netns: Remove __peernet2id_alloc()

__peernet2id_alloc() was used for both plain lookups and for netns ID
allocations (depending the value of '*alloc'). Let's separate lookups
from allocations instead. That is, integrate the lookup code into
__peernet2id() and make peernet2id_alloc() responsible for allocating
new netns IDs when necessary.

This makes it clear that __peernet2id() doesn't modify the idr and
prepares the code for lockless lookups.

Also, mark the 'net' argument of __peernet2id() as 'const', since we're
modifying this line.

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 3940284..05e07d2 100644 (file)
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -211,16 +211,10 @@ static int net_eq_idr(int id, void *net, void *peer)
        return 0;
 }
 
-/* Should be called with nsid_lock held. If a new id is assigned, the bool alloc
- * is set to true, thus the caller knows that the new id must be notified via
- * rtnl.
- */
-static int __peernet2id_alloc(struct net *net, struct net *peer, bool *alloc)
+/* Should be called with nsid_lock held. */
+static int __peernet2id(const struct net *net, struct net *peer)
 {
        int id = idr_for_each(&net->netns_ids, net_eq_idr, peer);
-       bool alloc_it = *alloc;
-
-       *alloc = false;
 
        /* Magic value for id 0. */
        if (id == NET_ID_ZERO)
@@ -228,23 +222,9 @@ static int __peernet2id_alloc(struct net *net, struct net *peer, bool *alloc)
        if (id > 0)
                return id;
 
-       if (alloc_it) {
-               id = alloc_netid(net, peer, -1);
-               *alloc = true;
-               return id >= 0 ? id : NETNSA_NSID_NOT_ASSIGNED;
-       }
-
        return NETNSA_NSID_NOT_ASSIGNED;
 }
 
-/* should be called with nsid_lock held */
-static int __peernet2id(struct net *net, struct net *peer)
-{
-       bool no = false;
-
-       return __peernet2id_alloc(net, peer, &no);
-}
-
 static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
                              struct nlmsghdr *nlh, gfp_t gfp);
 /* This function returns the id of a peer netns. If no id is assigned, one will
@@ -252,26 +232,37 @@ static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
  */
 int peernet2id_alloc(struct net *net, struct net *peer, gfp_t gfp)
 {
-       bool alloc = false, alive = false;
        int id;
 
        if (refcount_read(&net->count) == 0)
                return NETNSA_NSID_NOT_ASSIGNED;
+
        spin_lock_bh(&net->nsid_lock);
-       /*
-        * When peer is obtained from RCU lists, we may race with
+       id = __peernet2id(net, peer);
+       if (id >= 0) {
+               spin_unlock_bh(&net->nsid_lock);
+               return id;
+       }
+
+       /* When peer is obtained from RCU lists, we may race with
         * its cleanup. Check whether it's alive, and this guarantees
         * we never hash a peer back to net->netns_ids, after it has
         * just been idr_remove()'d from there in cleanup_net().
         */
-       if (maybe_get_net(peer))
-               alive = alloc = true;
-       id = __peernet2id_alloc(net, peer, &alloc);
+       if (!maybe_get_net(peer)) {
+               spin_unlock_bh(&net->nsid_lock);
+               return NETNSA_NSID_NOT_ASSIGNED;
+       }
+
+       id = alloc_netid(net, peer, -1);
        spin_unlock_bh(&net->nsid_lock);
-       if (alloc && id >= 0)
-               rtnl_net_notifyid(net, RTM_NEWNSID, id, 0, NULL, gfp);
-       if (alive)
-               put_net(peer);
+
+       put_net(peer);
+       if (id < 0)
+               return NETNSA_NSID_NOT_ASSIGNED;
+
+       rtnl_net_notifyid(net, RTM_NEWNSID, id, 0, NULL, gfp);
+
        return id;
 }
 EXPORT_SYMBOL_GPL(peernet2id_alloc);