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Message-Id: <E1qvJ9g-00AqQ5-5y@rmk-PC.armlinux.org.uk>
Date: Tue, 24 Oct 2023 16:17:16 +0100
From: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
To: 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
Cc: Salil Mehta <salil.mehta@...wei.com>,
Jean-Philippe Brucker <jean-philippe@...aro.org>,
jianyong.wu@....com, justin.he@....com,
James Morse <james.morse@....com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH 13/39] x86: intel_epb: Don't rely on link order
From: James Morse <james.morse@....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@....com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
---
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
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