netns: don't disable BHs when locking "nsid_lock"

When peernet2id() had to lock "nsid_lock" before iterating through the
nsid table, we had to disable BHs, because VXLAN can call peernet2id()
from the xmit path:
  vxlan_xmit() -> vxlan_fdb_miss() -> vxlan_fdb_notify()
    -> __vxlan_fdb_notify() -> vxlan_fdb_info() -> peernet2id().

Now that peernet2id() uses RCU protection, "nsid_lock" isn't used in BH
context anymore. Therefore, we can safely use plain
spin_lock()/spin_unlock() and let BHs run when holding "nsid_lock".

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index e7a5ff4..6412c1f 100644 (file)
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -237,10 +237,10 @@ int peernet2id_alloc(struct net *net, struct net *peer, gfp_t gfp)
        if (refcount_read(&net->count) == 0)
                return NETNSA_NSID_NOT_ASSIGNED;
 
-       spin_lock_bh(&net->nsid_lock);
+       spin_lock(&net->nsid_lock);
        id = __peernet2id(net, peer);
        if (id >= 0) {
-               spin_unlock_bh(&net->nsid_lock);
+               spin_unlock(&net->nsid_lock);
                return id;
        }
 
@@ -250,12 +250,12 @@ int peernet2id_alloc(struct net *net, struct net *peer, gfp_t gfp)
         * just been idr_remove()'d from there in cleanup_net().
         */
        if (!maybe_get_net(peer)) {
-               spin_unlock_bh(&net->nsid_lock);
+               spin_unlock(&net->nsid_lock);
                return NETNSA_NSID_NOT_ASSIGNED;
        }
 
        id = alloc_netid(net, peer, -1);
-       spin_unlock_bh(&net->nsid_lock);
+       spin_unlock(&net->nsid_lock);
 
        put_net(peer);
        if (id < 0)
@@ -520,20 +520,20 @@ static void unhash_nsid(struct net *net, struct net *last)
        for_each_net(tmp) {
                int id;
 
-               spin_lock_bh(&tmp->nsid_lock);
+               spin_lock(&tmp->nsid_lock);
                id = __peernet2id(tmp, net);
                if (id >= 0)
                        idr_remove(&tmp->netns_ids, id);
-               spin_unlock_bh(&tmp->nsid_lock);
+               spin_unlock(&tmp->nsid_lock);
                if (id >= 0)
                        rtnl_net_notifyid(tmp, RTM_DELNSID, id, 0, NULL,
                                          GFP_KERNEL);
                if (tmp == last)
                        break;
        }
-       spin_lock_bh(&net->nsid_lock);
+       spin_lock(&net->nsid_lock);
        idr_destroy(&net->netns_ids);
-       spin_unlock_bh(&net->nsid_lock);
+       spin_unlock(&net->nsid_lock);
 }
 
 static LLIST_HEAD(cleanup_list);
@@ -746,9 +746,9 @@ static int rtnl_net_newid(struct sk_buff *skb, struct nlmsghdr *nlh,
                return PTR_ERR(peer);
        }
 
-       spin_lock_bh(&net->nsid_lock);
+       spin_lock(&net->nsid_lock);
        if (__peernet2id(net, peer) >= 0) {
-               spin_unlock_bh(&net->nsid_lock);
+               spin_unlock(&net->nsid_lock);
                err = -EEXIST;
                NL_SET_BAD_ATTR(extack, nla);
                NL_SET_ERR_MSG(extack,
@@ -757,7 +757,7 @@ static int rtnl_net_newid(struct sk_buff *skb, struct nlmsghdr *nlh,
        }
 
        err = alloc_netid(net, peer, nsid);
-       spin_unlock_bh(&net->nsid_lock);
+       spin_unlock(&net->nsid_lock);
        if (err >= 0) {
                rtnl_net_notifyid(net, RTM_NEWNSID, err, NETLINK_CB(skb).portid,
                                  nlh, GFP_KERNEL);