From patchwork Mon Oct 28 12:07:57 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Liu X-Patchwork-Id: 286502 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 498612C0082 for ; Mon, 28 Oct 2013 23:08:04 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755572Ab3J1MH7 (ORCPT ); Mon, 28 Oct 2013 08:07:59 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:52192 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754442Ab3J1MH7 (ORCPT ); Mon, 28 Oct 2013 08:07:59 -0400 X-IronPort-AV: E=Sophos;i="4.93,585,1378857600"; d="scan'208";a="65319449" Received: from accessns.citrite.net (HELO FTLPEX01CL02.citrite.net) ([10.9.154.239]) by FTLPIPO02.CITRIX.COM with ESMTP; 28 Oct 2013 12:07:58 +0000 Received: from ukmail1.uk.xensource.com (10.80.16.128) by smtprelay.citrix.com (10.13.107.79) with Microsoft SMTP Server id 14.2.342.4; Mon, 28 Oct 2013 08:07:57 -0400 Received: from dt47.uk.xensource.com ([10.80.229.47] helo=dt47.uk.xensource.com.) by ukmail1.uk.xensource.com with esmtp (Exim 4.69) (envelope-from ) id 1Valbx-0004aC-HT; Mon, 28 Oct 2013 12:07:57 +0000 From: Wei Liu To: , CC: , , , Wei Liu , Ian Campbell , Jason Luan Subject: [PATCH net V3] xen-netback: use jiffies_64 value to calculate credit timeout Date: Mon, 28 Oct 2013 12:07:57 +0000 Message-ID: <1382962077-13406-1-git-send-email-wei.liu2@citrix.com> X-Mailer: git-send-email 1.7.10.4 MIME-Version: 1.0 X-DLP: MIA2 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org time_after_eq() only works if the delta is < MAX_ULONG/2. For a 32bit Dom0, if netfront sends packets at a very low rate, the time between subsequent calls to tx_credit_exceeded() may exceed MAX_ULONG/2 and the test for timer_after_eq() will be incorrect. Credit will not be replenished and the guest may become unable to send packets (e.g., if prior to the long gap, all credit was exhausted). Use jiffies_64 variant to mitigate this problem for 32bit Dom0. Suggested-by: Jan Beulich Signed-off-by: Wei Liu Reviewed-by: David Vrabel Cc: Ian Campbell Cc: Jason Luan --- drivers/net/xen-netback/common.h | 1 + drivers/net/xen-netback/interface.c | 3 +-- drivers/net/xen-netback/netback.c | 10 +++++----- 3 files changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h index 5715318..400fea1 100644 --- a/drivers/net/xen-netback/common.h +++ b/drivers/net/xen-netback/common.h @@ -163,6 +163,7 @@ struct xenvif { unsigned long credit_usec; unsigned long remaining_credit; struct timer_list credit_timeout; + u64 credit_window_start; /* Statistics */ unsigned long rx_gso_checksum_fixup; diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 01bb854..459935a 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -312,8 +312,7 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid, vif->credit_bytes = vif->remaining_credit = ~0UL; vif->credit_usec = 0UL; init_timer(&vif->credit_timeout); - /* Initialize 'expires' now: it's used to track the credit window. */ - vif->credit_timeout.expires = jiffies; + vif->credit_window_start = get_jiffies_64(); dev->netdev_ops = &xenvif_netdev_ops; dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO; diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index f3e591c..900da4b 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1185,9 +1185,8 @@ out: static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) { - unsigned long now = jiffies; - unsigned long next_credit = - vif->credit_timeout.expires + + u64 now = get_jiffies_64(); + u64 next_credit = vif->credit_window_start + msecs_to_jiffies(vif->credit_usec / 1000); /* Timer could already be pending in rare cases. */ @@ -1195,8 +1194,8 @@ static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) return true; /* Passed the point where we can replenish credit? */ - if (time_after_eq(now, next_credit)) { - vif->credit_timeout.expires = now; + if (time_after_eq64(now, next_credit)) { + vif->credit_window_start = now; tx_add_credit(vif); } @@ -1208,6 +1207,7 @@ static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) tx_credit_callback; mod_timer(&vif->credit_timeout, next_credit); + vif->credit_window_start = next_credit; return true; }