From 2540e0511ea17e25831be543cdf9381e6209950d Mon Sep 17 00:00:00 2001
From: Jarek Poplawski <jarkao2@gmail.com>
Date: Thu, 21 Aug 2008 05:11:14 -0700
Subject: [PATCH] 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>
---
include/net/sch_generic.h | 5 +++++
net/sched/sch_api.c | 4 ++++
net/sched/sch_cbq.c | 4 ++++
3 files changed, 13 insertions(+)
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 84d25f2e61887..b1d2cfea89c52 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -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
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index ef0efeca63521..45f442d7de470 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -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));
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 47ef492c4ff40..8fa90d68ec6d8 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -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;
--
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