workqueue: add queue_work and activate_work trace points

These two tracepoints allow tracking when and how a work is queued and
activated.  This patch is based on Frederic's patch to add queue_work
trace point.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>

2 files changed, 56 insertions, 0 deletions

diff --git a/include/trace/events/workqueue.h b/include/trace/events/workqueue.h
index ec9d7244eb9f..7d497291c85d 100644
--- a/include/trace/events/workqueue.h
+++ b/include/trace/events/workqueue.h
@@ -25,6 +25,59 @@ DECLARE_EVENT_CLASS(workqueue_work,
 );
 
 /**
+ * workqueue_queue_work - called when a work gets queued
+ * @req_cpu:    the requested cpu
+ * @cwq:        pointer to struct cpu_workqueue_struct
+ * @work:       pointer to struct work_struct
+ *
+ * This event occurs when a work is queued immediately or once a
+ * delayed work is actually queued on a workqueue (ie: once the delay
+ * has been reached).
+ */
+TRACE_EVENT(workqueue_queue_work,
+
+        TP_PROTO(unsigned int req_cpu, struct cpu_workqueue_struct *cwq,
+                 struct work_struct *work),
+
+        TP_ARGS(req_cpu, cwq, work),
+
+        TP_STRUCT__entry(
+                __field( void *,        work    )
+                __field( void *,        function)
+                __field( void *,        workqueue)
+                __field( unsigned int,  req_cpu )
+                __field( unsigned int,  cpu     )
+        ),
+
+        TP_fast_assign(
+                __entry->work           = work;
+                __entry->function       = work->func;
+                __entry->workqueue      = cwq->wq;
+                __entry->req_cpu        = req_cpu;
+                __entry->cpu            = cwq->gcwq->cpu;
+        ),
+
+        TP_printk("work struct=%p function=%pf workqueue=%p req_cpu=%u cpu=%u",
+                  __entry->work, __entry->function, __entry->workqueue,
+                  __entry->req_cpu, __entry->cpu)
+);
+
+/**
+ * workqueue_activate_work - called when a work gets activated
+ * @work:       pointer to struct work_struct
+ *
+ * This event occurs when a queued work is put on the active queue,
+ * which happens immediately after queueing unless @max_active limit
+ * is reached.
+ */
+DEFINE_EVENT(workqueue_work, workqueue_activate_work,
+
+        TP_PROTO(struct work_struct *work),
+
+        TP_ARGS(work)
+);
+
+/**
  * workqueue_execute_start - called immediately before the workqueue callback
  * @work:       pointer to struct work_struct
  *
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 026f778e879b..cb2ccfbed0c6 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -997,6 +997,7 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
 
         /* gcwq determined, get cwq and queue */
         cwq = get_cwq(gcwq->cpu, wq);
+        trace_workqueue_queue_work(cpu, cwq, work);
 
         BUG_ON(!list_empty(&work->entry));
 
@@ -1004,6 +1005,7 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
         work_flags = work_color_to_flags(cwq->work_color);
 
         if (likely(cwq->nr_active < cwq->max_active)) {
+                trace_workqueue_activate_work(work);
                 cwq->nr_active++;
                 worklist = gcwq_determine_ins_pos(gcwq, cwq);
         } else {
@@ -1679,6 +1681,7 @@ static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
                                                     struct work_struct, entry);
         struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq);
 
+        trace_workqueue_activate_work(work);
         move_linked_works(work, pos, NULL);
         __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
         cwq->nr_active++;