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ip6mr: ip6mr_cache_report() changes
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ip6mr_cache_report() first argument can be marked const, and we change
the caller convention about which lock needs to be held.

Instead of read_lock(&mrt_lock), we can use rcu_read_lock().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Eric Dumazet authored and David S. Miller committed Jun 24, 2022
1 parent e4cd986 commit 3493a5b
Showing 1 changed file with 20 additions and 15 deletions.
35 changes: 20 additions & 15 deletions net/ipv6/ip6mr.c
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Original file line number Diff line number Diff line change
Expand Up @@ -91,11 +91,11 @@ static void ip6mr_free_table(struct mr_table *mrt);
static void ip6_mr_forward(struct net *net, struct mr_table *mrt,
struct net_device *dev, struct sk_buff *skb,
struct mfc6_cache *cache);
static int ip6mr_cache_report(struct mr_table *mrt, struct sk_buff *pkt,
static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt,
mifi_t mifi, int assert);
static void mr6_netlink_event(struct mr_table *mrt, struct mfc6_cache *mfc,
int cmd);
static void mrt6msg_netlink_event(struct mr_table *mrt, struct sk_buff *pkt);
static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pkt);
static int ip6mr_rtm_dumproute(struct sk_buff *skb,
struct netlink_callback *cb);
static void mroute_clean_tables(struct mr_table *mrt, int flags);
Expand Down Expand Up @@ -608,11 +608,12 @@ static netdev_tx_t reg_vif_xmit(struct sk_buff *skb,
if (ip6mr_fib_lookup(net, &fl6, &mrt) < 0)
goto tx_err;

read_lock(&mrt_lock);
dev->stats.tx_bytes += skb->len;
dev->stats.tx_packets++;
ip6mr_cache_report(mrt, skb, mrt->mroute_reg_vif_num, MRT6MSG_WHOLEPKT);
read_unlock(&mrt_lock);
rcu_read_lock();
ip6mr_cache_report(mrt, skb, READ_ONCE(mrt->mroute_reg_vif_num),
MRT6MSG_WHOLEPKT);
rcu_read_unlock();
kfree_skb(skb);
return NETDEV_TX_OK;

Expand Down Expand Up @@ -718,8 +719,10 @@ static int mif6_delete(struct mr_table *mrt, int vifi, int notify,
RCU_INIT_POINTER(v->dev, NULL);

#ifdef CONFIG_IPV6_PIMSM_V2
if (vifi == mrt->mroute_reg_vif_num)
mrt->mroute_reg_vif_num = -1;
if (vifi == mrt->mroute_reg_vif_num) {
/* Pairs with READ_ONCE() in ip6mr_cache_report() and reg_vif_xmit() */
WRITE_ONCE(mrt->mroute_reg_vif_num, -1);
}
#endif

if (vifi + 1 == mrt->maxvif) {
Expand Down Expand Up @@ -922,7 +925,7 @@ static int mif6_add(struct net *net, struct mr_table *mrt,
netdev_tracker_alloc(dev, &v->dev_tracker, GFP_ATOMIC);
#ifdef CONFIG_IPV6_PIMSM_V2
if (v->flags & MIFF_REGISTER)
mrt->mroute_reg_vif_num = vifi;
WRITE_ONCE(mrt->mroute_reg_vif_num, vifi);
#endif
if (vifi + 1 > mrt->maxvif)
mrt->maxvif = vifi + 1;
Expand Down Expand Up @@ -1033,10 +1036,10 @@ static void ip6mr_cache_resolve(struct net *net, struct mr_table *mrt,
/*
* Bounce a cache query up to pim6sd and netlink.
*
* Called under mrt_lock.
* Called under rcu_read_lock()
*/

static int ip6mr_cache_report(struct mr_table *mrt, struct sk_buff *pkt,
static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt,
mifi_t mifi, int assert)
{
struct sock *mroute6_sk;
Expand Down Expand Up @@ -1077,7 +1080,7 @@ static int ip6mr_cache_report(struct mr_table *mrt, struct sk_buff *pkt,
if (assert == MRT6MSG_WRMIFWHOLE)
msg->im6_mif = mifi;
else
msg->im6_mif = mrt->mroute_reg_vif_num;
msg->im6_mif = READ_ONCE(mrt->mroute_reg_vif_num);
msg->im6_pad = 0;
msg->im6_src = ipv6_hdr(pkt)->saddr;
msg->im6_dst = ipv6_hdr(pkt)->daddr;
Expand Down Expand Up @@ -1112,10 +1115,8 @@ static int ip6mr_cache_report(struct mr_table *mrt, struct sk_buff *pkt,
skb->ip_summed = CHECKSUM_UNNECESSARY;
}

rcu_read_lock();
mroute6_sk = rcu_dereference(mrt->mroute_sk);
if (!mroute6_sk) {
rcu_read_unlock();
kfree_skb(skb);
return -EINVAL;
}
Expand All @@ -1124,7 +1125,7 @@ static int ip6mr_cache_report(struct mr_table *mrt, struct sk_buff *pkt,

/* Deliver to user space multicast routing algorithms */
ret = sock_queue_rcv_skb(mroute6_sk, skb);
rcu_read_unlock();

if (ret < 0) {
net_warn_ratelimited("mroute6: pending queue full, dropping entries\n");
kfree_skb(skb);
Expand Down Expand Up @@ -2042,7 +2043,9 @@ static int ip6mr_forward2(struct net *net, struct mr_table *mrt,
vif->bytes_out += skb->len;
vif_dev->stats.tx_bytes += skb->len;
vif_dev->stats.tx_packets++;
rcu_read_lock();
ip6mr_cache_report(mrt, skb, vifi, MRT6MSG_WHOLEPKT);
rcu_read_unlock();
goto out_free;
}
#endif
Expand Down Expand Up @@ -2155,10 +2158,12 @@ static void ip6_mr_forward(struct net *net, struct mr_table *mrt,
c->_c.mfc_un.res.last_assert +
MFC_ASSERT_THRESH)) {
c->_c.mfc_un.res.last_assert = jiffies;
rcu_read_lock();
ip6mr_cache_report(mrt, skb, true_vifi, MRT6MSG_WRONGMIF);
if (mrt->mroute_do_wrvifwhole)
ip6mr_cache_report(mrt, skb, true_vifi,
MRT6MSG_WRMIFWHOLE);
rcu_read_unlock();
}
goto dont_forward;
}
Expand Down Expand Up @@ -2465,7 +2470,7 @@ static size_t mrt6msg_netlink_msgsize(size_t payloadlen)
return len;
}

static void mrt6msg_netlink_event(struct mr_table *mrt, struct sk_buff *pkt)
static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pkt)
{
struct net *net = read_pnet(&mrt->net);
struct nlmsghdr *nlh;
Expand Down

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