On Mon, Jun 30, 2014 at 04:50:44PM +0800, Yan, Zheng wrote:
>  void intel_pmu_lbr_enable(struct perf_event *event)
>  {
>  	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
> +	struct x86_perf_task_context *task_ctx;

This won't compile; you've forgotten to declare that type.