From: Ben Pfaff <blp@nicira.com>
Date: Mon, 21 Jul 2008 20:51:02 +0000 (-0700)
Subject: Don't use atomic_t for tracking table flow counts.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7d73c8bac528e3c997dcd070cf87c4383f809c4c;p=openvswitch

Don't use atomic_t for tracking table flow counts.

Changes to n_flows is already fully serialized by dp_mutex.
---

diff --git a/datapath/hwtable_dummy/hwtable_dummy.c b/datapath/hwtable_dummy/hwtable_dummy.c
index 6f7ed8c1..4c6e5372 100644
--- a/datapath/hwtable_dummy/hwtable_dummy.c
+++ b/datapath/hwtable_dummy/hwtable_dummy.c
@@ -63,7 +63,7 @@ struct sw_table_dummy {
 	struct sw_table swt;
 
 	unsigned int max_flows;
-	atomic_t n_flows;
+	unsigned int n_flows;
 	struct list_head flows;
 	struct list_head iter_flows;
 	unsigned long int next_serial;
@@ -151,8 +151,7 @@ static int table_dummy_delete(struct sw_table *swt,
 		    && (!strict || (flow->priority == priority)))
 			count += do_delete(swt, flow);
 	}
-	if (count)
-		atomic_sub(count, &td->n_flows);
+	td->n_flows -= count;
 	return count;
 }
 
@@ -201,8 +200,7 @@ static int table_dummy_timeout(struct datapath *dp, struct sw_table *swt)
 	spin_unlock_bh(&pending_free_lock);
 	mutex_unlock(&dp_mutex);
 
-	if (del_count)
-		atomic_sub(del_count, &td->n_flows);
+	td->n_flows -= del_count;
 	return del_count;
 }
 
@@ -256,7 +254,7 @@ static void table_dummy_stats(struct sw_table *swt,
 {
 	struct sw_table_dummy *td = (struct sw_table_dummy *) swt;
 	stats->name = "dummy";
-	stats->n_flows = atomic_read(&td->n_flows);
+	stats->n_flows = td->n_flows;
 	stats->max_flows = td->max_flows;
 }
 
@@ -280,7 +278,7 @@ static struct sw_table *table_dummy_create(void)
 	swt->stats = table_dummy_stats;
 
 	td->max_flows = DUMMY_MAX_FLOW;
-	atomic_set(&td->n_flows, 0);
+	td->n_flows = 0;
 	INIT_LIST_HEAD(&td->flows);
 	INIT_LIST_HEAD(&td->iter_flows);
 	td->next_serial = 0;
diff --git a/datapath/table-hash.c b/datapath/table-hash.c
index b7475e3b..202114b6 100644
--- a/datapath/table-hash.c
+++ b/datapath/table-hash.c
@@ -22,7 +22,7 @@ static void kmem_free(void *, size_t);
 struct sw_table_hash {
 	struct sw_table swt;
 	struct crc32 crc32;
-	atomic_t n_flows;
+	unsigned int n_flows;
 	unsigned int bucket_mask; /* Number of buckets minus 1. */
 	struct sw_flow **buckets;
 };
@@ -53,7 +53,7 @@ static int table_hash_insert(struct sw_table *swt, struct sw_flow *flow)
 
 	bucket = find_bucket(swt, &flow->key);
 	if (*bucket == NULL) {
-		atomic_inc(&th->n_flows);
+		th->n_flows++;
 		rcu_assign_pointer(*bucket, flow);
 		retval = 1;
 	} else {
@@ -106,8 +106,7 @@ static int table_hash_delete(struct sw_table *swt,
 				count += do_delete(bucket, flow);
 		}
 	}
-	if (count)
-		atomic_sub(count, &th->n_flows);
+	th->n_flows -= count;
 	return count;
 }
 
@@ -127,10 +126,9 @@ static int table_hash_timeout(struct datapath *dp, struct sw_table *swt)
 				dp_send_flow_expired(dp, flow);
 		}
 	}
+	th->n_flows -= count;
 	mutex_unlock(&dp_mutex);
 
-	if (count)
-		atomic_sub(count, &th->n_flows);
 	return count;
 }
 
@@ -189,7 +187,7 @@ static void table_hash_stats(struct sw_table *swt,
 {
 	struct sw_table_hash *th = (struct sw_table_hash *) swt;
 	stats->name = "hash";
-	stats->n_flows = atomic_read(&th->n_flows);
+	stats->n_flows = th->n_flows;
 	stats->max_flows = th->bucket_mask + 1;
 }
 
@@ -222,7 +220,7 @@ struct sw_table *table_hash_create(unsigned int polynomial,
 	swt->stats = table_hash_stats;
 
 	crc32_init(&th->crc32, polynomial);
-	atomic_set(&th->n_flows, 0);
+	th->n_flows = 0;
 
 	return swt;
 }
diff --git a/datapath/table-linear.c b/datapath/table-linear.c
index e4092996..e1274bf3 100644
--- a/datapath/table-linear.c
+++ b/datapath/table-linear.c
@@ -16,7 +16,7 @@ struct sw_table_linear {
 	struct sw_table swt;
 
 	unsigned int max_flows;
-	atomic_t n_flows;
+	unsigned int n_flows;
 	struct list_head flows;
 	struct list_head iter_flows;
 	unsigned long int next_serial;
@@ -61,10 +61,10 @@ static int table_linear_insert(struct sw_table *swt, struct sw_flow *flow)
 	}
 
 	/* Make sure there's room in the table. */
-	if (atomic_read(&tl->n_flows) >= tl->max_flows) {
+	if (tl->n_flows >= tl->max_flows) {
 		return 0;
 	}
-	atomic_inc(&tl->n_flows);
+	tl->n_flows++;
 
 	/* Insert the entry immediately in front of where we're pointing. */
 	flow->serial = tl->next_serial++;
@@ -96,8 +96,7 @@ static int table_linear_delete(struct sw_table *swt,
 				&& (!strict || (flow->priority == priority)))
 			count += do_delete(swt, flow);
 	}
-	if (count)
-		atomic_sub(count, &tl->n_flows);
+	tl->n_flows -= count;
 	return count;
 }
 
@@ -115,10 +114,8 @@ static int table_linear_timeout(struct datapath *dp, struct sw_table *swt)
 				dp_send_flow_expired(dp, flow);
 		}
 	}
+	tl->n_flows -= count;
 	mutex_unlock(&dp_mutex);
-
-	if (count)
-		atomic_sub(count, &tl->n_flows);
 	return count;
 }
 
@@ -163,7 +160,7 @@ static void table_linear_stats(struct sw_table *swt,
 {
 	struct sw_table_linear *tl = (struct sw_table_linear *) swt;
 	stats->name = "linear";
-	stats->n_flows = atomic_read(&tl->n_flows);
+	stats->n_flows = tl->n_flows;
 	stats->max_flows = tl->max_flows;
 }
 
@@ -187,7 +184,7 @@ struct sw_table *table_linear_create(unsigned int max_flows)
 	swt->stats = table_linear_stats;
 
 	tl->max_flows = max_flows;
-	atomic_set(&tl->n_flows, 0);
+	tl->n_flows = 0;
 	INIT_LIST_HEAD(&tl->flows);
 	INIT_LIST_HEAD(&tl->iter_flows);
 	tl->next_serial = 0;