kernel/cgroup/debug.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Debug controller
  *
  * WARNING: This controller is for cgroup core debugging only.
  * Its interfaces are unstable and subject to changes at any time.
  */
 #include <linux/ctype.h>
 #include <linux/mm.h>
 #include <linux/slab.h>

 #include "cgroup-internal.h"

 static struct cgroup_subsys_state *
 debug_css_alloc(struct cgroup_subsys_state *parent_css)
 {
 	struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);

 	if (!css)
 		return ERR_PTR(-ENOMEM);

 	return css;
 }

 static void debug_css_free(struct cgroup_subsys_state *css)
 {
 	kfree(css);
 }

 /*
  * debug_taskcount_read - return the number of tasks in a cgroup.
  * @cgrp: the cgroup in question
  */
 static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
 				struct cftype *cft)
 {
 	return cgroup_task_count(css->cgroup);
 }

 static int current_css_set_read(struct seq_file *seq, void *v)
 {
 	struct kernfs_open_file *of = seq->private;
 	struct css_set *cset;
 	struct cgroup_subsys *ss;
 	struct cgroup_subsys_state *css;
 	int i, refcnt;

 	if (!cgroup_kn_lock_live(of->kn, false))
 		return -ENODEV;

 	spin_lock_irq(&css_set_lock);
 	rcu_read_lock();
 	cset = task_css_set(current);
 	refcnt = refcount_read(&cset->refcount);
 	seq_printf(seq, "css_set %pK %d", cset, refcnt);
 	if (refcnt > cset->nr_tasks)
 		seq_printf(seq, " +%d", refcnt - cset->nr_tasks);
 	seq_puts(seq, "\n");

 	/*
 	 * Print the css'es stored in the current css_set.
 	 */
 	for_each_subsys(ss, i) {
 		css = cset->subsys[ss->id];
 		if (!css)
 			continue;
 		seq_printf(seq, "%2d: %-4s\t- %p[%d]\n", ss->id, ss->name,
 			  css, css->id);
 	}
 	rcu_read_unlock();
 	spin_unlock_irq(&css_set_lock);
 	cgroup_kn_unlock(of->kn);
 	return 0;
 }

 static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
 					 struct cftype *cft)
 {
 	u64 count;

 	rcu_read_lock();
 	count = refcount_read(&task_css_set(current)->refcount);
 	rcu_read_unlock();
 	return count;
 }

 static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
 {
 	struct cgrp_cset_link *link;
 	struct css_set *cset;
 	char *name_buf;

 	name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
 	if (!name_buf)
 		return -ENOMEM;

 	spin_lock_irq(&css_set_lock);
 	rcu_read_lock();
 	cset = task_css_set(current);
 	list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
 		struct cgroup *c = link->cgrp;

 		cgroup_name(c, name_buf, NAME_MAX + 1);
 		seq_printf(seq, "Root %d group %s\n",
 			   c->root->hierarchy_id, name_buf);
 	}
 	rcu_read_unlock();
 	spin_unlock_irq(&css_set_lock);
 	kfree(name_buf);
 	return 0;
 }

 #define MAX_TASKS_SHOWN_PER_CSS 25
 static int cgroup_css_links_read(struct seq_file *seq, void *v)
 {
 	struct cgroup_subsys_state *css = seq_css(seq);
 	struct cgrp_cset_link *link;
 	int dead_cnt = 0, extra_refs = 0, threaded_csets = 0;

 	spin_lock_irq(&css_set_lock);

 	list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
 		struct css_set *cset = link->cset;
 		struct task_struct *task;
 		int count = 0;
 		int refcnt = refcount_read(&cset->refcount);

 		/*
 		 * Print out the proc_cset and threaded_cset relationship
 		 * and highlight difference between refcount and task_count.
 		 */
 		seq_printf(seq, "css_set %pK", cset);
 		if (rcu_dereference_protected(cset->dom_cset, 1) != cset) {
 			threaded_csets++;
 			seq_printf(seq, "=>%pK", cset->dom_cset);
 		}
 		if (!list_empty(&cset->threaded_csets)) {
 			struct css_set *tcset;
 			int idx = 0;

 			list_for_each_entry(tcset, &cset->threaded_csets,
 					    threaded_csets_node) {
 				seq_puts(seq, idx ? "," : "<=");
 				seq_printf(seq, "%pK", tcset);
 				idx++;
 			}
 		} else {
 			seq_printf(seq, " %d", refcnt);
 			if (refcnt - cset->nr_tasks > 0) {
 				int extra = refcnt - cset->nr_tasks;

 				seq_printf(seq, " +%d", extra);
 				/*
 				 * Take out the one additional reference in
 				 * init_css_set.
 				 */
 				if (cset == &init_css_set)
 					extra--;
 				extra_refs += extra;
 			}
 		}
 		seq_puts(seq, "\n");

 		list_for_each_entry(task, &cset->tasks, cg_list) {
 			if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
 				seq_printf(seq, "  task %d\n",
 					   task_pid_vnr(task));
 		}

 		list_for_each_entry(task, &cset->mg_tasks, cg_list) {
 			if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
 				seq_printf(seq, "  task %d\n",
 					   task_pid_vnr(task));
 		}
 		/* show # of overflowed tasks */
 		if (count > MAX_TASKS_SHOWN_PER_CSS)
 			seq_printf(seq, "  ... (%d)\n",
 				   count - MAX_TASKS_SHOWN_PER_CSS);

 		if (cset->dead) {
 			seq_puts(seq, "    [dead]\n");
 			dead_cnt++;
 		}

 		WARN_ON(count != cset->nr_tasks);
 	}
 	spin_unlock_irq(&css_set_lock);

 	if (!dead_cnt && !extra_refs && !threaded_csets)
 		return 0;

 	seq_puts(seq, "\n");
 	if (threaded_csets)
 		seq_printf(seq, "threaded css_sets = %d\n", threaded_csets);
 	if (extra_refs)
 		seq_printf(seq, "extra references = %d\n", extra_refs);
 	if (dead_cnt)
 		seq_printf(seq, "dead css_sets = %d\n", dead_cnt);

 	return 0;
 }

 static int cgroup_subsys_states_read(struct seq_file *seq, void *v)
 {
 	struct kernfs_open_file *of = seq->private;
 	struct cgroup *cgrp;
 	struct cgroup_subsys *ss;
 	struct cgroup_subsys_state *css;
 	char pbuf[16];
 	int i;

 	cgrp = cgroup_kn_lock_live(of->kn, false);
 	if (!cgrp)
 		return -ENODEV;

 	for_each_subsys(ss, i) {
 		css = rcu_dereference_check(cgrp->subsys[ss->id], true);
 		if (!css)
 			continue;

 		pbuf[0] = '\0';

 		/* Show the parent CSS if applicable*/
 		if (css->parent)
 			snprintf(pbuf, sizeof(pbuf) - 1, " P=%d",
 				 css->parent->id);
 		seq_printf(seq, "%2d: %-4s\t- %p[%d] %d%s\n", ss->id, ss->name,
 			  css, css->id,
 			  atomic_read(&css->online_cnt), pbuf);
 	}

 	cgroup_kn_unlock(of->kn);
 	return 0;
 }

 static void cgroup_masks_read_one(struct seq_file *seq, const char *name,
 				  u16 mask)
 {
 	struct cgroup_subsys *ss;
 	int ssid;
 	bool first = true;

 	seq_printf(seq, "%-17s: ", name);
 	for_each_subsys(ss, ssid) {
 		if (!(mask & (1 << ssid)))
 			continue;
 		if (!first)
 			seq_puts(seq, ", ");
 		seq_puts(seq, ss->name);
 		first = false;
 	}
 	seq_putc(seq, '\n');
 }

 static int cgroup_masks_read(struct seq_file *seq, void *v)
 {
 	struct kernfs_open_file *of = seq->private;
 	struct cgroup *cgrp;

 	cgrp = cgroup_kn_lock_live(of->kn, false);
 	if (!cgrp)
 		return -ENODEV;

 	cgroup_masks_read_one(seq, "subtree_control", cgrp->subtree_control);
 	cgroup_masks_read_one(seq, "subtree_ss_mask", cgrp->subtree_ss_mask);

 	cgroup_kn_unlock(of->kn);
 	return 0;
 }

 static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
 {
 	return (!cgroup_is_populated(css->cgroup) &&
 		!css_has_online_children(&css->cgroup->self));
 }

 static struct cftype debug_legacy_files[] =  {
 	{
 		.name = "taskcount",
 		.read_u64 = debug_taskcount_read,
 	},

 	{
 		.name = "current_css_set",
 		.seq_show = current_css_set_read,
 		.flags = CFTYPE_ONLY_ON_ROOT,
 	},

 	{
 		.name = "current_css_set_refcount",
 		.read_u64 = current_css_set_refcount_read,
 		.flags = CFTYPE_ONLY_ON_ROOT,
 	},

 	{
 		.name = "current_css_set_cg_links",
 		.seq_show = current_css_set_cg_links_read,
 		.flags = CFTYPE_ONLY_ON_ROOT,
 	},

 	{
 		.name = "cgroup_css_links",
 		.seq_show = cgroup_css_links_read,
 	},

 	{
 		.name = "cgroup_subsys_states",
 		.seq_show = cgroup_subsys_states_read,
 	},

 	{
 		.name = "cgroup_masks",
 		.seq_show = cgroup_masks_read,
 	},

 	{
 		.name = "releasable",
 		.read_u64 = releasable_read,
 	},

 	{ }	/* terminate */
 };

 static struct cftype debug_files[] =  {
 	{
 		.name = "taskcount",
 		.read_u64 = debug_taskcount_read,
 	},

 	{
 		.name = "current_css_set",
 		.seq_show = current_css_set_read,
 		.flags = CFTYPE_ONLY_ON_ROOT,
 	},

 	{
 		.name = "current_css_set_refcount",
 		.read_u64 = current_css_set_refcount_read,
 		.flags = CFTYPE_ONLY_ON_ROOT,
 	},

 	{
 		.name = "current_css_set_cg_links",
 		.seq_show = current_css_set_cg_links_read,
 		.flags = CFTYPE_ONLY_ON_ROOT,
 	},

 	{
 		.name = "css_links",
 		.seq_show = cgroup_css_links_read,
 	},

 	{
 		.name = "csses",
 		.seq_show = cgroup_subsys_states_read,
 	},

 	{
 		.name = "masks",
 		.seq_show = cgroup_masks_read,
 	},

 	{ }	/* terminate */
 };

 struct cgroup_subsys debug_cgrp_subsys = {
 	.css_alloc	= debug_css_alloc,
 	.css_free	= debug_css_free,
 	.legacy_cftypes	= debug_legacy_files,
 };

 /*
  * On v2, debug is an implicit controller enabled by "cgroup_debug" boot
  * parameter.
  */
 void __init enable_debug_cgroup(void)
 {
 	debug_cgrp_subsys.dfl_cftypes = debug_files;
 	debug_cgrp_subsys.implicit_on_dfl = true;
 	debug_cgrp_subsys.threaded = true;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Debug controller
	*
	* WARNING: This controller is for cgroup core debugging only.
	* Its interfaces are unstable and subject to changes at any time.
	*/
	#include <linux/ctype.h>
	#include <linux/mm.h>
	#include <linux/slab.h>

	#include "cgroup-internal.h"

	static struct cgroup_subsys_state *
	debug_css_alloc(struct cgroup_subsys_state *parent_css)
	{
	struct cgroup_subsys_state css = kzalloc(sizeof(css), GFP_KERNEL);

	if (!css)
	return ERR_PTR(-ENOMEM);

	return css;
	}

	static void debug_css_free(struct cgroup_subsys_state *css)
	{
	kfree(css);
	}

	/*
	* debug_taskcount_read - return the number of tasks in a cgroup.
	* @cgrp: the cgroup in question
	*/
	static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
	struct cftype *cft)
	{
	return cgroup_task_count(css->cgroup);
	}

	static int current_css_set_read(struct seq_file seq, void v)
	{
	struct kernfs_open_file *of = seq->private;
	struct css_set *cset;
	struct cgroup_subsys *ss;
	struct cgroup_subsys_state *css;
	int i, refcnt;

	if (!cgroup_kn_lock_live(of->kn, false))
	return -ENODEV;

	spin_lock_irq(&css_set_lock);
	rcu_read_lock();
	cset = task_css_set(current);
	refcnt = refcount_read(&cset->refcount);
	seq_printf(seq, "css_set %pK %d", cset, refcnt);
	if (refcnt > cset->nr_tasks)
	seq_printf(seq, " +%d", refcnt - cset->nr_tasks);
	seq_puts(seq, "\n");

	/*
	* Print the css'es stored in the current css_set.
	*/
	for_each_subsys(ss, i) {
	css = cset->subsys[ss->id];
	if (!css)
	continue;
	seq_printf(seq, "%2d: %-4s\t- %p[%d]\n", ss->id, ss->name,
	css, css->id);
	}
	rcu_read_unlock();
	spin_unlock_irq(&css_set_lock);
	cgroup_kn_unlock(of->kn);
	return 0;
	}

	static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
	struct cftype *cft)
	{
	u64 count;

	rcu_read_lock();
	count = refcount_read(&task_css_set(current)->refcount);
	rcu_read_unlock();
	return count;
	}

	static int current_css_set_cg_links_read(struct seq_file seq, void v)
	{
	struct cgrp_cset_link *link;
	struct css_set *cset;
	char *name_buf;

	name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
	if (!name_buf)
	return -ENOMEM;

	spin_lock_irq(&css_set_lock);
	rcu_read_lock();
	cset = task_css_set(current);
	list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
	struct cgroup *c = link->cgrp;

	cgroup_name(c, name_buf, NAME_MAX + 1);
	seq_printf(seq, "Root %d group %s\n",
	c->root->hierarchy_id, name_buf);
	}
	rcu_read_unlock();
	spin_unlock_irq(&css_set_lock);
	kfree(name_buf);
	return 0;
	}

	#define MAX_TASKS_SHOWN_PER_CSS 25
	static int cgroup_css_links_read(struct seq_file seq, void v)
	{
	struct cgroup_subsys_state *css = seq_css(seq);
	struct cgrp_cset_link *link;
	int dead_cnt = 0, extra_refs = 0, threaded_csets = 0;

	spin_lock_irq(&css_set_lock);

	list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
	struct css_set *cset = link->cset;
	struct task_struct *task;
	int count = 0;
	int refcnt = refcount_read(&cset->refcount);

	/*
	* Print out the proc_cset and threaded_cset relationship
	* and highlight difference between refcount and task_count.
	*/
	seq_printf(seq, "css_set %pK", cset);
	if (rcu_dereference_protected(cset->dom_cset, 1) != cset) {
	threaded_csets++;
	seq_printf(seq, "=>%pK", cset->dom_cset);
	}
	if (!list_empty(&cset->threaded_csets)) {
	struct css_set *tcset;
	int idx = 0;

	list_for_each_entry(tcset, &cset->threaded_csets,
	threaded_csets_node) {
	seq_puts(seq, idx ? "," : "<=");
	seq_printf(seq, "%pK", tcset);
	idx++;
	}
	} else {
	seq_printf(seq, " %d", refcnt);
	if (refcnt - cset->nr_tasks > 0) {
	int extra = refcnt - cset->nr_tasks;

	seq_printf(seq, " +%d", extra);
	/*
	* Take out the one additional reference in
	* init_css_set.
	*/
	if (cset == &init_css_set)
	extra--;
	extra_refs += extra;
	}
	}
	seq_puts(seq, "\n");

	list_for_each_entry(task, &cset->tasks, cg_list) {
	if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
	seq_printf(seq, " task %d\n",
	task_pid_vnr(task));
	}

	list_for_each_entry(task, &cset->mg_tasks, cg_list) {
	if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
	seq_printf(seq, " task %d\n",
	task_pid_vnr(task));
	}
	/* show # of overflowed tasks */
	if (count > MAX_TASKS_SHOWN_PER_CSS)
	seq_printf(seq, " ... (%d)\n",
	count - MAX_TASKS_SHOWN_PER_CSS);

	if (cset->dead) {
	seq_puts(seq, " [dead]\n");
	dead_cnt++;
	}

	WARN_ON(count != cset->nr_tasks);
	}
	spin_unlock_irq(&css_set_lock);

	if (!dead_cnt && !extra_refs && !threaded_csets)
	return 0;

	seq_puts(seq, "\n");
	if (threaded_csets)
	seq_printf(seq, "threaded css_sets = %d\n", threaded_csets);
	if (extra_refs)
	seq_printf(seq, "extra references = %d\n", extra_refs);
	if (dead_cnt)
	seq_printf(seq, "dead css_sets = %d\n", dead_cnt);

	return 0;
	}

	static int cgroup_subsys_states_read(struct seq_file seq, void v)
	{
	struct kernfs_open_file *of = seq->private;
	struct cgroup *cgrp;
	struct cgroup_subsys *ss;
	struct cgroup_subsys_state *css;
	char pbuf[16];
	int i;

	cgrp = cgroup_kn_lock_live(of->kn, false);
	if (!cgrp)
	return -ENODEV;

	for_each_subsys(ss, i) {
	css = rcu_dereference_check(cgrp->subsys[ss->id], true);
	if (!css)
	continue;

	pbuf[0] = '\0';

	/* Show the parent CSS if applicable*/
	if (css->parent)
	snprintf(pbuf, sizeof(pbuf) - 1, " P=%d",
	css->parent->id);
	seq_printf(seq, "%2d: %-4s\t- %p[%d] %d%s\n", ss->id, ss->name,
	css, css->id,
	atomic_read(&css->online_cnt), pbuf);
	}

	cgroup_kn_unlock(of->kn);
	return 0;
	}

	static void cgroup_masks_read_one(struct seq_file seq, const char name,
	u16 mask)
	{
	struct cgroup_subsys *ss;
	int ssid;
	bool first = true;

	seq_printf(seq, "%-17s: ", name);
	for_each_subsys(ss, ssid) {
	if (!(mask & (1 << ssid)))
	continue;
	if (!first)
	seq_puts(seq, ", ");
	seq_puts(seq, ss->name);
	first = false;
	}
	seq_putc(seq, '\n');
	}

	static int cgroup_masks_read(struct seq_file seq, void v)
	{
	struct kernfs_open_file *of = seq->private;
	struct cgroup *cgrp;

	cgrp = cgroup_kn_lock_live(of->kn, false);
	if (!cgrp)
	return -ENODEV;

	cgroup_masks_read_one(seq, "subtree_control", cgrp->subtree_control);
	cgroup_masks_read_one(seq, "subtree_ss_mask", cgrp->subtree_ss_mask);

	cgroup_kn_unlock(of->kn);
	return 0;
	}

	static u64 releasable_read(struct cgroup_subsys_state css, struct cftype cft)
	{
	return (!cgroup_is_populated(css->cgroup) &&
	!css_has_online_children(&css->cgroup->self));
	}

	static struct cftype debug_legacy_files[] = {
	{
	.name = "taskcount",
	.read_u64 = debug_taskcount_read,
	},

	{
	.name = "current_css_set",
	.seq_show = current_css_set_read,
	.flags = CFTYPE_ONLY_ON_ROOT,
	},

	{
	.name = "current_css_set_refcount",
	.read_u64 = current_css_set_refcount_read,
	.flags = CFTYPE_ONLY_ON_ROOT,
	},

	{
	.name = "current_css_set_cg_links",
	.seq_show = current_css_set_cg_links_read,
	.flags = CFTYPE_ONLY_ON_ROOT,
	},

	{
	.name = "cgroup_css_links",
	.seq_show = cgroup_css_links_read,
	},

	{
	.name = "cgroup_subsys_states",
	.seq_show = cgroup_subsys_states_read,
	},

	{
	.name = "cgroup_masks",
	.seq_show = cgroup_masks_read,
	},

	{
	.name = "releasable",
	.read_u64 = releasable_read,
	},

	{ } /* terminate */
	};

	static struct cftype debug_files[] = {
	{
	.name = "taskcount",
	.read_u64 = debug_taskcount_read,
	},

	{
	.name = "current_css_set",
	.seq_show = current_css_set_read,
	.flags = CFTYPE_ONLY_ON_ROOT,
	},

	{
	.name = "current_css_set_refcount",
	.read_u64 = current_css_set_refcount_read,
	.flags = CFTYPE_ONLY_ON_ROOT,
	},

	{
	.name = "current_css_set_cg_links",
	.seq_show = current_css_set_cg_links_read,
	.flags = CFTYPE_ONLY_ON_ROOT,
	},

	{
	.name = "css_links",
	.seq_show = cgroup_css_links_read,
	},

	{
	.name = "csses",
	.seq_show = cgroup_subsys_states_read,
	},

	{
	.name = "masks",
	.seq_show = cgroup_masks_read,
	},

	{ } /* terminate */
	};

	struct cgroup_subsys debug_cgrp_subsys = {
	.css_alloc = debug_css_alloc,
	.css_free = debug_css_free,
	.legacy_cftypes = debug_legacy_files,
	};

	/*
	* On v2, debug is an implicit controller enabled by "cgroup_debug" boot
	* parameter.
	*/
	void __init enable_debug_cgroup(void)
	{
	debug_cgrp_subsys.dfl_cftypes = debug_files;
	debug_cgrp_subsys.implicit_on_dfl = true;
	debug_cgrp_subsys.threaded = true;
	}