On 2020/9/3 15:24, Eric Dumazet wrote:
>
>
> On 9/2/20 6:14 PM, Yunsheng Lin wrote:
>
>>
>> It seems semantics for some_qdisc_is_busy() is changed, which does not only
>> do
>> the checking, but also do the reseting?
>
> Yes, obviously, we would have to rename to a better name.
>
>>
>> Also, qdisc_reset() could be called multi times for the same qdisc if
>> some_qdisc_is_busy()
>> return true multi times?
>
> This should not matter, qdisc_reset() can be called multiple times,
> as we also call it from qdisc_destroy() anyway.
How about the below patch, which does not need to change the semantics
for some_qdisc_is_busy() and avoid calling qdisc_reset() multi times?
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 265a61d..ce9031c 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -1131,24 +1131,7 @@ EXPORT_SYMBOL(dev_activate);
static void qdisc_deactivate(struct Qdisc *qdisc)
{
- bool nolock = qdisc->flags & TCQ_F_NOLOCK;
-
- if (qdisc->flags & TCQ_F_BUILTIN)
- return;
- if (test_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state))
- return;
-
- if (nolock)
- spin_lock_bh(&qdisc->seqlock);
- spin_lock_bh(qdisc_lock(qdisc));
-
set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
-
- qdisc_reset(qdisc);
-
- spin_unlock_bh(qdisc_lock(qdisc));
- if (nolock)
- spin_unlock_bh(&qdisc->seqlock);
}
static void dev_deactivate_queue(struct net_device *dev,
@@ -1165,6 +1148,33 @@ static void dev_deactivate_queue(struct net_device *dev,
}
}
+static void dev_reset_qdisc(struct net_device *dev)
+{
+ unsigned int i;
+
+ for (i = 0; i < dev->num_tx_queues; i++) {
+ struct netdev_queue *dev_queue;
+ struct Qdisc *q;
+ bool nolock;
+
+ dev_queue = netdev_get_tx_queue(dev, i);
+ q = dev_queue->qdisc_sleeping;
+ nolock = q->flags & TCQ_F_NOLOCK;
+
+ if (nolock)
+ spin_lock_bh(&q->seqlock);
+
+ spin_lock_bh(qdisc_lock(q));
+
+ qdisc_reset(q);
+
+ spin_unlock_bh(qdisc_lock(q));
+
+ if (nolock)
+ spin_unlock_bh(&q->seqlock);
+ }
+}
+
static bool some_qdisc_is_busy(struct net_device *dev)
{
unsigned int i;
@@ -1219,6 +1229,9 @@ void dev_deactivate_many(struct list_head *head)
*/
synchronize_net();
+ list_for_each_entry(dev, head, close_list)
+ dev_reset_qdisc(dev);
+
/* Wait for outstanding qdisc_run calls. */
list_for_each_entry(dev, head, close_list) {
while (some_qdisc_is_busy(dev)) {
>
>
