netdev - [PATCH net-next 07/11] virtio_net: Use existing classifier if possible

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Message-ID: <20250827183852.2471-8-danielj@nvidia.com>
Date: Wed, 27 Aug 2025 13:38:48 -0500
From: Daniel Jurgens <danielj@...dia.com>
To: <netdev@...r.kernel.org>, <mst@...hat.com>, <jasowang@...hat.com>,
	<alex.williamson@...hat.com>, <virtualization@...ts.linux.dev>,
	<pabeni@...hat.com>
CC: <parav@...dia.com>, <shshitrit@...dia.com>, <yohadt@...dia.com>, "Daniel
 Jurgens" <danielj@...dia.com>
Subject: [PATCH net-next 07/11] virtio_net: Use existing classifier if possible

Classifiers can be used by more than one rule. If there is an exisitng
classifier, use it instead of creating a new one.

Signed-off-by: Daniel Jurgens <danielj@...dia.com>
Reviewed-by: Parav Pandit <parav@...dia.com>
Reviewed-by: Shahar Shitrit <shshitrit@...dia.com>
---
 drivers/net/virtio_net/virtio_net_ff.c | 39 ++++++++++++++++++--------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/drivers/net/virtio_net/virtio_net_ff.c b/drivers/net/virtio_net/virtio_net_ff.c
index 473c2f169cfa..ebdac1fb49dd 100644
--- a/drivers/net/virtio_net/virtio_net_ff.c
+++ b/drivers/net/virtio_net/virtio_net_ff.c
@@ -17,6 +17,7 @@ struct virtnet_ethtool_rule {
 /* New fields must be added before the classifier struct */
 struct virtnet_classifier {
 	size_t size;
+	refcount_t refcount;
 	u32 id;
 	struct virtio_net_resource_obj_ff_classifier classifier;
 };
@@ -105,11 +106,24 @@ static bool validate_mask(const struct virtnet_ff *ff,
 	return false;
 }
 
-static int setup_classifier(struct virtnet_ff *ff, struct virtnet_classifier *c)
+static int setup_classifier(struct virtnet_ff *ff,
+			    struct virtnet_classifier **c)
 {
+	struct virtnet_classifier *tmp;
+	unsigned long i;
 	int err;
 
-	err = xa_alloc(&ff->classifiers, &c->id, c,
+	xa_for_each(&ff->classifiers, i, tmp) {
+		if ((*c)->size == tmp->size &&
+		    !memcmp(&tmp->classifier, &(*c)->classifier, tmp->size)) {
+			refcount_inc(&tmp->refcount);
+			kfree(*c);
+			*c = tmp;
+			goto out;
+		}
+	}
+
+	err = xa_alloc(&ff->classifiers, &(*c)->id, *c,
 		       XA_LIMIT(0, ff->ff_caps->classifiers_limit - 1),
 		       GFP_KERNEL);
 	if (err)
@@ -117,27 +131,28 @@ static int setup_classifier(struct virtnet_ff *ff, struct virtnet_classifier *c)
 
 	err = virtio_device_object_create(ff->vdev,
 					  VIRTIO_NET_RESOURCE_OBJ_FF_CLASSIFIER,
-					  c->id,
-					  &c->classifier,
-					  c->size);
+					  (*c)->id,
+					  &(*c)->classifier,
+					  (*c)->size);
 	if (err)
 		goto err_xarray;
 
+	refcount_set(&(*c)->refcount, 1);
+out:
 	return 0;
 
 err_xarray:
-	xa_erase(&ff->classifiers, c->id);
+	xa_erase(&ff->classifiers, (*c)->id);
 
 	return err;
 }
 
-static void destroy_classifier(struct virtnet_ff *ff,
-			       u32 classifier_id)
+static void try_destroy_classifier(struct virtnet_ff *ff, u32 classifier_id)
 {
 	struct virtnet_classifier *c;
 
 	c = xa_load(&ff->classifiers, classifier_id);
-	if (c) {
+	if (c && refcount_dec_and_test(&c->refcount)) {
 		virtio_device_object_destroy(ff->vdev,
 					     VIRTIO_NET_RESOURCE_OBJ_FF_CLASSIFIER,
 					     c->id);
@@ -157,7 +172,7 @@ static void destroy_ethtool_rule(struct virtnet_ff *ff,
 				     eth_rule->flow_spec.location);
 
 	xa_erase(&ff->ethtool.rules, eth_rule->flow_spec.location);
-	destroy_classifier(ff, eth_rule->classifier_id);
+	try_destroy_classifier(ff, eth_rule->classifier_id);
 	kfree(eth_rule);
 }
 
@@ -338,13 +353,13 @@ static int build_and_insert(struct virtnet_ff *ff,
 	if (err)
 		goto err_key;
 
-	err = setup_classifier(ff, c);
+	err = setup_classifier(ff, &c);
 	if (err)
 		goto err_classifier;
 
 	err = insert_rule(ff, eth_rule, c->id, key, key_size);
 	if (err) {
-		destroy_classifier(ff, c->id);
+		try_destroy_classifier(ff, c->id);
 		goto err_key;
 	}
 
-- 
2.50.1