From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB08DC433FE for ; Mon, 20 Dec 2021 15:18:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239391AbhLTPSe (ORCPT ); Mon, 20 Dec 2021 10:18:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237687AbhLTPRV (ORCPT ); Mon, 20 Dec 2021 10:17:21 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 83966C08E9BA; Mon, 20 Dec 2021 06:58:30 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 256FE61183; Mon, 20 Dec 2021 14:58:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F42BC36AE7; Mon, 20 Dec 2021 14:58:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1640012309; bh=Im4tbQPwP58RFUcR/Ks3T2gBkUksFtFY3ChGZAR2pjM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lcokpnYVXg33JOyRb4W6H9+xQoGXXxU4kiwgjqFtOIqtUDOjpbcPrVEynehpLAmDV 20U5vwEXVCI2K99+UTObsDaf1zcBUDJrKXtNpF5p4M/Y4MoEBgqV0mWsb5NfxdQDgS MM+oZQo3hVa4WZnMdwJaBSFYS5RDKn2rLM/lYsPc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Keith Wiles , Magnus Karlsson , Daniel Borkmann , Maciej Fijalkowski Subject: [PATCH 5.15 155/177] xsk: Do not sleep in poll() when need_wakeup set Date: Mon, 20 Dec 2021 15:35:05 +0100 Message-Id: <20211220143045.289751892@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211220143040.058287525@linuxfoundation.org> References: <20211220143040.058287525@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Magnus Karlsson 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 Signed-off-by: Magnus Karlsson Signed-off-by: Daniel Borkmann Acked-by: Maciej Fijalkowski Link: https://lore.kernel.org/bpf/20211214102607.7677-1-magnus.karlsson@gmail.com Signed-off-by: Greg Kroah-Hartman --- net/xdp/xsk.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -692,8 +692,6 @@ static __poll_t xsk_poll(struct file *fi 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; @@ -705,6 +703,8 @@ 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_prod_is_empty(xs->rx))