[PATCH v23 04/20] net/tls,core: export get_netdev_for_sock

[Aurelien Aptel]

* remove netdev_sk_get_lowest_dev() from net/core
* move get_netdev_for_sock() from net/tls to net/core
* update exising users in net/tls/tls_device.c

get_netdev_for_sock() is a utility that is used to obtain
the net_device structure from a connected socket.

Later patches will use this for nvme-tcp DDP and DDP DDGST offloads.

Suggested-by: Christoph Hellwig <hch at lst.de>
Signed-off-by: Ben Ben-Ishay <benishay at nvidia.com>
Signed-off-by: Shai Malin <smalin at nvidia.com>
Signed-off-by: Aurelien Aptel <aaptel at nvidia.com>
---
 include/linux/netdevice.h |  5 +++--
 net/core/dev.c            | 30 +++++++++++++++++-------------
 net/tls/tls_device.c      | 31 +++++++++----------------------
 3 files changed, 29 insertions(+), 37 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 610d0530c9f9..9dda1a5f3dbb 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3209,8 +3209,9 @@ void init_dummy_netdev(struct net_device *dev);
 struct net_device *netdev_get_xmit_slave(struct net_device *dev,
 					 struct sk_buff *skb,
 					 bool all_slaves);
-struct net_device *netdev_sk_get_lowest_dev(struct net_device *dev,
-					    struct sock *sk);
+struct net_device *get_netdev_for_sock(struct sock *sk,
+				       netdevice_tracker *tracker,
+				       gfp_t gfp);
 struct net_device *dev_get_by_index(struct net *net, int ifindex);
 struct net_device *__dev_get_by_index(struct net *net, int ifindex);
 struct net_device *netdev_get_by_index(struct net *net, int ifindex,
diff --git a/net/core/dev.c b/net/core/dev.c
index cc9c2eda65ac..e839a6b4fdf3 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8315,27 +8315,31 @@ static struct net_device *netdev_sk_get_lower_dev(struct net_device *dev,
 }
 
 /**
- * netdev_sk_get_lowest_dev - Get the lowest device in chain given device and socket
- * @dev: device
+ * get_netdev_for_sock - Get the lowest device in socket
  * @sk: the socket
+ * @tracker: tracking object for the acquired reference
+ * @gfp: allocation flags for the tracker
  *
- * %NULL is returned if no lower device is found.
+ * Assumes that the socket is already connected.
+ * Returns the lower device or %NULL if no lower device is found.
  */
-
-struct net_device *netdev_sk_get_lowest_dev(struct net_device *dev,
-					    struct sock *sk)
+struct net_device *get_netdev_for_sock(struct sock *sk,
+				       netdevice_tracker *tracker,
+				       gfp_t gfp)
 {
-	struct net_device *lower;
+	struct dst_entry *dst = sk_dst_get(sk);
+	struct net_device *dev, *lower;
 
-	lower = netdev_sk_get_lower_dev(dev, sk);
-	while (lower) {
+	if (unlikely(!dst))
+		return NULL;
+	dev = dst->dev;
+	while ((lower = netdev_sk_get_lower_dev(dev, sk)))
 		dev = lower;
-		lower = netdev_sk_get_lower_dev(dev, sk);
-	}
-
+	netdev_hold(dev, tracker, gfp);
+	dst_release(dst);
 	return dev;
 }
-EXPORT_SYMBOL(netdev_sk_get_lowest_dev);
+EXPORT_SYMBOL_GPL(get_netdev_for_sock);
 
 static void netdev_adjacent_add_links(struct net_device *dev)
 {
diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index bf8ed36b1ad6..5868daf36ae2 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -119,22 +119,6 @@ static void tls_device_queue_ctx_destruction(struct tls_context *ctx)
 		tls_device_free_ctx(ctx);
 }
 
-/* We assume that the socket is already connected */
-static struct net_device *get_netdev_for_sock(struct sock *sk)
-{
-	struct dst_entry *dst = sk_dst_get(sk);
-	struct net_device *netdev = NULL;
-
-	if (likely(dst)) {
-		netdev = netdev_sk_get_lowest_dev(dst->dev, sk);
-		dev_hold(netdev);
-	}
-
-	dst_release(dst);
-
-	return netdev;
-}
-
 static void destroy_record(struct tls_record_info *record)
 {
 	int i;
@@ -1063,6 +1047,7 @@ int tls_set_device_offload(struct sock *sk)
 	struct tls_offload_context_tx *offload_ctx;
 	const struct tls_cipher_desc *cipher_desc;
 	struct tls_crypto_info *crypto_info;
+	netdevice_tracker netdev_tracker;
 	struct tls_prot_info *prot;
 	struct net_device *netdev;
 	struct tls_context *ctx;
@@ -1076,7 +1061,7 @@ int tls_set_device_offload(struct sock *sk)
 	if (ctx->priv_ctx_tx)
 		return -EEXIST;
 
-	netdev = get_netdev_for_sock(sk);
+	netdev = get_netdev_for_sock(sk, &netdev_tracker, GFP_KERNEL);
 	if (!netdev) {
 		pr_err_ratelimited("%s: netdev not found\n", __func__);
 		return -EINVAL;
@@ -1172,7 +1157,7 @@ int tls_set_device_offload(struct sock *sk)
 	 * by the netdev's xmit function.
 	 */
 	smp_store_release(&sk->sk_validate_xmit_skb, tls_validate_xmit_skb);
-	dev_put(netdev);
+	netdev_put(netdev, &netdev_tracker);
 
 	return 0;
 
@@ -1186,7 +1171,7 @@ int tls_set_device_offload(struct sock *sk)
 free_marker_record:
 	kfree(start_marker_record);
 release_netdev:
-	dev_put(netdev);
+	netdev_put(netdev, &netdev_tracker);
 	return rc;
 }
 
@@ -1194,13 +1179,15 @@ int tls_set_device_offload_rx(struct sock *sk, struct tls_context *ctx)
 {
 	struct tls12_crypto_info_aes_gcm_128 *info;
 	struct tls_offload_context_rx *context;
+	netdevice_tracker netdev_tracker;
 	struct net_device *netdev;
+
 	int rc = 0;
 
 	if (ctx->crypto_recv.info.version != TLS_1_2_VERSION)
 		return -EOPNOTSUPP;
 
-	netdev = get_netdev_for_sock(sk);
+	netdev = get_netdev_for_sock(sk, &netdev_tracker, GFP_KERNEL);
 	if (!netdev) {
 		pr_err_ratelimited("%s: netdev not found\n", __func__);
 		return -EINVAL;
@@ -1249,7 +1236,7 @@ int tls_set_device_offload_rx(struct sock *sk, struct tls_context *ctx)
 	tls_device_attach(ctx, sk, netdev);
 	up_read(&device_offload_lock);
 
-	dev_put(netdev);
+	netdev_put(netdev, &netdev_tracker);
 
 	return 0;
 
@@ -1262,7 +1249,7 @@ int tls_set_device_offload_rx(struct sock *sk, struct tls_context *ctx)
 release_lock:
 	up_read(&device_offload_lock);
 release_netdev:
-	dev_put(netdev);
+	netdev_put(netdev, &netdev_tracker);
 	return rc;
 }
 
-- 
2.34.1