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Message-ID: <2023102411-ascent-plot-04fd@gregkh>
Date: Tue, 24 Oct 2023 18:02:30 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Russell King <rmk+kernel@...linux.org.uk>
Cc: linux-pm@...r.kernel.org, loongarch@...ts.linux.dev,
linux-acpi@...r.kernel.org, linux-arch@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-riscv@...ts.infradead.org, kvmarm@...ts.linux.dev,
x86@...nel.org, linux-csky@...r.kernel.org,
linux-doc@...r.kernel.org, linux-ia64@...r.kernel.org,
linux-parisc@...r.kernel.org, Salil Mehta <salil.mehta@...wei.com>,
Jean-Philippe Brucker <jean-philippe@...aro.org>,
jianyong.wu@....com, justin.he@....com,
James Morse <james.morse@....com>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Yury Norov <yury.norov@...il.com>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 38/39] cpumask: Add enabled cpumask for present CPUs that
can be brought online
On Tue, Oct 24, 2023 at 04:19:24PM +0100, Russell King wrote:
> From: James Morse <james.morse@....com>
>
> The 'offline' file in sysfs shows all offline CPUs, including those
> that aren't present. User-space is expected to remove not-present CPUs
> from this list to learn which CPUs could be brought online.
>
> CPUs can be present but not-enabled. These CPUs can't be brought online
> until the firmware policy changes, which comes with an ACPI notification
> that will register the CPUs.
>
> With only the offline and present files, user-space is unable to
> determine which CPUs it can try to bring online. Add a new CPU mask
> that shows this based on all the registered CPUs.
>
> Signed-off-by: James Morse <james.morse@....com>
> ---
> drivers/base/cpu.c | 10 ++++++++++
> include/linux/cpumask.h | 25 +++++++++++++++++++++++++
> kernel/cpu.c | 3 +++
> 3 files changed, 38 insertions(+)
>
> diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> index 2b9cb2667654..f8bf1d4c7d71 100644
> --- a/drivers/base/cpu.c
> +++ b/drivers/base/cpu.c
> @@ -95,6 +95,7 @@ void unregister_cpu(struct cpu *cpu)
> {
> int logical_cpu = cpu->dev.id;
>
> + set_cpu_enabled(logical_cpu, false);
> unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
>
> device_unregister(&cpu->dev);
> @@ -273,6 +274,13 @@ static ssize_t print_cpus_offline(struct device *dev,
> }
> static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
>
> +static ssize_t print_cpus_enabled(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(cpu_enabled_mask));
> +}
> +static DEVICE_ATTR(enabled, 0444, print_cpus_enabled, NULL);
This needs to be documented somewhere in Documentation/ABI/ did I miss
that patch?
thanks,
greg k-h
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