Commit bd0687c1 authored by Magnus Karlsson's avatar Magnus Karlsson Committed by Daniel Borkmann

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

Do not sleep in poll() when the need_wakeup flag is set. When this
flag is set, the application needs to explicitly wake up the driver
with a syscall (poll, recvmsg, sendmsg, etc.) to guarantee that Rx
and/or Tx processing will be processed promptly. But the current code
in poll(), sleeps first then wakes up the driver. This means that no
driver processing will occur (baring any interrupts) until the timeout
has expired.

Fix this by checking the need_wakeup flag first and if set, wake the
driver and return to the application. Only if need_wakeup is not set
should the process sleep if there is a timeout set in the poll() call.

Fixes: 77cd0d7b ("xsk: add support for need_wakeup flag in AF_XDP rings")
Reported-by: default avatarKeith Wiles <keith.wiles@intel.com>
Signed-off-by: default avatarMagnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarMaciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/20211214102607.7677-1-magnus.karlsson@gmail.com
parent 0be2516f
......@@ -677,8 +677,6 @@ 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;
......@@ -690,6 +688,8 @@ 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))
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment