[RFC PATCH bpf-next 01/12] xsk: remove rebind support

[Björn Töpel]

From: Björn Töpel <bjorn.to...@intel.com>

Supporting rebind, i.e. after a successful bind the process can call
bind again without closing the socket, makes the setup state machine
more complex. Let us constrain the state space, but not supporting
rebind.

Signed-off-by: Björn Töpel <bjorn.to...@intel.com>
---
 net/xdp/xsk.c | 30 +++++++++---------------------
 1 file changed, 9 insertions(+), 21 deletions(-)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 009c5af5bba5..e59ca8e2618d 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -236,14 +236,6 @@ static int xsk_init_queue(u32 entries, struct xsk_queue 
**queue,
        return 0;
 }
 
-static void __xsk_release(struct xdp_sock *xs)
-{
-       /* Wait for driver to stop using the xdp socket. */
-       synchronize_net();
-
-       dev_put(xs->dev);
-}
-
 static int xsk_release(struct socket *sock)
 {
        struct sock *sk = sock->sk;
@@ -260,7 +252,9 @@ static int xsk_release(struct socket *sock)
        local_bh_enable();
 
        if (xs->dev) {
-               __xsk_release(xs);
+               /* Wait for driver to stop using the xdp socket. */
+               synchronize_net();
+               dev_put(xs->dev);
                xs->dev = NULL;
        }
 
@@ -294,9 +288,8 @@ static int xsk_bind(struct socket *sock, struct sockaddr 
*addr, int addr_len)
 {
        struct sockaddr_xdp *sxdp = (struct sockaddr_xdp *)addr;
        struct sock *sk = sock->sk;
-       struct net_device *dev, *dev_curr;
        struct xdp_sock *xs = xdp_sk(sk);
-       struct xdp_umem *old_umem = NULL;
+       struct net_device *dev;
        int err = 0;
 
        if (addr_len < sizeof(struct sockaddr_xdp))
@@ -305,7 +298,11 @@ static int xsk_bind(struct socket *sock, struct sockaddr 
*addr, int addr_len)
                return -EINVAL;
 
        mutex_lock(&xs->mutex);
-       dev_curr = xs->dev;
+       if (xs->dev) {
+               err = -EBUSY;
+               goto out_release;
+       }
+
        dev = dev_get_by_index(sock_net(sk), sxdp->sxdp_ifindex);
        if (!dev) {
                err = -ENODEV;
@@ -352,7 +349,6 @@ static int xsk_bind(struct socket *sock, struct sockaddr 
*addr, int addr_len)
                }
 
                xdp_get_umem(umem_xs->umem);
-               old_umem = xs->umem;
                xs->umem = umem_xs->umem;
                sockfd_put(sock);
        } else if (!xs->umem || !xdp_umem_validate_queues(xs->umem)) {
@@ -364,14 +360,6 @@ static int xsk_bind(struct socket *sock, struct sockaddr 
*addr, int addr_len)
                xskq_set_umem(xs->umem->cq, &xs->umem->props);
        }
 
-       /* Rebind? */
-       if (dev_curr && (dev_curr != dev ||
-                        xs->queue_id != sxdp->sxdp_queue_id)) {
-               __xsk_release(xs);
-               if (old_umem)
-                       xdp_put_umem(old_umem);
-       }
-
        xs->dev = dev;
        xs->queue_id = sxdp->sxdp_queue_id;
 
-- 
2.14.1