From: David S. Miller Date: Wed, 13 Aug 2008 22:18:38 +0000 (-0700) Subject: pkt_sched: Fix queue quiescence testing in dev_deactivate(). X-Git-Tag: v2.6.27-rc4~103^2~27 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=b9a3b1102bc80b4044224494100f67de132d5448;p=linux-2.6-omap-h63xx.git pkt_sched: Fix queue quiescence testing in dev_deactivate(). Based upon discussions with Jarek P. and Herbert Xu. First, we're testing the wrong qdisc. We just reset the device queue qdiscs to &noop_qdisc and checking it's state is completely pointless here. We want to wait until the previous qdisc that was sitting at the ->qdisc pointer is not busy any more. And that would be ->qdisc_sleeping. Because of how we propagate the samples qdisc pointer down into qdisc_run and friends via per-cpu ->output_queue and netif_schedule, we have to wait also for the __QDISC_STATE_SCHED bit to clear as well. Signed-off-by: David S. Miller --- diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index 7cf83b37459..468574682ca 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -647,7 +647,7 @@ static void dev_deactivate_queue(struct net_device *dev, } } -static bool some_qdisc_is_running(struct net_device *dev, int lock) +static bool some_qdisc_is_busy(struct net_device *dev, int lock) { unsigned int i; @@ -658,13 +658,14 @@ static bool some_qdisc_is_running(struct net_device *dev, int lock) int val; dev_queue = netdev_get_tx_queue(dev, i); - q = dev_queue->qdisc; + q = dev_queue->qdisc_sleeping; root_lock = qdisc_lock(q); if (lock) spin_lock_bh(root_lock); - val = test_bit(__QDISC_STATE_RUNNING, &q->state); + val = (test_bit(__QDISC_STATE_RUNNING, &q->state) || + test_bit(__QDISC_STATE_SCHED, &q->state)); if (lock) spin_unlock_bh(root_lock); @@ -689,14 +690,14 @@ void dev_deactivate(struct net_device *dev) /* Wait for outstanding qdisc_run calls. */ do { - while (some_qdisc_is_running(dev, 0)) + while (some_qdisc_is_busy(dev, 0)) yield(); /* * Double-check inside queue lock to ensure that all effects * of the queue run are visible when we return. */ - running = some_qdisc_is_running(dev, 1); + running = some_qdisc_is_busy(dev, 1); /* * The running flag should never be set at this point because