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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 842DAC2D0DB for ; Wed, 22 Jan 2020 09:46:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 596D72468A for ; Wed, 22 Jan 2020 09:46:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579686410; bh=1uSgDFWlOyqmdj8luV1rCXcZUiJea10XFnyoKQ6D5QQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=QsUjqkLqwu1FYdlhsikIGnCY9w4h0wOljtl1qSQjAYt4Kuqb5vtw1zddKp+ECI+w+ oLNuvXMfjFsu7DEWgQtCuO/jd00d2PX5jbtKW1wk3F2w0Oc+ydPfqECrxx+OWJyWOP zcEmJwn6yuDU3r3so05++Jyo8FgxquzDEpBwBXGM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387840AbgAVJnL (ORCPT ); Wed, 22 Jan 2020 04:43:11 -0500 Received: from mail.kernel.org ([198.145.29.99]:35488 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387837AbgAVJnK (ORCPT ); Wed, 22 Jan 2020 04:43:10 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 745842467B; Wed, 22 Jan 2020 09:43:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579686189; bh=1uSgDFWlOyqmdj8luV1rCXcZUiJea10XFnyoKQ6D5QQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yQ1oSkCs9o397YJzqOg9BAAzisMjQm0voFhXVHdtfPNVfTerTRVqZF/OOIH8Sy93o 5mIrQCyIeo9CYzqoVsA6pj47giCEWivLBnGrLYQhtYfyQzn2rkwJjNIt+HnZlAr2K+ Artl98dN6x4keC2YGJbtI+7thV7sBH79sg1ldgO0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Jason Baron , Neal Cardwell , Soheil Hassas Yeganeh , Jakub Kicinski Subject: [PATCH 4.19 080/103] tcp: refine rule to allow EPOLLOUT generation under mem pressure Date: Wed, 22 Jan 2020 10:29:36 +0100 Message-Id: <20200122092814.811302071@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200122092803.587683021@linuxfoundation.org> References: <20200122092803.587683021@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Dumazet commit 216808c6ba6d00169fd2aa928ec3c0e63bef254f upstream. At the time commit ce5ec440994b ("tcp: ensure epoll edge trigger wakeup when write queue is empty") was added to the kernel, we still had a single write queue, combining rtx and write queues. Once we moved the rtx queue into a separate rb-tree, testing if sk_write_queue is empty has been suboptimal. Indeed, if we have packets in the rtx queue, we probably want to delay the EPOLLOUT generation at the time incoming packets will free them, making room, but more importantly avoiding flooding application with EPOLLOUT events. Solution is to use tcp_rtx_and_write_queues_empty() helper. Fixes: 75c119afe14f ("tcp: implement rb-tree based retransmit queue") Signed-off-by: Eric Dumazet Cc: Jason Baron Cc: Neal Cardwell Acked-by: Soheil Hassas Yeganeh Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1077,8 +1077,7 @@ do_error: goto out; out_err: /* make sure we wake any epoll edge trigger waiter */ - if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && - err == -EAGAIN)) { + if (unlikely(tcp_rtx_and_write_queues_empty(sk) && err == -EAGAIN)) { sk->sk_write_space(sk); tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED); } @@ -1437,8 +1436,7 @@ out_err: sock_zerocopy_put_abort(uarg); err = sk_stream_error(sk, flags, err); /* make sure we wake any epoll edge trigger waiter */ - if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && - err == -EAGAIN)) { + if (unlikely(tcp_rtx_and_write_queues_empty(sk) && err == -EAGAIN)) { sk->sk_write_space(sk); tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED); }