From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757090Ab3KYOLR (ORCPT ); Mon, 25 Nov 2013 09:11:17 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:58920 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754101Ab3KYNxp (ORCPT ); Mon, 25 Nov 2013 08:53:45 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Ian Campbell" , "Jason Luan" , "Wei Liu" , "David S. Miller" , "David Vrabel" , "Jan Beulich" Date: Mon, 25 Nov 2013 13:44:29 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 29/87] xen-netback: use jiffies_64 value to calculate credit timeout In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.212 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.53-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Wei Liu [ Upstream commit 059dfa6a93b779516321e5112db9d7621b1367ba ] 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 Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- 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 9d7f172..093bf0a 100644 --- a/drivers/net/xen-netback/common.h +++ b/drivers/net/xen-netback/common.h @@ -88,6 +88,7 @@ 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 8eaf0e2..2cb9c92 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -272,8 +272,7 @@ 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 fd2b92d..9a4626c 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1365,9 +1365,8 @@ 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. */ @@ -1375,8 +1374,8 @@ 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); } @@ -1388,6 +1387,7 @@ 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; }