From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934342Ab2JKBcp (ORCPT ); Wed, 10 Oct 2012 21:32:45 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:60107 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933982Ab2JKBUO (ORCPT ); Wed, 10 Oct 2012 21:20:14 -0400 X-Sasl-enc: LYghFRywIyWerhdAfqyiJLhQ3gNkAU7cf/Hf8Omqv7A2 1349918411 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Michal Kubecek , "David S. Miller" Subject: [ 043/120] tcp: flush DMA queue before sk_wait_data if rcv_wnd is zero Date: Thu, 11 Oct 2012 09:59:55 +0900 Message-Id: <20121011005833.411043471@linuxfoundation.org> X-Mailer: git-send-email 1.8.0.rc0.18.gf84667d In-Reply-To: <20121011005825.364610894@linuxfoundation.org> References: <20121011005825.364610894@linuxfoundation.org> User-Agent: quilt/0.60-2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: =?UTF-8?q?Michal=20Kube=C4=8Dek?= [ Upstream commit 15c041759bfcd9ab0a4e43f1c16e2644977d0467 ] If recv() syscall is called for a TCP socket so that - IOAT DMA is used - MSG_WAITALL flag is used - requested length is bigger than sk_rcvbuf - enough data has already arrived to bring rcv_wnd to zero then when tcp_recvmsg() gets to calling sk_wait_data(), receive window can be still zero while sk_async_wait_queue exhausts enough space to keep it zero. As this queue isn't cleaned until the tcp_service_net_dma() call, sk_wait_data() cannot receive any data and blocks forever. If zero receive window and non-empty sk_async_wait_queue is detected before calling sk_wait_data(), process the queue first. Signed-off-by: Michal Kubecek Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1594,8 +1594,14 @@ int tcp_recvmsg(struct kiocb *iocb, stru } #ifdef CONFIG_NET_DMA - if (tp->ucopy.dma_chan) - dma_async_memcpy_issue_pending(tp->ucopy.dma_chan); + if (tp->ucopy.dma_chan) { + if (tp->rcv_wnd == 0 && + !skb_queue_empty(&sk->sk_async_wait_queue)) { + tcp_service_net_dma(sk, true); + tcp_cleanup_rbuf(sk, copied); + } else + dma_async_memcpy_issue_pending(tp->ucopy.dma_chan); + } #endif if (copied >= target) { /* Do not sleep, just process backlog. */