Commit 575313f4 authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo

cgroup: Make debug cgroup support v2 and thread mode

Besides supporting cgroup v2 and thread mode, the following changes
are also made:
 1) current_* cgroup files now resides only at the root as we don't
    need duplicated files of the same function all over the cgroup
    hierarchy.
 2) The cgroup_css_links_read() function is modified to report
    the number of tasks that are skipped because of overflow.
 3) The number of extra unaccounted references are displayed.
 4) The current_css_set_read() function now prints out the addresses of
    the css'es associated with the current css_set.
 5) A new cgroup_subsys_states file is added to display the css objects
    associated with a cgroup.
 6) A new cgroup_masks file is added to display the various controller
    bit masks in the cgroup.

tj: Dropped thread mode related information for now so that debug
    controller changes aren't blocked on the thread mode.
Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 23b0be48
......@@ -36,10 +36,37 @@ static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
return cgroup_task_count(css->cgroup);
}
static u64 current_css_set_read(struct cgroup_subsys_state *css,
struct cftype *cft)
static int current_css_set_read(struct seq_file *seq, void *v)
{
return (u64)(unsigned long)current->cgroups;
struct css_set *cset;
struct cgroup_subsys *ss;
struct cgroup_subsys_state *css;
int i, refcnt;
mutex_lock(&cgroup_mutex);
spin_lock_irq(&css_set_lock);
rcu_read_lock();
cset = rcu_dereference(current->cgroups);
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- %lx[%d]\n", ss->id, ss->name,
(unsigned long)css, css->id);
}
rcu_read_unlock();
spin_unlock_irq(&css_set_lock);
mutex_unlock(&cgroup_mutex);
return 0;
}
static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
......@@ -84,31 +111,126 @@ 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;
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);
seq_printf(seq, " %d", refcnt);
if (refcnt - cset->nr_tasks > 0) {
int extra = refcnt - cset->nr_tasks;
seq_printf(seq, "css_set %pK\n", cset);
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)
goto overflow;
seq_printf(seq, " task %d\n", task_pid_vnr(task));
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)
goto overflow;
seq_printf(seq, " task %d\n", task_pid_vnr(task));
if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
seq_printf(seq, " task %d\n",
task_pid_vnr(task));
}
continue;
overflow:
seq_puts(seq, " ...\n");
/* 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)
return 0;
seq_puts(seq, "\n");
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 cgroup *cgrp = seq_css(seq)->cgroup;
struct cgroup_subsys *ss;
struct cgroup_subsys_state *css;
char pbuf[16];
int i;
mutex_lock(&cgroup_mutex);
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- %lx[%d] %d%s\n", ss->id, ss->name,
(unsigned long)css, css->id,
atomic_read(&css->online_cnt), pbuf);
}
mutex_unlock(&cgroup_mutex);
return 0;
}
static int cgroup_masks_read(struct seq_file *seq, void *v)
{
struct cgroup *cgrp = seq_css(seq)->cgroup;
struct cgroup_subsys *ss;
int i, j;
struct {
u16 *mask;
char *name;
} mask_list[] = {
{ &cgrp->subtree_control, "subtree_control" },
{ &cgrp->subtree_ss_mask, "subtree_ss_mask" },
};
mutex_lock(&cgroup_mutex);
for (i = 0; i < ARRAY_SIZE(mask_list); i++) {
u16 mask = *mask_list[i].mask;
bool first = true;
seq_printf(seq, "%-17s: ", mask_list[i].name);
for_each_subsys(ss, j) {
if (!(mask & (1 << ss->id)))
continue;
if (!first)
seq_puts(seq, ", ");
seq_puts(seq, ss->name);
first = false;
}
seq_putc(seq, '\n');
}
mutex_unlock(&cgroup_mutex);
return 0;
}
......@@ -126,17 +248,20 @@ static struct cftype debug_files[] = {
{
.name = "current_css_set",
.read_u64 = current_css_set_read,
.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,
},
{
......@@ -144,6 +269,16 @@ static struct cftype debug_files[] = {
.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,
......@@ -156,4 +291,5 @@ struct cgroup_subsys debug_cgrp_subsys = {
.css_alloc = debug_css_alloc,
.css_free = debug_css_free,
.legacy_cftypes = debug_files,
.dfl_cftypes = debug_files,
};
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