[tip: x86/cpu] x86/cpu/intel_epb: Don't rely on link order

[tip-bot2 for James Morse]

The following commit has been merged into the x86/cpu branch of tip:

Commit-ID:     5bfa0e45e9e7212b87fe1564ab45f146c7d56e5f
Gitweb:        https://git.kernel.org/tip/5bfa0e45e9e7212b87fe1564ab45f146c7d56e5f
Author:        James Morse <james.morse@xxxxxxx>
AuthorDate:    Fri, 24 Nov 2023 09:38:53 
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 24 Nov 2023 13:54:31 +01:00

x86/cpu/intel_epb: Don't rely on link order

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>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
 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 e4c3ba9..f18d35f 100644
--- a/arch/x86/kernel/cpu/intel_epb.c
+++ b/arch/x86/kernel/cpu/intel_epb.c
@@ -237,4 +237,4 @@ err_out_online:
 	cpuhp_remove_state(CPUHP_AP_X86_INTEL_EPB_ONLINE);
 	return ret;
 }
-subsys_initcall(intel_epb_init);
+late_initcall(intel_epb_init);