Messages in this thread | | | Date | Thu, 5 Oct 2017 14:12:50 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH tip/core/rcu 1/3] membarrier: Provide register expedited private command |
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On Wed, Oct 04, 2017 at 02:37:53PM -0700, Paul E. McKenney wrote: > diff --git a/arch/powerpc/kernel/membarrier.c b/arch/powerpc/kernel/membarrier.c > new file mode 100644 > index 000000000000..b0d79a5f5981 > --- /dev/null > +++ b/arch/powerpc/kernel/membarrier.c > @@ -0,0 +1,45 @@
> +void membarrier_arch_register_private_expedited(struct task_struct *p) > +{ > + struct task_struct *t; > + > + if (get_nr_threads(p) == 1) { > + set_thread_flag(TIF_MEMBARRIER_PRIVATE_EXPEDITED); > + return; > + } > + /* > + * Coherence of TIF_MEMBARRIER_PRIVATE_EXPEDITED against thread > + * fork is protected by siglock. > + */ > + spin_lock(&p->sighand->siglock); > + for_each_thread(p, t) > + set_ti_thread_flag(task_thread_info(t), > + TIF_MEMBARRIER_PRIVATE_EXPEDITED);
I'm not sure this works correctly vs CLONE_VM without CLONE_THREAD.
> + spin_unlock(&p->sighand->siglock); > + /* > + * Ensure all future scheduler executions will observe the new > + * thread flag state for this process. > + */ > + synchronize_sched();
This relies on the flag being read inside rq->lock, right?
> +}
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