[PATCH] VM: zone reclaim atomic ops cleanup

Christoph Lameter and Marcelo Tosatti asked to get rid of the
atomic_inc_and_test() to cleanup the atomic ops in the zone reclaim code.

Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 6 insertions, 5 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 620aa11b24eb..d157dae8c9f3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1909,7 +1909,7 @@ static void __init free_area_init_core(struct pglist_data *pgdat,
                 zone->nr_scan_inactive = 0;
                 zone->nr_active = 0;
                 zone->nr_inactive = 0;
-                atomic_set(&zone->reclaim_in_progress, -1);
+                atomic_set(&zone->reclaim_in_progress, 0);
                 if (!size)
                         continue;
 
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ab631a3c62c3..0095533cdde9 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -822,6 +822,8 @@ shrink_zone(struct zone *zone, struct scan_control *sc)
         unsigned long nr_active;
         unsigned long nr_inactive;
 
+        atomic_inc(&zone->reclaim_in_progress);
+
         /*
          * Add one to `nr_to_scan' just to make sure that the kernel will
          * slowly sift through the active list.
@@ -861,6 +863,8 @@ shrink_zone(struct zone *zone, struct scan_control *sc)
         }
 
         throttle_vm_writeout();
+
+        atomic_dec(&zone->reclaim_in_progress);
 }
 
 /*
@@ -900,9 +904,7 @@ shrink_caches(struct zone **zones, struct scan_control *sc)
                 if (zone->all_unreclaimable && sc->priority != DEF_PRIORITY)
                         continue;       /* Let kswapd poll it */
 
-                atomic_inc(&zone->reclaim_in_progress);
                 shrink_zone(zone, sc);
-                atomic_dec(&zone->reclaim_in_progress);
         }
 }
  
@@ -1358,14 +1360,13 @@ int zone_reclaim(struct zone *zone, unsigned int gfp_mask, unsigned int order)
                 sc.swap_cluster_max = SWAP_CLUSTER_MAX;
 
         /* Don't reclaim the zone if there are other reclaimers active */
-        if (!atomic_inc_and_test(&zone->reclaim_in_progress))
+        if (atomic_read(&zone->reclaim_in_progress) > 0)
                 goto out;
 
         shrink_zone(zone, &sc);
         total_reclaimed = sc.nr_reclaimed;
 
  out:
-        atomic_dec(&zone->reclaim_in_progress);
         return total_reclaimed;
 }