From: "Jan Beulich" <JBeulich@suse.com>
To: Wei Wang <wei.w.wang@intel.com>
Cc: andrew.cooper3@citrix.com, xen-devel@lists.xen.org
Subject: Re: [PATCH v3 04/11] x86/intel_pstate: relocate the driver register function
Date: Thu, 18 Jun 2015 15:30:12 +0100 [thread overview]
Message-ID: <5582F2140200007800086ADF@mail.emea.novell.com> (raw)
In-Reply-To: <1434011230-17052-1-git-send-email-wei.w.wang@intel.com>
>>> On 11.06.15 at 10:27, <wei.w.wang@intel.com> wrote:
> Register the CPU hotplug notifier when the driver is
> registered, and move the driver register function to
> the cpufreq.c.
The first half of the sentence fails to say why. And I suppose if you
explained that (to yourself) you'd figure that the change is wrong (or
at least altering behavior in a way that needs more explanation to
be verifiably correct): The calls to cpufreq_register_driver() sit in
__initcall handlers, yet what you replace is a presmp_initcall. I.e. all
APs being brought up at boot time won't get the callback invoked for
them anymore.
I suppose you tested your series on a system where the new driver
will kick in. You of course also need to test the case where this isn't
the case - everything needs to continue to function there.
> --- a/xen/drivers/cpufreq/cpufreq.c
> +++ b/xen/drivers/cpufreq/cpufreq.c
> @@ -630,12 +630,21 @@ static struct notifier_block cpu_nfb = {
> .notifier_call = cpu_callback
> };
>
> -static int __init cpufreq_presmp_init(void)
> +int cpufreq_register_driver(struct cpufreq_driver *driver_data)
> {
> void *cpu = (void *)(long)smp_processor_id();
> cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
> + if (!driver_data || !driver_data->init
> + || !driver_data->verify || !driver_data->exit
> + || (!driver_data->target == !driver_data->setpolicy))
Do you really want/need to enforce this policy (target set if and only
if setpolicy is not set) here? And if that's to uniformly hold, the two
could be put into a union...
Also - coding style.
> --- a/xen/include/acpi/cpufreq/cpufreq.h
> +++ b/xen/include/acpi/cpufreq/cpufreq.h
> @@ -171,32 +171,8 @@ struct cpufreq_driver {
>
> extern struct cpufreq_driver *cpufreq_driver;
>
> -static __inline__
> -int cpufreq_register_driver(struct cpufreq_driver *driver_data)
> -{
> - if (!driver_data ||
> - !driver_data->init ||
> - !driver_data->exit ||
> - !driver_data->verify ||
> - !driver_data->target)
> - return -EINVAL;
> -
> - if (cpufreq_driver)
> - return -EBUSY;
> -
> - cpufreq_driver = driver_data;
> - return 0;
> -}
> -
> -static __inline__
> -int cpufreq_unregister_driver(struct cpufreq_driver *driver)
> -{
> - if (!cpufreq_driver || (driver != cpufreq_driver))
> - return -EINVAL;
> -
> - cpufreq_driver = NULL;
> - return 0;
> -}
> +extern int cpufreq_register_driver(struct cpufreq_driver *driver_data);
> +extern int cpufreq_unregister_driver(struct cpufreq_driver *driver);
What's this declaration good for when there's no implementation?
Jan
next prev parent reply other threads:[~2015-06-18 14:30 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-11 8:27 [PATCH v3 04/11] x86/intel_pstate: relocate the driver register function Wei Wang
2015-06-18 14:30 ` Jan Beulich [this message]
2015-06-23 3:40 ` Wang, Wei W
2015-06-23 7:31 ` Jan Beulich
2015-06-23 8:01 ` Wang, Wei W
2015-06-23 8:11 ` Jan Beulich
2015-06-23 8:24 ` Wang, Wei W
2015-06-23 8:37 ` Jan Beulich
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