From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Russell King (Oracle)" <linux@armlinux.org.uk>,
linux-pm@vger.kernel.org, loongarch@lists.linux.dev,
linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
x86@kernel.org, Miguel Luis <miguel.luis@oracle.com>,
James Morse <james.morse@arm.com>,
Salil Mehta <salil.mehta@huawei.com>,
Jean-Philippe Brucker <jean-philippe@linaro.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linuxarm@huawei.com, justin.he@arm.com, jianyong.wu@arm.com
Subject: Re: [PATCH v5 03/18] ACPI: processor: Register deferred CPUs from acpi_processor_get_info()
Date: Tue, 16 Apr 2024 21:02:02 +0200 [thread overview]
Message-ID: <CAJZ5v0iK61_ihUZX_tXoSGdhpYDWFhEBbEuFf6WFiiD0QSeTDg@mail.gmail.com> (raw)
In-Reply-To: <20240416184116.0000513c@huawei.com>
On Tue, Apr 16, 2024 at 7:41 PM Jonathan Cameron
<Jonathan.Cameron@huawei.com> wrote:
>
> On Mon, 15 Apr 2024 13:23:51 +0100
> Jonathan Cameron <Jonathan.Cameron@huawei.com> wrote:
>
> > On Mon, 15 Apr 2024 14:04:26 +0200
> > "Rafael J. Wysocki" <rafael@kernel.org> wrote:
[cut]
> > > > I'm still very much stuck on the hotadd_init flag however, so any suggestions
> > > > on that would be very welcome!
> > >
> > > I need to do some investigation which will take some time I suppose.
> >
> > I'll do so as well once I've gotten the rest sorted out. That whole
> > structure seems overly complex and liable to race, though maybe sufficient
> > locking happens to be held that it's not a problem.
>
> Back to this a (maybe) last outstanding problem.
>
> Superficially I think we might be able to get around this by always
> doing the setup in the initial online. In brief that looks something the
> below code. Relying on the cpu hotplug callback registration calling
> the acpi_soft_cpu_online for all instances that are already online.
>
> Very lightly tested on arm64 and x86 with cold and hotplugged CPUs.
> However this is all in emulation and I don't have access to any significant
> x86 test farms :( So help will be needed if it's not immediately obvious why
> we can't do this.
AFAICS, this should work. At least I don't see why it wouldn't.
> Of course, I'm open to other suggestions!
>
> For now I'll put a tidied version of this one is as an RFC with the rest of v6.
>
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index 06e718b650e5..97ca53b516d0 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -340,7 +340,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
> */
> per_cpu(processor_device_array, pr->id) = device;
> per_cpu(processors, pr->id) = pr;
> -
> + pr->flags.need_hotplug_init = 1;
> /*
> * Extra Processor objects may be enumerated on MP systems with
> * less than the max # of CPUs. They should be ignored _iff
> diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
> index 67db60eda370..930f911fc435 100644
> --- a/drivers/acpi/processor_driver.c
> +++ b/drivers/acpi/processor_driver.c
> @@ -206,7 +206,7 @@ static int acpi_processor_start(struct device *dev)
>
> /* Protect against concurrent CPU hotplug operations */
> cpu_hotplug_disable();
> - ret = __acpi_processor_start(device);
> + // ret = __acpi_processor_start(device);
> cpu_hotplug_enable();
> return ret;
> }
So it looks like acpi_processor_start() is not necessary any more, is it?
> @@ -279,7 +279,7 @@ static int __init acpi_processor_driver_init(void)
> if (result < 0)
> return result;
>
> - result = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
> + result = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
> "acpi/cpu-drv:online",
> acpi_soft_cpu_online, NULL);
> if (result < 0)
> >
> > Jonathan
Thanks!
next prev parent reply other threads:[~2024-04-16 19:02 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-12 14:37 [PATCH v5 00/18] ACPI/arm64: add support for virtual cpu hotplug Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 01/18] cpu: Do not warn on arch_register_cpu() returning -EPROBE_DEFER Jonathan Cameron
2024-04-12 17:42 ` Rafael J. Wysocki
2024-04-22 3:53 ` Gavin Shan
2024-04-12 14:37 ` [PATCH v5 02/18] ACPI: processor: Set the ACPI_COMPANION for the struct cpu instance Jonathan Cameron
2024-04-12 18:10 ` Rafael J. Wysocki
2024-04-15 15:48 ` Jonathan Cameron
2024-04-15 16:16 ` Rafael J. Wysocki
2024-04-15 16:19 ` Rafael J. Wysocki
2024-04-15 16:50 ` Jonathan Cameron
2024-04-15 17:34 ` Jonathan Cameron
2024-04-15 17:41 ` Rafael J. Wysocki
2024-04-16 17:35 ` Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 03/18] ACPI: processor: Register deferred CPUs from acpi_processor_get_info() Jonathan Cameron
2024-04-12 18:30 ` Rafael J. Wysocki
2024-04-12 20:16 ` Russell King (Oracle)
2024-04-12 20:54 ` Thomas Gleixner
2024-04-12 21:52 ` Russell King (Oracle)
2024-04-12 23:23 ` Thomas Gleixner
2024-04-15 8:45 ` Jonathan Cameron
2024-04-15 9:16 ` Jonathan Cameron
2024-04-15 9:31 ` Jonathan Cameron
2024-04-15 11:57 ` Jonathan Cameron
2024-04-15 11:37 ` Rafael J. Wysocki
2024-04-15 11:56 ` Jonathan Cameron
2024-04-15 12:04 ` Rafael J. Wysocki
2024-04-15 12:23 ` Jonathan Cameron
2024-04-16 17:41 ` Jonathan Cameron
2024-04-16 19:02 ` Rafael J. Wysocki [this message]
2024-04-17 10:39 ` Jonathan Cameron
2024-04-15 12:37 ` Salil Mehta
2024-04-15 12:41 ` Rafael J. Wysocki
2024-04-15 11:51 ` Salil Mehta
2024-04-15 12:51 ` Rafael J. Wysocki
2024-04-15 15:31 ` Salil Mehta
2024-04-15 16:38 ` Rafael J. Wysocki
2024-04-17 15:01 ` Salil Mehta
2024-04-17 16:19 ` Rafael J. Wysocki
2024-04-15 10:52 ` Jonathan Cameron
2024-04-15 11:11 ` Jonathan Cameron
2024-04-15 11:52 ` Rafael J. Wysocki
2024-04-15 11:07 ` Salil Mehta
2024-04-16 14:00 ` Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 04/18] ACPI: Rename acpi_processor_hotadd_init and remove pre-processor guards Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 05/18] ACPI: utils: Add an acpi_sta_enabled() helper and use it in acpi_processor_make_present() Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 06/18] ACPI: scan: Add parameter to allow defering some actions in acpi_scan_check_and_detach Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 07/18] ACPI: Add post_eject to struct acpi_scan_handler for cpu hotplug Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 08/18] ACPI: convert acpi_processor_post_eject() to use IS_ENABLED() Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 09/18] ACPI: Check _STA present bit before making CPUs not present Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 10/18] ACPI: Warn when the present bit changes but the feature is not enabled Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 11/18] arm64: acpi: Move get_cpu_for_acpi_id() to a header Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 12/18] irqchip/gic-v3: Don't return errors from gic_acpi_match_gicc() Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 13/18] irqchip/gic-v3: Add support for ACPI's disabled but 'online capable' CPUs Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 14/18] arm64: psci: Ignore DENIED CPUs Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 15/18] arm64: arch_register_cpu() variant to allow checking of ACPI _STA Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 16/18] ACPI: add support to (un)register CPUs based on the _STA enabled bit Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 17/18] arm64: document virtual CPU hotplug's expectations Jonathan Cameron
2024-04-12 14:37 ` [PATCH v5 18/18] cpumask: Add enabled cpumask for present CPUs that can be brought online Jonathan Cameron
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