[PATCH 2/2] x86/acpi: Fix error handling steps in parsing the lapic/x2apic entry

[Dou Liyang]

Originally, in acpi_parse_x2apic(), when the apic_id is invalid and
enabled is false, the acpi_register_lapic() also can be executed.
This does not make sense.

Optimize the decision logic to avoid performing meaningless operations
if the apic_id is invalid.

Signed-off-by: Dou Liyang <douly.f...@cn.fujitsu.com>
---
 arch/x86/kernel/acpi/boot.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index d642c95..343e752 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -203,17 +203,20 @@ acpi_parse_x2apic(struct acpi_subtable_header *header, 
const unsigned long end)
        apic_id = processor->local_apic_id;
        enabled = processor->lapic_flags & ACPI_MADT_ENABLED;
 #ifdef CONFIG_X86_X2APIC
+       if (!apic->apic_id_valid(apic_id)) {
+               if (enabled)
+                       printk(KERN_WARNING PREFIX "x2apic entry ignored\n");
+               return -EINVAL;
+       }
+
        /*
-        * We need to register disabled CPU as well to permit
-        * counting disabled CPUs. This allows us to size
-        * cpus_possible_map more accurately, to permit
-        * to not preallocating memory for all NR_CPUS
-        * when we use CPU hotplug.
-        */
-       if (!apic->apic_id_valid(apic_id) && enabled)
-               printk(KERN_WARNING PREFIX "x2apic entry ignored\n");
-       else
-               acpi_register_lapic(apic_id, processor->uid, enabled);
+       * We need to register disabled CPU as well to permit
+       * counting disabled CPUs. This allows us to size
+       * cpus_possible_map more accurately, to permit
+       * to not preallocating memory for all NR_CPUS
+       * when we use CPU hotplug.
+       */
+       acpi_register_lapic(apic_id, processor->uid, enabled);
 #else
        printk(KERN_WARNING PREFIX "x2apic entry ignored\n");
 #endif
@@ -225,6 +228,7 @@ static int __init
 acpi_parse_lapic(struct acpi_subtable_header * header, const unsigned long end)
 {
        struct acpi_madt_local_apic *processor = NULL;
+       u8 enabled;
 
        processor = (struct acpi_madt_local_apic *)header;
 
@@ -233,9 +237,14 @@ acpi_parse_lapic(struct acpi_subtable_header * header, 
const unsigned long end)
 
        acpi_table_print_madt_entry(header);
 
+       enabled = processor->lapic_flags & ACPI_MADT_ENABLED;
+
        /* the 0xff is an invalid local APIC id */
-       if (processor->id == 0xff)
+       if (processor->id == 0xff) {
+               if (enabled)
+                       printk(KERN_WARNING PREFIX "lapic entry ignored\n");
                return -EINVAL;
+       }
 
        /*
         * We need to register disabled CPU as well to permit
@@ -246,7 +255,7 @@ acpi_parse_lapic(struct acpi_subtable_header * header, 
const unsigned long end)
         */
        acpi_register_lapic(processor->id,      /* APIC ID */
                            processor->processor_id, /* ACPI ID */
-                           processor->lapic_flags & ACPI_MADT_ENABLED);
+                           enabled);
 
        return 0;
 }
-- 
2.5.5