Re: [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@xxxxxxx>

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@xxxxxxx>
Signed-off-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
---
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@xxxxxxxxxx>





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