54 lines
1.9 KiB
Diff
54 lines
1.9 KiB
Diff
From 76d71ed3285a58cffa740ed2ab4c4de0c244aedd Mon Sep 17 00:00:00 2001
|
|
From: Steven Rostedt <rostedt@goodmis.org>
|
|
Date: Thu, 29 Sep 2011 12:24:30 -0500
|
|
Subject: [PATCH 050/365] tracing: Account for preempt off in
|
|
preempt_schedule()
|
|
|
|
The preempt_schedule() uses the preempt_disable_notrace() version
|
|
because it can cause infinite recursion by the function tracer as
|
|
the function tracer uses preempt_enable_notrace() which may call
|
|
back into the preempt_schedule() code as the NEED_RESCHED is still
|
|
set and the PREEMPT_ACTIVE has not been set yet.
|
|
|
|
See commit: d1f74e20b5b064a130cd0743a256c2d3cfe84010 that made this
|
|
change.
|
|
|
|
The preemptoff and preemptirqsoff latency tracers require the first
|
|
and last preempt count modifiers to enable tracing. But this skips
|
|
the checks. Since we can not convert them back to the non notrace
|
|
version, we can use the idle() hooks for the latency tracers here.
|
|
That is, the start/stop_critical_timings() works well to manually
|
|
start and stop the latency tracer for preempt off timings.
|
|
|
|
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
Signed-off-by: Clark Williams <williams@redhat.com>
|
|
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
|
---
|
|
kernel/sched/core.c | 9 +++++++++
|
|
1 file changed, 9 insertions(+)
|
|
|
|
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
|
|
index 4a97a2562ca2..964438bebe44 100644
|
|
--- a/kernel/sched/core.c
|
|
+++ b/kernel/sched/core.c
|
|
@@ -3705,7 +3705,16 @@ asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
|
|
* an infinite recursion.
|
|
*/
|
|
prev_ctx = exception_enter();
|
|
+ /*
|
|
+ * The add/subtract must not be traced by the function
|
|
+ * tracer. But we still want to account for the
|
|
+ * preempt off latency tracer. Since the _notrace versions
|
|
+ * of add/subtract skip the accounting for latency tracer
|
|
+ * we must force it manually.
|
|
+ */
|
|
+ start_critical_timings();
|
|
__schedule(true);
|
|
+ stop_critical_timings();
|
|
exception_exit(prev_ctx);
|
|
|
|
preempt_latency_stop(1);
|
|
--
|
|
2.28.0
|
|
|