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[patch] add patch "net: sch_generic: fix the missing new qdisc assign…
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…ment bug" (#213)

To fix ENOBUFS returned by send() instead of ENETDOWN when interface flaps.

The original issue is - when performing LAG memeber flapping, a LAG memeber can stuck in disabled state until next interface flap. This is because, teamd calls lacp_send() when setting internal LAG member state which ignores ENETDOWN but not ENOBUFS. This will lead to a situation when internal LACP member state stucks in disabled state.
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stepanblyschak authored May 31, 2021
1 parent 12d8a0a commit fcf7cdc
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45 changes: 45 additions & 0 deletions patch/net-sch_generic-fix-the-missing-new-qdisc-assignment.patch
Original file line number Diff line number Diff line change
@@ -0,0 +1,45 @@
From 81504d1952d712c8bb9c3966896efee8a37ea966 Mon Sep 17 00:00:00 2001
From: Yunsheng Lin <linyunsheng@huawei.com>
Date: Tue, 3 Nov 2020 11:25:38 +0800
Subject: net: sch_generic: fix the missing new qdisc assignment bug

When commit 2fb541c862c9 ("net: sch_generic: aviod concurrent reset and
enqueue op for lockless qdisc") is backported to stable kernel, one
assignment is missing, which causes two problems reported by Joakim and
Vishwanath, see [1] and [2].

So add the assignment back to fix it.

1. https://www.spinics.net/lists/netdev/msg693916.html
2. https://www.spinics.net/lists/netdev/msg695131.html

Fixes: 749cc0b0c7f3 ("net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sched/sch_generic.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index bd96fd261dba3..4e15913e7519e 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -1116,10 +1116,13 @@ static void dev_deactivate_queue(struct net_device *dev,
void *_qdisc_default)
{
struct Qdisc *qdisc = rtnl_dereference(dev_queue->qdisc);
+ struct Qdisc *qdisc_default = _qdisc_default;

if (qdisc) {
if (!(qdisc->flags & TCQ_F_BUILTIN))
set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
+
+ rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
}
}

--
cgit 1.2.3-1.el7

1 change: 1 addition & 0 deletions patch/series
Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@ netlink-add-NLA_MIN_LEN.patch
macsec-Netlink-support-of-XPN-cipher-suites-IEEE-802.patch
Support-for-fullcone-nat.patch
driver-ixgbe-external-phy.patch
net-sch_generic-fix-the-missing-new-qdisc-assignment.patch
#
# This series applies on GIT commit 1451b36b2b0d62178e42f648d8a18131af18f7d8
# Tkernel-sched-core-fix-cgroup-fork-race.patch
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