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Date: Fri, 24 Aug 2012 16:01:39 +0200
From: Daniel Wagner <wagi@...om.org>
To: netdev@...r.kernel.org, cgroups@...r.kernel.org
Cc: Daniel Wagner <daniel.wagner@...-carit.de>,
Tejun Heo <tj@...nel.org>, Li Zefan <lizefan@...wei.com>,
"David S. Miller" <davem@...emloft.net>
Subject: [PATCH v2 05/10] cgroup: Remove CGROUP_BUILTIN_SUBSYS_COUNT
From: Daniel Wagner <daniel.wagner@...-carit.de>
CGROUP_BUILTIN_SUBSYS_COUNT is used as start or stop point
when looping over the subsys array. Since the subsys array is
64 entries long this is a good thing to do. Though we'd like
to reduce the array size considerable but we need to get rid
of CGROUP_BUILTIN_SUBSYS_COUNT to ease up the review process.
Signed-off-by: Daniel Wagner <daniel.wagner@...-carit.de>
Cc: Tejun Heo <tj@...nel.org>
Cc: Li Zefan <lizefan@...wei.com>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Cc: cgroups@...r.kernel.org
---
include/linux/cgroup.h | 1 -
kernel/cgroup.c | 75 +++++++++++++++++++++++++++++++-------------------
2 files changed, 47 insertions(+), 29 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index c90eaa8..3787872 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -47,7 +47,6 @@ extern const struct file_operations proc_cgroup_operations;
#define SUBSYS(_x) _x ## _subsys_id,
enum cgroup_subsys_id {
#include <linux/cgroup_subsys.h>
- CGROUP_BUILTIN_SUBSYS_COUNT
};
#undef SUBSYS
/*
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 7981850..f9433b4 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -88,7 +88,7 @@ static DEFINE_MUTEX(cgroup_root_mutex);
/*
* Generate an array of cgroup subsystem pointers. At boot time, this is
- * populated up to CGROUP_BUILTIN_SUBSYS_COUNT, and modular subsystems are
+ * populated with the built in subsystems, and modular subsystems are
* registered after that. The mutable section of this array is protected by
* cgroup_mutex.
*/
@@ -1291,11 +1291,13 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
* take duplicate reference counts on a subsystem that's already used,
* but rebind_subsystems handles this case.
*/
- for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
unsigned long bit = 1UL << i;
if (!(bit & opts->subsys_bits))
continue;
+ if (!subsys[i]->module)
+ continue;
if (!try_module_get(subsys[i]->module)) {
module_pin_failed = true;
break;
@@ -1307,12 +1309,14 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
* raced with a module_delete call, and to the user this is
* essentially a "subsystem doesn't exist" case.
*/
- for (i--; i >= CGROUP_BUILTIN_SUBSYS_COUNT; i--) {
+ for (i--; i > 1; i--) {
/* drop refcounts only on the ones we took */
unsigned long bit = 1UL << i;
if (!(bit & opts->subsys_bits))
continue;
+ if (!subsys[i]->module)
+ continue;
module_put(subsys[i]->module);
}
return -ENOENT;
@@ -1324,11 +1328,13 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
static void drop_parsed_module_refcounts(unsigned long subsys_bits)
{
int i;
- for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
unsigned long bit = 1UL << i;
if (!(bit & subsys_bits))
continue;
+ if (!subsys[i]->module)
+ continue;
module_put(subsys[i]->module);
}
}
@@ -1401,6 +1407,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
mutex_init(&cgrp->pidlist_mutex);
INIT_LIST_HEAD(&cgrp->event_list);
spin_lock_init(&cgrp->event_list_lock);
+ memset(cgrp->subsys, 0, sizeof(cgrp->subsys));
}
static void init_cgroup_root(struct cgroupfs_root *root)
@@ -4321,8 +4328,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
* since cgroup_init_subsys will have already taken care of it.
*/
if (ss->module == NULL) {
- /* a few sanity checks */
- BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT);
+ /* a sanity check */
BUG_ON(subsys[ss->subsys_id] != ss);
return 0;
}
@@ -4336,7 +4342,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
*/
mutex_lock(&cgroup_mutex);
/* find the first empty slot in the array */
- for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
if (subsys[i] == NULL)
break;
}
@@ -4439,7 +4445,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
mutex_lock(&cgroup_mutex);
/* deassign the subsys_id */
- BUG_ON(ss->subsys_id < CGROUP_BUILTIN_SUBSYS_COUNT);
subsys[ss->subsys_id] = NULL;
/* remove subsystem from rootnode's list of subsystems */
@@ -4502,10 +4507,13 @@ int __init cgroup_init_early(void)
for (i = 0; i < CSS_SET_TABLE_SIZE; i++)
INIT_HLIST_HEAD(&css_set_table[i]);
- /* at bootup time, we don't worry about modular subsystems */
- for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
+ /* at bootup time, we don't worry about modular subsystems */
+ if (!ss || (ss && ss->module))
+ continue;
+
BUG_ON(!ss->name);
BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
BUG_ON(!ss->create);
@@ -4538,9 +4546,12 @@ int __init cgroup_init(void)
if (err)
return err;
- /* at bootup time, we don't worry about modular subsystems */
- for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
+
+ /* at bootup time, we don't worry about modular subsystems */
+ if (!ss || (ss && ss->module))
+ continue;
if (!ss->early_init)
cgroup_init_subsys(ss);
if (ss->use_id)
@@ -4735,13 +4746,16 @@ void cgroup_fork_callbacks(struct task_struct *child)
{
if (need_forkexit_callback) {
int i;
- /*
- * forkexit callbacks are only supported for builtin
- * subsystems, and the builtin section of the subsys array is
- * immutable, so we don't need to lock the subsys array here.
- */
- for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
+
+ /*
+ * forkexit callbacks are only supported for
+ * builtin subsystems.
+ */
+ if (!ss || (ss && ss->module))
+ continue;
+
if (ss->fork)
ss->fork(child);
}
@@ -4846,12 +4860,13 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks)
tsk->cgroups = &init_css_set;
if (run_callbacks && need_forkexit_callback) {
- /*
- * modular subsystems can't use callbacks, so no need to lock
- * the subsys array
- */
- for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
+
+ /* modular subsystems can't use callbacks */
+ if (!ss || (ss && ss->module))
+ continue;
+
if (ss->exit) {
struct cgroup *old_cgrp =
rcu_dereference_raw(cg->subsys[i])->cgroup;
@@ -5037,13 +5052,17 @@ static int __init cgroup_disable(char *str)
while ((token = strsep(&str, ",")) != NULL) {
if (!*token)
continue;
- /*
- * cgroup_disable, being at boot time, can't know about module
- * subsystems, so we don't worry about them.
- */
- for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
+ /*
+ * cgroup_disable, being at boot time, can't
+ * know about module subsystems, so we don't
+ * worry about them.
+ */
+ if (!ss || (ss && ss->module))
+ continue;
+
if (!strcmp(token, ss->name)) {
ss->disabled = 1;
printk(KERN_INFO "Disabling %s control group"
--
1.7.12.rc1.16.g05a20c8
--
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