On Tue, May 15, 2018 at 04:24:37PM +0200, Paolo Abeni wrote:
> After the previous patch, for NOLOCK qdiscs, q->seqlock is
> always held when the dequeue() is invoked, we can drop
> any additional locking to protect such operation.
>
> Signed-off-by: Paolo Abeni <pab...@redhat.com>
> ---
> include/linux/skb_array.h | 5 +++++
> net/sched/sch_generic.c | 4 ++--
> 2 files changed, 7 insertions(+), 2 deletions(-)
Is the seqlock taken during qdisc_change_tx_queue_len?
We need to prevent that racing with dequeue.
> diff --git a/include/linux/skb_array.h b/include/linux/skb_array.h
> index a6b6e8bb3d7b..62d9b0a6329f 100644
> --- a/include/linux/skb_array.h
> +++ b/include/linux/skb_array.h
> @@ -97,6 +97,11 @@ static inline bool skb_array_empty_any(struct skb_array *a)
> return ptr_ring_empty_any(&a->ring);
> }
>
> +static inline struct sk_buff *__skb_array_consume(struct skb_array *a)
> +{
> + return __ptr_ring_consume(&a->ring);
> +}
> +
> static inline struct sk_buff *skb_array_consume(struct skb_array *a)
> {
> return ptr_ring_consume(&a->ring);
> diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
> index a126f16bc30b..760ab1b09f8b 100644
> --- a/net/sched/sch_generic.c
> +++ b/net/sched/sch_generic.c
> @@ -656,7 +656,7 @@ static struct sk_buff *pfifo_fast_dequeue(struct Qdisc
> *qdisc)
> if (__skb_array_empty(q))
> continue;
>
> - skb = skb_array_consume_bh(q);
> + skb = __skb_array_consume(q);
> }
> if (likely(skb)) {
> qdisc_qstats_cpu_backlog_dec(qdisc, skb);
> @@ -697,7 +697,7 @@ static void pfifo_fast_reset(struct Qdisc *qdisc)
> if (!q->ring.queue)
> continue;
>
> - while ((skb = skb_array_consume_bh(q)) != NULL)
> + while ((skb = __skb_array_consume(q)) != NULL)
> kfree_skb(skb);
> }
>
> --
> 2.14.3
