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Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c276
1 files changed, 178 insertions, 98 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index f221446aa02d..c29831076e7a 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -84,7 +84,7 @@ struct cgroupfs_root {
/* Tracks how many cgroups are currently defined in hierarchy.*/
int number_of_cgroups;
- /* A list running through the mounted hierarchies */
+ /* A list running through the active hierarchies */
struct list_head root_list;
/* Hierarchy-specific flags */
@@ -148,8 +148,8 @@ static int notify_on_release(const struct cgroup *cgrp)
#define for_each_subsys(_root, _ss) \
list_for_each_entry(_ss, &_root->subsys_list, sibling)
-/* for_each_root() allows you to iterate across the active hierarchies */
-#define for_each_root(_root) \
+/* for_each_active_root() allows you to iterate across the active hierarchies */
+#define for_each_active_root(_root) \
list_for_each_entry(_root, &roots, root_list)
/* the list of cgroups eligible for automatic release. Protected by
@@ -271,7 +271,7 @@ static void __put_css_set(struct css_set *cg, int taskexit)
rcu_read_lock();
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
- struct cgroup *cgrp = cg->subsys[i]->cgroup;
+ struct cgroup *cgrp = rcu_dereference(cg->subsys[i]->cgroup);
if (atomic_dec_and_test(&cgrp->count) &&
notify_on_release(cgrp)) {
if (taskexit)
@@ -384,6 +384,25 @@ static int allocate_cg_links(int count, struct list_head *tmp)
return 0;
}
+/**
+ * link_css_set - a helper function to link a css_set to a cgroup
+ * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links()
+ * @cg: the css_set to be linked
+ * @cgrp: the destination cgroup
+ */
+static void link_css_set(struct list_head *tmp_cg_links,
+ struct css_set *cg, struct cgroup *cgrp)
+{
+ struct cg_cgroup_link *link;
+
+ BUG_ON(list_empty(tmp_cg_links));
+ link = list_first_entry(tmp_cg_links, struct cg_cgroup_link,
+ cgrp_link_list);
+ link->cg = cg;
+ list_move(&link->cgrp_link_list, &cgrp->css_sets);
+ list_add(&link->cg_link_list, &cg->cg_links);
+}
+
/*
* find_css_set() takes an existing cgroup group and a
* cgroup object, and returns a css_set object that's
@@ -399,7 +418,6 @@ static struct css_set *find_css_set(
int i;
struct list_head tmp_cg_links;
- struct cg_cgroup_link *link;
struct hlist_head *hhead;
@@ -444,26 +462,11 @@ static struct css_set *find_css_set(
* only do it for the first subsystem in each
* hierarchy
*/
- if (ss->root->subsys_list.next == &ss->sibling) {
- BUG_ON(list_empty(&tmp_cg_links));
- link = list_entry(tmp_cg_links.next,
- struct cg_cgroup_link,
- cgrp_link_list);
- list_del(&link->cgrp_link_list);
- list_add(&link->cgrp_link_list, &cgrp->css_sets);
- link->cg = res;
- list_add(&link->cg_link_list, &res->cg_links);
- }
- }
- if (list_empty(&rootnode.subsys_list)) {
- link = list_entry(tmp_cg_links.next,
- struct cg_cgroup_link,
- cgrp_link_list);
- list_del(&link->cgrp_link_list);
- list_add(&link->cgrp_link_list, &dummytop->css_sets);
- link->cg = res;
- list_add(&link->cg_link_list, &res->cg_links);
+ if (ss->root->subsys_list.next == &ss->sibling)
+ link_css_set(&tmp_cg_links, res, cgrp);
}
+ if (list_empty(&rootnode.subsys_list))
+ link_css_set(&tmp_cg_links, res, dummytop);
BUG_ON(!list_empty(&tmp_cg_links));
@@ -586,11 +589,18 @@ static void cgroup_call_pre_destroy(struct cgroup *cgrp)
{
struct cgroup_subsys *ss;
for_each_subsys(cgrp->root, ss)
- if (ss->pre_destroy && cgrp->subsys[ss->subsys_id])
+ if (ss->pre_destroy)
ss->pre_destroy(ss, cgrp);
return;
}
+static void free_cgroup_rcu(struct rcu_head *obj)
+{
+ struct cgroup *cgrp = container_of(obj, struct cgroup, rcu_head);
+
+ kfree(cgrp);
+}
+
static void cgroup_diput(struct dentry *dentry, struct inode *inode)
{
/* is dentry a directory ? if so, kfree() associated cgroup */
@@ -610,19 +620,19 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
/*
* Release the subsystem state objects.
*/
- for_each_subsys(cgrp->root, ss) {
- if (cgrp->subsys[ss->subsys_id])
- ss->destroy(ss, cgrp);
- }
+ for_each_subsys(cgrp->root, ss)
+ ss->destroy(ss, cgrp);
cgrp->root->number_of_cgroups--;
mutex_unlock(&cgroup_mutex);
- /* Drop the active superblock reference that we took when we
- * created the cgroup */
+ /*
+ * Drop the active superblock reference that we took when we
+ * created the cgroup
+ */
deactivate_super(cgrp->root->sb);
- kfree(cgrp);
+ call_rcu(&cgrp->rcu_head, free_cgroup_rcu);
}
iput(inode);
}
@@ -712,23 +722,26 @@ static int rebind_subsystems(struct cgroupfs_root *root,
BUG_ON(cgrp->subsys[i]);
BUG_ON(!dummytop->subsys[i]);
BUG_ON(dummytop->subsys[i]->cgroup != dummytop);
+ mutex_lock(&ss->hierarchy_mutex);
cgrp->subsys[i] = dummytop->subsys[i];
cgrp->subsys[i]->cgroup = cgrp;
- list_add(&ss->sibling, &root->subsys_list);
- rcu_assign_pointer(ss->root, root);
+ list_move(&ss->sibling, &root->subsys_list);
+ ss->root = root;
if (ss->bind)
ss->bind(ss, cgrp);
-
+ mutex_unlock(&ss->hierarchy_mutex);
} else if (bit & removed_bits) {
/* We're removing this subsystem */
BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]);
BUG_ON(cgrp->subsys[i]->cgroup != cgrp);
+ mutex_lock(&ss->hierarchy_mutex);
if (ss->bind)
ss->bind(ss, dummytop);
dummytop->subsys[i]->cgroup = dummytop;
cgrp->subsys[i] = NULL;
- rcu_assign_pointer(subsys[i]->root, &rootnode);
- list_del(&ss->sibling);
+ subsys[i]->root = &rootnode;
+ list_move(&ss->sibling, &rootnode.subsys_list);
+ mutex_unlock(&ss->hierarchy_mutex);
} else if (bit & final_bits) {
/* Subsystem state should already exist */
BUG_ON(!cgrp->subsys[i]);
@@ -990,7 +1003,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
root = NULL;
} else {
/* New superblock */
- struct cgroup *cgrp = &root->top_cgroup;
+ struct cgroup *root_cgrp = &root->top_cgroup;
struct inode *inode;
int i;
@@ -1031,7 +1044,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
list_add(&root->root_list, &roots);
root_count++;
- sb->s_root->d_fsdata = &root->top_cgroup;
+ sb->s_root->d_fsdata = root_cgrp;
root->top_cgroup.dentry = sb->s_root;
/* Link the top cgroup in this hierarchy into all
@@ -1042,29 +1055,18 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
struct hlist_node *node;
struct css_set *cg;
- hlist_for_each_entry(cg, node, hhead, hlist) {
- struct cg_cgroup_link *link;
-
- BUG_ON(list_empty(&tmp_cg_links));
- link = list_entry(tmp_cg_links.next,
- struct cg_cgroup_link,
- cgrp_link_list);
- list_del(&link->cgrp_link_list);
- link->cg = cg;
- list_add(&link->cgrp_link_list,
- &root->top_cgroup.css_sets);
- list_add(&link->cg_link_list, &cg->cg_links);
- }
+ hlist_for_each_entry(cg, node, hhead, hlist)
+ link_css_set(&tmp_cg_links, cg, root_cgrp);
}
write_unlock(&css_set_lock);
free_cg_links(&tmp_cg_links);
- BUG_ON(!list_empty(&cgrp->sibling));
- BUG_ON(!list_empty(&cgrp->children));
+ BUG_ON(!list_empty(&root_cgrp->sibling));
+ BUG_ON(!list_empty(&root_cgrp->children));
BUG_ON(root->number_of_cgroups != 1);
- cgroup_populate_dir(cgrp);
+ cgroup_populate_dir(root_cgrp);
mutex_unlock(&inode->i_mutex);
mutex_unlock(&cgroup_mutex);
}
@@ -1113,10 +1115,9 @@ static void cgroup_kill_sb(struct super_block *sb) {
}
write_unlock(&css_set_lock);
- if (!list_empty(&root->root_list)) {
- list_del(&root->root_list);
- root_count--;
- }
+ list_del(&root->root_list);
+ root_count--;
+
mutex_unlock(&cgroup_mutex);
kfree(root);
@@ -1145,14 +1146,16 @@ static inline struct cftype *__d_cft(struct dentry *dentry)
* @buf: the buffer to write the path into
* @buflen: the length of the buffer
*
- * Called with cgroup_mutex held. Writes path of cgroup into buf.
- * Returns 0 on success, -errno on error.
+ * Called with cgroup_mutex held or else with an RCU-protected cgroup
+ * reference. Writes path of cgroup into buf. Returns 0 on success,
+ * -errno on error.
*/
int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
{
char *start;
+ struct dentry *dentry = rcu_dereference(cgrp->dentry);
- if (cgrp == dummytop) {
+ if (!dentry || cgrp == dummytop) {
/*
* Inactive subsystems have no dentry for their root
* cgroup
@@ -1165,13 +1168,14 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
*--start = '\0';
for (;;) {
- int len = cgrp->dentry->d_name.len;
+ int len = dentry->d_name.len;
if ((start -= len) < buf)
return -ENAMETOOLONG;
memcpy(start, cgrp->dentry->d_name.name, len);
cgrp = cgrp->parent;
if (!cgrp)
break;
+ dentry = rcu_dereference(cgrp->dentry);
if (!cgrp->parent)
continue;
if (--start < buf)
@@ -1216,7 +1220,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
int retval = 0;
struct cgroup_subsys *ss;
struct cgroup *oldcgrp;
- struct css_set *cg = tsk->cgroups;
+ struct css_set *cg;
struct css_set *newcg;
struct cgroupfs_root *root = cgrp->root;
int subsys_id;
@@ -1236,11 +1240,16 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
}
}
+ task_lock(tsk);
+ cg = tsk->cgroups;
+ get_css_set(cg);
+ task_unlock(tsk);
/*
* Locate or allocate a new css_set for this task,
* based on its final set of cgroups
*/
newcg = find_css_set(cg, cgrp);
+ put_css_set(cg);
if (!newcg)
return -ENOMEM;
@@ -1445,7 +1454,7 @@ static ssize_t cgroup_file_write(struct file *file, const char __user *buf,
struct cftype *cft = __d_cft(file->f_dentry);
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
- if (!cft || cgroup_is_removed(cgrp))
+ if (cgroup_is_removed(cgrp))
return -ENODEV;
if (cft->write)
return cft->write(cgrp, cft, file, buf, nbytes, ppos);
@@ -1490,7 +1499,7 @@ static ssize_t cgroup_file_read(struct file *file, char __user *buf,
struct cftype *cft = __d_cft(file->f_dentry);
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
- if (!cft || cgroup_is_removed(cgrp))
+ if (cgroup_is_removed(cgrp))
return -ENODEV;
if (cft->read)
@@ -1554,10 +1563,8 @@ static int cgroup_file_open(struct inode *inode, struct file *file)
err = generic_file_open(inode, file);
if (err)
return err;
-
cft = __d_cft(file->f_dentry);
- if (!cft)
- return -ENODEV;
+
if (cft->read_map || cft->read_seq_string) {
struct cgroup_seqfile_state *state =
kzalloc(sizeof(*state), GFP_USER);
@@ -1671,7 +1678,7 @@ static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry,
if (!error) {
dentry->d_fsdata = cgrp;
inc_nlink(parent->d_inode);
- cgrp->dentry = dentry;
+ rcu_assign_pointer(cgrp->dentry, dentry);
dget(dentry);
}
dput(dentry);
@@ -1812,6 +1819,7 @@ struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
{
struct task_struct *res;
struct list_head *l = it->task;
+ struct cg_cgroup_link *link;
/* If the iterator cg is NULL, we have no tasks */
if (!it->cg_link)
@@ -1819,7 +1827,8 @@ struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
res = list_entry(l, struct task_struct, cg_list);
/* Advance iterator to find next entry */
l = l->next;
- if (l == &res->cgroups->tasks) {
+ link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list);
+ if (l == &link->cg->tasks) {
/* We reached the end of this task list - move on to
* the next cg_cgroup_link */
cgroup_advance_iter(cgrp, it);
@@ -2013,14 +2022,16 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan)
*/
static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cgrp)
{
- int n = 0;
+ int n = 0, pid;
struct cgroup_iter it;
struct task_struct *tsk;
cgroup_iter_start(cgrp, &it);
while ((tsk = cgroup_iter_next(cgrp, &it))) {
if (unlikely(n == npids))
break;
- pidarray[n++] = task_pid_vnr(tsk);
+ pid = task_pid_vnr(tsk);
+ if (pid > 0)
+ pidarray[n++] = pid;
}
cgroup_iter_end(cgrp, &it);
return n;
@@ -2052,7 +2063,6 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
ret = 0;
cgrp = dentry->d_fsdata;
- rcu_read_lock();
cgroup_iter_start(cgrp, &it);
while ((tsk = cgroup_iter_next(cgrp, &it))) {
@@ -2077,7 +2087,6 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
}
cgroup_iter_end(cgrp, &it);
- rcu_read_unlock();
err:
return ret;
}
@@ -2324,7 +2333,7 @@ static void init_cgroup_css(struct cgroup_subsys_state *css,
struct cgroup *cgrp)
{
css->cgroup = cgrp;
- atomic_set(&css->refcnt, 0);
+ atomic_set(&css->refcnt, 1);
css->flags = 0;
if (cgrp == dummytop)
set_bit(CSS_ROOT, &css->flags);
@@ -2332,6 +2341,29 @@ static void init_cgroup_css(struct cgroup_subsys_state *css,
cgrp->subsys[ss->subsys_id] = css;
}
+static void cgroup_lock_hierarchy(struct cgroupfs_root *root)
+{
+ /* We need to take each hierarchy_mutex in a consistent order */
+ int i;
+
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+ if (ss->root == root)
+ mutex_lock_nested(&ss->hierarchy_mutex, i);
+ }
+}
+
+static void cgroup_unlock_hierarchy(struct cgroupfs_root *root)
+{
+ int i;
+
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+ if (ss->root == root)
+ mutex_unlock(&ss->hierarchy_mutex);
+ }
+}
+
/*
* cgroup_create - create a cgroup
* @parent: cgroup that will be parent of the new cgroup
@@ -2380,7 +2412,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
init_cgroup_css(css, ss, cgrp);
}
+ cgroup_lock_hierarchy(root);
list_add(&cgrp->sibling, &cgrp->parent->children);
+ cgroup_unlock_hierarchy(root);
root->number_of_cgroups++;
err = cgroup_create_dir(cgrp, dentry, mode);
@@ -2431,7 +2465,7 @@ static int cgroup_has_css_refs(struct cgroup *cgrp)
{
/* Check the reference count on each subsystem. Since we
* already established that there are no tasks in the
- * cgroup, if the css refcount is also 0, then there should
+ * cgroup, if the css refcount is also 1, then there should
* be no outstanding references, so the subsystem is safe to
* destroy. We scan across all subsystems rather than using
* the per-hierarchy linked list of mounted subsystems since
@@ -2452,19 +2486,67 @@ static int cgroup_has_css_refs(struct cgroup *cgrp)
* matter, since it can only happen if the cgroup
* has been deleted and hence no longer needs the
* release agent to be called anyway. */
- if (css && atomic_read(&css->refcnt))
+ if (css && (atomic_read(&css->refcnt) > 1))
return 1;
}
return 0;
}
+/*
+ * Atomically mark all (or else none) of the cgroup's CSS objects as
+ * CSS_REMOVED. Return true on success, or false if the cgroup has
+ * busy subsystems. Call with cgroup_mutex held
+ */
+
+static int cgroup_clear_css_refs(struct cgroup *cgrp)
+{
+ struct cgroup_subsys *ss;
+ unsigned long flags;
+ bool failed = false;
+ local_irq_save(flags);
+ for_each_subsys(cgrp->root, ss) {
+ struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
+ int refcnt;
+ do {
+ /* We can only remove a CSS with a refcnt==1 */
+ refcnt = atomic_read(&css->refcnt);
+ if (refcnt > 1) {
+ failed = true;
+ goto done;
+ }
+ BUG_ON(!refcnt);
+ /*
+ * Drop the refcnt to 0 while we check other
+ * subsystems. This will cause any racing
+ * css_tryget() to spin until we set the
+ * CSS_REMOVED bits or abort
+ */
+ } while (atomic_cmpxchg(&css->refcnt, refcnt, 0) != refcnt);
+ }
+ done:
+ for_each_subsys(cgrp->root, ss) {
+ struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
+ if (failed) {
+ /*
+ * Restore old refcnt if we previously managed
+ * to clear it from 1 to 0
+ */
+ if (!atomic_read(&css->refcnt))
+ atomic_set(&css->refcnt, 1);
+ } else {
+ /* Commit the fact that the CSS is removed */
+ set_bit(CSS_REMOVED, &css->flags);
+ }
+ }
+ local_irq_restore(flags);
+ return !failed;
+}
+
static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
{
struct cgroup *cgrp = dentry->d_fsdata;
struct dentry *d;
struct cgroup *parent;
- struct super_block *sb;
- struct cgroupfs_root *root;
/* the vfs holds both inode->i_mutex already */
@@ -2487,12 +2569,10 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
mutex_lock(&cgroup_mutex);
parent = cgrp->parent;
- root = cgrp->root;
- sb = root->sb;
if (atomic_read(&cgrp->count)
|| !list_empty(&cgrp->children)
- || cgroup_has_css_refs(cgrp)) {
+ || !cgroup_clear_css_refs(cgrp)) {
mutex_unlock(&cgroup_mutex);
return -EBUSY;
}
@@ -2502,8 +2582,12 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
if (!list_empty(&cgrp->release_list))
list_del(&cgrp->release_list);
spin_unlock(&release_list_lock);
- /* delete my sibling from parent->children */
+
+ cgroup_lock_hierarchy(cgrp->root);
+ /* delete this cgroup from parent->children */
list_del(&cgrp->sibling);
+ cgroup_unlock_hierarchy(cgrp->root);
+
spin_lock(&cgrp->dentry->d_lock);
d = dget(cgrp->dentry);
spin_unlock(&d->d_lock);
@@ -2525,6 +2609,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
/* Create the top cgroup state for this subsystem */
+ list_add(&ss->sibling, &rootnode.subsys_list);
ss->root = &rootnode;
css = ss->create(ss, dummytop);
/* We don't handle early failures gracefully */
@@ -2544,6 +2629,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
* need to invoke fork callbacks here. */
BUG_ON(!list_empty(&init_task.tasks));
+ mutex_init(&ss->hierarchy_mutex);
ss->active = 1;
}
@@ -2562,7 +2648,6 @@ int __init cgroup_init_early(void)
INIT_HLIST_NODE(&init_css_set.hlist);
css_set_count = 1;
init_cgroup_root(&rootnode);
- list_add(&rootnode.root_list, &roots);
root_count = 1;
init_task.cgroups = &init_css_set;
@@ -2669,15 +2754,12 @@ static int proc_cgroup_show(struct seq_file *m, void *v)
mutex_lock(&cgroup_mutex);
- for_each_root(root) {
+ for_each_active_root(root) {
struct cgroup_subsys *ss;
struct cgroup *cgrp;
int subsys_id;
int count = 0;
- /* Skip this hierarchy if it has no active subsystems */
- if (!root->actual_subsys_bits)
- continue;
seq_printf(m, "%lu:", root->subsys_bits);
for_each_subsys(root, ss)
seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
@@ -2800,8 +2882,10 @@ void cgroup_post_fork(struct task_struct *child)
{
if (use_task_css_set_links) {
write_lock(&css_set_lock);
+ task_lock(child);
if (list_empty(&child->cg_list))
list_add(&child->cg_list, &child->cgroups->tasks);
+ task_unlock(child);
write_unlock(&css_set_lock);
}
}
@@ -2907,6 +2991,7 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
mutex_unlock(&cgroup_mutex);
return 0;
}
+ task_lock(tsk);
cg = tsk->cgroups;
parent = task_cgroup(tsk, subsys->subsys_id);
@@ -2919,6 +3004,7 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
/* Keep the cgroup alive */
get_css_set(cg);
+ task_unlock(tsk);
mutex_unlock(&cgroup_mutex);
/* Now do the VFS work to create a cgroup */
@@ -2937,7 +3023,7 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
}
/* Create the cgroup directory, which also creates the cgroup */
- ret = vfs_mkdir(inode, dentry, S_IFDIR | 0755);
+ ret = vfs_mkdir(inode, dentry, 0755);
child = __d_cgrp(dentry);
dput(dentry);
if (ret) {
@@ -2947,13 +3033,6 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
goto out_release;
}
- if (!child) {
- printk(KERN_INFO
- "Couldn't find new cgroup %s\n", nodename);
- ret = -ENOMEM;
- goto out_release;
- }
-
/* The cgroup now exists. Retake cgroup_mutex and check
* that we're still in the same state that we thought we
* were. */
@@ -3049,7 +3128,8 @@ void __css_put(struct cgroup_subsys_state *css)
{
struct cgroup *cgrp = css->cgroup;
rcu_read_lock();
- if (atomic_dec_and_test(&css->refcnt) && notify_on_release(cgrp)) {
+ if ((atomic_dec_return(&css->refcnt) == 1) &&
+ notify_on_release(cgrp)) {
set_bit(CGRP_RELEASABLE, &cgrp->flags);
check_for_release(cgrp);
}
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-14 09:06:20 +0000