This is a note to let you know that I've just added the patch titled net: sch_generic: fix the missing new qdisc assignment bug to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-sch_generic-fix-the-missing-new-qdisc-assignment-bug.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From linyunsheng@xxxxxxxxxx Tue Nov 17 13:08:29 2020 From: Yunsheng Lin <linyunsheng@xxxxxxxxxx> Date: Tue, 3 Nov 2020 11:25:38 +0800 Subject: net: sch_generic: fix the missing new qdisc assignment bug To: <gregkh@xxxxxxxxxxxxxxxxxxx>, <stable@xxxxxxxxxxxxxxx> Cc: <vpai@xxxxxxxxxx>, <Joakim.Tjernlund@xxxxxxxxxxxx>, <xiyou.wangcong@xxxxxxxxx>, <johunt@xxxxxxxxxx>, <jhs@xxxxxxxxxxxx>, <jiri@xxxxxxxxxxx>, <davem@xxxxxxxxxxxxx>, <kuba@xxxxxxxxxx>, <netdev@xxxxxxxxxxxxxxx>, <linux-kernel@xxxxxxxxxxxxxxx>, <linuxarm@xxxxxxxxxx>, <john.fastabend@xxxxxxxxx>, <eric.dumazet@xxxxxxxxx>, <dsahern@xxxxxxxxx> Message-ID: <1604373938-211588-1-git-send-email-linyunsheng@xxxxxxxxxx> 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@xxxxxxxxxx> Acked-by: Jakub Kicinski <kuba@xxxxxxxxxx> Tested-by: Brian Norris <briannorris@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/sched/sch_generic.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -1127,10 +1127,13 @@ static void dev_deactivate_queue(struct 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); } } Patches currently in stable-queue which might be from linyunsheng@xxxxxxxxxx are queue-5.4/net-sch_generic-fix-the-missing-new-qdisc-assignment-bug.patch