xsk: simplify AF_XDP socket teardown

Prior this commit, when the struct socket object was being released,
the UMEM did not have its reference count decreased. Instead, this was
done in the struct sock sk_destruct function.

There is no reason to keep the UMEM reference around when the socket
is being orphaned, so in this patch the xdp_put_mem is called in the
xsk_release function. This results in that the xsk_destruct function
can be removed!

Note that, it still holds that a struct xsk_sock reference might still
linger in the XSKMAP after the UMEM is released, e.g. if a user does
not clear the XSKMAP prior to closing the process. This sock will be
in a "released" zombie like state, until the XSKMAP is removed.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 07156f43d29593ffad99dbd14827fc6352969413..a03268454a2762d12b9dec3e0d3858869e34b742 100644 (file)
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -366,6 +366,7 @@ static int xsk_release(struct socket *sock)
 
        xskq_destroy(xs->rx);
        xskq_destroy(xs->tx);
+       xdp_put_umem(xs->umem);
 
        sock_orphan(sk);
        sock->sk = NULL;
@@ -713,18 +714,6 @@ static const struct proto_ops xsk_proto_ops = {
        .sendpage       = sock_no_sendpage,
 };
 
-static void xsk_destruct(struct sock *sk)
-{
-       struct xdp_sock *xs = xdp_sk(sk);
-
-       if (!sock_flag(sk, SOCK_DEAD))
-               return;
-
-       xdp_put_umem(xs->umem);
-
-       sk_refcnt_debug_dec(sk);
-}
-
 static int xsk_create(struct net *net, struct socket *sock, int protocol,
                      int kern)
 {
@@ -751,9 +740,6 @@ static int xsk_create(struct net *net, struct socket *sock, int protocol,
 
        sk->sk_family = PF_XDP;
 
-       sk->sk_destruct = xsk_destruct;
-       sk_refcnt_debug_inc(sk);
-
        sock_set_flag(sk, SOCK_RCU_FREE);
 
        xs = xdp_sk(sk);