+/*
+ * Statedump the task's namespaces using the proc filesystem inode number as
+ * the unique identifier. The user and pid ns are nested and will be dumped
+ * recursively.
+ *
+ * Called with task lock held.
+ */
+static
+void lttng_statedump_process_ns(struct lttng_session *session,
+ struct task_struct *p,
+ enum lttng_thread_type type,
+ enum lttng_execution_mode mode,
+ enum lttng_execution_submode submode,
+ enum lttng_process_status status)
+{
+ struct nsproxy *proxy;
+ struct pid_namespace *pid_ns;
+ struct user_namespace *user_ns;
+
+ /*
+ * The pid and user namespaces are special, they are nested and
+ * accessed with specific functions instead of the nsproxy struct
+ * like the other namespaces.
+ */
+ pid_ns = task_active_pid_ns(p);
+ do {
+ trace_lttng_statedump_process_pid_ns(session, p, pid_ns);
+ pid_ns = pid_ns ? pid_ns->parent : NULL;
+ } while (pid_ns);
+
+
+ user_ns = task_cred_xxx(p, user_ns);
+ do {
+ trace_lttng_statedump_process_user_ns(session, p, user_ns);
+ /*
+ * trace_lttng_statedump_process_user_ns() internally
+ * checks whether user_ns is NULL. While this does not
+ * appear to be a possible return value for
+ * task_cred_xxx(), err on the safe side and check
+ * for NULL here as well to be consistent with the
+ * paranoid behavior of
+ * trace_lttng_statedump_process_user_ns().
+ */
+ user_ns = user_ns ? user_ns->lttng_user_ns_parent : NULL;
+ } while (user_ns);
+
+ /*
+ * Back and forth on locking strategy within Linux upstream for nsproxy.
+ * See Linux upstream commit 728dba3a39c66b3d8ac889ddbe38b5b1c264aec3
+ * "namespaces: Use task_lock and not rcu to protect nsproxy"
+ * for details.
+ */
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0) || \
+ LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,36, 3,14,0,0) || \
+ LTTNG_UBUNTU_KERNEL_RANGE(3,16,1,11, 3,17,0,0) || \
+ LTTNG_RHEL_KERNEL_RANGE(3,10,0,229,13,0, 3,11,0,0,0,0))
+ proxy = p->nsproxy;
+#else
+ rcu_read_lock();
+ proxy = task_nsproxy(p);
+#endif
+ if (proxy) {
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,6,0))
+ trace_lttng_statedump_process_cgroup_ns(session, p, proxy->cgroup_ns);
+#endif
+ trace_lttng_statedump_process_ipc_ns(session, p, proxy->ipc_ns);
+#ifndef LTTNG_MNT_NS_MISSING_HEADER
+ trace_lttng_statedump_process_mnt_ns(session, p, proxy->mnt_ns);
+#endif
+ trace_lttng_statedump_process_net_ns(session, p, proxy->net_ns);
+ trace_lttng_statedump_process_uts_ns(session, p, proxy->uts_ns);
+ }
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0) || \
+ LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,36, 3,14,0,0) || \
+ LTTNG_UBUNTU_KERNEL_RANGE(3,16,1,11, 3,17,0,0) || \
+ LTTNG_RHEL_KERNEL_RANGE(3,10,0,229,13,0, 3,11,0,0,0,0))
+ /* (nothing) */
+#else
+ rcu_read_unlock();
+#endif
+}
+