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Date: Tue, 02 May 2017 08:38:37 -0700
From: John Fastabend <john.fastabend@...il.com>
To: eric.dumazet@...il.com
Cc: netdev@...r.kernel.org, john.fastabend@...il.com
Subject: [RFC PATCH v2 08/17] net: sched: support skb_bad_tx with lockless
qdisc
Similar to how gso is handled skb_bad_tx needs to be per cpu to handle
lockless qdisc with multiple writer/producers.
Signed-off-by: John Fastabend <john.r.fastabend@...el.com>
---
include/net/sch_generic.h | 2 -
net/sched/sch_generic.c | 100 ++++++++++++++++++++++++++++++++++++---------
2 files changed, 82 insertions(+), 20 deletions(-)
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 3021bbb..4288222 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -92,7 +92,7 @@ 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;
struct rcu_head rcu_head;
int padded;
atomic_t refcnt;
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 37cd54e..d4194c2 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -44,6 +44,68 @@
* - 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);
@@ -116,9 +178,15 @@ 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_qstats_backlog_inc(q, nskb);
- q->q.qlen++;
+ 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;
@@ -179,18 +247,9 @@ 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--;
- goto bulk;
- }
- return NULL;
- }
+ skb = qdisc_dequeue_skb_bad_txq(q);
+ if (unlikely(skb))
+ goto bulk;
if (!(q->flags & TCQ_F_ONETXQUEUE) ||
!netif_xmit_frozen_or_stopped(txq))
skb = q->dequeue(q);
@@ -673,6 +732,7 @@ 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);
@@ -746,12 +806,12 @@ 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)
kfree_skb_list(skb);
+ skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp)
+ kfree_skb_list(skb);
+
qdisc->q.qlen = 0;
}
EXPORT_SYMBOL(qdisc_reset);
@@ -793,8 +853,9 @@ void qdisc_destroy(struct Qdisc *qdisc)
skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp)
kfree_skb_list(skb);
+ skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp)
+ kfree_skb_list(skb);
- kfree_skb(qdisc->skb_bad_txq);
/*
* gen_estimator est_timer() might access qdisc->q.lock,
* wait a RCU grace period before freeing qdisc.
@@ -1036,6 +1097,7 @@ 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)
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