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Commit 805194c3 authored by Li Zefan's avatar Li Zefan Committed by Ingo Molnar
Browse files

sched: partly revert "sched debug: remove NULL checking in print_cfs_rt_rq()" 



Impact: avoid accessing NULL tg.css->cgroup

In commit 0a0db8f5, I removed checking
NULL tg.css->cgroup, but I realized I was wrong when I found reading
/proc/sched_debug can race with cgroup_create().

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 62ea9ceb

kernel/sched_debug.c

+17 −4
Original line number Diff line number Diff line
@@ -145,6 +145,19 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu) 
	read_unlock_irqrestore(&tasklist_lock, flags);

}



#if defined(CONFIG_CGROUP_SCHED) && \

	(defined(CONFIG_FAIR_GROUP_SCHED) || defined(CONFIG_RT_GROUP_SCHED))

static void task_group_path(struct task_group *tg, char *buf, int buflen)

{

	/* may be NULL if the underlying cgroup isn't fully-created yet */

	if (!tg->css.cgroup) {

		buf[0] = '\0';

		return;

	}

	cgroup_path(tg->css.cgroup, buf, buflen);

}

#endif



void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)

{

	s64 MIN_vruntime = -1, min_vruntime, max_vruntime = -1,
@@ -154,10 +167,10 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq) 
	unsigned long flags;



#if defined(CONFIG_CGROUP_SCHED) && defined(CONFIG_FAIR_GROUP_SCHED)

	char path[128] = "";

	char path[128];

	struct task_group *tg = cfs_rq->tg;



	cgroup_path(tg->css.cgroup, path, sizeof(path));

	task_group_path(tg, path, sizeof(path));



	SEQ_printf(m, "\ncfs_rq[%d]:%s\n", cpu, path);

#elif defined(CONFIG_USER_SCHED) && defined(CONFIG_FAIR_GROUP_SCHED)
@@ -208,10 +221,10 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq) 
void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq)

{

#if defined(CONFIG_CGROUP_SCHED) && defined(CONFIG_RT_GROUP_SCHED)

	char path[128] = "";

	char path[128];

	struct task_group *tg = rt_rq->tg;



	cgroup_path(tg->css.cgroup, path, sizeof(path));

	task_group_path(tg, path, sizeof(path));



	SEQ_printf(m, "\nrt_rq[%d]:%s\n", cpu, path);

#else