From patchwork Wed May 4 16:45:05 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 569733 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 15D30C433EF for ; Wed, 4 May 2022 17:07:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345314AbiEDRLc (ORCPT ); Wed, 4 May 2022 13:11:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40790 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356918AbiEDRJt (ORCPT ); Wed, 4 May 2022 13:09:49 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C376547381; Wed, 4 May 2022 09:56:24 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id 7118BB82795; Wed, 4 May 2022 16:56:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 25D12C385A5; Wed, 4 May 2022 16:56:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651683382; bh=ubcQyke9vPFH9s6nU+Un2l/Q2Wf/PRFTnF/wUNLwwzo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Kl0snVSGz7jgGwKPfld7VSbDkcyyet/R3OIaORyILvA9AqOYo1Fq+V+9yhphWnsKE CQ7ErSGW5D8K9MSCq7qbJaSXEW++PuiMcNqNJDhNpSFwMlwYC3700SWV50YmAiZQw0 J2t1fwn7mIyEXRam5+90h64ggtgk7fV0Me5bHfkU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Maciej Fijalkowski , Daniel Borkmann , Sasha Levin Subject: [PATCH 5.17 067/225] xsk: Fix l2fwd for copy mode + busy poll combo Date: Wed, 4 May 2022 18:45:05 +0200 Message-Id: <20220504153117.092670935@linuxfoundation.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220504153110.096069935@linuxfoundation.org> References: <20220504153110.096069935@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Maciej Fijalkowski [ Upstream commit 8de8b71b787f38983d414d2dba169a3bfefa668a ] While checking AF_XDP copy mode combined with busy poll, strange results were observed. rxdrop and txonly scenarios worked fine, but l2fwd broke immediately. After a deeper look, it turned out that for l2fwd, Tx side was exiting early due to xsk_no_wakeup() returning true and in the end xsk_generic_xmit() was never called. Note that AF_XDP Tx in copy mode is syscall steered, so the current behavior is broken. Txonly scenario only worked due to the fact that sk_mark_napi_id_once_xdp() was never called - since Rx side is not in the picture for this case and mentioned function is called in xsk_rcv_check(), sk::sk_napi_id was never set, which in turn meant that xsk_no_wakeup() was returning false (see the sk->sk_napi_id >= MIN_NAPI_ID check in there). To fix this, prefer busy poll in xsk_sendmsg() only when zero copy is enabled on a given AF_XDP socket. By doing so, busy poll in copy mode would not exit early on Tx side and eventually xsk_generic_xmit() will be called. Fixes: a0731952d9cd ("xsk: Add busy-poll support for {recv,send}msg()") Signed-off-by: Maciej Fijalkowski Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220406155804.434493-1-maciej.fijalkowski@intel.com Signed-off-by: Sasha Levin --- net/xdp/xsk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index ac343cd8ff3f..39a82bfb5caa 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -640,7 +640,7 @@ static int __xsk_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len if (sk_can_busy_loop(sk)) sk_busy_loop(sk, 1); /* only support non-blocking sockets */ - if (xsk_no_wakeup(sk)) + if (xs->zc && xsk_no_wakeup(sk)) return 0; pool = xs->pool;