From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shirley Ma Subject: [PATCH V2] vhost: fix check for # of outstanding buffers Date: Wed, 20 Jul 2011 10:23:12 -0700 Message-ID: <1311182592.8573.45.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org, jasowang@redhat.com To: mst@redhat.com Return-path: Received: from e4.ny.us.ibm.com ([32.97.182.144]:40220 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751437Ab1GTRXS (ORCPT ); Wed, 20 Jul 2011 13:23:18 -0400 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e4.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id p6KH0tuf028455 for ; Wed, 20 Jul 2011 13:00:55 -0400 Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p6KHNFIH094576 for ; Wed, 20 Jul 2011 13:23:16 -0400 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p6KHNEIw027071 for ; Wed, 20 Jul 2011 11:23:14 -0600 Sender: netdev-owner@vger.kernel.org List-ID: Fix the check for number of outstanding buffers returns incorrect results due to vq->pend_idx wrap around; Signed-off-by: Shirley Ma --- drivers/vhost/net.c | 12 +++++++++--- 1 files changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 70ac604..946a71e 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -182,15 +182,21 @@ static void handle_tx(struct vhost_net *net) break; /* Nothing new? Wait for eventfd to tell us they refilled. */ if (head == vq->num) { + int num_pends; + wmem = atomic_read(&sock->sk->sk_wmem_alloc); if (wmem >= sock->sk->sk_sndbuf * 3 / 4) { tx_poll_start(net, sock); set_bit(SOCK_ASYNC_NOSPACE, &sock->flags); break; } - /* If more outstanding DMAs, queue the work */ - if (unlikely(vq->upend_idx - vq->done_idx > - VHOST_MAX_PEND)) { + /* If more outstanding DMAs, queue the work + * handle upend_idx wrap around + */ + num_pends = (vq->upend_idx >= vq->done_idx) ? + (vq->upend_idx - vq->done_idx) : + (vq->upend_idx + UIO_MAXIOV - vq->done_idx); + if (unlikely(num_pends > VHOST_MAX_PEND)) { tx_poll_start(net, sock); set_bit(SOCK_ASYNC_NOSPACE, &sock->flags); break;