| Message ID | 150314622756.18396.5215271249872220640.stgit@buzz |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
I've seen this as loops in hfsc rb-trees and hungs in hfsc_dequeue() -> rb_first(). Simple debug catched insering already inserted rb-tree nodes and similar mess. Most likely this could explain warning in hfsc_dequeue() https://bugzilla.kernel.org/show_bug.cgi?id=109581 On 19.08.2017 15:37, Konstantin Khlebnikov wrote: > 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")hfsc_dequeue > Cc: Stable <stable@vger.kernel.org> > --- > include/net/sch_generic.h | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h > index 1c123e2b2415..67f815e5d525 100644 > --- a/include/net/sch_generic.h > +++ b/include/net/sch_generic.h > @@ -806,8 +806,11 @@ static inline struct Qdisc *qdisc_replace(struct Qdisc *sch, struct Qdisc *new, > 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); > >
On Sat, Aug 19, 2017 at 5:37 AM, Konstantin Khlebnikov <khlebnikov@yandex-team.ru> wrote: > 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. Good catch! I didn't realize qdisc_reset() actually resets all classes... Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Date: Sat, 19 Aug 2017 15:37:07 +0300 > 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") Applied and queued up for -stable, thanks. Please do not add an explict "CC: stable" to networking patches, simply ask me to queue it up as I handle all networking -stable submissions myself by hand. Thank you.
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index 1c123e2b2415..67f815e5d525 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -806,8 +806,11 @@ static inline struct Qdisc *qdisc_replace(struct Qdisc *sch, struct Qdisc *new, 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);
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") Cc: Stable <stable@vger.kernel.org> --- include/net/sch_generic.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)