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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>
This commit is contained in:
Jarek Poplawski 2008-08-21 05:11:14 -07:00 committed by David S. Miller
parent 5e739d1752
commit 2540e0511e
3 changed files with 13 additions and 0 deletions
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5
include/net/sch_generic.h
View File

@ -193,6 +193,11 @@ static inline struct Qdisc *qdisc_root(struct Qdisc *qdisc)
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

4
net/sched/sch_api.c
View File

@ -444,6 +444,10 @@ void qdisc_watchdog_schedule(struct qdisc_watchdog *wd, psched_time_t expires)
{
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));

4
net/sched/sch_cbq.c
View File

@ -521,6 +521,10 @@ static void cbq_ovl_delay(struct cbq_class *cl)
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;