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cgroup: Add task_under_cgroup_hierarchy cgroup inline function to headers 

This commit adds an inline function to cgroup.h to check whether a given
task is under a given cgroup hierarchy. This is to avoid having to put
ifdefs in .c files to gate access to cgroups. When cgroups are disabled
this always returns true.

Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sargun Dhillon 2016-08-12 08:56:40 -07:00 committed by David S. Miller
parent f9f9ab1726
commit aed704b7a6
1 changed files with 23 additions and 0 deletions
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23
include/linux/cgroup.h
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@ -497,6 +497,23 @@ static inline bool cgroup_is_descendant(struct cgroup *cgrp,
return cgrp->ancestor_ids[ancestor->level] == ancestor->id;
}
/**
* task_under_cgroup_hierarchy - test task's membership of cgroup ancestry
* @task: the task to be tested
* @ancestor: possible ancestor of @task's cgroup
*
* Tests whether @task's default cgroup hierarchy is a descendant of @ancestor.
* It follows all the same rules as cgroup_is_descendant, and only applies
* to the default hierarchy.
*/
static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
struct cgroup *ancestor)
{
struct css_set *cset = task_css_set(task);
return cgroup_is_descendant(cset->dfl_cgrp, ancestor);
}
/* no synchronization, the result can only be used as a hint */
static inline bool cgroup_is_populated(struct cgroup *cgrp)
{
@ -557,6 +574,7 @@ static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
#else /* !CONFIG_CGROUPS */
struct cgroup_subsys_state;
struct cgroup;
static inline void css_put(struct cgroup_subsys_state *css) {}
static inline int cgroup_attach_task_all(struct task_struct *from,
@ -574,6 +592,11 @@ static inline void cgroup_free(struct task_struct *p) {}
static inline int cgroup_init_early(void) { return 0; }
static inline int cgroup_init(void) { return 0; }
static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
struct cgroup *ancestor)
{
return true;
}
#endif /* !CONFIG_CGROUPS */
/*