Jan Beulich
2012-May-10 15:17 UTC
[PATCH 2/4] linux-2.6.18/gntdev: fix multi-page slot allocation
Any range with the first slot available would have got considered
usable, as range_length never got reset when encountering an in-use
slot.
Additionally fold the two almost identical loops into a single
instance, at once avoiding to go through both loops when start_index
was zero even for the first one.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/drivers/xen/gntdev/gntdev.c
+++ b/drivers/xen/gntdev/gntdev.c
@@ -285,35 +285,27 @@ static void compress_free_list(gntdev_fi
static int find_contiguous_free_range(gntdev_file_private_data_t *private_data,
uint32_t num_slots)
{
- uint32_t i, start_index = private_data->next_fit_index;
- uint32_t range_start = 0, range_length;
-
- /* First search from the start_index to the end of the array. */
- range_length = 0;
- for (i = start_index; i < private_data->grants_size; ++i) {
- if (private_data->grants[i].state == GNTDEV_SLOT_INVALID) {
- if (range_length == 0) {
- range_start = i;
- }
- ++range_length;
- if (range_length == num_slots) {
- return range_start;
- }
- }
- }
-
- /* Now search from the start of the array to the start_index. */
- range_length = 0;
- for (i = 0; i < start_index; ++i) {
- if (private_data->grants[i].state == GNTDEV_SLOT_INVALID) {
- if (range_length == 0) {
- range_start = i;
- }
- ++range_length;
- if (range_length == num_slots) {
- return range_start;
- }
- }
+ /* First search from next_fit_index to the end of the array. */
+ uint32_t start_index = private_data->next_fit_index;
+ uint32_t end_index = private_data->grants_size;
+
+ for (;;) {
+ uint32_t i, range_start = 0, range_length = 0;
+
+ for (i = start_index; i < end_index; ++i) {
+ if (private_data->grants[i].state == GNTDEV_SLOT_INVALID) {
+ if (range_length == 0)
+ range_start = i;
+ if (++range_length == num_slots)
+ return range_start;
+ } else
+ range_length = 0;
+ }
+ /* Now search from the start of the array to next_fit_index. */
+ if (!start_index)
+ break;
+ end_index = start_index;
+ start_index = 0;
}
return -ENOMEM;
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