linux-kernel - [RFC] trace_irqsoff: remove redundant reset per-CPU buff

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Message-Id: <1445278226-16187-1-git-send-email-0x7f454c46@gmail.com>
Date:	Mon, 19 Oct 2015 21:10:26 +0300
From:	Dmitry Safonov <0x7f454c46@...il.com>
To:	rostedt@...dmis.org, mingo@...hat.com
Cc:	linux-kernel@...r.kernel.org, Dmitry Safonov <0x7f454c46@...il.com>
Subject: [RFC] trace_irqsoff: remove redundant reset per-CPU buff

  There is no reason to do it twice: from commit b6f11df26fdc28
("trace: Call tracing_reset_online_cpus before tracer->init()")
resetting of per-CPU buffers done before tracer->init() call.

tracer->init() calls {irqs,preempt,preemptirqs}off_tracer_init() and it
calls __irqsoff_tracer_init(), which resets per-CPU ringbuffer second
time.
It's slowpath, but anyway.

Signed-off-by: Dmitry Safonov <0x7f454c46@...il.com>
---
 kernel/trace/trace_irqsoff.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 8523ea345f2b1a..4ebcb8bfaced24 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -612,7 +612,6 @@ static int __irqsoff_tracer_init(struct trace_array *tr)
 	irqsoff_trace = tr;
 	/* make sure that the tracer is visible */
 	smp_wmb();
-	tracing_reset_online_cpus(&tr->trace_buffer);
 
 	ftrace_init_array_ops(tr, irqsoff_tracer_call);
 
-- 
2.6.1

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