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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>
This commit is contained in:
Kuniyuki Iwashima 2025-10-29 17:32:58 +00:00 committed by Jakub Kicinski
parent bc7ebc569e
commit ab061f3347
3 changed files with 12 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
net/mpls/af_mpls.c
View File

@ -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,

5
net/mpls/internal.h
View File

@ -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);

2
net/mpls/mpls_iptunnel.c
View File

@ -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);