On Fri, May 12, 2017 at 01:15:45PM -0400, Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)" <rost...@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) <rost...@goodmis.org>
Assuming that you never get to __trace_stack() if in an NMI handler,
this looks good to me!
In contrast, if if __trace_stack() ever is called from an NMI handler,
invoking rcu_irq_enter() can be fatal.
Thanx, Paul
> ---
> 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
>
>
