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Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c158
1 files changed, 99 insertions, 59 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 8ba680985335..14efffed72c8 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -49,6 +49,7 @@
#include <linux/namei.h>
#include <linux/smp_lock.h>
#include <linux/pid_namespace.h>
+#include <linux/idr.h>
#include <asm/atomic.h>
@@ -77,6 +78,9 @@ struct cgroupfs_root {
*/
unsigned long subsys_bits;
+ /* Unique id for this hierarchy. */
+ int hierarchy_id;
+
/* The bitmask of subsystems currently attached to this hierarchy */
unsigned long actual_subsys_bits;
@@ -147,6 +151,10 @@ struct css_id {
static LIST_HEAD(roots);
static int root_count;
+static DEFINE_IDA(hierarchy_ida);
+static int next_hierarchy_id;
+static DEFINE_SPINLOCK(hierarchy_id_lock);
+
/* dummytop is a shorthand for the dummy hierarchy's top cgroup */
#define dummytop (&rootnode.top_cgroup)
@@ -264,42 +272,10 @@ static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[])
* compiled into their kernel but not actually in use */
static int use_task_css_set_links __read_mostly;
-/* When we create or destroy a css_set, the operation simply
- * takes/releases a reference count on all the cgroups referenced
- * by subsystems in this css_set. This can end up multiple-counting
- * some cgroups, but that's OK - the ref-count is just a
- * busy/not-busy indicator; ensuring that we only count each cgroup
- * once would require taking a global lock to ensure that no
- * subsystems moved between hierarchies while we were doing so.
- *
- * Possible TODO: decide at boot time based on the number of
- * registered subsystems and the number of CPUs or NUMA nodes whether
- * it's better for performance to ref-count every subsystem, or to
- * take a global lock and only add one ref count to each hierarchy.
- */
-
-/*
- * unlink a css_set from the list and free it
- */
-static void unlink_css_set(struct css_set *cg)
+static void __put_css_set(struct css_set *cg, int taskexit)
{
struct cg_cgroup_link *link;
struct cg_cgroup_link *saved_link;
-
- hlist_del(&cg->hlist);
- css_set_count--;
-
- list_for_each_entry_safe(link, saved_link, &cg->cg_links,
- cg_link_list) {
- list_del(&link->cg_link_list);
- list_del(&link->cgrp_link_list);
- kfree(link);
- }
-}
-
-static void __put_css_set(struct css_set *cg, int taskexit)
-{
- int i;
/*
* Ensure that the refcount doesn't hit zero while any readers
* can see it. Similar to atomic_dec_and_lock(), but for an
@@ -312,20 +288,27 @@ static void __put_css_set(struct css_set *cg, int taskexit)
write_unlock(&css_set_lock);
return;
}
- unlink_css_set(cg);
- write_unlock(&css_set_lock);
- rcu_read_lock();
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
- struct cgroup *cgrp = rcu_dereference(cg->subsys[i]->cgroup);
+ /* This css_set is dead. unlink it and release cgroup refcounts */
+ hlist_del(&cg->hlist);
+ css_set_count--;
+
+ list_for_each_entry_safe(link, saved_link, &cg->cg_links,
+ cg_link_list) {
+ struct cgroup *cgrp = link->cgrp;
+ list_del(&link->cg_link_list);
+ list_del(&link->cgrp_link_list);
if (atomic_dec_and_test(&cgrp->count) &&
notify_on_release(cgrp)) {
if (taskexit)
set_bit(CGRP_RELEASABLE, &cgrp->flags);
check_for_release(cgrp);
}
+
+ kfree(link);
}
- rcu_read_unlock();
+
+ write_unlock(&css_set_lock);
kfree(cg);
}
@@ -519,6 +502,7 @@ static void link_css_set(struct list_head *tmp_cg_links,
cgrp_link_list);
link->cg = cg;
link->cgrp = cgrp;
+ atomic_inc(&cgrp->count);
list_move(&link->cgrp_link_list, &cgrp->css_sets);
/*
* Always add links to the tail of the list so that the list
@@ -539,7 +523,6 @@ static struct css_set *find_css_set(
{
struct css_set *res;
struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
- int i;
struct list_head tmp_cg_links;
@@ -578,10 +561,6 @@ static struct css_set *find_css_set(
write_lock(&css_set_lock);
/* Add reference counts and links from the new css_set. */
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
- struct cgroup *cgrp = res->subsys[i]->cgroup;
- atomic_inc(&cgrp->count);
- }
list_for_each_entry(link, &oldcg->cg_links, cg_link_list) {
struct cgroup *c = link->cgrp;
if (c->root == cgrp->root)
@@ -972,8 +951,11 @@ struct cgroup_sb_opts {
unsigned long flags;
char *release_agent;
char *name;
+ /* User explicitly requested empty subsystem */
+ bool none;
struct cgroupfs_root *new_root;
+
};
/* Convert a hierarchy specifier into a bitmask of subsystems and
@@ -1002,6 +984,9 @@ static int parse_cgroupfs_options(char *data,
if (!ss->disabled)
opts->subsys_bits |= 1ul << i;
}
+ } else if (!strcmp(token, "none")) {
+ /* Explicitly have no subsystems */
+ opts->none = true;
} else if (!strcmp(token, "noprefix")) {
set_bit(ROOT_NOPREFIX, &opts->flags);
} else if (!strncmp(token, "release_agent=", 14)) {
@@ -1051,6 +1036,8 @@ static int parse_cgroupfs_options(char *data,
}
}
+ /* Consistency checks */
+
/*
* Option noprefix was introduced just for backward compatibility
* with the old cpuset, so we allow noprefix only if mounting just
@@ -1060,7 +1047,15 @@ static int parse_cgroupfs_options(char *data,
(opts->subsys_bits & mask))
return -EINVAL;
- /* We can't have an empty hierarchy */
+
+ /* Can't specify "none" and some subsystems */
+ if (opts->subsys_bits && opts->none)
+ return -EINVAL;
+
+ /*
+ * We either have to specify by name or by subsystems. (So all
+ * empty hierarchies must have a name).
+ */
if (!opts->subsys_bits && !opts->name)
return -EINVAL;
@@ -1141,6 +1136,31 @@ static void init_cgroup_root(struct cgroupfs_root *root)
init_cgroup_housekeeping(cgrp);
}
+static bool init_root_id(struct cgroupfs_root *root)
+{
+ int ret = 0;
+
+ do {
+ if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL))
+ return false;
+ spin_lock(&hierarchy_id_lock);
+ /* Try to allocate the next unused ID */
+ ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id,
+ &root->hierarchy_id);
+ if (ret == -ENOSPC)
+ /* Try again starting from 0 */
+ ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id);
+ if (!ret) {
+ next_hierarchy_id = root->hierarchy_id + 1;
+ } else if (ret != -EAGAIN) {
+ /* Can only get here if the 31-bit IDR is full ... */
+ BUG_ON(ret);
+ }
+ spin_unlock(&hierarchy_id_lock);
+ } while (ret);
+ return true;
+}
+
static int cgroup_test_super(struct super_block *sb, void *data)
{
struct cgroup_sb_opts *opts = data;
@@ -1150,8 +1170,12 @@ static int cgroup_test_super(struct super_block *sb, void *data)
if (opts->name && strcmp(opts->name, root->name))
return 0;
- /* If we asked for subsystems then they must match */
- if (opts->subsys_bits && (opts->subsys_bits != root->subsys_bits))
+ /*
+ * If we asked for subsystems (or explicitly for no
+ * subsystems) then they must match
+ */
+ if ((opts->subsys_bits || opts->none)
+ && (opts->subsys_bits != root->subsys_bits))
return 0;
return 1;
@@ -1161,15 +1185,19 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
{
struct cgroupfs_root *root;
- /* Empty hierarchies aren't supported */
- if (!opts->subsys_bits)
+ if (!opts->subsys_bits && !opts->none)
return NULL;
root = kzalloc(sizeof(*root), GFP_KERNEL);
if (!root)
return ERR_PTR(-ENOMEM);
+ if (!init_root_id(root)) {
+ kfree(root);
+ return ERR_PTR(-ENOMEM);
+ }
init_cgroup_root(root);
+
root->subsys_bits = opts->subsys_bits;
root->flags = opts->flags;
if (opts->release_agent)
@@ -1179,6 +1207,18 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
return root;
}
+static void cgroup_drop_root(struct cgroupfs_root *root)
+{
+ if (!root)
+ return;
+
+ BUG_ON(!root->hierarchy_id);
+ spin_lock(&hierarchy_id_lock);
+ ida_remove(&hierarchy_ida, root->hierarchy_id);
+ spin_unlock(&hierarchy_id_lock);
+ kfree(root);
+}
+
static int cgroup_set_super(struct super_block *sb, void *data)
{
int ret;
@@ -1188,7 +1228,7 @@ static int cgroup_set_super(struct super_block *sb, void *data)
if (!opts->new_root)
return -EINVAL;
- BUG_ON(!opts->subsys_bits);
+ BUG_ON(!opts->subsys_bits && !opts->none);
ret = set_anon_super(sb, NULL);
if (ret)
@@ -1257,7 +1297,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts);
if (IS_ERR(sb)) {
ret = PTR_ERR(sb);
- kfree(opts.new_root);
+ cgroup_drop_root(opts.new_root);
goto out_err;
}
@@ -1351,7 +1391,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
* We re-used an existing hierarchy - the new root (if
* any) is not needed
*/
- kfree(opts.new_root);
+ cgroup_drop_root(opts.new_root);
}
simple_set_mnt(mnt, sb);
@@ -1410,7 +1450,7 @@ static void cgroup_kill_sb(struct super_block *sb) {
mutex_unlock(&cgroup_mutex);
kill_litter_super(sb);
- kfree(root);
+ cgroup_drop_root(root);
}
static struct file_system_type cgroup_fs_type = {
@@ -3109,7 +3149,7 @@ int __init cgroup_init(void)
/* Add init_css_set to the hash table */
hhead = css_set_hash(init_css_set.subsys);
hlist_add_head(&init_css_set.hlist, hhead);
-
+ BUG_ON(!init_root_id(&rootnode));
err = register_filesystem(&cgroup_fs_type);
if (err < 0)
goto out;
@@ -3164,7 +3204,7 @@ static int proc_cgroup_show(struct seq_file *m, void *v)
struct cgroup *cgrp;
int count = 0;
- seq_printf(m, "%lu:", root->subsys_bits);
+ seq_printf(m, "%d:", root->hierarchy_id);
for_each_subsys(root, ss)
seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
if (strlen(root->name))
@@ -3210,8 +3250,8 @@ static int proc_cgroupstats_show(struct seq_file *m, void *v)
mutex_lock(&cgroup_mutex);
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
- seq_printf(m, "%s\t%lu\t%d\t%d\n",
- ss->name, ss->root->subsys_bits,
+ seq_printf(m, "%s\t%d\t%d\t%d\n",
+ ss->name, ss->root->hierarchy_id,
ss->root->number_of_cgroups, !ss->disabled);
}
mutex_unlock(&cgroup_mutex);
@@ -3929,8 +3969,8 @@ static int current_css_set_cg_links_read(struct cgroup *cont,
name = c->dentry->d_name.name;
else
name = "?";
- seq_printf(seq, "Root %lu group %s\n",
- c->root->subsys_bits, name);
+ seq_printf(seq, "Root %d group %s\n",
+ c->root->hierarchy_id, name);
}
rcu_read_unlock();
read_unlock(&css_set_lock);