2024-03-28 02:29:06

by Wei Yang

Subject: [PATCH 1/2] x86/boot/e820: not necessary to iterate whole overlap_list

We are sure there is only one entry to be removed from overlap_list.

Signed-off-by: Wei Yang <[email protected]>
---
arch/x86/kernel/e820.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 6f1b379e3b38..ecbeb76ed08f 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -377,10 +377,11 @@ int __init e820__update_table(struct e820_table *table)
} else {
/* Remove entry from list (order independent, so swap with last): */
for (i = 0; i < overlap_entries; i++) {
- if (overlap_list[i] == change_point[chg_idx]->entry)
- overlap_list[i] = overlap_list[overlap_entries-1];
+ if (overlap_list[i] == change_point[chg_idx]->entry) {
+ overlap_list[i] = overlap_list[--overlap_entries];
+ break;
+ }
}
- overlap_entries--;
}
/*
* If there are overlapping entries, decide which
--
2.34.1

2024-03-28 02:31:10

by Wei Yang

Subject: [PATCH 2/2] x86/boot/e820: a local variable for last_addr is not necessary

We only use this to calculate the size of new entry as the start
address, which is already stored in new_entries->addr.

Signed-off-by: Wei Yang <[email protected]>
---
arch/x86/kernel/e820.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index ecbeb76ed08f..8d431ac3f76e 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -324,7 +324,6 @@ int __init e820__update_table(struct e820_table *table)
struct e820_entry *entries = table->entries;
u32 max_nr_entries = ARRAY_SIZE(table->entries);
enum e820_type current_type, last_type;
- unsigned long long last_addr;
u32 new_nr_entries, overlap_entries;
u32 i, chg_idx, chg_nr;

@@ -366,7 +365,6 @@ int __init e820__update_table(struct e820_table *table)
overlap_entries = 0; /* Number of entries in the overlap table */
new_nr_entries = 0; /* Index for creating new map entries */
last_type = 0; /* Start with undefined memory type */
- last_addr = 0; /* Start with 0 as last starting address */

/* Loop through change-points, determining effect on the new map: */
for (chg_idx = 0; chg_idx < chg_nr; chg_idx++) {
@@ -397,7 +395,8 @@ int __init e820__update_table(struct e820_table *table)
/* Continue building up new map based on this information: */
if (current_type != last_type || e820_nomerge(current_type)) {
if (last_type) {
- new_entries[new_nr_entries].size = change_point[chg_idx]->addr - last_addr;
+ new_entries[new_nr_entries].size =
+ change_point[chg_idx]->addr - new_entries[new_nr_entries].addr;
/* Move forward only if the new size was non-zero: */
if (new_entries[new_nr_entries].size != 0)
/* No more space left for new entries? */
@@ -407,7 +406,6 @@ int __init e820__update_table(struct e820_table *table)
if (current_type) {
new_entries[new_nr_entries].addr = change_point[chg_idx]->addr;
new_entries[new_nr_entries].type = current_type;
- last_addr = change_point[chg_idx]->addr;
}
last_type = current_type;
}
--
2.34.1