mpls: Add mpls_dev_rcu().

mpls_dev_get() uses rcu_dereference_rtnl() to fetch dev->mpls_ptr.

We will replace RTNL with a dedicated mutex to protect the field.

Then, we will use rcu_dereference_protected() for clarity.

Let's add mpls_dev_rcu() for the RCU reader.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Link: https://patch.msgid.link/20251029173344.2934622-7-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index efc6c7da5766aa17e091f40c37179cbfbef87cee..10130b90c439a5b903b858cf9c8dfde4a124a69a 100644 (file)
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -136,7 +136,7 @@ void mpls_stats_inc_outucastpkts(struct net *net,
        struct mpls_dev *mdev;
 
        if (skb->protocol == htons(ETH_P_MPLS_UC)) {
-               mdev = mpls_dev_get(dev);
+               mdev = mpls_dev_rcu(dev);
                if (mdev)
                        MPLS_INC_STATS_LEN(mdev, skb->len,
                                           tx_packets,
@@ -358,7 +358,7 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
 
        /* Careful this entire function runs inside of an rcu critical section */
 
-       mdev = mpls_dev_get(dev);
+       mdev = mpls_dev_rcu(dev);
        if (!mdev)
                goto drop;
 
@@ -467,7 +467,7 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
        return 0;
 
 tx_err:
-       out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL;
+       out_mdev = out_dev ? mpls_dev_rcu(out_dev) : NULL;
        if (out_mdev)
                MPLS_INC_STATS(out_mdev, tx_errors);
        goto drop;
@@ -1118,7 +1118,7 @@ static int mpls_fill_stats_af(struct sk_buff *skb,
        struct mpls_dev *mdev;
        struct nlattr *nla;
 
-       mdev = mpls_dev_get(dev);
+       mdev = mpls_dev_rcu(dev);
        if (!mdev)
                return -ENODATA;
 
@@ -1138,7 +1138,7 @@ static size_t mpls_get_stats_af_size(const struct net_device *dev)
 {
        struct mpls_dev *mdev;
 
-       mdev = mpls_dev_get(dev);
+       mdev = mpls_dev_rcu(dev);
        if (!mdev)
                return 0;
 
@@ -1341,7 +1341,7 @@ static int mpls_netconf_dump_devconf(struct sk_buff *skb,
 
        rcu_read_lock();
        for_each_netdev_dump(net, dev, ctx->ifindex) {
-               mdev = mpls_dev_get(dev);
+               mdev = mpls_dev_rcu(dev);
                if (!mdev)
                        continue;
                err = mpls_netconf_fill_devconf(skb, mdev,

diff --git a/net/mpls/internal.h b/net/mpls/internal.h
index e491427ea08aea5571df7ec141737ae36c563bbe..080e820100222a196826fbeb7ca18c5965762d72 100644 (file)
--- a/net/mpls/internal.h
+++ b/net/mpls/internal.h
@@ -185,6 +185,11 @@ static inline struct mpls_entry_decoded mpls_entry_decode(struct mpls_shim_hdr *
        return result;
 }
 
+static inline struct mpls_dev *mpls_dev_rcu(const struct net_device *dev)
+{
+       return rcu_dereference(dev->mpls_ptr);
+}
+
 static inline struct mpls_dev *mpls_dev_get(const struct net_device *dev)
 {
        return rcu_dereference_rtnl(dev->mpls_ptr);

diff --git a/net/mpls/mpls_iptunnel.c b/net/mpls/mpls_iptunnel.c
index cfbab7b2fec739a572de4a689dff0b442587fb3c..1a1a0eb5b787f5916e789ed540606c5552519f97 100644 (file)
--- a/net/mpls/mpls_iptunnel.c
+++ b/net/mpls/mpls_iptunnel.c
@@ -153,7 +153,7 @@ static int mpls_xmit(struct sk_buff *skb)
        return LWTUNNEL_XMIT_DONE;
 
 drop:
-       out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL;
+       out_mdev = out_dev ? mpls_dev_rcu(out_dev) : NULL;
        if (out_mdev)
                MPLS_INC_STATS(out_mdev, tx_errors);
        kfree_skb(skb);