Messages in this thread |  | | | Date | Thu, 2 Mar 2006 23:14:52 -0800 | | From | Andrew Morton <> | | Subject | Re: 2.6.16rc5 'found' an extra CPU. |
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Ashok Raj <ashok.raj@intel.com> wrote: > > Local apic entries are only 8 bits, but it seemed to not be caught with > u8 return value result in the check > > cpu_index >= NR_CPUS becomming always false. > > drivers/acpi/processor_core.c: In function `acpi_processor_get_info': > drivers/acpi/processor_core.c:483: warning: comparison is always false due to limited range of data type > > > Signed-off-by: Ashok Raj <ashok.raj@intel.com> > ----------------------------------------------------- > drivers/acpi/processor_core.c | 8 ++++---- > 1 files changed, 4 insertions(+), 4 deletions(-) > > Index: linux-2.6.16-rc5-mm1/drivers/acpi/processor_core.c > =================================================================== > --- linux-2.6.16-rc5-mm1.orig/drivers/acpi/processor_core.c > +++ linux-2.6.16-rc5-mm1/drivers/acpi/processor_core.c > @@ -395,7 +395,7 @@ static int acpi_processor_remove_fs(stru > #define ARCH_BAD_APICID (0xff) > #endif > > -static u8 convert_acpiid_to_cpu(u8 acpi_id) > +static int convert_acpiid_to_cpu(u8 acpi_id) > { > u16 apic_id; > int i; > @@ -421,7 +421,7 @@ static int acpi_processor_get_info(struc > acpi_status status = 0; > union acpi_object object = { 0 }; > struct acpi_buffer buffer = { sizeof(union acpi_object), &object }; > - u8 cpu_index; > + int cpu_index; > static int cpu0_initialized; > > ACPI_FUNCTION_TRACE("acpi_processor_get_info"); > @@ -466,7 +466,7 @@ static int acpi_processor_get_info(struc > cpu_index = convert_acpiid_to_cpu(pr->acpi_id); > > /* Handle UP system running SMP kernel, with no LAPIC in MADT */ > - if (!cpu0_initialized && (cpu_index == 0xff) && > + if (!cpu0_initialized && (cpu_index == -1) && > (num_online_cpus() == 1)) { > cpu_index = 0; > } > @@ -480,7 +480,7 @@ static int acpi_processor_get_info(struc > * less than the max # of CPUs. They should be ignored _iff > * they are physically not present. > */ > - if (cpu_index >= NR_CPUS) { > + if (cpu_index == -1) { > if (ACPI_FAILURE > (acpi_processor_hotadd_init(pr->handle, &pr->id))) { > ACPI_ERROR((AE_INFO,
On a uniprocessor build this causes a crash in acpi_processor_start():
BUG_ON((pr->id >= NR_CPUS) || (pr->id < 0)); pr->id is 255.
I could bodge around this in various ways, but the semantics of cpu IDs in there seem to be a bit opaque, and I suspect some more thought needs to go into it all.
As well as uniprocessor testing ;)
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