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Message-ID: <20140210230659.GJ25350@mtj.dyndns.org>
Date: Mon, 10 Feb 2014 18:06:59 -0500
From: Tejun Heo <tj@...nel.org>
To: lizefan@...wei.com
Cc: containers@...ts.linux-foundation.org, cgroups@...r.kernel.org,
linux-kernel@...r.kernel.org,
Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH v2 15/16] cgroup: cosmetic updates to cgroup_attach_task()
cgroup_attach_task() is planned to go through restructuring. Let's
tidy it up a bit in preparation.
* Update cgroup_attach_task() to receive the target task argument in
@leader instead of @tsk.
* Rename @tsk to @task.
* Rename @retval to @ret.
This is purely cosmetic.
v2: get_nr_threads() was using uninitialized @task instead of @leader.
Fixed. Reported by Dan Carpenter.
Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Dan Carpenter <dan.carpenter@...cle.com>
---
Hello,
The fixed part doesn't affect the end result. It gets removed by the
next patchset. I'll leave the git branch as-is for now.
Thanks.
kernel/cgroup.c | 45 +++++++++++++++++++++++----------------------
1 file changed, 23 insertions(+), 22 deletions(-)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1726,20 +1726,20 @@ static void cgroup_task_migrate(struct c
/**
* cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
* @cgrp: the cgroup to attach to
- * @tsk: the task or the leader of the threadgroup to be attached
+ * @leader: the task or the leader of the threadgroup to be attached
* @threadgroup: attach the whole threadgroup?
*
* Call holding cgroup_mutex and the group_rwsem of the leader. Will take
* task_lock of @tsk or each thread in the threadgroup individually in turn.
*/
-static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk,
+static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *leader,
bool threadgroup)
{
- int retval, i, group_size;
+ int ret, i, group_size;
struct cgroupfs_root *root = cgrp->root;
struct cgroup_subsys_state *css, *failed_css = NULL;
/* threadgroup list cursor and array */
- struct task_struct *leader = tsk;
+ struct task_struct *task;
struct task_and_cgroup *tc;
struct flex_array *group;
struct cgroup_taskset tset = { };
@@ -1752,7 +1752,7 @@ static int cgroup_attach_task(struct cgr
* threads exit, this will just be an over-estimate.
*/
if (threadgroup)
- group_size = get_nr_threads(tsk);
+ group_size = get_nr_threads(leader);
else
group_size = 1;
/* flex_array supports very large thread-groups better than kmalloc. */
@@ -1760,8 +1760,8 @@ static int cgroup_attach_task(struct cgr
if (!group)
return -ENOMEM;
/* pre-allocate to guarantee space while iterating in rcu read-side. */
- retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL);
- if (retval)
+ ret = flex_array_prealloc(group, 0, group_size, GFP_KERNEL);
+ if (ret)
goto out_free_group_list;
i = 0;
@@ -1772,17 +1772,18 @@ static int cgroup_attach_task(struct cgr
*/
down_read(&css_set_rwsem);
rcu_read_lock();
+ task = leader;
do {
struct task_and_cgroup ent;
- /* @tsk either already exited or can't exit until the end */
- if (tsk->flags & PF_EXITING)
+ /* @task either already exited or can't exit until the end */
+ if (task->flags & PF_EXITING)
goto next;
/* as per above, nr_threads may decrease, but not increase. */
BUG_ON(i >= group_size);
- ent.task = tsk;
- ent.cgrp = task_cgroup_from_root(tsk, root);
+ ent.task = task;
+ ent.cgrp = task_cgroup_from_root(task, root);
/* nothing to do if this task is already in the cgroup */
if (ent.cgrp == cgrp)
goto next;
@@ -1790,13 +1791,13 @@ static int cgroup_attach_task(struct cgr
* saying GFP_ATOMIC has no effect here because we did prealloc
* earlier, but it's good form to communicate our expectations.
*/
- retval = flex_array_put(group, i, &ent, GFP_ATOMIC);
- BUG_ON(retval != 0);
+ ret = flex_array_put(group, i, &ent, GFP_ATOMIC);
+ BUG_ON(ret != 0);
i++;
next:
if (!threadgroup)
break;
- } while_each_thread(leader, tsk);
+ } while_each_thread(leader, task);
rcu_read_unlock();
up_read(&css_set_rwsem);
/* remember the number of threads in the array for later. */
@@ -1805,7 +1806,7 @@ static int cgroup_attach_task(struct cgr
tset.tc_array_len = group_size;
/* methods shouldn't be called if no task is actually migrating */
- retval = 0;
+ ret = 0;
if (!group_size)
goto out_free_group_list;
@@ -1814,8 +1815,8 @@ static int cgroup_attach_task(struct cgr
*/
for_each_css(css, i, cgrp) {
if (css->ss->can_attach) {
- retval = css->ss->can_attach(css, &tset);
- if (retval) {
+ ret = css->ss->can_attach(css, &tset);
+ if (ret) {
failed_css = css;
goto out_cancel_attach;
}
@@ -1833,7 +1834,7 @@ static int cgroup_attach_task(struct cgr
old_cset = task_css_set(tc->task);
tc->cset = find_css_set(old_cset, cgrp);
if (!tc->cset) {
- retval = -ENOMEM;
+ ret = -ENOMEM;
goto out_put_css_set_refs;
}
}
@@ -1861,9 +1862,9 @@ static int cgroup_attach_task(struct cgr
/*
* step 5: success! and cleanup
*/
- retval = 0;
+ ret = 0;
out_put_css_set_refs:
- if (retval) {
+ if (ret) {
for (i = 0; i < group_size; i++) {
tc = flex_array_get(group, i);
if (!tc->cset)
@@ -1872,7 +1873,7 @@ out_put_css_set_refs:
}
}
out_cancel_attach:
- if (retval) {
+ if (ret) {
for_each_css(css, i, cgrp) {
if (css == failed_css)
break;
@@ -1882,7 +1883,7 @@ out_cancel_attach:
}
out_free_group_list:
flex_array_free(group);
- return retval;
+ return ret;
}
/*
--
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