This is a note to let you know that I've just added the patch titled Revert "xsk: Do not sleep in poll() when need_wakeup set" to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: revert-xsk-do-not-sleep-in-poll-when-need_wakeup-set.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 0706a78f31c4217ca144f630063ec9561a21548d Mon Sep 17 00:00:00 2001 From: Magnus Karlsson <magnus.karlsson@xxxxxxxxx> Date: Fri, 17 Dec 2021 15:56:46 +0100 Subject: Revert "xsk: Do not sleep in poll() when need_wakeup set" From: Magnus Karlsson <magnus.karlsson@xxxxxxxxx> 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@xxxxxxxxx> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Link: https://lore.kernel.org/bpf/20211217145646.26449-1-magnus.karlsson@xxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/xdp/xsk.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -434,6 +434,8 @@ static __poll_t xsk_poll(struct file *fi struct xdp_sock *xs = xdp_sk(sk); struct xdp_umem *umem; + sock_poll_wait(file, sock, wait); + if (unlikely(!xsk_is_bound(xs))) return mask; @@ -445,8 +447,6 @@ static __poll_t xsk_poll(struct file *fi else /* Poll needs to drive Tx also in copy mode */ __xsk_sendmsg(sk); - } else { - sock_poll_wait(file, sock, wait); } if (xs->rx && !xskq_empty_desc(xs->rx)) Patches currently in stable-queue which might be from magnus.karlsson@xxxxxxxxx are queue-5.4/revert-xsk-do-not-sleep-in-poll-when-need_wakeup-set.patch queue-5.4/xsk-do-not-sleep-in-poll-when-need_wakeup-set.patch