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Subject[PATCH 1/2] workqueue: add worker function to workqueue_execute_end tracepoint
Date
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
---
include/trace/events/workqueue.h | 19 ++++++++++++++++---
kernel/workqueue.c | 2 +-
2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/include/trace/events/workqueue.h b/include/trace/events/workqueue.h
index e172549283be..bdfc53e7f82f 100644
--- a/include/trace/events/workqueue.h
+++ b/include/trace/events/workqueue.h
@@ -108,14 +108,27 @@ TRACE_EVENT(workqueue_execute_start,
/**
* workqueue_execute_end - called immediately after the workqueue callback
* @work: pointer to struct work_struct
+ * @function: pointer to worker function
*
* Allows to track workqueue execution.
*/
-DEFINE_EVENT(workqueue_work, workqueue_execute_end,
+TRACE_EVENT(workqueue_execute_end,

- TP_PROTO(struct work_struct *work),
+ TP_PROTO(struct work_struct *work, work_func_t function),

- TP_ARGS(work)
+ TP_ARGS(work, function),
+
+ TP_STRUCT__entry(
+ __field( void *, work )
+ __field( void *, function)
+ ),
+
+ TP_fast_assign(
+ __entry->work = work;
+ __entry->function = function;
+ ),
+
+ TP_printk("work struct %p: function %ps", __entry->work, __entry->function)
);

#endif /* _TRACE_WORKQUEUE_H */
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index cfc923558e04..4bdfa270a37b 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);

--
2.24.1
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