[linux-2.6-block.git] / include / net / busy_poll.h

/*
 * net busy poll support
 * Copyright(c) 2013 Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Author: Eliezer Tamir
 *
 * Contact Information:
 * e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
 */

#ifndef _LINUX_NET_BUSY_POLL_H
#define _LINUX_NET_BUSY_POLL_H

#include <linux/netdevice.h>
#include <net/ip.h>

#ifdef CONFIG_NET_RX_BUSY_POLL

struct napi_struct;
extern unsigned int sysctl_net_busy_read __read_mostly;
extern unsigned int sysctl_net_busy_poll __read_mostly;

/* return values from ndo_ll_poll */
#define LL_FLUSH_FAILED		-1
#define LL_FLUSH_BUSY		-2

static inline bool net_busy_loop_on(void)
{
	return sysctl_net_busy_poll;
}

/* a wrapper to make debug_smp_processor_id() happy
 * we can use sched_clock() because we don't care much about precision
 * we only care that the average is bounded
 */
#ifdef CONFIG_DEBUG_PREEMPT
static inline u64 busy_loop_us_clock(void)
{
	u64 rc;

	preempt_disable_notrace();
	rc = sched_clock();
	preempt_enable_no_resched_notrace();

	return rc >> 10;
}
#else /* CONFIG_DEBUG_PREEMPT */
static inline u64 busy_loop_us_clock(void)
{
	return sched_clock() >> 10;
}
#endif /* CONFIG_DEBUG_PREEMPT */

static inline unsigned long sk_busy_loop_end_time(struct sock *sk)
{
	return busy_loop_us_clock() + ACCESS_ONCE(sk->sk_ll_usec);
}

/* in poll/select we use the global sysctl_net_ll_poll value */
static inline unsigned long busy_loop_end_time(void)
{
	return busy_loop_us_clock() + ACCESS_ONCE(sysctl_net_busy_poll);
}

static inline bool sk_can_busy_loop(struct sock *sk)
{
	return sk->sk_ll_usec && sk->sk_napi_id &&
	       !need_resched() && !signal_pending(current);
}


static inline bool busy_loop_timeout(unsigned long end_time)
{
	unsigned long now = busy_loop_us_clock();

	return time_after(now, end_time);
}

/* when used in sock_poll() nonblock is known at compile time to be true
 * so the loop and end_time will be optimized out
 */
static inline bool sk_busy_loop(struct sock *sk, int nonblock)
{
	unsigned long end_time = !nonblock ? sk_busy_loop_end_time(sk) : 0;
	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_busy_poll)
		goto out;

	do {
		rc = ops->ndo_busy_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_BUSYPOLLRXPACKETS, rc);
		cpu_relax();

	} while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) &&
		 !need_resched() && !busy_loop_timeout(end_time));

	rc = !skb_queue_empty(&sk->sk_receive_queue);
out:
	rcu_read_unlock_bh();
	return rc;
}

/* used in the NIC receive handler to mark the skb */
static inline void skb_mark_napi_id(struct sk_buff *skb,
				    struct napi_struct *napi)
{
	skb->napi_id = napi->napi_id;
}

/* used in the protocol hanlder to propagate the napi_id to the socket */
static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb)
{
	sk->sk_napi_id = skb->napi_id;
}

#else /* CONFIG_NET_RX_BUSY_POLL */
static inline unsigned long net_busy_loop_on(void)
{
	return 0;
}

static inline unsigned long busy_loop_end_time(void)
{
	return 0;
}

static inline bool sk_can_busy_loop(struct sock *sk)
{
	return false;
}

static inline void skb_mark_napi_id(struct sk_buff *skb,
				    struct napi_struct *napi)
{
}

static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb)
{
}

static inline bool busy_loop_timeout(unsigned long end_time)
{
	return true;
}

static inline bool sk_busy_loop(struct sock *sk, int nonblock)
{
	return false;
}

#endif /* CONFIG_NET_RX_BUSY_POLL */
#endif /* _LINUX_NET_BUSY_POLL_H */
Commit	Line	Data
06021292	1	/*
8b80cda5	2	* net busy poll support
06021292 ET	3	* Copyright(c) 2013 Intel Corporation.
	4	*
	5	* This program is free software; you can redistribute it and/or modify it
	6	* under the terms and conditions of the GNU General Public License,
	7	* version 2, as published by the Free Software Foundation.
	8	*
	9	* This program is distributed in the hope it will be useful, but WITHOUT
	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	12	* more details.
	13	*
	14	* You should have received a copy of the GNU General Public License along with
	15	* this program; if not, write to the Free Software Foundation, Inc.,
	16	* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
	17	*
	18	* Author: Eliezer Tamir
	19	*
	20	* Contact Information:
	21	* e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
	22	*/
	23
8b80cda5 ET	24	#ifndef _LINUX_NET_BUSY_POLL_H
8b80cda5 ET	25	#define _LINUX_NET_BUSY_POLL_H
06021292 ET	26
	27	#include <linux/netdevice.h>
	28	#include <net/ip.h>
	29
e0d1095a	30	#ifdef CONFIG_NET_RX_BUSY_POLL
06021292 ET	31
06021292 ET	32	struct napi_struct;
64b0dc51 ET	33	extern unsigned int sysctl_net_busy_read __read_mostly;
64b0dc51 ET	34	extern unsigned int sysctl_net_busy_poll __read_mostly;
06021292 ET	35
	36	/* return values from ndo_ll_poll */
	37	#define LL_FLUSH_FAILED -1
	38	#define LL_FLUSH_BUSY -2
	39
cbf55001	40	static inline bool net_busy_loop_on(void)
91e2fd33	41	{
64b0dc51	42	return sysctl_net_busy_poll;
91e2fd33 ET	43	}
91e2fd33 ET	44
ad6276e0 ET	45	/* a wrapper to make debug_smp_processor_id() happy
ad6276e0 ET	46	* we can use sched_clock() because we don't care much about precision
9a3c71aa	47	* we only care that the average is bounded
ad6276e0 ET	48	*/
ad6276e0 ET	49	#ifdef CONFIG_DEBUG_PREEMPT
76b1e9b9	50	static inline u64 busy_loop_us_clock(void)
ad6276e0 ET	51	{
	52	u64 rc;
	53
	54	preempt_disable_notrace();
	55	rc = sched_clock();
	56	preempt_enable_no_resched_notrace();
	57
76b1e9b9	58	return rc >> 10;
ad6276e0 ET	59	}
ad6276e0 ET	60	#else /* CONFIG_DEBUG_PREEMPT */
76b1e9b9	61	static inline u64 busy_loop_us_clock(void)
ad6276e0	62	{
76b1e9b9	63	return sched_clock() >> 10;
ad6276e0 ET	64	}
	65	#endif /* CONFIG_DEBUG_PREEMPT */
	66
76b1e9b9	67	static inline unsigned long sk_busy_loop_end_time(struct sock *sk)
06021292	68	{
76b1e9b9	69	return busy_loop_us_clock() + ACCESS_ONCE(sk->sk_ll_usec);
2d48d67f	70	}
9a3c71aa	71
76b1e9b9 ET	72	/* in poll/select we use the global sysctl_net_ll_poll value */
76b1e9b9 ET	73	static inline unsigned long busy_loop_end_time(void)
1bc2774d	74	{
64b0dc51	75	return busy_loop_us_clock() + ACCESS_ONCE(sysctl_net_busy_poll);
06021292 ET	76	}
06021292 ET	77
cbf55001	78	static inline bool sk_can_busy_loop(struct sock *sk)
06021292	79	{
dafcc438	80	return sk->sk_ll_usec && sk->sk_napi_id &&
06021292 ET	81	!need_resched() && !signal_pending(current);
	82	}
	83
76b1e9b9 ET	84
76b1e9b9 ET	85	static inline bool busy_loop_timeout(unsigned long end_time)
06021292	86	{
76b1e9b9	87	unsigned long now = busy_loop_us_clock();
1bc2774d	88
76b1e9b9	89	return time_after(now, end_time);
06021292 ET	90	}
06021292 ET	91
2d48d67f ET	92	/* when used in sock_poll() nonblock is known at compile time to be true
	93	* so the loop and end_time will be optimized out
	94	*/
cbf55001	95	static inline bool sk_busy_loop(struct sock *sk, int nonblock)
06021292	96	{
76b1e9b9	97	unsigned long end_time = !nonblock ? sk_busy_loop_end_time(sk) : 0;
06021292 ET	98	const struct net_device_ops *ops;
	99	struct napi_struct *napi;
	100	int rc = false;
	101
	102	/*
	103	* rcu read lock for napi hash
	104	* bh so we don't race with net_rx_action
	105	*/
	106	rcu_read_lock_bh();
	107
	108	napi = napi_by_id(sk->sk_napi_id);
	109	if (!napi)
	110	goto out;
	111
	112	ops = napi->dev->netdev_ops;
8b80cda5	113	if (!ops->ndo_busy_poll)
06021292 ET	114	goto out;
	115
	116	do {
8b80cda5	117	rc = ops->ndo_busy_poll(napi);
06021292 ET	118
	119	if (rc == LL_FLUSH_FAILED)
	120	break; /* permanent failure */
	121
	122	if (rc > 0)
	123	/* local bh are disabled so it is ok to use _BH */
	124	NET_ADD_STATS_BH(sock_net(sk),
288a9376	125	LINUX_MIB_BUSYPOLLRXPACKETS, rc);
3046e2f5	126	cpu_relax();
06021292	127
2d48d67f	128	} while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) &&
76b1e9b9	129	!need_resched() && !busy_loop_timeout(end_time));
06021292 ET	130
	131	rc = !skb_queue_empty(&sk->sk_receive_queue);
	132	out:
	133	rcu_read_unlock_bh();
	134	return rc;
	135	}
	136
	137	/* used in the NIC receive handler to mark the skb */
8b80cda5 ET	138	static inline void skb_mark_napi_id(struct sk_buff *skb,
8b80cda5 ET	139	struct napi_struct *napi)
06021292 ET	140	{
	141	skb->napi_id = napi->napi_id;
	142	}
	143
	144	/* used in the protocol hanlder to propagate the napi_id to the socket */
8b80cda5	145	static inline void sk_mark_napi_id(struct sock sk, struct sk_buff skb)
06021292 ET	146	{
	147	sk->sk_napi_id = skb->napi_id;
	148	}
	149
e0d1095a	150	#else /* CONFIG_NET_RX_BUSY_POLL */
cbf55001	151	static inline unsigned long net_busy_loop_on(void)
91e2fd33 ET	152	{
	153	return 0;
	154	}
06021292	155
76b1e9b9	156	static inline unsigned long busy_loop_end_time(void)
06021292 ET	157	{
	158	return 0;
	159	}
	160
cbf55001	161	static inline bool sk_can_busy_loop(struct sock *sk)
06021292 ET	162	{
	163	return false;
	164	}
	165
8b80cda5 ET	166	static inline void skb_mark_napi_id(struct sk_buff *skb,
8b80cda5 ET	167	struct napi_struct *napi)
06021292 ET	168	{
	169	}
	170
8b80cda5	171	static inline void sk_mark_napi_id(struct sock sk, struct sk_buff skb)
06021292 ET	172	{
	173	}
	174
76b1e9b9	175	static inline bool busy_loop_timeout(unsigned long end_time)
06021292	176	{
76b1e9b9	177	return true;
06021292 ET	178	}
06021292 ET	179
dfcefb0b CW	180	static inline bool sk_busy_loop(struct sock *sk, int nonblock)
	181	{
	182	return false;
	183	}
	184
e0d1095a	185	#endif /* CONFIG_NET_RX_BUSY_POLL */
8b80cda5	186	#endif /* _LINUX_NET_BUSY_POLL_H */