On Fri, Mar 04, 2016 at 03:13:06PM +1100, Stephen Rothwell wrote:
> Hi Paul,
>
> Today's linux-next merge of the rcu tree got a conflict in:
>
> kernel/rcu/tree.c
>
> between commit:
>
> 27d50c7eeb0f ("rcu: Make CPU_DYING_IDLE an explicit call")
>
> from the tip tree and commit:
>
> 67c583a7de34 ("RCU: Privatize rcu_node::lock")
>
> from the rcu tree.
>
> I fixed it up (see below) and can carry the fix as necessary (no action
> is required).
Thank you! I have applied this resolution to -rcu and am testing it.
Thanx, Paul
> --
> Cheers,
> Stephen Rothwell
>
> diff --cc kernel/rcu/tree.c
> index 0bbc1497a0e4,55cea189783f..000000000000
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@@ -4227,43 -4246,6 +4224,43 @@@ static void rcu_prepare_cpu(int cpu
> rcu_init_percpu_data(cpu, rsp);
> }
>
> +#ifdef CONFIG_HOTPLUG_CPU
> +/*
> + * The CPU is exiting the idle loop into the arch_cpu_idle_dead()
> + * function. We now remove it from the rcu_node tree's ->qsmaskinit
> + * bit masks.
> + */
> +static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
> +{
> + unsigned long flags;
> + unsigned long mask;
> + struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
> + struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */
> +
> + if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
> + return;
> +
> + /* Remove outgoing CPU from mask in the leaf rcu_node structure. */
> + mask = rdp->grpmask;
> + raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */
> + rnp->qsmaskinitnext &= ~mask;
> - raw_spin_unlock_irqrestore(&rnp->lock, flags);
> ++ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
> +}
> +
> +void rcu_report_dead(unsigned int cpu)
> +{
> + struct rcu_state *rsp;
> +
> + /* QS for any half-done expedited RCU-sched GP. */
> + preempt_disable();
> + rcu_report_exp_rdp(&rcu_sched_state,
> + this_cpu_ptr(rcu_sched_state.rda), true);
> + preempt_enable();
> + for_each_rcu_flavor(rsp)
> + rcu_cleanup_dying_idle_cpu(cpu, rsp);
> +}
> +#endif
> +
> /*
> * Handle CPU online/offline notification events.
> */
>
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