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authorLi Zefan <lizf@cn.fujitsu.com>2009-01-10 02:43:15 -0500
committerIngo Molnar <mingo@elte.hu>2009-01-10 20:40:32 -0500
commit805194c35b91999b139e4d6b6145f4f84fd4c814 (patch)
tree7530c66ec53045858bba70ad8f1c626c450d12cc
parent62ea9ceb17a74bc7544211bfeecf4170c554ac4f (diff)
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.c21
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)
145 read_unlock_irqrestore(&tasklist_lock, flags); 145 read_unlock_irqrestore(&tasklist_lock, flags);
146} 146}
147 147
148#if defined(CONFIG_CGROUP_SCHED) && \
149 (defined(CONFIG_FAIR_GROUP_SCHED) || defined(CONFIG_RT_GROUP_SCHED))
150static void task_group_path(struct task_group *tg, char *buf, int buflen)
151{
152 /* may be NULL if the underlying cgroup isn't fully-created yet */
153 if (!tg->css.cgroup) {
154 buf[0] = '\0';
155 return;
156 }
157 cgroup_path(tg->css.cgroup, buf, buflen);
158}
159#endif
160
148void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq) 161void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
149{ 162{
150 s64 MIN_vruntime = -1, min_vruntime, max_vruntime = -1, 163 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)
154 unsigned long flags; 167 unsigned long flags;
155 168
156#if defined(CONFIG_CGROUP_SCHED) && defined(CONFIG_FAIR_GROUP_SCHED) 169#if defined(CONFIG_CGROUP_SCHED) && defined(CONFIG_FAIR_GROUP_SCHED)
157 char path[128] = ""; 170 char path[128];
158 struct task_group *tg = cfs_rq->tg; 171 struct task_group *tg = cfs_rq->tg;
159 172
160 cgroup_path(tg->css.cgroup, path, sizeof(path)); 173 task_group_path(tg, path, sizeof(path));
161 174
162 SEQ_printf(m, "\ncfs_rq[%d]:%s\n", cpu, path); 175 SEQ_printf(m, "\ncfs_rq[%d]:%s\n", cpu, path);
163#elif defined(CONFIG_USER_SCHED) && defined(CONFIG_FAIR_GROUP_SCHED) 176#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)
208void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq) 221void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq)
209{ 222{
210#if defined(CONFIG_CGROUP_SCHED) && defined(CONFIG_RT_GROUP_SCHED) 223#if defined(CONFIG_CGROUP_SCHED) && defined(CONFIG_RT_GROUP_SCHED)
211 char path[128] = ""; 224 char path[128];
212 struct task_group *tg = rt_rq->tg; 225 struct task_group *tg = rt_rq->tg;
213 226
214 cgroup_path(tg->css.cgroup, path, sizeof(path)); 227 task_group_path(tg, path, sizeof(path));
215 228
216 SEQ_printf(m, "\nrt_rq[%d]:%s\n", cpu, path); 229 SEQ_printf(m, "\nrt_rq[%d]:%s\n", cpu, path);
217#else 230#else