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SubjectRe: [PATCH v9 net-next 2/7] net: add low latency socket poll
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On Wed, 2013-06-05 at 13:34 +0300, Eliezer Tamir wrote:


This is probably too big to be inlined, and nonblock should be a bool


It would also make sense to give end_time as a parameter, so that the
polling() code could really give a end_time for the whole duration of
poll().

(You then should test can_poll_ll(end_time) _before_ call to
ndo_ll_poll())


> +static inline bool sk_poll_ll(struct sock *sk, int nonblock)
> +{
> + cycles_t end_time = ll_end_time();
> + const struct net_device_ops *ops;
> + struct napi_struct *napi;
> + int rc = false;
> +
> + /*
> + * rcu read lock for napi hash
> + * bh so we don't race with net_rx_action
> + */
> + rcu_read_lock_bh();
> +
> + napi = napi_by_id(sk->sk_napi_id);
> + if (!napi)
> + goto out;
> +
> + ops = napi->dev->netdev_ops;
> + if (!ops->ndo_ll_poll)
> + goto out;
> +
> + do {
> +
> + rc = ops->ndo_ll_poll(napi);
> +
> + if (rc == LL_FLUSH_FAILED)
> + break; /* permanent failure */
> +
> + if (rc > 0)
> + /* local bh are disabled so it is ok to use _BH */
> + NET_ADD_STATS_BH(sock_net(sk),
> + LINUX_MIB_LOWLATENCYRXPACKETS, rc);
> +
> + } while (skb_queue_empty(&sk->sk_receive_queue)
> + && can_poll_ll(end_time) && !nonblock);
> +
> + rc = !skb_queue_empty(&sk->sk_receive_queue);
> +out:
> + rcu_read_unlock_bh();
> + return rc;
> +}





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