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-rw-r--r--kernel/cgroup.c99
1 files changed, 78 insertions, 21 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index f1603c1..470f653 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -98,6 +98,12 @@ static DEFINE_SPINLOCK(css_set_lock);
static DEFINE_SPINLOCK(cgroup_idr_lock);
/*
+ * Protects cgroup_file->kn for !self csses. It synchronizes notifications
+ * against file removal/re-creation across css hiding.
+ */
+static DEFINE_SPINLOCK(cgroup_file_kn_lock);
+
+/*
* Protects cgroup_subsys->release_agent_path. Modifying it also requires
* cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
*/
@@ -754,9 +760,11 @@ static void put_css_set_locked(struct css_set *cset)
if (!atomic_dec_and_test(&cset->refcount))
return;
- /* This css_set is dead. unlink it and release cgroup refcounts */
- for_each_subsys(ss, ssid)
+ /* This css_set is dead. unlink it and release cgroup and css refs */
+ for_each_subsys(ss, ssid) {
list_del(&cset->e_cset_node[ssid]);
+ css_put(cset->subsys[ssid]);
+ }
hash_del(&cset->hlist);
css_set_count--;
@@ -1056,9 +1064,13 @@ static struct css_set *find_css_set(struct css_set *old_cset,
key = css_set_hash(cset->subsys);
hash_add(css_set_table, &cset->hlist, key);
- for_each_subsys(ss, ssid)
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *css = cset->subsys[ssid];
+
list_add_tail(&cset->e_cset_node[ssid],
- &cset->subsys[ssid]->cgroup->e_csets[ssid]);
+ &css->cgroup->e_csets[ssid]);
+ css_get(css);
+ }
spin_unlock_bh(&css_set_lock);
@@ -1393,6 +1405,16 @@ static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
char name[CGROUP_FILE_NAME_MAX];
lockdep_assert_held(&cgroup_mutex);
+
+ if (cft->file_offset) {
+ struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss);
+ struct cgroup_file *cfile = (void *)css + cft->file_offset;
+
+ spin_lock_irq(&cgroup_file_kn_lock);
+ cfile->kn = NULL;
+ spin_unlock_irq(&cgroup_file_kn_lock);
+ }
+
kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
}
@@ -1856,7 +1878,6 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
INIT_LIST_HEAD(&cgrp->self.sibling);
INIT_LIST_HEAD(&cgrp->self.children);
- INIT_LIST_HEAD(&cgrp->self.files);
INIT_LIST_HEAD(&cgrp->cset_links);
INIT_LIST_HEAD(&cgrp->pidlists);
mutex_init(&cgrp->pidlist_mutex);
@@ -2216,6 +2237,9 @@ struct cgroup_taskset {
struct list_head src_csets;
struct list_head dst_csets;
+ /* the subsys currently being processed */
+ int ssid;
+
/*
* Fields for cgroup_taskset_*() iteration.
*
@@ -2278,25 +2302,29 @@ static void cgroup_taskset_add(struct task_struct *task,
/**
* cgroup_taskset_first - reset taskset and return the first task
* @tset: taskset of interest
+ * @dst_cssp: output variable for the destination css
*
* @tset iteration is initialized and the first task is returned.
*/
-struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset)
+struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
+ struct cgroup_subsys_state **dst_cssp)
{
tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
tset->cur_task = NULL;
- return cgroup_taskset_next(tset);
+ return cgroup_taskset_next(tset, dst_cssp);
}
/**
* cgroup_taskset_next - iterate to the next task in taskset
* @tset: taskset of interest
+ * @dst_cssp: output variable for the destination css
*
* Return the next task in @tset. Iteration must have been initialized
* with cgroup_taskset_first().
*/
-struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset)
+struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
+ struct cgroup_subsys_state **dst_cssp)
{
struct css_set *cset = tset->cur_cset;
struct task_struct *task = tset->cur_task;
@@ -2311,6 +2339,18 @@ struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset)
if (&task->cg_list != &cset->mg_tasks) {
tset->cur_cset = cset;
tset->cur_task = task;
+
+ /*
+ * This function may be called both before and
+ * after cgroup_taskset_migrate(). The two cases
+ * can be distinguished by looking at whether @cset
+ * has its ->mg_dst_cset set.
+ */
+ if (cset->mg_dst_cset)
+ *dst_cssp = cset->mg_dst_cset->subsys[tset->ssid];
+ else
+ *dst_cssp = cset->subsys[tset->ssid];
+
return task;
}
@@ -2346,7 +2386,8 @@ static int cgroup_taskset_migrate(struct cgroup_taskset *tset,
/* check that we can legitimately attach to the cgroup */
for_each_e_css(css, i, dst_cgrp) {
if (css->ss->can_attach) {
- ret = css->ss->can_attach(css, tset);
+ tset->ssid = i;
+ ret = css->ss->can_attach(tset);
if (ret) {
failed_css = css;
goto out_cancel_attach;
@@ -2379,9 +2420,12 @@ static int cgroup_taskset_migrate(struct cgroup_taskset *tset,
*/
tset->csets = &tset->dst_csets;
- for_each_e_css(css, i, dst_cgrp)
- if (css->ss->attach)
- css->ss->attach(css, tset);
+ for_each_e_css(css, i, dst_cgrp) {
+ if (css->ss->attach) {
+ tset->ssid = i;
+ css->ss->attach(tset);
+ }
+ }
ret = 0;
goto out_release_tset;
@@ -2390,8 +2434,10 @@ out_cancel_attach:
for_each_e_css(css, i, dst_cgrp) {
if (css == failed_css)
break;
- if (css->ss->cancel_attach)
- css->ss->cancel_attach(css, tset);
+ if (css->ss->cancel_attach) {
+ tset->ssid = i;
+ css->ss->cancel_attach(tset);
+ }
}
out_release_tset:
spin_lock_bh(&css_set_lock);
@@ -3313,9 +3359,9 @@ static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
if (cft->file_offset) {
struct cgroup_file *cfile = (void *)css + cft->file_offset;
- kernfs_get(kn);
+ spin_lock_irq(&cgroup_file_kn_lock);
cfile->kn = kn;
- list_add(&cfile->node, &css->files);
+ spin_unlock_irq(&cgroup_file_kn_lock);
}
return 0;
@@ -3553,6 +3599,22 @@ int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
}
/**
+ * cgroup_file_notify - generate a file modified event for a cgroup_file
+ * @cfile: target cgroup_file
+ *
+ * @cfile must have been obtained by setting cftype->file_offset.
+ */
+void cgroup_file_notify(struct cgroup_file *cfile)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&cgroup_file_kn_lock, flags);
+ if (cfile->kn)
+ kernfs_notify(cfile->kn);
+ spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
+}
+
+/**
* cgroup_task_count - count the number of tasks in a cgroup.
* @cgrp: the cgroup in question
*
@@ -4613,13 +4675,9 @@ static void css_free_work_fn(struct work_struct *work)
container_of(work, struct cgroup_subsys_state, destroy_work);
struct cgroup_subsys *ss = css->ss;
struct cgroup *cgrp = css->cgroup;
- struct cgroup_file *cfile;
percpu_ref_exit(&css->refcnt);
- list_for_each_entry(cfile, &css->files, node)
- kernfs_put(cfile->kn);
-
if (ss) {
/* css free path */
int id = css->id;
@@ -4724,7 +4782,6 @@ static void init_and_link_css(struct cgroup_subsys_state *css,
css->ss = ss;
INIT_LIST_HEAD(&css->sibling);
INIT_LIST_HEAD(&css->children);
- INIT_LIST_HEAD(&css->files);
css->serial_nr = css_serial_nr_next++;
if (cgroup_parent(cgrp)) {
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