Messages in this thread Patch in this message | | | Date | Wed, 28 Jul 2021 14:23:05 -0400 (EDT) | From | Mathieu Desnoyers <> | Subject | Re: [PATCH v2 rcu 04/18] rcu: Weaken ->dynticks accesses and updates |
| |
----- On Jul 28, 2021, at 1:37 PM, paulmck paulmck@kernel.org wrote: [...] > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 42a0032dd99f7..c87b3a271d65b 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -251,6 +251,15 @@ void rcu_softirq_qs(void) > rcu_tasks_qs(current, false); > } > > +/* > + * Increment the current CPU's rcu_data structure's ->dynticks field > + * with ordering. Return the new value. > + */ > +static noinstr unsigned long rcu_dynticks_inc(int incby) > +{ > + return arch_atomic_add_return(incby, this_cpu_ptr(&rcu_data.dynticks)); > +} > +
[...]
> @@ -308,7 +317,7 @@ static void rcu_dynticks_eqs_online(void) > > if (atomic_read(&rdp->dynticks) & 0x1) > return;
Can the thread be migrated at this point ? If yes, then the check and the increment may happen on different cpu's rdps. Is that OK ?
> - atomic_inc(&rdp->dynticks); > + rcu_dynticks_inc(1); > }
Thanks,
Mathieu
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
| |