xsk: Skip polling event check for unbound socket

In xsk_poll(), checking available events and setting mask bits should
be executed only when a socket has been bound. Setting mask bits for
unbound socket is meaningless.

Currently, it checks events even when xsk_check_common() failed.
To prevent this, we move goto location (skip_tx) after that checking.

Fixes: 1596dae2f17e ("xsk: check IFF_UP earlier in Tx path")
Signed-off-by: Yewon Choi <woni9911@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20231201061048.GA1510@libra05

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index ae9f8cb611f6ca9b1bd0693fd5771198f7555d8f..3da0b52f308d4a4f4cd946301987fb246e25b76b 100644 (file)
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -947,7 +947,7 @@ static __poll_t xsk_poll(struct file *file, struct socket *sock,
 
        rcu_read_lock();
        if (xsk_check_common(xs))
-               goto skip_tx;
+               goto out;
 
        pool = xs->pool;
 
@@ -959,12 +959,11 @@ static __poll_t xsk_poll(struct file *file, struct socket *sock,
                        xsk_generic_xmit(sk);
        }
 
-skip_tx:
        if (xs->rx && !xskq_prod_is_empty(xs->rx))
                mask |= EPOLLIN | EPOLLRDNORM;
        if (xs->tx && xsk_tx_writeable(xs))
                mask |= EPOLLOUT | EPOLLWRNORM;
-
+out:
        rcu_read_unlock();
        return mask;
 }