Re: [PATCH v2] tracing: Make sure RCU is watching before calling a stack trace

[Miroslav Benes]

On Thu, 18 May 2017, Steven Rostedt wrote:

> 
> From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
> 
> As stack tracing now requires "rcu watching", force RCU to be watching when
> recording a stack trace.
> 
> Link: http://lkml.kernel.org/r/20170512172449.879684501@xxxxxxxxxxx
> 
> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> ---
> 
> Changes since v1:
> 
>    My testing discovered that the stack trace can be called with
>    interrupts enabled, which is a no no to have when calling
>    rcu_irq_enter(). When interrupts are enabled, as with being in an
>    NMI, RCU will also be watching.

Would rcu_irq_enter_irqson() help then? This is what Petr used in a live 
patching handler.

Your solution works too, of course. Just asking if I am not missing 
something.

Thanks,
Miroslav