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Message-ID: <20121113202745.GB21185@mtj.dyndns.org>
Date: Tue, 13 Nov 2012 12:27:45 -0800
From: Tejun Heo <tj@...nel.org>
To: Li Zefan <lizefan@...wei.com>
Cc: containers@...ts.linux-foundation.org, cgroups@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] cgroup, cpuset: remove cgroup_subsys->post_clone()
>From bbf2566f9f4fc79ff3320e83cafb69533efc9ea0 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@...nel.org>
Date: Tue, 13 Nov 2012 12:21:50 -0800
Currently CGRP_CPUSET_CLONE_CHILDREN triggers ->post_clone(). Now
that clone_children is cpuset specific, there's no reason to have this
rather odd option activation mechanism in cgroup core. cpuset can
check the flag from its ->css_allocate() and take the necessary
action.
Move cpuset_post_clone() logic to the end of cpuset_css_alloc() and
remove cgroup_subsys->post_clone().
Loosely based on Glauber's "generalize post_clone into post_create"
patch.
Signed-off-by: Tejun Heo <tj@...nel.org>
Original-patch-by: Glauber Costa <glommer@...allels.com>
Original-patch: <1351686554-22592-2-git-send-email-glommer@...allels.com>
Cc: Glauber Costa <glommer@...allels.com>
---
Documentation/cgroups/cgroups.txt | 8 ----
include/linux/cgroup.h | 1 -
kernel/cgroup.c | 4 --
kernel/cpuset.c | 80 ++++++++++++++++++---------------------
4 files changed, 36 insertions(+), 57 deletions(-)
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt
index 24cdf76..bcf1a00 100644
--- a/Documentation/cgroups/cgroups.txt
+++ b/Documentation/cgroups/cgroups.txt
@@ -642,14 +642,6 @@ void exit(struct task_struct *task)
Called during task exit.
-void post_clone(struct cgroup *cgrp)
-(cgroup_mutex held by caller)
-
-Called during cgroup_create() to do any parameter
-initialization which might be required before a task could attach. For
-example, in cpusets, no task may attach before 'cpus' and 'mems' are set
-up.
-
void bind(struct cgroup *root)
(cgroup_mutex held by caller)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 926d8d1..d5fc8a7 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -449,7 +449,6 @@ struct cgroup_subsys {
void (*fork)(struct task_struct *task);
void (*exit)(struct cgroup *cgrp, struct cgroup *old_cgrp,
struct task_struct *task);
- void (*post_clone)(struct cgroup *cgrp);
void (*bind)(struct cgroup *root);
int subsys_id;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index a49572e..35aa18b 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4142,10 +4142,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
if (err)
goto err_free_all;
}
- /* At error, ->css_free() callback has to free assigned ID. */
- if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags) &&
- ss->post_clone)
- ss->post_clone(cgrp);
if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
parent->parent) {
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 0693133..b017887 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1784,56 +1784,20 @@ static struct cftype files[] = {
};
/*
- * post_clone() is called during cgroup_create() when the
- * clone_children mount argument was specified. The cgroup
- * can not yet have any tasks.
- *
- * Currently we refuse to set up the cgroup - thereby
- * refusing the task to be entered, and as a result refusing
- * the sys_unshare() or clone() which initiated it - if any
- * sibling cpusets have exclusive cpus or mem.
- *
- * If this becomes a problem for some users who wish to
- * allow that scenario, then cpuset_post_clone() could be
- * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
- * (and likewise for mems) to the new cgroup. Called with cgroup_mutex
- * held.
- */
-static void cpuset_post_clone(struct cgroup *cgroup)
-{
- struct cgroup *parent, *child;
- struct cpuset *cs, *parent_cs;
-
- parent = cgroup->parent;
- list_for_each_entry(child, &parent->children, sibling) {
- cs = cgroup_cs(child);
- if (is_mem_exclusive(cs) || is_cpu_exclusive(cs))
- return;
- }
- cs = cgroup_cs(cgroup);
- parent_cs = cgroup_cs(parent);
-
- mutex_lock(&callback_mutex);
- cs->mems_allowed = parent_cs->mems_allowed;
- cpumask_copy(cs->cpus_allowed, parent_cs->cpus_allowed);
- mutex_unlock(&callback_mutex);
- return;
-}
-
-/*
* cpuset_css_alloc - allocate a cpuset css
* cont: control group that the new cpuset will be part of
*/
static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
{
- struct cpuset *cs;
- struct cpuset *parent;
+ struct cgroup *parent_cg = cont->parent;
+ struct cgroup *tmp_cg;
+ struct cpuset *parent, *cs;
- if (!cont->parent) {
+ if (!parent_cg)
return &top_cpuset.css;
- }
- parent = cgroup_cs(cont->parent);
+ parent = cgroup_cs(parent_cg);
+
cs = kmalloc(sizeof(*cs), GFP_KERNEL);
if (!cs)
return ERR_PTR(-ENOMEM);
@@ -1855,7 +1819,36 @@ static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
cs->parent = parent;
number_of_cpusets++;
- return &cs->css ;
+
+ if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cont->flags))
+ goto skip_clone;
+
+ /*
+ * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
+ * set. This flag handling is implemented in cgroup core for
+ * histrical reasons - the flag may be specified during mount.
+ *
+ * Currently, if any sibling cpusets have exclusive cpus or mem, we
+ * refuse to clone the configuration - thereby refusing the task to
+ * be entered, and as a result refusing the sys_unshare() or
+ * clone() which initiated it. If this becomes a problem for some
+ * users who wish to allow that scenario, then this could be
+ * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
+ * (and likewise for mems) to the new cgroup.
+ */
+ list_for_each_entry(tmp_cg, &parent_cg->children, sibling) {
+ struct cpuset *tmp_cs = cgroup_cs(tmp_cg);
+
+ if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs))
+ goto skip_clone;
+ }
+
+ mutex_lock(&callback_mutex);
+ cs->mems_allowed = parent->mems_allowed;
+ cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
+ mutex_unlock(&callback_mutex);
+skip_clone:
+ return &cs->css;
}
/*
@@ -1882,7 +1875,6 @@ struct cgroup_subsys cpuset_subsys = {
.css_free = cpuset_css_free,
.can_attach = cpuset_can_attach,
.attach = cpuset_attach,
- .post_clone = cpuset_post_clone,
.subsys_id = cpuset_subsys_id,
.base_cftypes = files,
.early_init = 1,
--
1.7.11.7
--
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