From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Russell King <rmk+kernel@armlinux.org.uk>
Cc: 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,
linux-riscv@lists.infradead.org, kvmarm@lists.linux.dev,
x86@kernel.org, linux-csky@vger.kernel.org,
linux-doc@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-parisc@vger.kernel.org,
Salil Mehta <salil.mehta@huawei.com>,
Jean-Philippe Brucker <jean-philippe@linaro.org>,
jianyong.wu@arm.com, justin.he@arm.com,
James Morse <james.morse@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH 02/21] x86: intel_epb: Don't rely on link order
Date: Wed, 22 Nov 2023 21:12:04 +0100 [thread overview]
Message-ID: <CAJZ5v0jbjykNooJ_PvkOjpE6hA0QFJUw+kpwYfNY7jOtkcPA0Q@mail.gmail.com> (raw)
In-Reply-To: <E1r5R2m-00Csyb-2S@rmk-PC.armlinux.org.uk>
On Tue, Nov 21, 2023 at 2:44 PM Russell King <rmk+kernel@armlinux.org.uk> wrote:
>
> From: James Morse <james.morse@arm.com>
>
> intel_epb_init() is called as a subsys_initcall() to register cpuhp
> callbacks. The callbacks make use of get_cpu_device() which will return
> NULL unless register_cpu() has been called. register_cpu() is called
> from topology_init(), which is also a subsys_initcall().
>
> This is fragile. Moving the register_cpu() to a different
> subsys_initcall() leads to a NULL dereference during boot.
>
> Make intel_epb_init() a late_initcall(), user-space can't provide a
> policy before this point anyway.
>
> Signed-off-by: James Morse <james.morse@arm.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
and I'd suggest sending this separately to the x86 list.
> ---
> subsys_initcall_sync() would be an option, but moving the register_cpu()
> calls into ACPI also means adding a safety net for CPUs that are online
> but not described properly by firmware. This lives in subsys_initcall_sync().
> ---
> arch/x86/kernel/cpu/intel_epb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/intel_epb.c b/arch/x86/kernel/cpu/intel_epb.c
> index e4c3ba91321c..f18d35fe27a9 100644
> --- a/arch/x86/kernel/cpu/intel_epb.c
> +++ b/arch/x86/kernel/cpu/intel_epb.c
> @@ -237,4 +237,4 @@ static __init int intel_epb_init(void)
> cpuhp_remove_state(CPUHP_AP_X86_INTEL_EPB_ONLINE);
> return ret;
> }
> -subsys_initcall(intel_epb_init);
> +late_initcall(intel_epb_init);
> --
> 2.30.2
>
>
next prev parent reply other threads:[~2023-11-22 20:12 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-21 13:43 [PATCH 00/21] Initial cleanups for vCPU hotplug Russell King (Oracle)
2023-11-21 13:43 ` [PATCH 01/21] arch_topology: Make register_cpu_capacity_sysctl() tolerant to late CPUs Russell King
2023-11-30 16:46 ` Jonathan Cameron
2023-12-01 10:45 ` Thomas Gleixner
2023-11-21 13:44 ` [PATCH 02/21] x86: intel_epb: Don't rely on link order Russell King
2023-11-22 20:12 ` Rafael J. Wysocki [this message]
2023-11-21 13:44 ` [PATCH 03/21] x86/topology: remove arch_*register_cpu() exports Russell King (Oracle)
2023-11-30 16:48 ` Jonathan Cameron
2023-11-21 13:44 ` [PATCH 04/21] Loongarch: " Russell King (Oracle)
2023-11-30 16:48 ` Jonathan Cameron
2023-11-21 13:44 ` [PATCH 05/21] ACPI: Move ACPI_HOTPLUG_CPU to be disabled on arm64 and riscv Russell King
2023-11-22 20:16 ` Rafael J. Wysocki
2023-11-30 16:49 ` Jonathan Cameron
2023-11-21 13:44 ` [PATCH 06/21] drivers: base: Use present CPUs in GENERIC_CPU_DEVICES Russell King
2023-11-21 13:44 ` [PATCH 07/21] drivers: base: Allow parts of GENERIC_CPU_DEVICES to be overridden Russell King
2023-11-30 16:50 ` Jonathan Cameron
2023-11-21 13:44 ` [PATCH 08/21] drivers: base: Implement weak arch_unregister_cpu() Russell King
2023-11-30 16:50 ` Jonathan Cameron
2023-12-01 3:47 ` Gavin Shan
2023-12-01 11:06 ` Thomas Gleixner
2023-11-21 13:44 ` [PATCH 09/21] drivers: base: add arch_cpu_is_hotpluggable() Russell King (Oracle)
2023-11-30 16:51 ` Jonathan Cameron
2023-12-01 3:47 ` Gavin Shan
2023-11-21 13:44 ` [PATCH 10/21] drivers: base: Move cpu_dev_init() after node_dev_init() Russell King
2023-11-30 16:52 ` Jonathan Cameron
2023-12-01 3:48 ` Gavin Shan
2023-11-21 13:44 ` [PATCH 11/21] drivers: base: Print a warning instead of panic() when register_cpu() fails Russell King
2023-11-30 16:53 ` Jonathan Cameron
2023-12-01 3:49 ` Gavin Shan
2023-11-21 13:44 ` [PATCH 12/21] arm64: setup: Switch over to GENERIC_CPU_DEVICES using arch_register_cpu() Russell King
2023-11-30 16:54 ` Jonathan Cameron
2023-12-11 13:20 ` Will Deacon
2023-11-21 13:44 ` [PATCH 13/21] arm64: convert to arch_cpu_is_hotpluggable() Russell King (Oracle)
2023-11-30 16:54 ` Jonathan Cameron
2023-12-11 13:21 ` Will Deacon
2023-11-21 13:45 ` [PATCH 14/21] x86/topology: Switch over to GENERIC_CPU_DEVICES Russell King
2023-11-30 16:56 ` Jonathan Cameron
2023-11-21 13:45 ` [PATCH 15/21] x86/topology: use weak version of arch_unregister_cpu() Russell King (Oracle)
2023-11-30 16:57 ` Jonathan Cameron
2023-11-21 13:45 ` [PATCH 16/21] x86/topology: convert to use arch_cpu_is_hotpluggable() Russell King (Oracle)
2023-11-30 16:55 ` Jonathan Cameron
2023-11-21 13:45 ` [PATCH 17/21] LoongArch: Switch over to GENERIC_CPU_DEVICES Russell King
2023-11-30 16:57 ` Jonathan Cameron
2023-11-21 13:45 ` [PATCH 18/21] LoongArch: Use the __weak version of arch_unregister_cpu() Russell King
2023-11-21 13:45 ` [PATCH 19/21] LoongArch: convert to use arch_cpu_is_hotpluggable() Russell King (Oracle)
2023-11-30 16:55 ` Jonathan Cameron
2023-11-21 13:45 ` [PATCH 20/21] riscv: Switch over to GENERIC_CPU_DEVICES Russell King
2023-11-22 20:05 ` Samuel Holland
2023-11-21 13:45 ` [PATCH 21/21] riscv: convert to use arch_cpu_is_hotpluggable() Russell King (Oracle)
2023-11-22 20:08 ` Samuel Holland
2023-11-30 16:55 ` Jonathan Cameron
2023-12-01 8:53 ` [PATCH 00/21] Initial cleanups for vCPU hotplug Thomas Gleixner
2023-12-01 11:25 ` Thomas Gleixner
2023-12-01 12:28 ` Greg Kroah-Hartman
2023-12-01 16:09 ` Thomas Gleixner
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