+static
+void vppid_get_value(struct lttng_ctx_field *field,
+ struct lttng_probe_ctx *lttng_probe_ctx,
+ union lttng_ctx_value *value)
+{
+ struct task_struct *parent;
+ pid_t vppid;
+
+ /*
+ * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
+ * the current thread nsproxy to perform the lookup.
+ */
+
+ /*
+ * TODO: when we eventually add RCU subsystem instrumentation,
+ * taking the rcu read lock here will trigger RCU tracing
+ * recursively. We should modify the kernel synchronization so
+ * it synchronizes both for RCU and RCU sched, and rely on
+ * rcu_read_lock_sched_notrace.
+ */
+
+ rcu_read_lock();
+ parent = rcu_dereference(current->real_parent);
+ if (!current->nsproxy)
+ vppid = 0;
+ else
+ vppid = task_tgid_vnr(parent);
+ rcu_read_unlock();
+ value->s64 = vppid;
+}
+