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    Subject[PATCH 5.4 382/475] ipv6: make mc_forwarding atomic
    Date
    From: Eric Dumazet <edumazet@google.com>

    [ Upstream commit 145c7a793838add5e004e7d49a67654dc7eba147 ]

    This fixes minor data-races in ip6_mc_input() and
    batadv_mcast_mla_rtr_flags_softif_get_ipv6()

    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    include/linux/ipv6.h | 2 +-
    net/batman-adv/multicast.c | 2 +-
    net/ipv6/addrconf.c | 4 ++--
    net/ipv6/ip6_input.c | 2 +-
    net/ipv6/ip6mr.c | 8 ++++----
    5 files changed, 9 insertions(+), 9 deletions(-)

    diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
    index bbe297bbbca5..d5c507311efb 100644
    --- a/include/linux/ipv6.h
    +++ b/include/linux/ipv6.h
    @@ -50,7 +50,7 @@ struct ipv6_devconf {
    __s32 use_optimistic;
    #endif
    #ifdef CONFIG_IPV6_MROUTE
    - __s32 mc_forwarding;
    + atomic_t mc_forwarding;
    #endif
    __s32 disable_ipv6;
    __s32 drop_unicast_in_l2_multicast;
    diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
    index 09d81f9c2a64..6f0a9f439233 100644
    --- a/net/batman-adv/multicast.c
    +++ b/net/batman-adv/multicast.c
    @@ -136,7 +136,7 @@ static u8 batadv_mcast_mla_rtr_flags_softif_get_ipv6(struct net_device *dev)
    {
    struct inet6_dev *in6_dev = __in6_dev_get(dev);

    - if (in6_dev && in6_dev->cnf.mc_forwarding)
    + if (in6_dev && atomic_read(&in6_dev->cnf.mc_forwarding))
    return BATADV_NO_FLAGS;
    else
    return BATADV_MCAST_WANT_NO_RTR6;
    diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
    index 60d070b25484..69aef71f32ea 100644
    --- a/net/ipv6/addrconf.c
    +++ b/net/ipv6/addrconf.c
    @@ -542,7 +542,7 @@ static int inet6_netconf_fill_devconf(struct sk_buff *skb, int ifindex,
    #ifdef CONFIG_IPV6_MROUTE
    if ((all || type == NETCONFA_MC_FORWARDING) &&
    nla_put_s32(skb, NETCONFA_MC_FORWARDING,
    - devconf->mc_forwarding) < 0)
    + atomic_read(&devconf->mc_forwarding)) < 0)
    goto nla_put_failure;
    #endif
    if ((all || type == NETCONFA_PROXY_NEIGH) &&
    @@ -5460,7 +5460,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
    array[DEVCONF_USE_OPTIMISTIC] = cnf->use_optimistic;
    #endif
    #ifdef CONFIG_IPV6_MROUTE
    - array[DEVCONF_MC_FORWARDING] = cnf->mc_forwarding;
    + array[DEVCONF_MC_FORWARDING] = atomic_read(&cnf->mc_forwarding);
    #endif
    array[DEVCONF_DISABLE_IPV6] = cnf->disable_ipv6;
    array[DEVCONF_ACCEPT_DAD] = cnf->accept_dad;
    diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
    index 7e5df23cbe7b..e6c4966aa956 100644
    --- a/net/ipv6/ip6_input.c
    +++ b/net/ipv6/ip6_input.c
    @@ -485,7 +485,7 @@ int ip6_mc_input(struct sk_buff *skb)
    /*
    * IPv6 multicast router mode is now supported ;)
    */
    - if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
    + if (atomic_read(&dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding) &&
    !(ipv6_addr_type(&hdr->daddr) &
    (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
    likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
    diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
    index aee1f6bc039a..6248e00c2bf7 100644
    --- a/net/ipv6/ip6mr.c
    +++ b/net/ipv6/ip6mr.c
    @@ -736,7 +736,7 @@ static int mif6_delete(struct mr_table *mrt, int vifi, int notify,

    in6_dev = __in6_dev_get(dev);
    if (in6_dev) {
    - in6_dev->cnf.mc_forwarding--;
    + atomic_dec(&in6_dev->cnf.mc_forwarding);
    inet6_netconf_notify_devconf(dev_net(dev), RTM_NEWNETCONF,
    NETCONFA_MC_FORWARDING,
    dev->ifindex, &in6_dev->cnf);
    @@ -904,7 +904,7 @@ static int mif6_add(struct net *net, struct mr_table *mrt,

    in6_dev = __in6_dev_get(dev);
    if (in6_dev) {
    - in6_dev->cnf.mc_forwarding++;
    + atomic_inc(&in6_dev->cnf.mc_forwarding);
    inet6_netconf_notify_devconf(dev_net(dev), RTM_NEWNETCONF,
    NETCONFA_MC_FORWARDING,
    dev->ifindex, &in6_dev->cnf);
    @@ -1553,7 +1553,7 @@ static int ip6mr_sk_init(struct mr_table *mrt, struct sock *sk)
    } else {
    rcu_assign_pointer(mrt->mroute_sk, sk);
    sock_set_flag(sk, SOCK_RCU_FREE);
    - net->ipv6.devconf_all->mc_forwarding++;
    + atomic_inc(&net->ipv6.devconf_all->mc_forwarding);
    }
    write_unlock_bh(&mrt_lock);

    @@ -1586,7 +1586,7 @@ int ip6mr_sk_done(struct sock *sk)
    * so the RCU grace period before sk freeing
    * is guaranteed by sk_destruct()
    */
    - net->ipv6.devconf_all->mc_forwarding--;
    + atomic_dec(&net->ipv6.devconf_all->mc_forwarding);
    write_unlock_bh(&mrt_lock);
    inet6_netconf_notify_devconf(net, RTM_NEWNETCONF,
    NETCONFA_MC_FORWARDING,
    --
    2.35.1


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