On Tue, 07 Nov 2023 10:29:28 +0000
Russell King <[email protected]> wrote:
> From: James Morse <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Russell King (Oracle) <[email protected]>
Seems reasonable. FWIW
Reviewed-by: Jonathan Cameron <[email protected]>
> ---
> 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);
On Tue, Nov 28, 2023 at 02:40:59PM +0000, Jonathan Cameron wrote:
> On Tue, 07 Nov 2023 10:29:28 +0000
> Russell King <[email protected]> wrote:
>
> > From: James Morse <[email protected]>
> >
> > 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 <[email protected]>
> > Signed-off-by: Russell King (Oracle) <[email protected]>
>
> Seems reasonable. FWIW
> Reviewed-by: Jonathan Cameron <[email protected]>
Thanks, however this has already been merged into the tip tree since
Rafael suggested sending it separately.
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