2013-06-10 02:39:50 -06:00
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/*
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* Low Latency Sockets
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* Copyright(c) 2013 Intel Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Author: Eliezer Tamir
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*
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* Contact Information:
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* e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
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*/
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#ifndef _LINUX_NET_LL_POLL_H
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#define _LINUX_NET_LL_POLL_H
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#include <linux/netdevice.h>
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#include <net/ip.h>
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#ifdef CONFIG_NET_LL_RX_POLL
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struct napi_struct;
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2013-06-24 01:28:03 -06:00
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extern unsigned int sysctl_net_ll_read __read_mostly;
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2013-06-14 07:33:25 -06:00
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extern unsigned int sysctl_net_ll_poll __read_mostly;
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2013-06-10 02:39:50 -06:00
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/* return values from ndo_ll_poll */
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#define LL_FLUSH_FAILED -1
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#define LL_FLUSH_BUSY -2
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2013-06-28 06:59:35 -06:00
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static inline unsigned int ll_get_flag(void)
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{
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return sysctl_net_ll_poll ? POLL_LL : 0;
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}
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2013-06-28 06:59:26 -06:00
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/* a wrapper to make debug_smp_processor_id() happy
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* we can use sched_clock() because we don't care much about precision
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2013-06-14 07:33:35 -06:00
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* we only care that the average is bounded
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2013-06-28 06:59:26 -06:00
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*/
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#ifdef CONFIG_DEBUG_PREEMPT
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static inline u64 ll_sched_clock(void)
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{
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u64 rc;
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preempt_disable_notrace();
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rc = sched_clock();
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preempt_enable_no_resched_notrace();
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return rc;
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}
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#else /* CONFIG_DEBUG_PREEMPT */
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static inline u64 ll_sched_clock(void)
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{
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return sched_clock();
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}
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#endif /* CONFIG_DEBUG_PREEMPT */
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/* we don't mind a ~2.5% imprecision so <<10 instead of *1000
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2013-06-24 01:28:03 -06:00
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* sk->sk_ll_usec is a u_int so this can't overflow
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2013-06-14 07:33:35 -06:00
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*/
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2013-07-02 14:22:47 -06:00
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static inline u64 ll_sk_run_time(struct sock *sk)
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2013-06-10 02:39:50 -06:00
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{
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2013-07-02 14:22:47 -06:00
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return (u64)ACCESS_ONCE(sk->sk_ll_usec) << 10;
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2013-06-24 01:28:03 -06:00
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}
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2013-06-14 07:33:35 -06:00
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2013-06-28 06:59:35 -06:00
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/* in poll/select we use the global sysctl_net_ll_poll value
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* only call sched_clock() if enabled
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*/
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2013-07-02 14:22:47 -06:00
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static inline u64 ll_run_time(void)
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2013-06-24 01:28:03 -06:00
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{
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2013-07-02 14:22:47 -06:00
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return (u64)ACCESS_ONCE(sysctl_net_ll_poll) << 10;
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}
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2013-06-28 06:59:35 -06:00
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2013-07-02 14:22:47 -06:00
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/* if flag is not set we don't need to know the time */
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static inline u64 ll_start_time(unsigned int flag)
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{
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return flag ? ll_sched_clock() : 0;
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2013-06-10 02:39:50 -06:00
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}
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static inline bool sk_valid_ll(struct sock *sk)
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{
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2013-06-14 07:33:57 -06:00
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return sk->sk_ll_usec && sk->sk_napi_id &&
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2013-06-10 02:39:50 -06:00
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!need_resched() && !signal_pending(current);
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}
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2013-07-02 14:22:47 -06:00
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/* careful! time_in_range64 will evaluate now twice */
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static inline bool can_poll_ll(u64 start_time, u64 run_time)
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2013-06-10 02:39:50 -06:00
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{
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2013-07-02 14:22:47 -06:00
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u64 now = ll_sched_clock();
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return time_in_range64(now, start_time, start_time + run_time);
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2013-06-10 02:39:50 -06:00
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}
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2013-06-24 01:28:03 -06:00
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/* when used in sock_poll() nonblock is known at compile time to be true
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* so the loop and end_time will be optimized out
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*/
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2013-06-10 02:39:50 -06:00
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static inline bool sk_poll_ll(struct sock *sk, int nonblock)
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{
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2013-07-02 14:22:47 -06:00
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u64 start_time = ll_start_time(!nonblock);
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u64 run_time = ll_sk_run_time(sk);
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2013-06-10 02:39:50 -06:00
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const struct net_device_ops *ops;
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struct napi_struct *napi;
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int rc = false;
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/*
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* rcu read lock for napi hash
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* bh so we don't race with net_rx_action
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*/
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rcu_read_lock_bh();
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napi = napi_by_id(sk->sk_napi_id);
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if (!napi)
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goto out;
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ops = napi->dev->netdev_ops;
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if (!ops->ndo_ll_poll)
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goto out;
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do {
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rc = ops->ndo_ll_poll(napi);
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if (rc == LL_FLUSH_FAILED)
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break; /* permanent failure */
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if (rc > 0)
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/* local bh are disabled so it is ok to use _BH */
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NET_ADD_STATS_BH(sock_net(sk),
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LINUX_MIB_LOWLATENCYRXPACKETS, rc);
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2013-06-24 01:28:03 -06:00
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} while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) &&
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2013-07-02 14:22:47 -06:00
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can_poll_ll(start_time, run_time));
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2013-06-10 02:39:50 -06:00
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rc = !skb_queue_empty(&sk->sk_receive_queue);
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out:
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rcu_read_unlock_bh();
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return rc;
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}
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/* used in the NIC receive handler to mark the skb */
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static inline void skb_mark_ll(struct sk_buff *skb, struct napi_struct *napi)
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{
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skb->napi_id = napi->napi_id;
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}
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/* used in the protocol hanlder to propagate the napi_id to the socket */
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static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb)
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{
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sk->sk_napi_id = skb->napi_id;
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}
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#else /* CONFIG_NET_LL_RX_POLL */
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2013-06-28 06:59:35 -06:00
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static inline unsigned long ll_get_flag(void)
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{
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return 0;
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}
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2013-06-10 02:39:50 -06:00
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2013-07-02 21:41:24 -06:00
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static inline u64 ll_start_time(unsigned int flag)
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2013-06-24 01:28:03 -06:00
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{
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return 0;
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}
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2013-07-02 21:41:24 -06:00
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static inline u64 ll_run_time(void)
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2013-06-10 02:39:50 -06:00
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{
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return 0;
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}
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static inline bool sk_valid_ll(struct sock *sk)
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{
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return false;
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}
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static inline bool sk_poll_ll(struct sock *sk, int nonblock)
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{
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return false;
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}
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static inline void skb_mark_ll(struct sk_buff *skb, struct napi_struct *napi)
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{
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}
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static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb)
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{
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}
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2013-07-02 21:41:24 -06:00
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static inline bool can_poll_ll(u64 start_time, u64 run_time)
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2013-06-10 02:39:50 -06:00
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{
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return false;
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}
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#endif /* CONFIG_NET_LL_RX_POLL */
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#endif /* _LINUX_NET_LL_POLL_H */
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