9 files changed, 45 insertions, 25 deletions

diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 628e50f6f8a8..8e5863e900bf 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -179,21 +179,25 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 
 
+static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
+{
+        return css ? container_of(css, struct blkcg, css) : NULL;
+}
+
 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
 {
-        return container_of(cgroup_css(cgroup, blkio_subsys_id),
-                            struct blkcg, css);
+        return css_to_blkcg(cgroup_css(cgroup, blkio_subsys_id));
 }
 
 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
 {
-        return container_of(task_css(tsk, blkio_subsys_id), struct blkcg, css);
+        return css_to_blkcg(task_css(tsk, blkio_subsys_id));
 }
 
 static inline struct blkcg *bio_blkcg(struct bio *bio)
 {
         if (bio && bio->bi_css)
-                return container_of(bio->bi_css, struct blkcg, css);
+                return css_to_blkcg(bio->bi_css);
         return task_blkcg(current);
 }
 
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 9d3f61566fec..1db686e47a22 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -45,16 +45,19 @@ struct freezer {
         spinlock_t                      lock;
 };
 
+static inline struct freezer *css_freezer(struct cgroup_subsys_state *css)
+{
+        return css ? container_of(css, struct freezer, css) : NULL;
+}
+
 static inline struct freezer *cgroup_freezer(struct cgroup *cgroup)
 {
-        return container_of(cgroup_css(cgroup, freezer_subsys_id),
-                            struct freezer, css);
+        return css_freezer(cgroup_css(cgroup, freezer_subsys_id));
 }
 
 static inline struct freezer *task_freezer(struct task_struct *task)
 {
-        return container_of(task_css(task, freezer_subsys_id),
-                            struct freezer, css);
+        return css_freezer(task_css(task, freezer_subsys_id));
 }
 
 static struct freezer *parent_freezer(struct freezer *freezer)
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index f7371341d42a..6e9cbdde25bd 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -114,18 +114,21 @@ struct cpuset {
         int relax_domain_level;
 };
 
+static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
+{
+        return css ? container_of(css, struct cpuset, css) : NULL;
+}
+
 /* Retrieve the cpuset for a cgroup */
 static inline struct cpuset *cgroup_cs(struct cgroup *cgrp)
 {
-        return container_of(cgroup_css(cgrp, cpuset_subsys_id),
-                            struct cpuset, css);
+        return css_cs(cgroup_css(cgrp, cpuset_subsys_id));
 }
 
 /* Retrieve the cpuset for a task */
 static inline struct cpuset *task_cs(struct task_struct *task)
 {
-        return container_of(task_css(task, cpuset_subsys_id),
-                            struct cpuset, css);
+        return css_cs(task_css(task, cpuset_subsys_id));
 }
 
 static inline struct cpuset *parent_cs(struct cpuset *cs)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 323d907eac1a..5bccb0277129 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7083,11 +7083,15 @@ int sched_rt_handler(struct ctl_table *table, int write,
 
 #ifdef CONFIG_CGROUP_SCHED
 
+static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
+{
+        return css ? container_of(css, struct task_group, css) : NULL;
+}
+
 /* return corresponding task_group object of a cgroup */
 static inline struct task_group *cgroup_tg(struct cgroup *cgrp)
 {
-        return container_of(cgroup_css(cgrp, cpu_cgroup_subsys_id),
-                            struct task_group, css);
+        return css_tg(cgroup_css(cgrp, cpu_cgroup_subsys_id));
 }
 
 static struct cgroup_subsys_state *cpu_cgroup_css_alloc(struct cgroup *cgrp)
diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 4a210faaab77..8ccfa10cc89f 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -33,18 +33,21 @@ struct cpuacct {
         struct kernel_cpustat __percpu *cpustat;
 };
 
+static inline struct cpuacct *css_ca(struct cgroup_subsys_state *css)
+{
+        return css ? container_of(css, struct cpuacct, css) : NULL;
+}
+
 /* return cpu accounting group corresponding to this container */
 static inline struct cpuacct *cgroup_ca(struct cgroup *cgrp)
 {
-        return container_of(cgroup_css(cgrp, cpuacct_subsys_id),
-                            struct cpuacct, css);
+        return css_ca(cgroup_css(cgrp, cpuacct_subsys_id));
 }
 
 /* return cpu accounting group to which this task belongs */
 static inline struct cpuacct *task_ca(struct task_struct *tsk)
 {
-        return container_of(task_css(tsk, cpuacct_subsys_id),
-                            struct cpuacct, css);
+        return css_ca(task_css(tsk, cpuacct_subsys_id));
 }
 
 static inline struct cpuacct *__parent_ca(struct cpuacct *ca)
diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index d2f9fc0b186e..95585a0b9c8d 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -36,7 +36,7 @@ static struct hugetlb_cgroup *root_h_cgroup __read_mostly;
 static inline
 struct hugetlb_cgroup *hugetlb_cgroup_from_css(struct cgroup_subsys_state *s)
 {
-        return container_of(s, struct hugetlb_cgroup, css);
+        return s ? container_of(s, struct hugetlb_cgroup, css) : NULL;
 }
 
 static inline
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b47bd3ad3c2b..11d659e3b08e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -486,7 +486,7 @@ static DEFINE_MUTEX(memcg_create_mutex);
 static inline
 struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s)
 {
-        return container_of(s, struct mem_cgroup, css);
+        return s ? container_of(s, struct mem_cgroup, css) : NULL;
 }
 
 /* Some nice accessors for the vmpressure. */
diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
index 5ee72a001df0..af412ab2b477 100644
--- a/net/sched/cls_cgroup.c
+++ b/net/sched/cls_cgroup.c
@@ -23,16 +23,19 @@
 #include <net/sock.h>
 #include <net/cls_cgroup.h>
 
+static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
+{
+        return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
+}
+
 static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
 {
-        return container_of(cgroup_css(cgrp, net_cls_subsys_id),
-                            struct cgroup_cls_state, css);
+        return css_cls_state(cgroup_css(cgrp, net_cls_subsys_id));
 }
 
 static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p)
 {
-        return container_of(task_css(p, net_cls_subsys_id),
-                            struct cgroup_cls_state, css);
+        return css_cls_state(task_css(p, net_cls_subsys_id));
 }
 
 static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 87a0a037fbd6..90953648c643 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -53,7 +53,7 @@ struct dev_cgroup {
 
 static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s)
 {
-        return container_of(s, struct dev_cgroup, css);
+        return s ? container_of(s, struct dev_cgroup, css) : NULL;
 }
 
 static inline struct dev_cgroup *cgroup_to_devcgroup(struct cgroup *cgroup)