1 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/pid.h b/include/linux/pid.h
index bb206c56d1f0..49f1c2f66e95 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -123,6 +123,24 @@ 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;