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| author | Li Zefan <lizf@cn.fujitsu.com> | 2009-01-10 15:43:15 +0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-01-11 02:40:32 +0100 |
| commit | 805194c35b91999b139e4d6b6145f4f84fd4c814 (patch) | |
| tree | 7530c66ec53045858bba70ad8f1c626c450d12cc | |
| parent | 62ea9ceb17a74bc7544211bfeecf4170c554ac4f (diff) | |
| download | linux-805194c35b91999b139e4d6b6145f4f84fd4c814.tar.gz linux-805194c35b91999b139e4d6b6145f4f84fd4c814.tar.bz2 linux-805194c35b91999b139e4d6b6145f4f84fd4c814.zip | |
sched: partly revert "sched debug: remove NULL checking in print_cfs_rt_rq()"
Impact: avoid accessing NULL tg.css->cgroup
In commit 0a0db8f5c9d4bbb9bbfcc2b6cb6bce2d0ef4d73d, 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: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | kernel/sched_debug.c | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c index 4293cfa9681d..16eeba4e4169 100644 --- a/kernel/sched_debug.c +++ b/kernel/sched_debug.c @@ -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 |