| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 14/53] net_sched: fix order of queue length updates in qdisc_replace() | Date | Mon, 28 Aug 2017 10:05:19 +0200 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
[ Upstream commit 68a66d149a8c78ec6720f268597302883e48e9fa ]
This important to call qdisc_tree_reduce_backlog() after changing queue length. Parent qdisc should deactivate class in ->qlen_notify() called from qdisc_tree_reduce_backlog() but this happens only if qdisc->q.qlen in zero.
Missed class deactivations leads to crashes/warnings at picking packets from empty qdisc and corrupting state at reactivating this class in future.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Fixes: 86a7996cc8a0 ("net_sched: introduce qdisc_replace() helper") Acked-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- include/net/sch_generic.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -717,8 +717,11 @@ static inline struct Qdisc *qdisc_replac old = *pold; *pold = new; if (old != NULL) { - qdisc_tree_reduce_backlog(old, old->q.qlen, old->qstats.backlog); + unsigned int qlen = old->q.qlen; + unsigned int backlog = old->qstats.backlog; + qdisc_reset(old); + qdisc_tree_reduce_backlog(old, qlen, backlog); } sch_tree_unlock(sch);
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