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-rw-r--r--include/linux/user_namespace.h10
-rw-r--r--kernel/user.c4
-rw-r--r--kernel/user_namespace.c17
3 files changed, 15 insertions, 16 deletions
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index b9bd2e6c73cc..4ce009324933 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -21,7 +21,7 @@ struct user_namespace {
struct uid_gid_map uid_map;
struct uid_gid_map gid_map;
struct uid_gid_map projid_map;
- struct kref kref;
+ atomic_t count;
struct user_namespace *parent;
kuid_t owner;
kgid_t group;
@@ -35,18 +35,18 @@ extern struct user_namespace init_user_ns;
static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
{
if (ns)
- kref_get(&ns->kref);
+ atomic_inc(&ns->count);
return ns;
}
extern int create_user_ns(struct cred *new);
extern int unshare_userns(unsigned long unshare_flags, struct cred **new_cred);
-extern void free_user_ns(struct kref *kref);
+extern void free_user_ns(struct user_namespace *ns);
static inline void put_user_ns(struct user_namespace *ns)
{
- if (ns)
- kref_put(&ns->kref, free_user_ns);
+ if (ns && atomic_dec_and_test(&ns->count))
+ free_user_ns(ns);
}
struct seq_operations;
diff --git a/kernel/user.c b/kernel/user.c
index 33acb5e53a5f..57ebfd42023c 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -47,9 +47,7 @@ struct user_namespace init_user_ns = {
.count = 4294967295U,
},
},
- .kref = {
- .refcount = ATOMIC_INIT(3),
- },
+ .count = ATOMIC_INIT(3),
.owner = GLOBAL_ROOT_UID,
.group = GLOBAL_ROOT_GID,
.proc_inum = PROC_USER_INIT_INO,
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 2b042c42fbc4..24f8ec3b64d8 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -78,7 +78,7 @@ int create_user_ns(struct cred *new)
return ret;
}
- kref_init(&ns->kref);
+ atomic_set(&ns->count, 1);
/* Leave the new->user_ns reference with the new user namespace. */
ns->parent = parent_ns;
ns->owner = owner;
@@ -104,15 +104,16 @@ int unshare_userns(unsigned long unshare_flags, struct cred **new_cred)
return create_user_ns(cred);
}
-void free_user_ns(struct kref *kref)
+void free_user_ns(struct user_namespace *ns)
{
- struct user_namespace *parent, *ns =
- container_of(kref, struct user_namespace, kref);
+ struct user_namespace *parent;
- parent = ns->parent;
- proc_free_inum(ns->proc_inum);
- kmem_cache_free(user_ns_cachep, ns);
- put_user_ns(parent);
+ do {
+ parent = ns->parent;
+ proc_free_inum(ns->proc_inum);
+ kmem_cache_free(user_ns_cachep, ns);
+ ns = parent;
+ } while (atomic_dec_and_test(&parent->count));
}
EXPORT_SYMBOL(free_user_ns);