On Mon, Jul 18, 2016 at 03:26:28PM +1000, Stephen Rothwell wrote:
> Hi Paul,
>
> Today's linux-next merge of the rcu tree got a conflict in:
>
> kernel/rcu/tree.c
>
> between commit:
>
> 4df8374254ea ("rcu: Convert rcutree to hotplug state machine")
>
> from the tip tree and commit:
>
> 2a84cde733b0 ("rcu: Exact CPU-online tracking for RCU")
>
> from the rcu tree.
>
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging. You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
Ah, that is in -tip now? Easier to test, then!
Thank you, the patch looks good at first glance, but will beat it up
a bit.
Thanx, Paul
> --
> Cheers,
> Stephen Rothwell
>
> diff --cc kernel/rcu/tree.c
> index e5164deb51e1,5663d1e899d3..000000000000
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@@ -3812,54 -3809,34 +3809,80 @@@ int rcutree_prepare_cpu(unsigned int cp
>
> for_each_rcu_flavor(rsp)
> rcu_init_percpu_data(cpu, rsp);
> +
> + rcu_prepare_kthreads(cpu);
> + rcu_spawn_all_nocb_kthreads(cpu);
> +
> + return 0;
> +}
> +
> +static void rcutree_affinity_setting(unsigned int cpu, int outgoing)
> +{
> + struct rcu_data *rdp = per_cpu_ptr(rcu_state_p->rda, cpu);
> +
> + rcu_boost_kthread_setaffinity(rdp->mynode, outgoing);
> +}
> +
> +int rcutree_online_cpu(unsigned int cpu)
> +{
> + sync_sched_exp_online_cleanup(cpu);
> + rcutree_affinity_setting(cpu, -1);
> + return 0;
> +}
> +
> +int rcutree_offline_cpu(unsigned int cpu)
> +{
> + rcutree_affinity_setting(cpu, cpu);
> + return 0;
> +}
> +
> +
> +int rcutree_dying_cpu(unsigned int cpu)
> +{
> + struct rcu_state *rsp;
> +
> + for_each_rcu_flavor(rsp)
> + rcu_cleanup_dying_cpu(rsp);
> + return 0;
> +}
> +
> +int rcutree_dead_cpu(unsigned int cpu)
> +{
> + struct rcu_state *rsp;
> +
> + for_each_rcu_flavor(rsp) {
> + rcu_cleanup_dead_cpu(cpu, rsp);
> + do_nocb_deferred_wakeup(per_cpu_ptr(rsp->rda, cpu));
> + }
> + return 0;
> }
>
> + /*
> + * Mark the specified CPU as being online so that subsequent grace periods
> + * (both expedited and normal) will wait on it. Note that this means that
> + * incoming CPUs are not allowed to use RCU read-side critical sections
> + * until this function is called. Failing to observe this restriction
> + * will result in lockdep splats.
> + */
> + void rcu_cpu_starting(unsigned int cpu)
> + {
> + unsigned long flags;
> + unsigned long mask;
> + struct rcu_data *rdp;
> + struct rcu_node *rnp;
> + struct rcu_state *rsp;
> +
> + for_each_rcu_flavor(rsp) {
> + rdp = this_cpu_ptr(rsp->rda);
> + rnp = rdp->mynode;
> + mask = rdp->grpmask;
> + raw_spin_lock_irqsave_rcu_node(rnp, flags);
> + rnp->qsmaskinitnext |= mask;
> + rnp->expmaskinitnext |= mask;
> + raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
> + }
> + }
> +
> #ifdef CONFIG_HOTPLUG_CPU
> /*
> * The CPU is exiting the idle loop into the arch_cpu_idle_dead()
> @@@ -4208,9 -4231,12 +4231,11 @@@ void __init rcu_init(void
> * this is called early in boot, before either interrupts
> * or the scheduler are operational.
> */
> - cpu_notifier(rcu_cpu_notify, 0);
> pm_notifier(rcu_pm_notify, 0);
> - for_each_online_cpu(cpu)
> + for_each_online_cpu(cpu) {
> - rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
> + rcutree_prepare_cpu(cpu);
> + rcu_cpu_starting(cpu);
> + }
> }
>
> #include "tree_exp.h"
>
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