54 lines
1.9 KiB
Diff
54 lines
1.9 KiB
Diff
From 4dae4850d39756ea45e54402e07ad63c8518c7ad Mon Sep 17 00:00:00 2001
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From: Steven Rostedt <rostedt@goodmis.org>
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Date: Thu, 29 Sep 2011 12:24:30 -0500
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Subject: [PATCH 049/352] tracing: Account for preempt off in
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preempt_schedule()
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The preempt_schedule() uses the preempt_disable_notrace() version
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because it can cause infinite recursion by the function tracer as
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the function tracer uses preempt_enable_notrace() which may call
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back into the preempt_schedule() code as the NEED_RESCHED is still
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set and the PREEMPT_ACTIVE has not been set yet.
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See commit: d1f74e20b5b064a130cd0743a256c2d3cfe84010 that made this
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change.
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The preemptoff and preemptirqsoff latency tracers require the first
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and last preempt count modifiers to enable tracing. But this skips
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the checks. Since we can not convert them back to the non notrace
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version, we can use the idle() hooks for the latency tracers here.
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That is, the start/stop_critical_timings() works well to manually
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start and stop the latency tracer for preempt off timings.
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Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Signed-off-by: Clark Williams <williams@redhat.com>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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kernel/sched/core.c | 9 +++++++++
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1 file changed, 9 insertions(+)
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diff --git a/kernel/sched/core.c b/kernel/sched/core.c
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index 986dec4..83f60bd 100644
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--- a/kernel/sched/core.c
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+++ b/kernel/sched/core.c
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@@ -3682,7 +3682,16 @@ asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
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* an infinite recursion.
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*/
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prev_ctx = exception_enter();
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+ /*
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+ * The add/subtract must not be traced by the function
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+ * tracer. But we still want to account for the
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+ * preempt off latency tracer. Since the _notrace versions
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+ * of add/subtract skip the accounting for latency tracer
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+ * we must force it manually.
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+ */
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+ start_critical_timings();
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__schedule(true);
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+ stop_critical_timings();
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exception_exit(prev_ctx);
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preempt_latency_stop(1);
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--
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2.7.4
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