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net: sched: use skb list for skb_bad_tx 

Similar to how gso is handled use skb list for skb_bad_tx this is
required with lockless qdiscs because we may have multiple cores
attempting to push skbs into skb_bad_tx concurrently

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
John Fastabend 2017-12-07 09:56:23 -08:00 committed by David S. Miller
parent 7bbde83b18
commit 70e57d5e3f
2 changed files with 87 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/sch_generic.h
View File

@ -95,7 +95,7 @@ struct Qdisc {
struct gnet_stats_queue qstats;
unsigned long state;
struct Qdisc *next_sched;
struct sk_buff *skb_bad_txq;
struct sk_buff_head skb_bad_txq;
int padded;
refcount_t refcnt;

100
net/sched/sch_generic.c
View File

@ -45,6 +45,68 @@ EXPORT_SYMBOL(default_qdisc_ops);
* - ingress filtering is also serialized via qdisc root lock
* - updates to tree and tree walking are only done under the rtnl mutex.
*/
static inline struct sk_buff *__skb_dequeue_bad_txq(struct Qdisc *q)
{
const struct netdev_queue *txq = q->dev_queue;
spinlock_t *lock = NULL;
struct sk_buff *skb;
if (q->flags & TCQ_F_NOLOCK) {
lock = qdisc_lock(q);
spin_lock(lock);
}
skb = skb_peek(&q->skb_bad_txq);
if (skb) {
/* check the reason of requeuing without tx lock first */
txq = skb_get_tx_queue(txq->dev, skb);
if (!netif_xmit_frozen_or_stopped(txq)) {
skb = __skb_dequeue(&q->skb_bad_txq);
if (qdisc_is_percpu_stats(q)) {
qdisc_qstats_cpu_backlog_dec(q, skb);
qdisc_qstats_cpu_qlen_dec(q);
} else {
qdisc_qstats_backlog_dec(q, skb);
q->q.qlen--;
}
} else {
skb = NULL;
}
}
if (lock)
spin_unlock(lock);
return skb;
}
static inline struct sk_buff *qdisc_dequeue_skb_bad_txq(struct Qdisc *q)
{
struct sk_buff *skb = skb_peek(&q->skb_bad_txq);
if (unlikely(skb))
skb = __skb_dequeue_bad_txq(q);
return skb;
}
static inline void qdisc_enqueue_skb_bad_txq(struct Qdisc *q,
struct sk_buff *skb)
{
spinlock_t *lock = NULL;
if (q->flags & TCQ_F_NOLOCK) {
lock = qdisc_lock(q);
spin_lock(lock);
}
__skb_queue_tail(&q->skb_bad_txq, skb);
if (lock)
spin_unlock(lock);
}
static inline int __dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
{
__skb_queue_head(&q->gso_skb, skb);
@ -117,9 +179,15 @@ static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
if (!nskb)
break;
if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
q->skb_bad_txq = nskb;
qdisc_enqueue_skb_bad_txq(q, nskb);
if (qdisc_is_percpu_stats(q)) {
qdisc_qstats_cpu_backlog_inc(q, nskb);
qdisc_qstats_cpu_qlen_inc(q);
} else {
qdisc_qstats_backlog_inc(q, nskb);
q->q.qlen++;
}
break;
}
skb->next = nskb;
@ -180,19 +248,9 @@ static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
}
validate:
*validate = true;
skb = q->skb_bad_txq;
if (unlikely(skb)) {
/* check the reason of requeuing without tx lock first */
txq = skb_get_tx_queue(txq->dev, skb);
if (!netif_xmit_frozen_or_stopped(txq)) {
q->skb_bad_txq = NULL;
qdisc_qstats_backlog_dec(q, skb);
q->q.qlen--;
skb = qdisc_dequeue_skb_bad_txq(q);
if (unlikely(skb))
goto bulk;
}
skb = NULL;
goto trace;
}
if (!(q->flags & TCQ_F_ONETXQUEUE) ||
!netif_xmit_frozen_or_stopped(txq))
skb = q->dequeue(q);
@ -680,6 +738,7 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
sch->padded = (char *) sch - (char *) p;
}
__skb_queue_head_init(&sch->gso_skb);
__skb_queue_head_init(&sch->skb_bad_txq);
qdisc_skb_head_init(&sch->q);
spin_lock_init(&sch->q.lock);
@ -753,14 +812,16 @@ void qdisc_reset(struct Qdisc *qdisc)
if (ops->reset)
ops->reset(qdisc);
kfree_skb(qdisc->skb_bad_txq);
qdisc->skb_bad_txq = NULL;
skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
__skb_unlink(skb, &qdisc->gso_skb);
kfree_skb_list(skb);
}
skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
__skb_unlink(skb, &qdisc->skb_bad_txq);
kfree_skb_list(skb);
}
qdisc->q.qlen = 0;
qdisc->qstats.backlog = 0;
}
@ -804,7 +865,11 @@ void qdisc_destroy(struct Qdisc *qdisc)
kfree_skb_list(skb);
}
kfree_skb(qdisc->skb_bad_txq);
skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
__skb_unlink(skb, &qdisc->skb_bad_txq);
kfree_skb_list(skb);
}
qdisc_free(qdisc);
}
EXPORT_SYMBOL(qdisc_destroy);
@ -1042,6 +1107,7 @@ 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)