Re: [PATCH tip/core/rcu 3/3] srcu: Make early-boot call_srcu() reuse workqueue lists

Steven Rostedt
2018-08-30T18:36:24Z

On Thu, 30 Aug 2018 10:37:42 -0700
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:

> > > But still triggered the following:
> > >
> > > WARNING: CPU: 0 PID: 0 at /work/git/linux-trace.git/kernel/rcu/srcutree.c:242 check_init_srcu_struct+0x85/0x90
> >
> > Gah!!! I needed to have removed that WARN_ON_ONCE(), didn't I?
> > In fact, I should have removed that once I started using workqueues,
> > quite some time back.
>
> As in the below patch.
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
> index 75571ff09c62..a8846ed7f352 100644
> --- a/kernel/rcu/srcutree.c
> +++ b/kernel/rcu/srcutree.c
> @@ -239,7 +239,6 @@ static void check_init_srcu_struct(struct srcu_struct *sp)
> {
> unsigned long flags;
>
> - WARN_ON_ONCE(rcu_scheduler_active == RCU_SCHEDULER_INIT);

Well it boots without warning ;-)

Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve

> /* The smp_load_acquire() pairs with the smp_store_release(). */
> if (!rcu_seq_state(smp_load_acquire(&sp->srcu_gp_seq_needed))) /*^^^*/
> return; /* Already initialized. */