netdev - Re: [PATCH v7 03/23] net/tls: export get_netdev_for

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Message-ID: <20221025161258.GC26372@lst.de>
Date:   Tue, 25 Oct 2022 18:12:58 +0200
From:   Christoph Hellwig <hch@....de>
To:     Aurelien Aptel <aaptel@...dia.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        edumazet@...gle.com, pabeni@...hat.com, saeedm@...dia.com,
        tariqt@...dia.com, leon@...nel.org, linux-nvme@...ts.infradead.org,
        sagi@...mberg.me, hch@....de, kbusch@...nel.org, axboe@...com,
        chaitanyak@...dia.com, smalin@...dia.com, ogerlitz@...dia.com,
        yorayz@...dia.com, borisp@...dia.com, aurelien.aptel@...il.com,
        malin1024@...il.com
Subject: Re: [PATCH v7 03/23] net/tls: export get_netdev_for_sock

Any reason to not just fold netdev_sk_get_lowest_dev into
get_netdev_for_sock?

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index eddf8ee270e74..10f47b157c683 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3040,8 +3040,7 @@ int 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);
 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 *dev_get_by_index_rcu(struct net *net, int ifindex);
diff --git a/net/core/dev.c b/net/core/dev.c
index 3be256051e99b..c180773e3dfd4 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8165,27 +8165,27 @@ 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
+ * netdev_sk_get_lowest_dev - Get the lowest device in socket
  * @sk: the socket
  *
- * %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)
 {
-	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);
-	}
-
+	dev_hold(dev);
+	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 a03d66046ca32..1eb92dab4f34f 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -120,22 +120,6 @@ 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;