| From foo@baz Thu Aug 24 17:49:47 PDT 2017 |
| From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> |
| Date: Sat, 19 Aug 2017 15:37:07 +0300 |
| Subject: net_sched: fix order of queue length updates in qdisc_replace() |
| |
| 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 |
| @@ -699,8 +699,11 @@ 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); |
| |
