From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
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 RFC 02/22] x86: intel_epb: Don't rely on link order
Date: Tue, 28 Nov 2023 14:40:59 +0000 [thread overview]
Message-ID: <20231128144059.000042c8@Huawei.com> (raw)
In-Reply-To: <E1r0JKq-00CTwZ-Mh@rmk-PC.armlinux.org.uk>
On Tue, 07 Nov 2023 10:29:28 +0000
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>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Seems reasonable. FWIW
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---
> 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);
next prev parent reply other threads:[~2023-11-28 14:41 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-07 10:28 [PATCH RFC 00/22] Initial cleanups for vCPU hotplug Russell King (Oracle)
2023-11-07 10:29 ` [PATCH RFC 01/22] arch_topology: Make register_cpu_capacity_sysctl() tolerant to late CPUs Russell King
2023-11-13 0:04 ` Gavin Shan
2023-11-28 14:37 ` Jonathan Cameron
2023-11-28 15:41 ` Russell King (Oracle)
2023-11-07 10:29 ` [PATCH RFC 02/22] x86: intel_epb: Don't rely on link order Russell King
2023-11-13 0:03 ` Gavin Shan
2023-11-28 14:40 ` Jonathan Cameron [this message]
2023-11-28 15:42 ` Russell King (Oracle)
2023-11-07 10:29 ` [PATCH RFC 03/22] x86/topology: remove arch_*register_cpu() exports Russell King (Oracle)
2023-11-13 0:08 ` Gavin Shan
2023-11-28 14:42 ` Jonathan Cameron
2023-11-07 10:29 ` [PATCH RFC 04/22] Loongarch: " Russell King (Oracle)
2023-11-13 0:11 ` Gavin Shan
2023-11-28 14:43 ` Jonathan Cameron
2023-11-07 10:29 ` [PATCH RFC 05/22] ACPI: Move ACPI_HOTPLUG_CPU to be disabled on arm64 and riscv Russell King
2023-11-09 9:43 ` Shaoqin Huang
2023-11-13 0:29 ` Gavin Shan
2023-11-13 8:56 ` Russell King (Oracle)
2023-11-13 10:01 ` Gavin Shan
2023-11-28 14:46 ` Jonathan Cameron
2023-11-07 10:29 ` [PATCH RFC 06/22] drivers: base: Use present CPUs in GENERIC_CPU_DEVICES Russell King
2023-11-09 10:09 ` Shaoqin Huang
2023-11-09 10:29 ` Russell King (Oracle)
2023-11-09 10:59 ` Shaoqin Huang
2023-11-13 0:37 ` Gavin Shan
2023-11-07 10:29 ` [PATCH RFC 07/22] drivers: base: Allow parts of GENERIC_CPU_DEVICES to be overridden Russell King
2023-11-09 10:13 ` Shaoqin Huang
2023-11-13 0:42 ` Gavin Shan
2023-11-28 14:49 ` Jonathan Cameron
2023-11-07 10:29 ` [PATCH RFC 08/22] drivers: base: Implement weak arch_unregister_cpu() Russell King
2023-11-09 10:51 ` Shaoqin Huang
2023-11-13 0:45 ` Gavin Shan
2023-11-21 13:33 ` Russell King (Oracle)
2023-11-28 14:51 ` Jonathan Cameron
2023-11-07 10:30 ` [PATCH RFC 09/22] drivers: base: add arch_cpu_is_hotpluggable() Russell King (Oracle)
2023-11-10 3:27 ` Shaoqin Huang
2023-11-13 0:56 ` Gavin Shan
2023-11-28 14:53 ` Jonathan Cameron
2023-11-07 10:30 ` [PATCH RFC 10/22] drivers: base: Move cpu_dev_init() after node_dev_init() Russell King
2023-11-13 0:58 ` Gavin Shan
2023-11-13 8:00 ` Russell King (Oracle)
2023-11-21 13:27 ` Russell King (Oracle)
2023-11-28 13:55 ` Jonathan Cameron
2023-11-28 15:00 ` Jonathan Cameron
2023-11-30 12:17 ` Russell King (Oracle)
2023-11-07 10:30 ` [PATCH RFC 11/22] drivers: base: remove unnecessary call to register_cpu_under_node() Russell King (Oracle)
2023-11-13 4:04 ` Gavin Shan
2023-11-15 10:11 ` Russell King (Oracle)
2023-11-07 10:30 ` [PATCH RFC 12/22] drivers: base: Print a warning instead of panic() when register_cpu() fails Russell King
2023-11-10 3:35 ` Shaoqin Huang
2023-11-13 4:03 ` Gavin Shan
2023-11-28 15:05 ` Jonathan Cameron
2023-11-07 10:30 ` [PATCH RFC 13/22] arm64: setup: Switch over to GENERIC_CPU_DEVICES using arch_register_cpu() Russell King
2023-11-10 3:36 ` Shaoqin Huang
2023-11-13 4:07 ` Gavin Shan
2023-11-28 15:08 ` Jonathan Cameron
2023-11-28 15:12 ` Jonathan Cameron
2023-11-07 10:30 ` [PATCH RFC 14/22] arm64: convert to arch_cpu_is_hotpluggable() Russell King (Oracle)
2023-11-10 3:37 ` Shaoqin Huang
2023-11-13 4:09 ` Gavin Shan
2023-11-28 15:11 ` Jonathan Cameron
2023-11-30 12:09 ` Russell King (Oracle)
2023-11-07 10:30 ` [PATCH RFC 15/22] x86/topology: Switch over to GENERIC_CPU_DEVICES Russell King
2023-11-13 4:13 ` Gavin Shan
2023-11-28 15:16 ` Jonathan Cameron
2023-11-07 10:30 ` [PATCH RFC 16/22] x86/topology: use weak version of arch_unregister_cpu() Russell King (Oracle)
2023-11-13 4:16 ` Gavin Shan
2023-11-28 15:17 ` Jonathan Cameron
2023-11-07 10:30 ` [PATCH RFC 17/22] x86/topology: convert to use arch_cpu_is_hotpluggable() Russell King (Oracle)
2023-11-13 4:18 ` Gavin Shan
2023-11-28 15:18 ` Jonathan Cameron
2023-11-07 10:30 ` [PATCH RFC 18/22] LoongArch: Switch over to GENERIC_CPU_DEVICES Russell King
2023-11-13 4:20 ` Gavin Shan
2023-11-28 15:19 ` Jonathan Cameron
2023-11-07 10:30 ` [PATCH RFC 19/22] LoongArch: Use the __weak version of arch_unregister_cpu() Russell King
2023-11-07 10:31 ` [PATCH RFC 20/22] LoongArch: convert to use arch_cpu_is_hotpluggable() Russell King (Oracle)
2023-11-13 4:22 ` Gavin Shan
2023-11-28 15:20 ` Jonathan Cameron
2023-11-07 10:31 ` [PATCH RFC 21/22] riscv: Switch over to GENERIC_CPU_DEVICES Russell King
2023-11-07 17:48 ` Palmer Dabbelt
2023-11-13 4:23 ` Gavin Shan
2023-11-07 10:31 ` [PATCH RFC 22/22] riscv: convert to use arch_cpu_is_hotpluggable() Russell King (Oracle)
2023-11-07 17:48 ` Palmer Dabbelt
2023-11-13 4:24 ` Gavin Shan
2023-11-28 15:21 ` Jonathan Cameron
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