[PATCH net-next] net: sched: avoid writing on noop_qdisc

[Eric Dumazet]

While noop_qdisc.gso_skb and noop_qdisc.skb_bad_txq are not used
in other places, it seems not correct to overwrite their fields
in dev_init_scheduler_queue().

noop_qdisc is essentially a shared and read-only object, even if
it is not marked as const because of some implementation detail.

Signed-off-by: Eric Dumazet <eduma...@google.com>
---
 net/sched/sch_generic.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 
3023929852e8c4aaa4172861d2d0beff17e25f27..de1663f7d3ad6e2c06cd2e031036cef5979366a5
 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -572,6 +572,18 @@ struct Qdisc noop_qdisc = {
        .dev_queue      =       &noop_netdev_queue,
        .running        =       SEQCNT_ZERO(noop_qdisc.running),
        .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
+       .gso_skb = {
+               .next = (struct sk_buff *)&noop_qdisc.gso_skb,
+               .prev = (struct sk_buff *)&noop_qdisc.gso_skb,
+               .qlen = 0,
+               .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
+       },
+       .skb_bad_txq = {
+               .next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
+               .prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
+               .qlen = 0,
+               .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
+       },
 };
 EXPORT_SYMBOL(noop_qdisc);
 
@@ -1273,8 +1285,6 @@ static void dev_init_scheduler_queue(struct net_device 
*dev,
 
        rcu_assign_pointer(dev_queue->qdisc, qdisc);
        dev_queue->qdisc_sleeping = qdisc;
-       __skb_queue_head_init(&qdisc->gso_skb);
-       __skb_queue_head_init(&qdisc->skb_bad_txq);
 }
 
 void dev_init_scheduler(struct net_device *dev)
-- 
2.19.0.605.g01d371f741-goog