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SubjectRe: [PATCH RFC 02/22] x86: intel_epb: Don't rely on link order
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On 11/7/23 20:29, Russell King (Oracle) 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>
> ---
> 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(-)
>

Reviewed-by: Gavin Shan <gshan@redhat.com>

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