cgroup, cpuset: remove cgroup_subsys->post_clone()

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@kernel.org> Original-patch-by: Glauber Costa <glommer@parallels.com> Original-patch: <1351686554-22592-2-git-send-email-glommer@parallels.com> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Glauber Costa <glommer@parallels.com>

cgroup, cpuset: remove cgroup_subsys->post_clone()
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@kernel.org> Original-patch-by: Glauber Costa <glommer@parallels.com> Original-patch: <1351686554-22592-2-git-send-email-glommer@parallels.com> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Glauber Costa <glommer@parallels.com>
Tejun Heo
1 parent 2260e7fc1f
Showing 4 changed files with 36 additions and 57 deletions Side-by-side Diff
Documentation/cgroups/cgroups.txt
include/linux/cgroup.h
kernel/cgroup.c
kernel/cpuset.c
@@ -642,14 +642,6 @@
  
 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)
  
@@ -452,7 +452,6 @@
 	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;
@@ -4142,10 +4142,6 @@
 			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) {
@@ -1784,56 +1784,20 @@
 };
  
 /*
- * 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 @@
  
 	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 @@
 	.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,
...	...	@@ -642,14 +642,6 @@
642	642
643	643	Called during task exit.
644	644
645		-void post_clone(struct cgroup *cgrp)
646		-(cgroup_mutex held by caller)
647		-
648		-Called during cgroup_create() to do any parameter
649		-initialization which might be required before a task could attach. For
650		-example, in cpusets, no task may attach before 'cpus' and 'mems' are set
651		-up.
652		-
653	645	void bind(struct cgroup *root)
654	646	(cgroup_mutex held by caller)
655	647
...	...	@@ -452,7 +452,6 @@
452	452	void (fork)(struct task_struct task);
453	453	void (exit)(struct cgroup cgrp, struct cgroup *old_cgrp,
454	454	struct task_struct *task);
455		- void (post_clone)(struct cgroup cgrp);
456	455	void (bind)(struct cgroup root);
457	456
458	457	int subsys_id;
...	...	@@ -4142,10 +4142,6 @@
4142	4142	if (err)
4143	4143	goto err_free_all;
4144	4144	}
4145		- /* At error, ->css_free() callback has to free assigned ID. */
4146		- if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags) &&
4147		- ss->post_clone)
4148		- ss->post_clone(cgrp);
4149	4145
4150	4146	if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
4151	4147	parent->parent) {
...	...	@@ -1784,56 +1784,20 @@
1784	1784	};
1785	1785
1786	1786	/*
1787		- * post_clone() is called during cgroup_create() when the
1788		- * clone_children mount argument was specified. The cgroup
1789		- * can not yet have any tasks.
1790		- *
1791		- * Currently we refuse to set up the cgroup - thereby
1792		- * refusing the task to be entered, and as a result refusing
1793		- * the sys_unshare() or clone() which initiated it - if any
1794		- * sibling cpusets have exclusive cpus or mem.
1795		- *
1796		- * If this becomes a problem for some users who wish to
1797		- * allow that scenario, then cpuset_post_clone() could be
1798		- * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
1799		- * (and likewise for mems) to the new cgroup. Called with cgroup_mutex
1800		- * held.
1801		- */
1802		-static void cpuset_post_clone(struct cgroup *cgroup)
1803		-{
1804		- struct cgroup parent, child;
1805		- struct cpuset cs, parent_cs;
1806		-
1807		- parent = cgroup->parent;
1808		- list_for_each_entry(child, &parent->children, sibling) {
1809		- cs = cgroup_cs(child);
1810		- if (is_mem_exclusive(cs) \|\| is_cpu_exclusive(cs))
1811		- return;
1812		- }
1813		- cs = cgroup_cs(cgroup);
1814		- parent_cs = cgroup_cs(parent);
1815		-
1816		- mutex_lock(&callback_mutex);
1817		- cs->mems_allowed = parent_cs->mems_allowed;
1818		- cpumask_copy(cs->cpus_allowed, parent_cs->cpus_allowed);
1819		- mutex_unlock(&callback_mutex);
1820		- return;
1821		-}
1822		-
1823		-/*
1824	1787	* cpuset_css_alloc - allocate a cpuset css
1825	1788	* cont: control group that the new cpuset will be part of
1826	1789	*/
1827	1790
1828	1791	static struct cgroup_subsys_state cpuset_css_alloc(struct cgroup cont)
1829	1792	{
1830		- struct cpuset *cs;
1831		- struct cpuset *parent;
	1793	+ struct cgroup *parent_cg = cont->parent;
	1794	+ struct cgroup *tmp_cg;
	1795	+ struct cpuset parent, cs;
1832	1796
1833		- if (!cont->parent) {
	1797	+ if (!parent_cg)
1834	1798	return &top_cpuset.css;
1835		- }
1836		- parent = cgroup_cs(cont->parent);
	1799	+ parent = cgroup_cs(parent_cg);
	1800	+
1837	1801	cs = kmalloc(sizeof(*cs), GFP_KERNEL);
1838	1802	if (!cs)
1839	1803	return ERR_PTR(-ENOMEM);
...	...	@@ -1855,7 +1819,36 @@
1855	1819
1856	1820	cs->parent = parent;
1857	1821	number_of_cpusets++;
1858		- return &cs->css ;
	1822	+
	1823	+ if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cont->flags))
	1824	+ goto skip_clone;
	1825	+
	1826	+ /*
	1827	+ * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
	1828	+ * set. This flag handling is implemented in cgroup core for
	1829	+ * histrical reasons - the flag may be specified during mount.
	1830	+ *
	1831	+ * Currently, if any sibling cpusets have exclusive cpus or mem, we
	1832	+ * refuse to clone the configuration - thereby refusing the task to
	1833	+ * be entered, and as a result refusing the sys_unshare() or
	1834	+ * clone() which initiated it. If this becomes a problem for some
	1835	+ * users who wish to allow that scenario, then this could be
	1836	+ * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
	1837	+ * (and likewise for mems) to the new cgroup.
	1838	+ */
	1839	+ list_for_each_entry(tmp_cg, &parent_cg->children, sibling) {
	1840	+ struct cpuset *tmp_cs = cgroup_cs(tmp_cg);
	1841	+
	1842	+ if (is_mem_exclusive(tmp_cs) \|\| is_cpu_exclusive(tmp_cs))
	1843	+ goto skip_clone;
	1844	+ }
	1845	+
	1846	+ mutex_lock(&callback_mutex);
	1847	+ cs->mems_allowed = parent->mems_allowed;
	1848	+ cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
	1849	+ mutex_unlock(&callback_mutex);
	1850	+skip_clone:
	1851	+ return &cs->css;
1859	1852	}
1860	1853
1861	1854	/*
...	...	@@ -1882,7 +1875,6 @@
1882	1875	.css_free = cpuset_css_free,
1883	1876	.can_attach = cpuset_can_attach,
1884	1877	.attach = cpuset_attach,
1885		- .post_clone = cpuset_post_clone,
1886	1878	.subsys_id = cpuset_subsys_id,
1887	1879	.base_cftypes = files,
1888	1880	.early_init = 1,