Logic in early_acpi_process_madt() & acpi_process_madt() is really hard to
follow now. Clean them up.
Done basic boot test on my x86-64 PC.
Cao jin (2):
x86/acpi: Improve code readablity of early madt processing
x86/acpi: Cleanup acpi_process_madt()
arch/x86/kernel/acpi/boot.c | 72 +++++++++++++++----------------------
1 file changed, 28 insertions(+), 44 deletions(-)
--
2.21.0
Current processing logic is confusing.
Return value of early_acpi_parse_madt_lapic_addr_ovr() indicates error(< 0),
parsed entry number(>= 0). So, it makes no sense to initialize acpi_lapic &
smp_found_config seeing no override entry, instead, initialize them seeing
MADT.
Put register_lapic_address() into override entry processing doesn't make
sense either.
Improved all the related comments too.
Signed-off-by: Cao jin <[email protected]>
---
arch/x86/kernel/acpi/boot.c | 28 ++++++++++------------------
1 file changed, 10 insertions(+), 18 deletions(-)
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 04205ce127a1..2131035bba98 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1003,11 +1003,7 @@ static int __init acpi_parse_fadt(struct acpi_table_header *table)
}
#ifdef CONFIG_X86_LOCAL_APIC
-/*
- * Parse LAPIC entries in MADT
- * returns 0 on success, < 0 on error
- */
-
+/* Returns >= 0 on success, indicates parsed entry number; < 0 on error. */
static int __init early_acpi_parse_madt_lapic_addr_ovr(void)
{
int count;
@@ -1025,11 +1021,8 @@ static int __init early_acpi_parse_madt_lapic_addr_ovr(void)
if (count < 0) {
printk(KERN_ERR PREFIX
"Error parsing LAPIC address override entry\n");
- return count;
}
- register_lapic_address(acpi_lapic_addr);
-
return count;
}
@@ -1234,19 +1227,16 @@ static inline int acpi_parse_madt_ioapic_entries(void)
static void __init early_acpi_process_madt(void)
{
#ifdef CONFIG_X86_LOCAL_APIC
- int error;
+ int ret;
if (!acpi_table_parse(ACPI_SIG_MADT, acpi_parse_madt)) {
+ /* Found MADT */
+ acpi_lapic = 1;
+ smp_found_config = 1;
- /*
- * Parse MADT LAPIC entries
- */
- error = early_acpi_parse_madt_lapic_addr_ovr();
- if (!error) {
- acpi_lapic = 1;
- smp_found_config = 1;
- }
- if (error == -EINVAL) {
+ /* See if override entry exists. */
+ ret = early_acpi_parse_madt_lapic_addr_ovr();
+ if (ret == -EINVAL) {
/*
* Dell Precision Workstation 410, 610 come here.
*/
@@ -1254,6 +1244,8 @@ static void __init early_acpi_process_madt(void)
"Invalid BIOS MADT, disabling ACPI\n");
disable_acpi();
}
+
+ register_lapic_address(acpi_lapic_addr);
}
#endif
}
--
2.21.0
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 <[email protected]>
---
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
On Wed, Jan 22, 2020 at 4:47 AM Cao jin <[email protected]> wrote:
>
> Logic in early_acpi_process_madt() & acpi_process_madt() is really hard to
> follow now. Clean them up.
>
> Done basic boot test on my x86-64 PC.
>
> Cao jin (2):
> x86/acpi: Improve code readablity of early madt processing
> x86/acpi: Cleanup acpi_process_madt()
>
> arch/x86/kernel/acpi/boot.c | 72 +++++++++++++++----------------------
> 1 file changed, 28 insertions(+), 44 deletions(-)
Please always CC ACPI patches to [email protected], thanks!