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Date: Thu, 3 Mar 2016 12:20:01 -0500
From: Tejun Heo <tj@...nel.org>
To: lizefan@...wei.com, hannes@...xchg.org
Cc: cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
kernel-team@...com, Tejun Heo <tj@...nel.org>
Subject: [PATCH 3/4] cgroup: make cgroup[_taskset]_migrate() take cgroup_root instead of cgroup
On the default hierarchy, a migration can be multi-source and/or
multi-destination. cgroup_taskest_migrate() used to incorrectly
assume single destination cgroup but the bug has been fixed by
1f7dd3e5a6e4 ("cgroup: fix handling of multi-destination migration
from subtree_control enabling").
Since the commit, @dst_cgrp to cgroup[_taskset]_migrate() is only used
to determine which subsystems are affected or which cgroup_root the
migration is taking place in. As such, @dst_cgrp is misleading. This
patch replaces @dst_cgrp with @root.
Signed-off-by: Tejun Heo <tj@...nel.org>
---
kernel/cgroup.c | 70 ++++++++++++++++++++++++++++-----------------------------
1 file changed, 35 insertions(+), 35 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 8a02076..5dd7613 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2355,38 +2355,38 @@ struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
}
/**
- * cgroup_taskset_migrate - migrate a taskset to a cgroup
+ * cgroup_taskset_migrate - migrate a taskset
* @tset: taget taskset
- * @dst_cgrp: destination cgroup
+ * @root: cgroup root the migration is taking place on
*
- * Migrate tasks in @tset to @dst_cgrp. This function fails iff one of the
- * ->can_attach callbacks fails and guarantees that either all or none of
- * the tasks in @tset are migrated. @tset is consumed regardless of
- * success.
+ * Migrate tasks in @tset as setup by migration preparation functions.
+ * This function fails iff one of the ->can_attach callbacks fails and
+ * guarantees that either all or none of the tasks in @tset are migrated.
+ * @tset is consumed regardless of success.
*/
static int cgroup_taskset_migrate(struct cgroup_taskset *tset,
- struct cgroup *dst_cgrp)
+ struct cgroup_root *root)
{
- struct cgroup_subsys_state *css, *failed_css = NULL;
+ struct cgroup_subsys *ss;
struct task_struct *task, *tmp_task;
struct css_set *cset, *tmp_cset;
- int i, ret;
+ int ssid, failed_ssid, ret;
/* methods shouldn't be called if no task is actually migrating */
if (list_empty(&tset->src_csets))
return 0;
/* check that we can legitimately attach to the cgroup */
- for_each_e_css(css, i, dst_cgrp) {
- if (css->ss->can_attach) {
- tset->ssid = i;
- ret = css->ss->can_attach(tset);
+ do_each_subsys_mask(ss, ssid, root->subsys_mask) {
+ if (ss->can_attach) {
+ tset->ssid = ssid;
+ ret = ss->can_attach(tset);
if (ret) {
- failed_css = css;
+ failed_ssid = ssid;
goto out_cancel_attach;
}
}
- }
+ } while_each_subsys_mask();
/*
* Now that we're guaranteed success, proceed to move all tasks to
@@ -2413,25 +2413,25 @@ static int cgroup_taskset_migrate(struct cgroup_taskset *tset,
*/
tset->csets = &tset->dst_csets;
- for_each_e_css(css, i, dst_cgrp) {
- if (css->ss->attach) {
- tset->ssid = i;
- css->ss->attach(tset);
+ do_each_subsys_mask(ss, ssid, root->subsys_mask) {
+ if (ss->attach) {
+ tset->ssid = ssid;
+ ss->attach(tset);
}
- }
+ } while_each_subsys_mask();
ret = 0;
goto out_release_tset;
out_cancel_attach:
- for_each_e_css(css, i, dst_cgrp) {
- if (css == failed_css)
+ do_each_subsys_mask(ss, ssid, root->subsys_mask) {
+ if (ssid == failed_ssid)
break;
- if (css->ss->cancel_attach) {
- tset->ssid = i;
- css->ss->cancel_attach(tset);
+ if (ss->cancel_attach) {
+ tset->ssid = ssid;
+ ss->cancel_attach(tset);
}
- }
+ } while_each_subsys_mask();
out_release_tset:
spin_lock_bh(&css_set_lock);
list_splice_init(&tset->dst_csets, &tset->src_csets);
@@ -2586,11 +2586,11 @@ static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp,
* cgroup_migrate - migrate a process or task to a cgroup
* @leader: the leader of the process or the task to migrate
* @threadgroup: whether @leader points to the whole process or a single task
- * @cgrp: the destination cgroup
+ * @root: cgroup root migration is taking place on
*
- * Migrate a process or task denoted by @leader to @cgrp. If migrating a
- * process, the caller must be holding cgroup_threadgroup_rwsem. The
- * caller is also responsible for invoking cgroup_migrate_add_src() and
+ * Migrate a process or task denoted by @leader. If migrating a process,
+ * the caller must be holding cgroup_threadgroup_rwsem. The caller is also
+ * responsible for invoking cgroup_migrate_add_src() and
* cgroup_migrate_prepare_dst() on the targets before invoking this
* function and following up with cgroup_migrate_finish().
*
@@ -2601,7 +2601,7 @@ static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp,
* actually starting migrating.
*/
static int cgroup_migrate(struct task_struct *leader, bool threadgroup,
- struct cgroup *cgrp)
+ struct cgroup_root *root)
{
struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset);
struct task_struct *task;
@@ -2622,7 +2622,7 @@ static int cgroup_migrate(struct task_struct *leader, bool threadgroup,
rcu_read_unlock();
spin_unlock_bh(&css_set_lock);
- return cgroup_taskset_migrate(&tset, cgrp);
+ return cgroup_taskset_migrate(&tset, root);
}
/**
@@ -2659,7 +2659,7 @@ static int cgroup_attach_task(struct cgroup *dst_cgrp,
/* prepare dst csets and commit */
ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets);
if (!ret)
- ret = cgroup_migrate(leader, threadgroup, dst_cgrp);
+ ret = cgroup_migrate(leader, threadgroup, dst_cgrp->root);
cgroup_migrate_finish(&preloaded_csets);
return ret;
@@ -2934,7 +2934,7 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp)
}
spin_unlock_bh(&css_set_lock);
- ret = cgroup_taskset_migrate(&tset, cgrp);
+ ret = cgroup_taskset_migrate(&tset, cgrp->root);
out_finish:
cgroup_migrate_finish(&preloaded_csets);
percpu_up_write(&cgroup_threadgroup_rwsem);
@@ -4172,7 +4172,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
css_task_iter_end(&it);
if (task) {
- ret = cgroup_migrate(task, false, to);
+ ret = cgroup_migrate(task, false, to->root);
put_task_struct(task);
}
} while (task && !ret);
--
2.5.0
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