From: Magnus Karlsson magnus.karlsson@intel.com
stable inclusion from stable-v5.10.88 commit 0413f7a1a53306bc7a0b7e4d6f5dbf94761db406 bugzilla: 186058 https://gitee.com/openeuler/kernel/issues/I4QW6A
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
--------------------------------
commit bd0687c18e635b63233dc87f38058cd728802ab4 upstream.
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: 77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") Reported-by: Keith Wiles keith.wiles@intel.com Signed-off-by: Magnus Karlsson magnus.karlsson@intel.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Maciej Fijalkowski maciej.fijalkowski@intel.com Link: https://lore.kernel.org/bpf/20211214102607.7677-1-magnus.karlsson@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Chen Jun chenjun102@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- net/xdp/xsk.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index ca4716b92774..12112f4b9f7c 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -499,8 +499,6 @@ 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;
@@ -512,6 +510,8 @@ 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))