tracing: Add missing forward declaration

Without this forward declaration compile may fail if this header is
included only for registering other probe event without struct
pool_workqueue.

Link: http://lkml.kernel.org/r/[email protected]
Reviewed-by: Todd Poynor <[email protected]>
Signed-off-by: Ahbong Chang <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

diff --git a/include/trace/events/workqueue.h b/include/trace/events/workqueue.h
index 2f057a494d93180dd0e3543b8c43ff7c4de5f629..9a761bc6a251a45358ef6d1a1b7ae3e678333561 100644 (file)
--- a/include/trace/events/workqueue.h
+++ b/include/trace/events/workqueue.h
@@ -25,6 +25,8 @@ DECLARE_EVENT_CLASS(workqueue_work,
        TP_printk("work struct %p", __entry->work)
 );
 
+struct pool_workqueue;
+
 /**
  * workqueue_queue_work - called when a work gets queued
  * @req_cpu:   the requested cpu