[PATCH net-next] ipv6: do not abuse GFP_ATOMIC in inet6_netconf_notify_devconf()

[Eric Dumazet]

From: Eric Dumazet <eduma...@google.com>

All inet6_netconf_notify_devconf() callers are in process context,
so we can use GFP_KERNEL allocations if we take care of not holding
a rwlock while not needed in ip6mr (we hold RTNL there)


Fixes: d67b8c616b48 ("netconf: advertise mc_forwarding status")
Fixes: f3a1bfb11ccb ("rtnl/ipv6: use netconf msg to advertise forwarding 
status")
Signed-off-by: Eric Dumazet <eduma...@google.com>
Cc: Nicolas Dichtel <nicolas.dich...@6wind.com>
---
 net/ipv6/addrconf.c |    4 ++--
 net/ipv6/ip6mr.c    |   13 +++++++------
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 
a1f6b7b315317f811cafbf386cf21dfc510c2010..24f1b0898e4013a45ce21cc73090607f9578131a
 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -547,7 +547,7 @@ void inet6_netconf_notify_devconf(struct net *net, int 
type, int ifindex,
        struct sk_buff *skb;
        int err = -ENOBUFS;
 
-       skb = nlmsg_new(inet6_netconf_msgsize_devconf(type), GFP_ATOMIC);
+       skb = nlmsg_new(inet6_netconf_msgsize_devconf(type), GFP_KERNEL);
        if (!skb)
                goto errout;
 
@@ -559,7 +559,7 @@ void inet6_netconf_notify_devconf(struct net *net, int 
type, int ifindex,
                kfree_skb(skb);
                goto errout;
        }
-       rtnl_notify(skb, net, 0, RTNLGRP_IPV6_NETCONF, NULL, GFP_ATOMIC);
+       rtnl_notify(skb, net, 0, RTNLGRP_IPV6_NETCONF, NULL, GFP_KERNEL);
        return;
 errout:
        rtnl_set_sk_err(net, RTNLGRP_IPV6_NETCONF, err);
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 
487ef3bc7bbcde7f3509b76b3a68aee9d2ab7e8b..c7ca0f5d1a3b7114abbf87db884ecb9c0fcfa8c6
 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -1592,14 +1592,15 @@ static int ip6mr_sk_init(struct mr6_table *mrt, struct 
sock *sk)
        if (likely(mrt->mroute6_sk == NULL)) {
                mrt->mroute6_sk = sk;
                net->ipv6.devconf_all->mc_forwarding++;
-               inet6_netconf_notify_devconf(net, NETCONFA_MC_FORWARDING,
-                                            NETCONFA_IFINDEX_ALL,
-                                            net->ipv6.devconf_all);
-       }
-       else
+       } else {
                err = -EADDRINUSE;
+       }
        write_unlock_bh(&mrt_lock);
 
+       if (!err)
+               inet6_netconf_notify_devconf(net, NETCONFA_MC_FORWARDING,
+                                            NETCONFA_IFINDEX_ALL,
+                                            net->ipv6.devconf_all);
        rtnl_unlock();
 
        return err;
@@ -1617,11 +1618,11 @@ int ip6mr_sk_done(struct sock *sk)
                        write_lock_bh(&mrt_lock);
                        mrt->mroute6_sk = NULL;
                        net->ipv6.devconf_all->mc_forwarding--;
+                       write_unlock_bh(&mrt_lock);
                        inet6_netconf_notify_devconf(net,
                                                     NETCONFA_MC_FORWARDING,
                                                     NETCONFA_IFINDEX_ALL,
                                                     net->ipv6.devconf_all);
-                       write_unlock_bh(&mrt_lock);
 
                        mroute_clean_tables(mrt, false);
                        err = 0;