Re: [PATCH] kernel/trace: Use rcu_assign_pointer() for setting fgraph hash pointers

[Joel Fernandes]

On Wed, Feb 05, 2020 at 05:25:29PM -0500, Steven Rostedt wrote:
> On Wed,  5 Feb 2020 17:18:08 -0500
> "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx> wrote:
> 
> > set_ftrace_early_graph() sets pointers without any explicit
> > release-barriers. Let us use rcu_assign_pointer() to ensure the same.
> > 
> > Note that ftrace_early_graph() calls ftrace_graph_set_hash() which does
> > do mutex_unlock(&ftrace_lock); which should imply a release barrier.
> > However it is better to not depend on it and just use
> > rcu_assign_pointer() which should also avoid sparse errors in the
> > future.
> 
> This is going to have to wait for the next merge window, as I'm already
> *very* late, and I've pushed the limit to what I will add at this time
> frame.

I understand, no problem. I will resend it next merge window.

thanks,

 - Joel

> 
> -- Steve
>