[PATCH net-next 3/9] net: openvswitch: shrink the mask array if necessary

[xiangxia . m . yue]

From: Tonghao Zhang <xiangxia.m....@gmail.com>

When creating and inserting flow-mask, if there is no available
flow-mask, we realloc the mask array. When removing flow-mask,
if necessary, we shrink mask array.

Signed-off-by: Tonghao Zhang <xiangxia.m....@gmail.com>
---
 net/openvswitch/flow_table.c | 33 +++++++++++++++++++++++----------
 1 file changed, 23 insertions(+), 10 deletions(-)

diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
index 99954fa..9c72aab 100644
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -701,6 +701,23 @@ static struct table_instance *table_instance_expand(struct 
table_instance *ti,
        return table_instance_rehash(ti, ti->n_buckets * 2, ufid);
 }
 
+static void tbl_mask_array_delete_mask(struct mask_array *ma,
+                                      struct sw_flow_mask *mask)
+{
+       int i;
+
+       /* Remove the deleted mask pointers from the array */
+       for (i = 0; i < ma->max; i++) {
+               if (mask == ovsl_dereference(ma->masks[i])) {
+                       RCU_INIT_POINTER(ma->masks[i], NULL);
+                       ma->count--;
+                       kfree_rcu(mask, rcu);
+                       return;
+               }
+       }
+       BUG();
+}
+
 /* Remove 'mask' from the mask list, if it is not needed any more. */
 static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
 {
@@ -714,18 +731,14 @@ static void flow_mask_remove(struct flow_table *tbl, 
struct sw_flow_mask *mask)
 
                if (!mask->ref_count) {
                        struct mask_array *ma;
-                       int i;
 
                        ma = ovsl_dereference(tbl->mask_array);
-                       for (i = 0; i < ma->max; i++) {
-                               if (mask == ovsl_dereference(ma->masks[i])) {
-                                       RCU_INIT_POINTER(ma->masks[i], NULL);
-                                       ma->count--;
-                                       kfree_rcu(mask, rcu);
-                                       return;
-                               }
-                       }
-                       BUG();
+                       tbl_mask_array_delete_mask(ma, mask);
+
+                       /* Shrink the mask array if necessary. */
+                       if (ma->max >= (MASK_ARRAY_SIZE_MIN * 2) &&
+                           ma->count <= (ma->max / 3))
+                               tbl_mask_array_realloc(tbl, ma->max / 2);
                }
        }
 }
-- 
1.8.3.1