| Message ID | 20230913163823.7880-8-james.morse@arm.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | ACPI/arm64: add support for virtual cpuhotplug | expand |
| Context | Check | Description |
|---|---|---|
| conchuod/cover_letter | success | Series has a cover letter |
| conchuod/tree_selection | success | Guessed tree name to be for-next at HEAD 0bb80ecc33a8 |
| conchuod/fixes_present | success | Fixes tag not required for -next series |
| conchuod/maintainers_pattern | success | MAINTAINERS pattern errors before the patch: 5 and now 5 |
| conchuod/verify_signedoff | success | Signed-off-by tag matches author and committer |
| conchuod/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| conchuod/build_rv64_clang_allmodconfig | success | Errors and warnings before: 9 this patch: 9 |
| conchuod/module_param | success | Was 0 now: 0 |
| conchuod/build_rv64_gcc_allmodconfig | success | Errors and warnings before: 9 this patch: 9 |
| conchuod/build_rv32_defconfig | success | Build OK |
| conchuod/dtb_warn_rv64 | success | Errors and warnings before: 25 this patch: 25 |
| conchuod/header_inline | success | No static functions without inline keyword in header files |
| conchuod/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 5 lines checked |
| conchuod/build_rv64_nommu_k210_defconfig | success | Build OK |
| conchuod/verify_fixes | success | No Fixes tag |
| conchuod/build_rv64_nommu_virt_defconfig | success | Build OK |
On Wed, Sep 13, 2023 at 04:37:55PM +0000, James Morse wrote: > 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 derefernce 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> I think someone knowledgeable from x86 land needs to ack/review this.
On 9/14/23 02:37, James Morse wrote: > 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 derefernce during boot. ^^^^^^^^^^ s/derefernce/dereference Reported by ./scripts/checkpatch.pl --codespell > > 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> > --- > 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); Thanks, Gavin
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);
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 derefernce 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> --- 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(-)