pkt_sched: Fix qdisc_watchdog() vs. dev_deactivate() race
dev_deactivate() can skip rescheduling of a qdisc by qdisc_watchdog()
or other timer calling netif_schedule() after dev_queue_deactivate().
We prevent this checking aliveness before scheduling the timer. Since
during deactivation the root qdisc is available only as qdisc_sleeping
additional accessor qdisc_root_sleeping() is created.
With feedback from Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 84d25f2..b1d2cfe 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -193,6 +193,11 @@
return qdisc->dev_queue->qdisc;
}
+static inline struct Qdisc *qdisc_root_sleeping(struct Qdisc *qdisc)
+{
+ return qdisc->dev_queue->qdisc_sleeping;
+}
+
/* The qdisc root lock is a mechanism by which to top level
* of a qdisc tree can be locked from any qdisc node in the
* forest. This allows changing the configuration of some
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index ef0efec..45f442d 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -444,6 +444,10 @@
{
ktime_t time;
+ if (test_bit(__QDISC_STATE_DEACTIVATED,
+ &qdisc_root_sleeping(wd->qdisc)->state))
+ return;
+
wd->qdisc->flags |= TCQ_F_THROTTLED;
time = ktime_set(0, 0);
time = ktime_add_ns(time, PSCHED_US2NS(expires));
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 47ef492..8fa90d6 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -521,6 +521,10 @@
struct cbq_sched_data *q = qdisc_priv(cl->qdisc);
psched_tdiff_t delay = cl->undertime - q->now;
+ if (test_bit(__QDISC_STATE_DEACTIVATED,
+ &qdisc_root_sleeping(cl->qdisc)->state))
+ return;
+
if (!cl->delayed) {
psched_time_t sched = q->now;
ktime_t expires;