linux-kernel - [PATCH 4/5] sched/tracing: Show stacktrace for wakeup tracers

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Date:   Tue,  1 Jan 2019 23:46:13 +0800
From:   Changbin Du <changbin.du@...il.com>
To:     rostedt@...dmis.org
Cc:     mingo@...hat.com, corbet@....net, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, Changbin Du <changbin.du@...il.com>
Subject: [PATCH 4/5] sched/tracing: Show stacktrace for wakeup tracers

This align the behavior of wakeup tracers with irqsoff latency tracer
that we record stacktrace at the beginning and end of waking up. The
stacktrace shows us what is happening in the kernel.

Signed-off-by: Changbin Du <changbin.du@...il.com>
---
 kernel/trace/trace_sched_wakeup.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index da5b6e012840..0ec136d408ff 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -474,6 +474,8 @@ probe_wakeup_sched_switch(void *ignore, bool preempt,
 	data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
 
 	__trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
+	/* Skip 2 functions to get to the task switch function */
+	__trace_stack(wakeup_trace, flags, 2, pc);
 	tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
 
 	T0 = data->preempt_timestamp;
@@ -593,6 +595,8 @@ probe_wakeup(void *ignore, struct task_struct *p)
 	 * it should be safe to use it here.
 	 */
 	__trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
+	/* Skip 2 functions to get to the task wakeup function */
+	__trace_stack(wakeup_trace, flags, 2, pc);
 
 out_locked:
 	arch_spin_unlock(&wakeup_lock);
-- 
2.17.1