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Commit b01c7466 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
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tracing/function-return-tracer: add a barrier to ensure return stack index is incremented in memory 



Impact: fix possible race condition in ftrace function return tracer

This fixes a possible race condition if index incrementation
is not immediately flushed in memory.

Thanks for Andi Kleen and Steven Rostedt for pointing out this issue
and give me this solution.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 98580960

arch/x86/kernel/ftrace.c

+1 −0
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ static int push_return_trace(unsigned long ret, unsigned long long time, 
		return -EBUSY;



	index = ++ti->curr_ret_stack;

	barrier();

	ti->ret_stack[index].ret = ret;

	ti->ret_stack[index].func = func;

	ti->ret_stack[index].calltime = time;