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authorTejun Heo <tj@kernel.org>2017-05-15 09:34:01 -0400
committerTejun Heo <tj@kernel.org>2017-07-21 11:14:51 -0400
commitbc2fb7ed089ffd16d26e1d95b898a37d2b37d201 (patch)
tree87675b436609b0a31ffde08798c761876e6c4db0 /kernel/cgroup/freezer.c
parent715c809d9a9e38d8fb9476757ddaf64c1a9f767f (diff)
cgroup: add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS
css_task_iter currently always walks all tasks. With the scheduled cgroup v2 thread support, the iterator would need to handle multiple types of iteration. As a preparation, add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS. If the flag is not specified, it walks all tasks as before. When asserted, the iterator only walks the group leaders. For now, the only user of the flag is cgroup v2 "cgroup.procs" file which no longer needs to skip non-leader tasks in cgroup_procs_next(). Note that cgroup v1 "cgroup.procs" can't use the group leader walk as v1 "cgroup.procs" doesn't mean "list all thread group leaders in the cgroup" but "list all thread group id's with any threads in the cgroup". While at it, update cgroup_procs_show() to use task_pid_vnr() instead of task_tgid_vnr(). As the iteration guarantees that the function only sees group leaders, this doesn't change the output and will allow sharing the function for thread iteration. Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup/freezer.c')
-rw-r--r--kernel/cgroup/freezer.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/cgroup/freezer.c b/kernel/cgroup/freezer.c
index 1b72d56edce5..08236798d173 100644
--- a/kernel/cgroup/freezer.c
+++ b/kernel/cgroup/freezer.c
@@ -268,7 +268,7 @@ static void update_if_frozen(struct cgroup_subsys_state *css)
rcu_read_unlock();
/* are all tasks frozen? */
- css_task_iter_start(css, &it);
+ css_task_iter_start(css, 0, &it);
while ((task = css_task_iter_next(&it))) {
if (freezing(task)) {
@@ -320,7 +320,7 @@ static void freeze_cgroup(struct freezer *freezer)
struct css_task_iter it;
struct task_struct *task;
- css_task_iter_start(&freezer->css, &it);
+ css_task_iter_start(&freezer->css, 0, &it);
while ((task = css_task_iter_next(&it)))
freeze_task(task);
css_task_iter_end(&it);
@@ -331,7 +331,7 @@ static void unfreeze_cgroup(struct freezer *freezer)
struct css_task_iter it;
struct task_struct *task;
- css_task_iter_start(&freezer->css, &it);
+ css_task_iter_start(&freezer->css, 0, &it);
while ((task = css_task_iter_next(&it)))
__thaw_task(task);
css_task_iter_end(&it);