[RFC][PATCH 1/5] tracing: Make sure RCU is watching before calling a stack trace

[Steven Rostedt <rostedt@goodmis.org>]

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From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

As stack tracing now requires "rcu watching", force RCU to be watching when
recording a stack trace.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c4536c449021..a4208cebb42b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2568,7 +2568,12 @@ static inline void ftrace_trace_stack(struct trace_array *tr,
 void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
 		   int pc)
 {
+	if (unlikely(rcu_irq_enter_disabled()))
+		return;
+
+	rcu_irq_enter();
 	__ftrace_trace_stack(tr->trace_buffer.buffer, flags, skip, pc, NULL);
+	rcu_irq_exit();
 }
 
 /**
-- 
2.10.2