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authorTejun Heo <tj@kernel.org>2013-08-08 20:11:23 -0400
committerTejun Heo <tj@kernel.org>2013-08-08 20:11:23 -0400
commita7c6d554aa01236ac2a9f851ab0f75704f76dfa2 (patch)
treefe62d07283a589daa39f843deaefafd11c572b84 /kernel/sched
parent72c97e54e0f043d33b246d7460ae0a36c4b8c643 (diff)
cgroup: add/update accessors which obtain subsys specific data from css
css (cgroup_subsys_state) is usually embedded in a subsys specific data structure. Subsystems either use container_of() directly to cast from css to such data structure or has an accessor function wrapping such cast. As cgroup as whole is moving towards using css as the main interface handle, add and update such accessors to ease dealing with css's. All accessors explicitly handle NULL input and return NULL in those cases. While this looks like an extra branch in the code, as all controllers specific data structures have css as the first field, the casting doesn't involve any offsetting and the compiler can trivially optimize out the branch. * blkio, freezer, cpuset, cpu, cpuacct and net_cls didn't have such accessor. Added. * memory, hugetlb and devices already had one but didn't explicitly handle NULL input. Updated. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/core.c8
-rw-r--r--kernel/sched/cpuacct.c11
2 files changed, 13 insertions, 6 deletions
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)