On Thu, Jul 04, 2019 at 10:16:47AM +0100, Joao Martins wrote:
> On 7/4/19 12:51 AM, Marcelo Tosatti wrote:
> > +++ linux-2.6-newcpuidle.git/drivers/cpuidle/cpuidle-haltpoll.c
> > @@ -0,0 +1,69 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * cpuidle driver for haltpoll governor.
> > + *
> > + * Copyright 2019 Red Hat, Inc. and/or its affiliates.
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2. See
> > + * the COPYING file in the top-level directory.
> > + *
> > + * Authors: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> > + */
> > +
> > +#include <linux/init.h>
> > +#include <linux/cpuidle.h>
> > +#include <linux/module.h>
> > +#include <linux/sched/idle.h>
> > +#include <linux/kvm_para.h>
> > +
> > +static int default_enter_idle(struct cpuidle_device *dev,
> > + struct cpuidle_driver *drv, int index)
> > +{
> > + if (current_clr_polling_and_test()) {
> > + local_irq_enable();
> > + return index;
> > + }
> > + default_idle();
> > + return index;
> > +}
> > +
> > +static struct cpuidle_driver haltpoll_driver = {
> > + .name = "haltpoll",
> > + .owner = THIS_MODULE,
> > + .states = {
> > + { /* entry 0 is for polling */ },
> > + {
> > + .enter = default_enter_idle,
> > + .exit_latency = 1,
> > + .target_residency = 1,
> > + .power_usage = -1,
> > + .name = "haltpoll idle",
> > + .desc = "default architecture idle",
> > + },
> > + },
> > + .safe_state_index = 0,
> > + .state_count = 2,
> > +};
> > +
> > +static int __init haltpoll_init(void)
> > +{
> > + struct cpuidle_driver *drv = &haltpoll_driver;
> > +
> > + cpuidle_poll_state_init(drv);
> > +
> > + if (!kvm_para_available())
> > + return 0;
> > +
>
> Isn't this meant to return -ENODEV value if the module is meant to not load?
Well, the cpuidle drivers return an error only if registration fails.
> Also this check should probably be placed before initializing the poll state,
> provided poll state isn't used anyways if you're not a kvm guest.
Poll state init is only local variable initialization, it does not
have any external effect.
