diff options
Diffstat (limited to 'include/linux/nsproxy.h')
| -rw-r--r-- | include/linux/nsproxy.h | 43 |
1 files changed, 34 insertions, 9 deletions
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h index f1eca68751a..0e66b57631f 100644 --- a/include/linux/nsproxy.h +++ b/include/linux/nsproxy.h @@ -32,8 +32,39 @@ struct nsproxy { }; extern struct nsproxy init_nsproxy; +/* + * the namespaces access rules are: + * + * 1. only current task is allowed to change tsk->nsproxy pointer or + * any pointer on the nsproxy itself + * + * 2. when accessing (i.e. reading) current task's namespaces - no + * precautions should be taken - just dereference the pointers + * + * 3. the access to other task namespaces is performed like this + * rcu_read_lock(); + * nsproxy = task_nsproxy(tsk); + * if (nsproxy != NULL) { + * / * + * * work with the namespaces here + * * e.g. get the reference on one of them + * * / + * } / * + * * NULL task_nsproxy() means that this task is + * * almost dead (zombie) + * * / + * rcu_read_unlock(); + * + */ + +static inline struct nsproxy *task_nsproxy(struct task_struct *tsk) +{ + return rcu_dereference(tsk->nsproxy); +} + int copy_namespaces(unsigned long flags, struct task_struct *tsk); -void get_task_namespaces(struct task_struct *tsk); +void exit_task_namespaces(struct task_struct *tsk); +void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); void free_nsproxy(struct nsproxy *ns); int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **, struct fs_struct *); @@ -45,15 +76,9 @@ static inline void put_nsproxy(struct nsproxy *ns) } } -static inline void exit_task_namespaces(struct task_struct *p) +static inline void get_nsproxy(struct nsproxy *ns) { - struct nsproxy *ns = p->nsproxy; - if (ns) { - task_lock(p); - p->nsproxy = NULL; - task_unlock(p); - put_nsproxy(ns); - } + atomic_inc(&ns->count); } #ifdef CONFIG_CGROUP_NS |