cgroup: cleanups after kernfs conversion

index b6c2652..6fe238e 100644
@@ -262,6 +262,8 @@ enum {
 	 * - "release_agent" and "notify_on_release" are removed.
 	 *   Replacement notification mechanism will be implemented.
 	 *
+	 * - "xattr" mount option is deprecated.  kernfs always enables it.
+	 *
 	 * - cpuset: tasks will be kept in empty cpusets when hotplug happens
 	 *   and take masks of ancestors with non-empty cpus/mems, instead of
 	 *   being moved to an ancestor.

index e60a5e3..056bd7d 100644
@@ -1265,6 +1265,9 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 			pr_err("cgroup: sane_behavior: clone_children is not allowed\n");
 			return -EINVAL;
 		}
+
+		if (opts->flags & CGRP_ROOT_XATTR)
+			pr_warning("cgroup: sane_behavior: xattr is always available, flag unnecessary\n");
 	}
 
 	/*

index 056bd7d..16eaf82 100644
@@ -2400,6 +2400,41 @@ static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
 }
 
 /**
+ * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Unregister @cfts.  Files described by @cfts are removed from all
+ * existing cgroups and all future cgroups won't have them either.  This
+ * function can be called anytime whether @cfts' subsys is attached or not.
+ *
+ * Returns 0 on successful unregistration, -ENOENT if @cfts is not
+ * registered.
+ */
+int cgroup_rm_cftypes(struct cftype *cfts)
+{
+	struct cftype *found = NULL;
+	struct cftype_set *set;
+
+	if (!cfts || !cfts[0].ss)
+		return -ENOENT;
+
+	cgroup_cfts_prepare();
+
+	list_for_each_entry(set, &cfts[0].ss->cftsets, node) {
+		if (set->cfts == cfts) {
+			list_del(&set->node);
+			kfree(set);
+			found = cfts;
+			break;
+		}
+	}
+
+	cgroup_cfts_commit(found, false);
+	cgroup_exit_cftypes(cfts);
+	return found ? 0 : -ENOENT;
+}
+
+/**
  * cgroup_add_cftypes - add an array of cftypes to a subsystem
  * @ss: target cgroup subsystem
  * @cfts: zero-length name terminated array of cftypes

@@ -2437,41 +2472,6 @@ int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
 EXPORT_SYMBOL_GPL(cgroup_add_cftypes);
 
 /**
- * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
- * @cfts: zero-length name terminated array of cftypes
- *
- * Unregister @cfts.  Files described by @cfts are removed from all
- * existing cgroups and all future cgroups won't have them either.  This
- * function can be called anytime whether @cfts' subsys is attached or not.
- *
- * Returns 0 on successful unregistration, -ENOENT if @cfts is not
- * registered.
- */
-int cgroup_rm_cftypes(struct cftype *cfts)
-{
-	struct cftype *found = NULL;
-	struct cftype_set *set;
-
-	if (!cfts || !cfts[0].ss)
-		return -ENOENT;
-
-	cgroup_cfts_prepare();
-
-	list_for_each_entry(set, &cfts[0].ss->cftsets, node) {
-		if (set->cfts == cfts) {
-			list_del(&set->node);
-			kfree(set);
-			found = cfts;
-			break;
-		}
-	}
-
-	cgroup_cfts_commit(found, false);
-	cgroup_exit_cftypes(cfts);
-	return found ? 0 : -ENOENT;
-}
-
-/**
  * cgroup_task_count - count the number of tasks in a cgroup.
  * @cgrp: the cgroup in question
  *

index 6fe238e..3c0c7e4 100644
@@ -410,12 +410,11 @@ struct cftype {
 	unsigned int flags;
 
 	/*
-	 * The subsys this file belongs to.  Initialized automatically
-	 * during registration.  NULL for cgroup core files.
+	 * Fields used for internal bookkeeping.  Initialized automatically
+	 * during registration.
 	 */
-	struct cgroup_subsys *ss;
-
-	/* kernfs_ops to use, initialized automatically during registration */
+	struct cgroup_subsys *ss;	/* NULL for cgroup core files */
+	struct list_head node;		/* anchored at ss->cfts */
 	struct kernfs_ops *kf_ops;
 
 	/*

@@ -470,16 +469,6 @@ struct cftype {
 };
 
 /*
- * cftype_sets describe cftypes belonging to a subsystem and are chained at
- * cgroup_subsys->cftsets.  Each cftset points to an array of cftypes
- * terminated by zero length name.
- */
-struct cftype_set {
-	struct list_head		node;	/* chained at subsys->cftsets */
-	struct cftype			*cfts;
-};
-
-/*
  * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details.  This
  * function can be called as long as @cgrp is accessible.
  */

@@ -595,8 +584,11 @@ struct cgroup_subsys {
 	/* link to parent, protected by cgroup_lock() */
 	struct cgroupfs_root *root;
 
-	/* list of cftype_sets */
-	struct list_head cftsets;
+	/*
+	 * List of cftypes.  Each entry is the first entry of an array
+	 * terminated by zero length name.
+	 */
+	struct list_head cfts;
 
 	/* base cftypes, automatically registered with subsys itself */
 	struct cftype *base_cftypes;

97 lines not on this page · raw message

index 64eccb2..5d015c1 100644
@@ -2287,46 +2287,19 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
 	return 0;
 }
 
-static void cgroup_cfts_prepare(void)
-	__acquires(&cgroup_mutex)
-{
-	/*
-	 * Thanks to the entanglement with vfs inode locking, we can't walk
-	 * the existing cgroups under cgroup_mutex and create files.
-	 * Instead, we use css_for_each_descendant_pre() and drop RCU read
-	 * lock before calling cgroup_addrm_files().
-	 */
-	mutex_lock(&cgroup_tree_mutex);
-	mutex_lock(&cgroup_mutex);
-}
-
-static int cgroup_cfts_commit(struct cftype *cfts, bool is_add)
-	__releases(&cgroup_mutex)
+static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
 {
 	LIST_HEAD(pending);
 	struct cgroup_subsys *ss = cfts[0].ss;
 	struct cgroup *root = &ss->root->top_cgroup;
-	struct cgroup *prev = NULL;
 	struct cgroup_subsys_state *css;
-	u64 update_before;
 	int ret = 0;
 
-	mutex_unlock(&cgroup_mutex);
+	lockdep_assert_held(&cgroup_tree_mutex);
 
-	/* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
-	if (!cfts || ss->root == &cgroup_dummy_root) {
-		mutex_unlock(&cgroup_tree_mutex);
+	/* don't bother if @ss isn't attached */
+	if (ss->root == &cgroup_dummy_root)
 		return 0;
-	}
-
-	cgroup_get_root(ss->root);
-
-	/*
-	 * All cgroups which are created after we drop cgroup_mutex will
-	 * have the updated set of files, so we only need to update the
-	 * cgroups created before the current @cgroup_serial_nr_next.
-	 */
-	update_before = cgroup_serial_nr_next;
 
 	/* add/rm files for all cgroups created before */
 	css_for_each_descendant_pre(css, cgroup_css(root, ss)) {

@@ -2335,22 +2308,13 @@ static int cgroup_cfts_commit(struct cftype *cfts, bool is_add)
 		if (cgroup_is_dead(cgrp))
 			continue;
 
-		cgroup_get(cgrp);
-		if (prev)
-			cgroup_put(prev);
-		prev = cgrp;
-
-		if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp)) {
-			ret = cgroup_addrm_files(cgrp, cfts, is_add);
-			if (is_add)
-				kernfs_activate(cgrp->kn);
-		}
+		ret = cgroup_addrm_files(cgrp, cfts, is_add);
 		if (ret)
 			break;
 	}
-	mutex_unlock(&cgroup_tree_mutex);
-	cgroup_put(prev);
-	cgroup_put_root(ss->root);
+
+	if (is_add && !ret)
+		kernfs_activate(root->kn);
 	return ret;
 }
 

@@ -2401,6 +2365,19 @@ static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
 	return 0;
 }
 
+static int cgroup_rm_cftypes_locked(struct cftype *cfts)
+{
+	lockdep_assert_held(&cgroup_tree_mutex);
+
+	if (!cfts || !cfts[0].ss)
+		return -ENOENT;
+
+	list_del(&cfts->node);
+	cgroup_apply_cftypes(cfts, false);
+	cgroup_exit_cftypes(cfts);
+	return 0;
+}
+
 /**
  * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
  * @cfts: zero-length name terminated array of cftypes

@@ -2414,15 +2391,12 @@ static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
  */
 int cgroup_rm_cftypes(struct cftype *cfts)
 {
-	if (!cfts || !cfts[0].ss)
-		return -ENOENT;
-
-	cgroup_cfts_prepare();
-	list_del(&cfts->node);
-	cgroup_cfts_commit(cfts, false);
+	int ret;
 
-	cgroup_exit_cftypes(cfts);
-	return 0;
+	mutex_lock(&cgroup_tree_mutex);
+	ret = cgroup_rm_cftypes_locked(cfts);
+	mutex_unlock(&cgroup_tree_mutex);
+	return ret;
 }
 
 /**

@@ -2447,11 +2421,14 @@ int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
 	if (ret)
 		return ret;
 
-	cgroup_cfts_prepare();
+	mutex_lock(&cgroup_tree_mutex);
+
 	list_add_tail(&cfts->node, &ss->cfts);
-	ret = cgroup_cfts_commit(cfts, true);
+	ret = cgroup_apply_cftypes(cfts, true);
 	if (ret)
-		cgroup_rm_cftypes(cfts);
+		cgroup_rm_cftypes_locked(cfts);
+
+	mutex_unlock(&cgroup_tree_mutex);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(cgroup_add_cftypes);

index 5d015c1..3e4df3c 100644
@@ -957,6 +957,8 @@ static void cgroup_free_fn(struct work_struct *work)
 
 	cgroup_pidlist_destroy_all(cgrp);
 
+	kernfs_put(cgrp->kn);
+
 	kfree(rcu_dereference_raw(cgrp->name));
 	kfree(cgrp);
 }

@@ -3768,6 +3770,12 @@ static long cgroup_create(struct cgroup *parent, const char *name_str,
 	}
 	cgrp->kn = kn;
 
+	/*
+	 * This extra ref will be put in cgroup_free_fn() and guarantees
+	 * that @cgrp->kn is always accessible.
+	 */
+	kernfs_get(kn);
+
 	cgrp->serial_nr = cgroup_serial_nr_next++;
 
 	/* allocation complete, commit to creation */

@@ -3948,7 +3956,6 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
 {
 	struct cgroup *child;
 	struct cgroup_subsys_state *css;
-	struct kernfs_node *kn;
 	bool empty;
 	int ssid;
 

@@ -4026,13 +4033,8 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
 	 * cgrp->kn->priv backpointer, which should be cleared after all
 	 * files under it have been removed.
 	 */
-	kn = cgrp->kn;
-	kernfs_get(kn);
-
-	kernfs_remove(cgrp->kn);
-
+	kernfs_remove(cgrp->kn);	/* @cgrp has an extra ref on its kn */
 	RCU_INIT_POINTER(cgrp->kn->priv, NULL);
-	kernfs_put(kn);
 
 	mutex_lock(&cgroup_mutex);
 

index 5d015c1..3e4df3c 100644
@@ -957,6 +957,8 @@ static void cgroup_free_fn(struct work_struct *work)
 
 	cgroup_pidlist_destroy_all(cgrp);
 
+	kernfs_put(cgrp->kn);
+
 	kfree(rcu_dereference_raw(cgrp->name));
 	kfree(cgrp);
 }

@@ -3768,6 +3770,12 @@ static long cgroup_create(struct cgroup *parent, const char *name_str,
 	}
 	cgrp->kn = kn;
 
+	/*
+	 * This extra ref will be put in cgroup_free_fn() and guarantees
+	 * that @cgrp->kn is always accessible.
+	 */
+	kernfs_get(kn);
+
 	cgrp->serial_nr = cgroup_serial_nr_next++;
 
 	/* allocation complete, commit to creation */

@@ -3948,7 +3956,6 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
 {
 	struct cgroup *child;
 	struct cgroup_subsys_state *css;
-	struct kernfs_node *kn;
 	bool empty;
 	int ssid;
 

@@ -4026,13 +4033,8 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
 	 * cgrp->kn->priv backpointer, which should be cleared after all
 	 * files under it have been removed.
 	 */
-	kn = cgrp->kn;
-	kernfs_get(kn);
-
-	kernfs_remove(cgrp->kn);
-
+	kernfs_remove(cgrp->kn);	/* @cgrp has an extra ref on its kn */
 	RCU_INIT_POINTER(cgrp->kn->priv, NULL);
-	kernfs_put(kn);
 
 	mutex_lock(&cgroup_mutex);
 

index b14abaf..6756c23 100644
@@ -280,12 +280,10 @@ struct cgroupfs_root {
 	/* The bitmask of subsystems attached to this hierarchy */
 	unsigned long subsys_mask;
 
-	atomic_t refcnt;
-
 	/* Unique id for this hierarchy. */
 	int hierarchy_id;
 
-	/* The root cgroup for this hierarchy */
+	/* The root cgroup.  Root is destroyed on its release. */
 	struct cgroup top_cgroup;
 
 	/* Number of cgroups in the hierarchy, used only for /proc/cgroups */

156 lines not on this page · raw message

index 453b528..15a8d64 100644
@@ -241,12 +241,16 @@ static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
  */
 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 {
-	int ret;
+	char *p;
 
-	ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
-	if (ret)
+	p = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
+	if (!p) {
 		strncpy(buf, "<unavailable>", buflen);
-	return ret;
+		return -ENAMETOOLONG;
+	}
+
+	memmove(buf, p, buf + buflen - p);
+	return 0;
 }
 
 /**

index a347792..939684e 100644
@@ -112,6 +112,7 @@ char *kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen)
 	spin_unlock_irqrestore(&kernfs_rename_lock, flags);
 	return p;
 }
+EXPORT_SYMBOL_GPL(kernfs_path);
 
 /**
  * pr_cont_kernfs_name - pr_cont name of a kernfs_node

84 lines not on this page · raw message

307 lines not on this page · raw message

index 2d018c7..e97a6e8 100644
@@ -2088,10 +2088,9 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
 		parent = parent_cs(parent);
 
 	if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
-		rcu_read_lock();
-		printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset %s\n",
-		       cgroup_name(cs->css.cgroup));
-		rcu_read_unlock();
+		printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset ");
+		pr_cont_cgroup_name(cs->css.cgroup);
+		pr_cont("\n");
 	}
 }
 

@@ -2619,19 +2618,17 @@ void cpuset_print_task_mems_allowed(struct task_struct *tsk)
 	 /* Statically allocated to prevent using excess stack. */
 	static char cpuset_nodelist[CPUSET_NODELIST_LEN];
 	static DEFINE_SPINLOCK(cpuset_buffer_lock);
-
 	struct cgroup *cgrp = task_cs(tsk)->css.cgroup;
 
-	rcu_read_lock();
 	spin_lock(&cpuset_buffer_lock);
 
 	nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
 			   tsk->mems_allowed);
-	printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
-	       tsk->comm, cgroup_name(cgrp), cpuset_nodelist);
+	printk(KERN_INFO "%s cpuset=", tsk->comm);
+	pr_cont_cgroup_name(cgrp);
+	pr_cont(" mems_allowed=%s\n", cpuset_nodelist);
 
 	spin_unlock(&cpuset_buffer_lock);
-	rcu_read_unlock();
 }
 
 /*

@@ -2681,12 +2678,12 @@ int proc_cpuset_show(struct seq_file *m, void *unused_v)
 {
 	struct pid *pid;
 	struct task_struct *tsk;
-	char *buf;
+	char *buf, *p;
 	struct cgroup_subsys_state *css;
 	int retval;
 
 	retval = -ENOMEM;
-	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	buf = kmalloc(PATH_MAX, GFP_KERNEL);
 	if (!buf)
 		goto out;
 

@@ -2696,14 +2693,16 @@ int proc_cpuset_show(struct seq_file *m, void *unused_v)
 	if (!tsk)
 		goto out_free;
 
+	retval = -ENAMETOOLONG;
 	rcu_read_lock();
 	css = task_css(tsk, cpuset_cgrp_id);
-	retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
+	p = cgroup_path(css->cgroup, buf, PATH_MAX);
 	rcu_read_unlock();
-	if (retval < 0)
+	if (!p)
 		goto out_put_task;
-	seq_puts(m, buf);
+	seq_puts(m, p);
 	seq_putc(m, '\n');
+	retval = 0;
 out_put_task:
 	put_task_struct(tsk);
 out_free:

index dd52e7f..30eee3b 100644
@@ -111,8 +111,7 @@ static char *task_group_path(struct task_group *tg)
 	if (autogroup_path(tg, group_path, PATH_MAX))
 		return group_path;
 
-	cgroup_path(tg->css.cgroup, group_path, PATH_MAX);
-	return group_path;
+	return cgroup_path(tg->css.cgroup, group_path, PATH_MAX);
 }
 #endif
 

101 lines not on this page · raw message

index 19d5d4274e22..d998baec5deb 100644
@@ -1684,8 +1684,7 @@ static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
 void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
 {
 	/*
-	 * protects memcg_name and makes sure that parallel ooms do not
-	 * interleave
+	 * Makes sure that parallel ooms do not interleave
 	 */
 	static DEFINE_SPINLOCK(oom_info_lock);
 	struct cgroup *task_cgrp;

index 19d5d4274e22..d998baec5deb 100644
@@ -1684,8 +1684,7 @@ static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
 void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
 {
 	/*
-	 * protects memcg_name and makes sure that parallel ooms do not
-	 * interleave
+	 * Makes sure that parallel ooms do not interleave
 	 */
 	static DEFINE_SPINLOCK(oom_info_lock);
 	struct cgroup *task_cgrp;

index 453b528..15a8d64 100644
@@ -241,12 +241,16 @@ static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
  */
 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 {
-	int ret;
+	char *p;
 
-	ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
-	if (ret)
+	p = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
+	if (!p) {
 		strncpy(buf, "<unavailable>", buflen);
-	return ret;
+		return -ENAMETOOLONG;
+	}
+
+	memmove(buf, p, buf + buflen - p);
+	return 0;
 }
 
 /**

index a347792..939684e 100644
@@ -112,6 +112,7 @@ char *kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen)
 	spin_unlock_irqrestore(&kernfs_rename_lock, flags);
 	return p;
 }
+EXPORT_SYMBOL_GPL(kernfs_path);
 
 /**
  * pr_cont_kernfs_name - pr_cont name of a kernfs_node

84 lines not on this page · raw message

307 lines not on this page · raw message

index 2d018c7..e97a6e8 100644
@@ -2088,10 +2088,9 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
 		parent = parent_cs(parent);
 
 	if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
-		rcu_read_lock();
-		printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset %s\n",
-		       cgroup_name(cs->css.cgroup));
-		rcu_read_unlock();
+		printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset ");
+		pr_cont_cgroup_name(cs->css.cgroup);
+		pr_cont("\n");
 	}
 }
 

@@ -2619,19 +2618,17 @@ void cpuset_print_task_mems_allowed(struct task_struct *tsk)
 	 /* Statically allocated to prevent using excess stack. */
 	static char cpuset_nodelist[CPUSET_NODELIST_LEN];
 	static DEFINE_SPINLOCK(cpuset_buffer_lock);
-
 	struct cgroup *cgrp = task_cs(tsk)->css.cgroup;
 
-	rcu_read_lock();
 	spin_lock(&cpuset_buffer_lock);
 
 	nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
 			   tsk->mems_allowed);
-	printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
-	       tsk->comm, cgroup_name(cgrp), cpuset_nodelist);
+	printk(KERN_INFO "%s cpuset=", tsk->comm);
+	pr_cont_cgroup_name(cgrp);
+	pr_cont(" mems_allowed=%s\n", cpuset_nodelist);
 
 	spin_unlock(&cpuset_buffer_lock);
-	rcu_read_unlock();
 }
 
 /*

@@ -2681,12 +2678,12 @@ int proc_cpuset_show(struct seq_file *m, void *unused_v)
 {
 	struct pid *pid;
 	struct task_struct *tsk;
-	char *buf;
+	char *buf, *p;
 	struct cgroup_subsys_state *css;
 	int retval;
 
 	retval = -ENOMEM;
-	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	buf = kmalloc(PATH_MAX, GFP_KERNEL);
 	if (!buf)
 		goto out;
 

@@ -2696,14 +2693,16 @@ int proc_cpuset_show(struct seq_file *m, void *unused_v)
 	if (!tsk)
 		goto out_free;
 
+	retval = -ENAMETOOLONG;
 	rcu_read_lock();
 	css = task_css(tsk, cpuset_cgrp_id);
-	retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
+	p = cgroup_path(css->cgroup, buf, PATH_MAX);
 	rcu_read_unlock();
-	if (retval < 0)
+	if (!p)
 		goto out_put_task;
-	seq_puts(m, buf);
+	seq_puts(m, p);
 	seq_putc(m, '\n');
+	retval = 0;
 out_put_task:
 	put_task_struct(tsk);
 out_free:

index dd52e7f..30eee3b 100644
@@ -111,8 +111,7 @@ static char *task_group_path(struct task_group *tg)
 	if (autogroup_path(tg, group_path, PATH_MAX))
 		return group_path;
 
-	cgroup_path(tg->css.cgroup, group_path, PATH_MAX);
-	return group_path;
+	return cgroup_path(tg->css.cgroup, group_path, PATH_MAX);
 }
 #endif
 

107 lines not on this page · raw message

index 453b528..15a8d64 100644
@@ -241,12 +241,16 @@ static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
  */
 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 {
-	int ret;
+	char *p;
 
-	ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
-	if (ret)
+	p = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
+	if (!p) {
 		strncpy(buf, "<unavailable>", buflen);
-	return ret;
+		return -ENAMETOOLONG;
+	}
+
+	memmove(buf, p, buf + buflen - p);
+	return 0;
 }
 
 /**

index a347792..939684e 100644
@@ -112,6 +112,7 @@ char *kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen)
 	spin_unlock_irqrestore(&kernfs_rename_lock, flags);
 	return p;
 }
+EXPORT_SYMBOL_GPL(kernfs_path);
 
 /**
  * pr_cont_kernfs_name - pr_cont name of a kernfs_node

84 lines not on this page · raw message

307 lines not on this page · raw message

index 2d018c7..e97a6e8 100644
@@ -2088,10 +2088,9 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
 		parent = parent_cs(parent);
 
 	if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
-		rcu_read_lock();
-		printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset %s\n",
-		       cgroup_name(cs->css.cgroup));
-		rcu_read_unlock();
+		printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset ");
+		pr_cont_cgroup_name(cs->css.cgroup);
+		pr_cont("\n");
 	}
 }
 

@@ -2619,19 +2618,17 @@ void cpuset_print_task_mems_allowed(struct task_struct *tsk)
 	 /* Statically allocated to prevent using excess stack. */
 	static char cpuset_nodelist[CPUSET_NODELIST_LEN];
 	static DEFINE_SPINLOCK(cpuset_buffer_lock);
-
 	struct cgroup *cgrp = task_cs(tsk)->css.cgroup;
 
-	rcu_read_lock();
 	spin_lock(&cpuset_buffer_lock);
 
 	nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
 			   tsk->mems_allowed);
-	printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
-	       tsk->comm, cgroup_name(cgrp), cpuset_nodelist);
+	printk(KERN_INFO "%s cpuset=", tsk->comm);
+	pr_cont_cgroup_name(cgrp);
+	pr_cont(" mems_allowed=%s\n", cpuset_nodelist);
 
 	spin_unlock(&cpuset_buffer_lock);
-	rcu_read_unlock();
 }
 
 /*

@@ -2681,12 +2678,12 @@ int proc_cpuset_show(struct seq_file *m, void *unused_v)
 {
 	struct pid *pid;
 	struct task_struct *tsk;
-	char *buf;
+	char *buf, *p;
 	struct cgroup_subsys_state *css;
 	int retval;
 
 	retval = -ENOMEM;
-	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	buf = kmalloc(PATH_MAX, GFP_KERNEL);
 	if (!buf)
 		goto out;
 

@@ -2696,14 +2693,16 @@ int proc_cpuset_show(struct seq_file *m, void *unused_v)
 	if (!tsk)
 		goto out_free;
 
+	retval = -ENAMETOOLONG;
 	rcu_read_lock();
 	css = task_css(tsk, cpuset_cgrp_id);
-	retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
+	p = cgroup_path(css->cgroup, buf, PATH_MAX);
 	rcu_read_unlock();
-	if (retval < 0)
+	if (!p)
 		goto out_put_task;
-	seq_puts(m, buf);
+	seq_puts(m, p);
 	seq_putc(m, '\n');
+	retval = 0;
 out_put_task:
 	put_task_struct(tsk);
 out_free:

index dd52e7f..30eee3b 100644
@@ -111,8 +111,7 @@ static char *task_group_path(struct task_group *tg)
 	if (autogroup_path(tg, group_path, PATH_MAX))
 		return group_path;
 
-	cgroup_path(tg->css.cgroup, group_path, PATH_MAX);
-	return group_path;
+	return cgroup_path(tg->css.cgroup, group_path, PATH_MAX);
 }
 #endif
 

107 lines not on this page · raw message

index 8202abb..b14abaf 100644
@@ -288,8 +288,8 @@ struct cgroupfs_root {
 	/* The root cgroup for this hierarchy */
 	struct cgroup top_cgroup;
 
-	/* Tracks how many cgroups are currently defined in hierarchy.*/
-	int number_of_cgroups;
+	/* Number of cgroups in the hierarchy, used only for /proc/cgroups */
+	atomic_t nr_cgrps;
 
 	/* A list running through the active hierarchies */
 	struct list_head root_list;

index 397aca3..41b6601 100644
@@ -758,7 +758,7 @@ static void cgroup_put_root(struct cgroupfs_root *root)
 	}
 	mutex_lock(&cgroup_mutex);
 
-	BUG_ON(root->number_of_cgroups != 1);
+	BUG_ON(atomic_read(&root->nr_cgrps) != 1);
 	BUG_ON(!list_empty(&cgrp->children));
 
 	/* Rebind all subsystems back to the default hierarchy */

@@ -928,9 +928,7 @@ static void cgroup_free_fn(struct work_struct *work)
 {
 	struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work);
 
-	mutex_lock(&cgroup_mutex);
-	cgrp->root->number_of_cgroups--;
-	mutex_unlock(&cgroup_mutex);
+	atomic_dec(&cgrp->root->nr_cgrps);
 
 	/*
 	 * We get a ref to the parent, and put the ref when this cgroup is

@@ -1318,7 +1316,7 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
 	}
 
 	/* remounting is not allowed for populated hierarchies */
-	if (root->number_of_cgroups > 1) {
+	if (!list_empty(&root->top_cgroup.children)) {
 		ret = -EBUSY;
 		goto out_unlock;
 	}

@@ -1358,7 +1356,7 @@ static void init_cgroup_root(struct cgroupfs_root *root)
 
 	atomic_set(&root->refcnt, 1);
 	INIT_LIST_HEAD(&root->root_list);
-	root->number_of_cgroups = 1;
+	atomic_set(&root->nr_cgrps, 1);
 	cgrp->root = root;
 	init_cgroup_housekeeping(cgrp);
 	idr_init(&root->cgroup_idr);

@@ -1458,7 +1456,7 @@ static int cgroup_setup_root(struct cgroupfs_root *root)
 	write_unlock(&css_set_lock);
 
 	BUG_ON(!list_empty(&root_cgrp->children));
-	BUG_ON(root->number_of_cgroups != 1);
+	BUG_ON(atomic_read(&root->nr_cgrps) != 1);
 
 	kernfs_activate(root_cgrp->kn);
 	ret = 0;

@@ -3691,7 +3689,7 @@ static long cgroup_create(struct cgroup *parent, const char *name,
 
 	/* allocation complete, commit to creation */
 	list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
-	root->number_of_cgroups++;
+	atomic_inc(&root->nr_cgrps);
 
 	/*
 	 * Grab a reference on the root and parent so that they don't get

@@ -4259,7 +4257,7 @@ static int proc_cgroupstats_show(struct seq_file *m, void *v)
 	for_each_subsys(ss, i)
 		seq_printf(m, "%s\t%d\t%d\t%d\n",
 			   ss->name, ss->root->hierarchy_id,
-			   ss->root->number_of_cgroups, !ss->disabled);
+			   atomic_read(&ss->root->nr_cgrps), !ss->disabled);
 
 	mutex_unlock(&cgroup_mutex);
 	return 0;

index b14abaf..6756c23 100644
@@ -280,12 +280,10 @@ struct cgroupfs_root {
 	/* The bitmask of subsystems attached to this hierarchy */
 	unsigned long subsys_mask;
 
-	atomic_t refcnt;
-
 	/* Unique id for this hierarchy. */
 	int hierarchy_id;
 
-	/* The root cgroup for this hierarchy */
+	/* The root cgroup.  Root is destroyed on its release. */
 	struct cgroup top_cgroup;
 
 	/* Number of cgroups in the hierarchy, used only for /proc/cgroups */

156 lines not on this page · raw message