A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-25 22:23:14 -04:00
Code Issues Projects Releases Packages Wiki Activity

qcacmn: Remove membership check from list APIs

Browse source 
Getting the next node of a linked list should be a O(1) operation.
qdf_list_peek_next, however, iterates though the list first, checking
for node membership, before returning the next node. This makes the O(1)
operation a O(n) operation instead. Code that uses this API for list
traversal inadvertently performs a O(n^2) operation, causing unexpected
performance issues. Similar problems exist for qdf_list_remove_node as
well. Remove the membership checks in qdf_list_peek_next and
qdf_list_remove_node to prevent unexpected performance penalties.

Change-Id: If20825690ad861815c8164caebbf75318e572f0a
CRs-Fixed: 2091815
This commit is contained in:
Dustin Brown 2017-08-10 17:27:50 -07:00 • committed by snandini
commit 56897ecb6c
1 changed files with 5 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

29
qdf/linux/src/qdf_list.c
View file

@ -192,10 +192,6 @@ QDF_STATUS qdf_list_remove_node(qdf_list_t *list,
if (list_empty(&list->anchor))
return QDF_STATUS_E_EMPTY;
/* verify that node_to_remove is indeed part of list list */
if (!qdf_list_has_node(list, node_to_remove))
return QDF_STATUS_E_INVAL;
list_del(node_to_remove);
list->count--;
@ -231,35 +227,20 @@ EXPORT_SYMBOL(qdf_list_peek_front);
*
* Return: QDF status
*/
QDF_STATUS qdf_list_peek_next(qdf_list_t *list, qdf_list_node_t *node,
QDF_STATUS qdf_list_peek_next(qdf_list_t *list,
qdf_list_node_t *node,
qdf_list_node_t **node2)
{
struct list_head *listptr;
int found = 0;
qdf_list_node_t *tmp;
if ((list == NULL) || (node == NULL) || (node2 == NULL))
if (!list || !node || !node2)
return QDF_STATUS_E_FAULT;
if (list_empty(&list->anchor))
return QDF_STATUS_E_EMPTY;
/* verify that node is indeed part of list list */
list_for_each(tmp, &list->anchor) {
if (tmp == node) {
found = 1;
break;
}
}
if (found == 0)
return QDF_STATUS_E_INVAL;
listptr = node->next;
if (listptr == &list->anchor)
if (node->next == &list->anchor)
return QDF_STATUS_E_EMPTY;
*node2 = listptr;
*node2 = node->next;
return QDF_STATUS_SUCCESS;
}