Attached patch implements for_each_zone(zont_t *) which is a helper
macro to cleanup code of the form:
for (pgdat = pgdat_list; pgdat; pgdat = pgdat->node_next) {
for (i = 0; i < MAX_NR_ZONES; ++i) {
zone_t * z = pgdat->node_zones + i;
/* ... */
}
}
and replace it with:
for_each_zone(zone) {
/* ... */
}
This patch only replaces one use of the above loop with the new macro.
Pending code, however, currently in the full rmap patch uses
for_each_zone more extensively.
This is from Rik's 2.4-rmap patch and by William Irwin.
This patch requires the previous for_each_pgdat patch, but only to apply
cleanly.
Robert Love
diff -urN linux-2.5.27/include/linux/mmzone.h linux/include/linux/mmzone.h
--- linux-2.5.27/include/linux/mmzone.h Sat Jul 20 12:11:05 2002
+++ linux/include/linux/mmzone.h Sat Jul 20 13:00:48 2002
@@ -163,6 +163,43 @@
extern pg_data_t contig_page_data;
+/*
+ * next_zone - helper magic for for_each_zone()
+ * Thanks to William Lee Irwin III for this piece of ingenuity.
+ */
+static inline zone_t * next_zone(zone_t * zone)
+{
+ pg_data_t *pgdat = zone->zone_pgdat;
+
+ if (zone - pgdat->node_zones < MAX_NR_ZONES - 1)
+ zone++;
+ else if (pgdat->node_next) {
+ pgdat = pgdat->node_next;
+ zone = pgdat->node_zones;
+ } else
+ zone = NULL;
+
+ return zone;
+}
+
+/**
+ * for_each_zone - helper macro to iterate over all memory zones
+ * @zone - pointer to zone_t variable
+ *
+ * The user only needs to declare the zone variable, for_each_zone
+ * fills it in. This basically means for_each_zone() is an
+ * easier to read version of this piece of code:
+ *
+ * for (pgdat = pgdat_list; pgdat; pgdat = pgdat->node_next)
+ * for (i = 0; i < MAX_NR_ZONES; ++i) {
+ * zone_t * z = pgdat->node_zones + i;
+ * ...
+ * }
+ * }
+ */
+#define for_each_zone(zone) \
+ for (zone = pgdat_list->node_zones; zone; zone = next_zone(zone))
+
#ifndef CONFIG_DISCONTIGMEM
#define NODE_DATA(nid) (&contig_page_data)
diff -urN linux-2.5.27/mm/page_alloc.c linux/mm/page_alloc.c
--- linux-2.5.27/mm/page_alloc.c Sat Jul 20 12:11:07 2002
+++ linux/mm/page_alloc.c Sat Jul 20 13:00:48 2002
@@ -477,12 +477,12 @@
*/
unsigned int nr_free_pages(void)
{
- unsigned int i, sum = 0;
- pg_data_t *pgdat;
+ unsigned int sum;
+ zone_t *zone;
- for (pgdat = pgdat_list; pgdat; pgdat = pgdat->node_next)
- for (i = 0; i < MAX_NR_ZONES; ++i)
- sum += pgdat->node_zones[i].free_pages;
+ sum = 0;
+ for_each_zone(zone)
+ sum += zone->free_pages;
return sum;
}
-
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