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-rw-r--r--kernel/cgroup/debug.c381
1 files changed, 381 insertions, 0 deletions
diff --git a/kernel/cgroup/debug.c b/kernel/cgroup/debug.c
new file mode 100644
index 000000000..80aa3f027
--- /dev/null
+++ b/kernel/cgroup/debug.c
@@ -0,0 +1,381 @@
+// 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;
+}