*
* Holding a reference to struct pid solves both of these problems.
* It is small so holding a reference does not consume a lot of
- * resources, and since a new struct pid is allocated when the numeric
- * pid value is reused we don't mistakenly refer to new processes.
+ * resources, and since a new struct pid is allocated when the numeric pid
+ * value is reused (when pids wrap around) we don't mistakenly refer to new
+ * processes.
*/
+
+/*
+ * struct upid is used to get the id of the struct pid, as it is
+ * seen in particular namespace. Later the struct pid is found with
+ * find_pid_ns() using the int nr and struct pid_namespace *ns.
+ */
+
+struct upid {
+ /* Try to keep pid_chain in the same cacheline as nr for find_vpid */
+ int nr;
+ struct pid_namespace *ns;
+ struct hlist_node pid_chain;
+};
+
struct pid
{
atomic_t count;
- /* Try to keep pid_chain in the same cacheline as nr for find_pid */
- int nr;
- struct hlist_node pid_chain;
+ unsigned int level;
/* lists of tasks that use this pid */
struct hlist_head tasks[PIDTYPE_MAX];
struct rcu_head rcu;
+ struct upid numbers[1];
};
+extern struct pid init_struct_pid;
+
struct pid_link
{
struct hlist_node node;
return pid;
}
-extern void FASTCALL(put_pid(struct pid *pid));
-extern struct task_struct *FASTCALL(pid_task(struct pid *pid, enum pid_type));
-extern struct task_struct *FASTCALL(get_pid_task(struct pid *pid,
- enum pid_type));
+extern void put_pid(struct pid *pid);
+extern struct task_struct *pid_task(struct pid *pid, enum pid_type);
+extern struct task_struct *get_pid_task(struct pid *pid, enum pid_type);
+
+extern struct pid *get_task_pid(struct task_struct *task, enum pid_type type);
/*
* attach_pid() and detach_pid() must be called with the tasklist_lock
* write-held.
*/
-extern int FASTCALL(attach_pid(struct task_struct *task,
- enum pid_type type, int nr));
+extern void attach_pid(struct task_struct *task, enum pid_type type,
+ struct pid *pid);
+extern void detach_pid(struct task_struct *task, enum pid_type);
+extern void change_pid(struct task_struct *task, enum pid_type,
+ struct pid *pid);
+extern void transfer_pid(struct task_struct *old, struct task_struct *new,
+ enum pid_type);
-extern void FASTCALL(detach_pid(struct task_struct *task, enum pid_type));
-extern void FASTCALL(transfer_pid(struct task_struct *old,
- struct task_struct *new, enum pid_type));
+struct pid_namespace;
+extern struct pid_namespace init_pid_ns;
/*
* look up a PID in the hash table. Must be called with the tasklist_lock
* or rcu_read_lock() held.
+ *
+ * find_pid_ns() finds the pid in the namespace specified
+ * find_vpid() finr the pid by its virtual id, i.e. in the current namespace
+ *
+ * see also find_task_by_vpid() set in include/linux/sched.h
*/
-extern struct pid *FASTCALL(find_pid(int nr));
+extern struct pid *find_pid_ns(int nr, struct pid_namespace *ns);
+extern struct pid *find_vpid(int nr);
/*
* Lookup a PID in the hash table, and return with it's count elevated.
*/
extern struct pid *find_get_pid(int nr);
-extern struct pid *find_ge_pid(int nr);
+extern struct pid *find_ge_pid(int nr, struct pid_namespace *);
+int next_pidmap(struct pid_namespace *pid_ns, int last);
-extern struct pid *alloc_pid(void);
-extern void FASTCALL(free_pid(struct pid *pid));
+extern struct pid *alloc_pid(struct pid_namespace *ns);
+extern void free_pid(struct pid *pid);
+
+/*
+ * ns_of_pid() returns the pid namespace in which the specified pid was
+ * allocated.
+ *
+ * NOTE:
+ * ns_of_pid() is expected to be called for a process (task) that has
+ * an attached 'struct pid' (see attach_pid(), detach_pid()) i.e @pid
+ * is expected to be non-NULL. If @pid is NULL, caller should handle
+ * the resulting NULL pid-ns.
+ */
+static inline struct pid_namespace *ns_of_pid(struct pid *pid)
+{
+ struct pid_namespace *ns = NULL;
+ if (pid)
+ ns = pid->numbers[pid->level].ns;
+ return ns;
+}
+
+/*
+ * the helpers to get the pid's id seen from different namespaces
+ *
+ * pid_nr() : global id, i.e. the id seen from the init namespace;
+ * pid_vnr() : virtual id, i.e. the id seen from the pid namespace of
+ * current.
+ * pid_nr_ns() : id seen from the ns specified.
+ *
+ * see also task_xid_nr() etc in include/linux/sched.h
+ */
static inline pid_t pid_nr(struct pid *pid)
{
pid_t nr = 0;
if (pid)
- nr = pid->nr;
+ nr = pid->numbers[0].nr;
return nr;
}
-
-#define do_each_task_pid(who, type, task) \
- do { \
- struct hlist_node *pos___; \
- struct pid *pid___ = find_pid(who); \
- if (pid___ != NULL) \
- hlist_for_each_entry_rcu((task), pos___, \
- &pid___->tasks[type], pids[type].node) {
-
-#define while_each_task_pid(who, type, task) \
- } \
+pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns);
+pid_t pid_vnr(struct pid *pid);
+
+#define do_each_pid_task(pid, type, task) \
+ do { \
+ struct hlist_node *pos___; \
+ if ((pid) != NULL) \
+ hlist_for_each_entry_rcu((task), pos___, \
+ &(pid)->tasks[type], pids[type].node) {
+
+ /*
+ * Both old and new leaders may be attached to
+ * the same pid in the middle of de_thread().
+ */
+#define while_each_pid_task(pid, type, task) \
+ if (type == PIDTYPE_PID) \
+ break; \
+ } \
} while (0)
+#define do_each_pid_thread(pid, type, task) \
+ do_each_pid_task(pid, type, task) { \
+ struct task_struct *tg___ = task; \
+ do {
-#define do_each_pid_task(pid, type, task) \
- do { \
- struct hlist_node *pos___; \
- if (pid != NULL) \
- hlist_for_each_entry_rcu((task), pos___, \
- &pid->tasks[type], pids[type].node) {
-
-#define while_each_pid_task(pid, type, task) \
- } \
- } while (0)
-
+#define while_each_pid_thread(pid, type, task) \
+ } while_each_thread(tg___, task); \
+ task = tg___; \
+ } while_each_pid_task(pid, type, task)
#endif /* _LINUX_PID_H */
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