efi_mem_sort: use list_for_each_entry_safe instead

Use list_for_each_entry_safe and comparisons against the current and
next efi_mem_desc. This reduces the computation required for merging
regions, prevents unnecessary additional iterations of the list, and
requires less temporary values.

Signed-off-by: Randolph Sapp <rs@ti.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>

diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index b77c2f980cc029a80ed5d5902d10e8818d9c9b4a..046a2bb46413b6d38ff0a9d2852e737361aa3443 100644 (file)
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -128,44 +128,29 @@ static uint64_t desc_get_end(struct efi_mem_desc *desc)
  */
 static void efi_mem_sort(void)
 {
-       struct efi_mem_list *lmem;
-       struct efi_mem_list *prevmem = NULL;
-       bool merge_again = true;
+       struct efi_mem_list *curmem, *nextmem = NULL;
 
        list_sort(NULL, &efi_mem, efi_mem_cmp);
 
        /* Now merge entries that can be merged */
-       while (merge_again) {
-               merge_again = false;
-               list_for_each_entry(lmem, &efi_mem, link) {
-                       struct efi_mem_desc *prev;
-                       struct efi_mem_desc *cur;
-                       uint64_t pages;
+       list_for_each_entry_safe(curmem, nextmem, &efi_mem, link) {
+               struct efi_mem_desc *cur;
+               struct efi_mem_desc *next;
 
-                       if (!prevmem) {
-                               prevmem = lmem;
-                               continue;
-                       }
+               /* Exit when we've got nothing to compare with */
+               if (&nextmem->link == &efi_mem)
+                       break;
 
-                       cur = &lmem->desc;
-                       prev = &prevmem->desc;
-
-                       if ((desc_get_end(cur) == prev->physical_start) &&
-                           (prev->type == cur->type) &&
-                           (prev->attribute == cur->attribute)) {
-                               /* There is an existing map before, reuse it */
-                               pages = cur->num_pages;
-                               prev->num_pages += pages;
-                               prev->physical_start -= pages << EFI_PAGE_SHIFT;
-                               prev->virtual_start -= pages << EFI_PAGE_SHIFT;
-                               list_del(&lmem->link);
-                               free(lmem);
-
-                               merge_again = true;
-                               break;
-                       }
+               cur = &curmem->desc;
+               next = &nextmem->desc;
 
-                       prevmem = lmem;
+               if ((cur->physical_start == desc_get_end(next)) &&
+                   (cur->type == next->type) &&
+                   (cur->attribute == next->attribute)) {
+                       /* There is another similar map coming up, reuse it */
+                       next->num_pages += cur->num_pages;
+                       list_del(&curmem->link);
+                       free(curmem);
                }
        }
 }