Re: [PATCH] rcu: Is it safe to enter an RCU read-side criticalsection?

[Steven Rostedt]

On Mon, 9 Sep 2013 09:22:15 -0700
"Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> wrote:


> However, the API we are arguing about is deep within the implementation.
> It is not at the level of rcu_read_lock().  It is something that should
> not have that many invocations -- after all, the things using it are
> binding themselves unusually close to RCU.
> 

Is it? I guess the question is, is dynamic ticks an extension of RCU,
or is it just using the RCU implementation as a convenience?

Also the OP patch is for function tracing, something not coupled by RCU
at all. Just a way to know if it is safe to call functions that use RCU
or not.

That can have "this_cpu()" by the way as a way to tell us that we must
disable preemption before hand. Which is what caused this thread to
start with, as it was suggested to combine rcu_is_cpu_idle() which
brought up why that function disables preemption.

-- Steve
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