workqueue: add worker function to workqueue_execute_end tracepoint

It's surprising that workqueue_execute_end includes only the work when
its counterpart workqueue_execute_start has both the work and the worker
function.

You can't set a tracing filter or trigger based on the function, and
postprocessing scripts interested in specific functions are harder to
write since they have to remember the work from _start and match it up
with the same field in _end.

Add the function name, taking care to use the copy stashed in the
worker since the work is no longer safe to touch.

Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index cfc9235..4bdfa27 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2266,7 +2266,7 @@ __acquires(&pool->lock)
 	 * While we must be careful to not use "work" after this, the trace
 	 * point will only record its address.
 	 */
-	trace_workqueue_execute_end(work);
+	trace_workqueue_execute_end(work, worker->current_func);
 	lock_map_release(&lockdep_map);
 	lock_map_release(&pwq->wq->lockdep_map);