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Subject[RFC PATCH 2/2] x86/acpi: Cleanup acpi_process_madt()
Date
After many duct-taped patches, the readablity of these code chunks are
really hard. This patch does following improvements:

1. Drop unnecessary comment that is self-documented by function name,
while supply with necessary comments.
2. Drop duplicated code: acpi_process_madt() has already been called
in early madt processing, acpi_lapic & smp_found_config is also
initialized there.
3. Fix code logic: variable count's usage is quite confusing now, and
some code logic is wrong, like count & x2count will never be negative
after assigned from madt_proc[n].count

Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
---
arch/x86/kernel/acpi/boot.c | 44 +++++++++++++++----------------------
1 file changed, 18 insertions(+), 26 deletions(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 2131035bba98..844fc9f26064 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1026,9 +1026,10 @@ static int __init early_acpi_parse_madt_lapic_addr_ovr(void)
return count;
}

+/* Returns 0 on success, < 0 on error. */
static int __init acpi_parse_madt_lapic_entries(void)
{
- int count;
+ int count = 0;
int x2count = 0;
int ret;
struct acpi_subtable_proc madt_proc[2];
@@ -1036,10 +1037,13 @@ static int __init acpi_parse_madt_lapic_entries(void)
if (!boot_cpu_has(X86_FEATURE_APIC))
return -ENODEV;

- count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_SAPIC,
- acpi_parse_sapic, MAX_LOCAL_APIC);
+ /* SAPIC is commonly found on Intel Itanium processor. */
+ ret = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_SAPIC,
+ acpi_parse_sapic, MAX_LOCAL_APIC);

- if (!count) {
+
+ /* No SAPIC entries implies it is not Itanium processor. */
+ if (!ret) {
memset(madt_proc, 0, sizeof(madt_proc));
madt_proc[0].id = ACPI_MADT_TYPE_LOCAL_APIC;
madt_proc[0].handler = acpi_parse_lapic;
@@ -1056,15 +1060,14 @@ static int __init acpi_parse_madt_lapic_entries(void)

count = madt_proc[0].count;
x2count = madt_proc[1].count;
- }
- if (!count && !x2count) {
- printk(KERN_ERR PREFIX "No LAPIC entries present\n");
- /* TBD: Cleanup to allow fallback to MPS */
- return -ENODEV;
- } else if (count < 0 || x2count < 0) {
- printk(KERN_ERR PREFIX "Error parsing LAPIC entry\n");
- /* TBD: Cleanup to allow fallback to MPS */
- return count;
+ if (!count && !x2count) {
+ printk(KERN_ERR PREFIX "No LAPIC entries present\n");
+ /* TBD: Cleanup to allow fallback to MPS */
+ return -ENODEV;
+ }
+ } else if (ret < 0) {
+ printk(KERN_ERR PREFIX "Error parsing SAPIC entries\n");
+ return ret;
}

x2count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_X2APIC_NMI,
@@ -1074,7 +1077,7 @@ static int __init acpi_parse_madt_lapic_entries(void)
if (count < 0 || x2count < 0) {
printk(KERN_ERR PREFIX "Error parsing LAPIC NMI entry\n");
/* TBD: Cleanup to allow fallback to MPS */
- return count;
+ return (count < 0) ? count : x2count;
}
return 0;
}
@@ -1255,25 +1258,14 @@ static void __init acpi_process_madt(void)
#ifdef CONFIG_X86_LOCAL_APIC
int error;

- if (!acpi_table_parse(ACPI_SIG_MADT, acpi_parse_madt)) {
-
- /*
- * Parse MADT LAPIC entries
- */
+ if (acpi_lapic) {
error = acpi_parse_madt_lapic_entries();
if (!error) {
- acpi_lapic = 1;
-
- /*
- * Parse MADT IO-APIC entries
- */
mutex_lock(&acpi_ioapic_lock);
error = acpi_parse_madt_ioapic_entries();
mutex_unlock(&acpi_ioapic_lock);
if (!error) {
acpi_set_irq_model_ioapic();
-
- smp_found_config = 1;
}
}
if (error == -EINVAL) {
--
2.21.0


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