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Subject[PATCH 07/19] workqueue_tracepoint: introduce workqueue_handler_exit tracepoint and rename workqueue_execution to workqueue_handler_entry
Date
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

Entry/exit handler pair is a useful common tracepoint technique.
It can mesure the consumption time of the handler.

Then, also add a workqueue handler_exit tracepoint and rename "execution"
to "handler_entry".

Changelog:
v1: From KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
introduce workqueue_handler_exit tracepoint
rename workqueue_execution to workqueue_handler_entry
v2: From Zhao Lei <zhaolei@cn.fujitsu.com>
Declare workqueue_handler_exit's work argument as void *, because
we can't safely access its contents (might be freed).
Add workqueue_handler_entry's &work_struct back to TP_printk,
to let it used as a'key' for workqueue_handler_entry/exit pair.

[ Impact: prepare to trace the time execution of worklets ]

Signed-off-by: KOSAKI Motohiro <kosaki@jp.fujitsu.com>
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>,
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
include/trace/events/workqueue.h | 36 ++++++++++++++++++++++++++++++------
kernel/trace/trace_workqueue.c | 10 +++++-----
kernel/workqueue.c | 3 ++-
3 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/include/trace/events/workqueue.h b/include/trace/events/workqueue.h
index 035f1bf..36f4939 100644
--- a/include/trace/events/workqueue.h
+++ b/include/trace/events/workqueue.h
@@ -30,26 +30,50 @@ TRACE_EVENT(workqueue_insertion,
__entry->thread_pid, __entry->func)
);

-TRACE_EVENT(workqueue_execution,
+TRACE_EVENT(workqueue_handler_entry,

TP_PROTO(struct task_struct *wq_thread, struct work_struct *work),

TP_ARGS(wq_thread, work),

TP_STRUCT__entry(
- __array(char, thread_comm, TASK_COMM_LEN)
- __field(pid_t, thread_pid)
- __field(work_func_t, func)
+ __array(char, thread_comm, TASK_COMM_LEN)
+ __field(pid_t, thread_pid)
+ __field(struct work_struct *, work)
+ __field(work_func_t, func)
),

TP_fast_assign(
memcpy(__entry->thread_comm, wq_thread->comm, TASK_COMM_LEN);
__entry->thread_pid = wq_thread->pid;
+ __entry->work = work;
__entry->func = work->func;
),

- TP_printk("thread=%s:%d func=%pF", __entry->thread_comm,
- __entry->thread_pid, __entry->func)
+ TP_printk("thread=%s:%d work=%p func=%pF", __entry->thread_comm,
+ __entry->thread_pid, __entry->work, __entry->func)
+);
+
+/* Declare work as void *, because we can't use work->... in after f(work) */
+TRACE_EVENT(workqueue_handler_exit,
+ TP_PROTO(struct task_struct *wq_thread, void *work),
+
+ TP_ARGS(wq_thread, work),
+
+ TP_STRUCT__entry(
+ __array(char, thread_comm, TASK_COMM_LEN)
+ __field(pid_t, thread_pid)
+ __field(void *, work)
+ ),
+
+ TP_fast_assign(
+ memcpy(__entry->thread_comm, wq_thread->comm, TASK_COMM_LEN);
+ __entry->thread_pid = wq_thread->pid;
+ __entry->work = work;
+ ),
+
+ TP_printk("thread=%s:%d work=%p", __entry->thread_comm,
+ __entry->thread_pid, __entry->work)
);

/* Trace the creation of one workqueue thread on a cpu */
diff --git a/kernel/trace/trace_workqueue.c b/kernel/trace/trace_workqueue.c
index 7c632b9..8d26db6 100644
--- a/kernel/trace/trace_workqueue.c
+++ b/kernel/trace/trace_workqueue.c
@@ -109,7 +109,7 @@ found:

/* Execution of a work */
static void
-probe_workqueue_execution(struct task_struct *wq_thread,
+probe_workqueue_entry(struct task_struct *wq_thread,
struct work_struct *work)
{
int cpu = cpumask_first(&wq_thread->cpus_allowed);
@@ -373,13 +373,13 @@ int __init trace_workqueue_early_init(void)
if (ret)
goto out;

- ret = register_trace_workqueue_execution(probe_workqueue_execution);
+ ret = register_trace_workqueue_handler_entry(probe_workqueue_entry);
if (ret)
goto no_insertion;

ret = register_trace_workqueue_creation(probe_workqueue_creation);
if (ret)
- goto no_execution;
+ goto no_handler_entry;

ret = register_trace_workqueue_destruction(probe_workqueue_destruction);
if (ret)
@@ -394,8 +394,8 @@ int __init trace_workqueue_early_init(void)

no_creation:
unregister_trace_workqueue_creation(probe_workqueue_creation);
-no_execution:
- unregister_trace_workqueue_execution(probe_workqueue_execution);
+no_handler_entry:
+ unregister_trace_workqueue_handler_entry(probe_workqueue_entry);
no_insertion:
unregister_trace_workqueue_insertion(probe_workqueue_insertion);
out:
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 0668795..fbcdfa2 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -279,7 +279,6 @@ static void run_workqueue(struct cpu_workqueue_struct *cwq)
*/
struct lockdep_map lockdep_map = work->lockdep_map;
#endif
- trace_workqueue_execution(cwq->thread, work);
cwq->current_work = work;
list_del_init(cwq->worklist.next);
spin_unlock_irq(&cwq->lock);
@@ -288,7 +287,9 @@ static void run_workqueue(struct cpu_workqueue_struct *cwq)
work_clear_pending(work);
lock_map_acquire(&cwq->wq->lockdep_map);
lock_map_acquire(&lockdep_map);
+ trace_workqueue_handler_entry(cwq->thread, work);
f(work);
+ trace_workqueue_handler_exit(cwq->thread, work);
lock_map_release(&lockdep_map);
lock_map_release(&cwq->wq->lockdep_map);

--
1.6.2.3


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