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/*
* Low Latency Sockets
* 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>
*/
/*
* For now this depends on CONFIG_X86_TSC
*/
#ifndef _LINUX_NET_LL_POLL_H
#define _LINUX_NET_LL_POLL_H
#include <linux/netdevice.h>
#include <net/ip.h>
#ifdef CONFIG_NET_LL_RX_POLL
struct napi_struct;
extern unsigned long sysctl_net_ll_poll __read_mostly;
/* return values from ndo_ll_poll */
#define LL_FLUSH_FAILED -1
#define LL_FLUSH_BUSY -2
/* we don't mind a ~2.5% imprecision */
#define TSC_MHZ (tsc_khz >> 10)
static inline cycles_t ll_end_time(void)
{
return TSC_MHZ * ACCESS_ONCE(sysctl_net_ll_poll) + get_cycles();
}
static inline bool sk_valid_ll(struct sock *sk)
{
return sysctl_net_ll_poll && sk->sk_napi_id &&
!need_resched() && !signal_pending(current);
}
static inline bool can_poll_ll(cycles_t end_time)
{
return !time_after((unsigned long)get_cycles(),
(unsigned long)end_time);
}
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;
}
/* used in the NIC receive handler to mark the skb */
static inline void skb_mark_ll(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_ll(struct sock *sk, struct sk_buff *skb)
{
sk->sk_napi_id = skb->napi_id;
}
#else /* CONFIG_NET_LL_RX_POLL */
static inline cycles_t ll_end_time(void)
{
return 0;
}
static inline bool sk_valid_ll(struct sock *sk)
{
return false;
}
static inline bool sk_poll_ll(struct sock *sk, int nonblock)
{
return false;
}
static inline void skb_mark_ll(struct sk_buff *skb, struct napi_struct *napi)
{
}
static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb)
{
}
static inline bool can_poll_ll(cycles_t end_time)
{
return false;
}
#endif /* CONFIG_NET_LL_RX_POLL */
#endif /* _LINUX_NET_LL_POLL_H */
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