pkt_sched: Add and use qdisc_root() and qdisc_root_lock().
When code wants to lock the qdisc tree state, the logic
operation it's doing is locking the top-level qdisc that
sits of the root of the netdev_queue.
Add qdisc_root_lock() to represent this and convert the
easiest cases.
In order for this to work out in all cases, we have to
hook up the noop_qdisc to a dummy netdev_queue.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index bc585f2..c5ea40c 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -180,7 +180,7 @@
* skb will be queued.
*/
if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
- struct Qdisc *rootq = sch->dev_queue->qdisc;
+ struct Qdisc *rootq = qdisc_root(sch);
u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
q->duplicate = 0;
@@ -319,6 +319,7 @@
struct netem_sched_data *q = qdisc_priv(sch);
unsigned long n = nla_len(attr)/sizeof(__s16);
const __s16 *data = nla_data(attr);
+ spinlock_t *root_lock;
struct disttable *d;
int i;
@@ -333,9 +334,11 @@
for (i = 0; i < n; i++)
d->table[i] = data[i];
- spin_lock_bh(&sch->dev_queue->lock);
+ root_lock = qdisc_root_lock(sch);
+
+ spin_lock_bh(root_lock);
d = xchg(&q->delay_dist, d);
- spin_unlock_bh(&sch->dev_queue->lock);
+ spin_unlock_bh(root_lock);
kfree(d);
return 0;
