Revert "xsk: Do not sleep in poll() when need_wakeup set"

commit 0706a78f31c4217ca144f630063ec9561a21548d upstream.

This reverts commit bd0687c18e635b63233dc87f38058cd728802ab4.

This patch causes a Tx only workload to go to sleep even when it does
not have to, leading to misserable performance in skb mode. It fixed
one rare problem but created a much worse one, so this need to be
reverted while I try to craft a proper solution to the original
problem.

Fixes: bd0687c18e63 ("xsk: Do not sleep in poll() when need_wakeup set")
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211217145646.26449-1-magnus.karlsson@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index d942e1b..d6b500d 100644 (file)
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -692,6 +692,8 @@ static __poll_t xsk_poll(struct file *file, struct socket *sock,
        struct xdp_sock *xs = xdp_sk(sk);
        struct xsk_buff_pool *pool;
 
+       sock_poll_wait(file, sock, wait);
+
        if (unlikely(!xsk_is_bound(xs)))
                return mask;
 
@@ -703,8 +705,6 @@ static __poll_t xsk_poll(struct file *file, struct socket *sock,
                else
                        /* Poll needs to drive Tx also in copy mode */
                        __xsk_sendmsg(sk);
-       } else {
-               sock_poll_wait(file, sock, wait);
        }
 
        if (xs->rx && !xskq_prod_is_empty(xs->rx))