+ * fork tracking
+ */
+
+struct perf_fork_event {
+ struct task_struct *task;
+
+ struct {
+ struct perf_event_header header;
+
+ u32 pid;
+ u32 ppid;
+ } event;
+};
+
+static void perf_counter_fork_output(struct perf_counter *counter,
+ struct perf_fork_event *fork_event)
+{
+ struct perf_output_handle handle;
+ int size = fork_event->event.header.size;
+ struct task_struct *task = fork_event->task;
+ int ret = perf_output_begin(&handle, counter, size, 0, 0);
+
+ if (ret)
+ return;
+
+ fork_event->event.pid = perf_counter_pid(counter, task);
+ fork_event->event.ppid = perf_counter_pid(counter, task->real_parent);
+
+ perf_output_put(&handle, fork_event->event);
+ perf_output_end(&handle);
+}
+
+static int perf_counter_fork_match(struct perf_counter *counter)
+{
+ if (counter->attr.comm || counter->attr.mmap)
+ return 1;
+
+ return 0;
+}
+
+static void perf_counter_fork_ctx(struct perf_counter_context *ctx,
+ struct perf_fork_event *fork_event)
+{
+ struct perf_counter *counter;
+
+ if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list))
+ return;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {
+ if (perf_counter_fork_match(counter))
+ perf_counter_fork_output(counter, fork_event);
+ }
+ rcu_read_unlock();
+}
+
+static void perf_counter_fork_event(struct perf_fork_event *fork_event)
+{
+ struct perf_cpu_context *cpuctx;
+ struct perf_counter_context *ctx;
+
+ cpuctx = &get_cpu_var(perf_cpu_context);
+ perf_counter_fork_ctx(&cpuctx->ctx, fork_event);
+ put_cpu_var(perf_cpu_context);
+
+ rcu_read_lock();
+ /*
+ * doesn't really matter which of the child contexts the
+ * events ends up in.
+ */
+ ctx = rcu_dereference(current->perf_counter_ctxp);
+ if (ctx)
+ perf_counter_fork_ctx(ctx, fork_event);
+ rcu_read_unlock();
+}
+
+void perf_counter_fork(struct task_struct *task)
+{
+ struct perf_fork_event fork_event;
+
+ if (!atomic_read(&nr_comm_counters) &&
+ !atomic_read(&nr_mmap_counters))
+ return;
+
+ fork_event = (struct perf_fork_event){
+ .task = task,
+ .event = {
+ .header = {
+ .type = PERF_EVENT_FORK,
+ .size = sizeof(fork_event.event),
+ },
+ },
+ };
+
+ perf_counter_fork_event(&fork_event);
+}
+
+/*