// 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 25static 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;}