Commit 7a0cf0e7 authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo
Browse files

cgroup: update debug controller to print out thread mode information 



Update debug controller so that it prints out debug info about thread
mode.

 1) The relationship between proc_cset and threaded_csets are displayed.
 2) The status of being a thread root or threaded cgroup is displayed.

This patch is extracted from Waiman's larger patch.

v2: - Removed [thread root] / [threaded] from debug.cgroup_css_links
      file as the same information is available from cgroup.type.
      Suggested by Waiman.
    - Threaded marking is moved to the previous patch.

Patch-originally-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 8cfd8147

kernel/cgroup/cgroup-internal.h

+2 −0
Original line number Diff line number Diff line
@@ -153,6 +153,8 @@ static inline void get_css_set(struct css_set *cset) 


bool cgroup_ssid_enabled(int ssid);

bool cgroup_on_dfl(const struct cgroup *cgrp);

bool cgroup_is_thread_root(struct cgroup *cgrp);

bool cgroup_is_threaded(struct cgroup *cgrp);



struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);

struct cgroup *task_cgroup_from_root(struct task_struct *task,

kernel/cgroup/cgroup.c

+2 −2
Original line number Diff line number Diff line
@@ -333,7 +333,7 @@ static bool cgroup_has_tasks(struct cgroup *cgrp) 
	return cgrp->nr_populated_csets;

}



static bool cgroup_is_threaded(struct cgroup *cgrp)

bool cgroup_is_threaded(struct cgroup *cgrp)

{

	return cgrp->dom_cgrp != cgrp;

}
@@ -372,7 +372,7 @@ static bool cgroup_can_be_thread_root(struct cgroup *cgrp) 
}



/* is @cgrp root of a threaded subtree? */

static bool cgroup_is_thread_root(struct cgroup *cgrp)

bool cgroup_is_thread_root(struct cgroup *cgrp)

{

	/* thread root should be a domain */

	if (cgroup_is_threaded(cgrp))

kernel/cgroup/debug.c

+38 −14
Original line number Diff line number Diff line
@@ -114,15 +114,36 @@ 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;

	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;
@@ -136,6 +157,7 @@ static int cgroup_css_links_read(struct seq_file *seq, void *v) 
					extra--;

				extra_refs += extra;

			}

		}

		seq_puts(seq, "\n");



		list_for_each_entry(task, &cset->tasks, cg_list) {
@@ -163,10 +185,12 @@ static int cgroup_css_links_read(struct seq_file *seq, void *v) 
	}

	spin_unlock_irq(&css_set_lock);



	if (!dead_cnt && !extra_refs)

	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)

CRA Git | Maintained and supported by SUSTech CRA and CCSE