONLY_ON_ROOT,
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},
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{
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.name = "current_css_set_cg_links",
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.seq_show = current_css_set_cg_links_read,
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.flags = CFTYPE_ONLY_ON_ROOT,
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},
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{
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.name = "css_links",
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.seq_show = cgroup_css_links_read,
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},
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{
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.name = "csses",
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.seq_show = cgroup_subsys_states_read,
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},
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{
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.name = "masks",
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.seq_show = cgroup_masks_read,
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},
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{ } /* terminate */
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};
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struct cgroup_subsys debug_cgrp_subsys = {
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.css_alloc = debug_css_alloc,
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.css_free = debug_css_free,
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.legacy_cftypes = debug_legacy_files,
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};
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/*
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* On v2, debug is an implicit controller enabled by "cgroup_debug" boot
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* parameter.
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*/
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void __init enable_debug_cgroup(void)
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{
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debug_cgrp_subsys.dfl_cftypes = debug_files;
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debug_cgrp_subsys.implicit_on_dfl = true;
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debug_cgrp_subsys.threaded = true;
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}
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