1 /* 2 * net busy poll support 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 24 #ifndef _LINUX_NET_BUSY_POLL_H 25 #define _LINUX_NET_BUSY_POLL_H 26 27 #include <linux/netdevice.h> 28 #include <net/ip.h> 29 30 #ifdef CONFIG_NET_RX_BUSY_POLL 31 32 struct napi_struct; 33 extern unsigned int sysctl_net_busy_read __read_mostly; 34 extern unsigned int sysctl_net_busy_poll __read_mostly; 35 36 /* return values from ndo_ll_poll */ 37 #define LL_FLUSH_FAILED -1 38 #define LL_FLUSH_BUSY -2 39 40 static inline bool net_busy_loop_on(void) 41 { 42 return sysctl_net_busy_poll; 43 } 44 45 static inline u64 busy_loop_us_clock(void) 46 { 47 return local_clock() >> 10; 48 } 49 50 static inline unsigned long sk_busy_loop_end_time(struct sock *sk) 51 { 52 return busy_loop_us_clock() + ACCESS_ONCE(sk->sk_ll_usec); 53 } 54 55 /* in poll/select we use the global sysctl_net_ll_poll value */ 56 static inline unsigned long busy_loop_end_time(void) 57 { 58 return busy_loop_us_clock() + ACCESS_ONCE(sysctl_net_busy_poll); 59 } 60 61 static inline bool sk_can_busy_loop(struct sock *sk) 62 { 63 return sk->sk_ll_usec && sk->sk_napi_id && 64 !need_resched() && !signal_pending(current); 65 } 66 67 68 static inline bool busy_loop_timeout(unsigned long end_time) 69 { 70 unsigned long now = busy_loop_us_clock(); 71 72 return time_after(now, end_time); 73 } 74 75 /* when used in sock_poll() nonblock is known at compile time to be true 76 * so the loop and end_time will be optimized out 77 */ 78 static inline bool sk_busy_loop(struct sock *sk, int nonblock) 79 { 80 unsigned long end_time = !nonblock ? sk_busy_loop_end_time(sk) : 0; 81 const struct net_device_ops *ops; 82 struct napi_struct *napi; 83 int rc = false; 84 85 /* 86 * rcu read lock for napi hash 87 * bh so we don't race with net_rx_action 88 */ 89 rcu_read_lock_bh(); 90 91 napi = napi_by_id(sk->sk_napi_id); 92 if (!napi) 93 goto out; 94 95 ops = napi->dev->netdev_ops; 96 if (!ops->ndo_busy_poll) 97 goto out; 98 99 do { 100 rc = ops->ndo_busy_poll(napi); 101 102 if (rc == LL_FLUSH_FAILED) 103 break; /* permanent failure */ 104 105 if (rc > 0) 106 /* local bh are disabled so it is ok to use _BH */ 107 NET_ADD_STATS_BH(sock_net(sk), 108 LINUX_MIB_BUSYPOLLRXPACKETS, rc); 109 cpu_relax(); 110 111 } while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) && 112 !need_resched() && !busy_loop_timeout(end_time)); 113 114 rc = !skb_queue_empty(&sk->sk_receive_queue); 115 out: 116 rcu_read_unlock_bh(); 117 return rc; 118 } 119 120 /* used in the NIC receive handler to mark the skb */ 121 static inline void skb_mark_napi_id(struct sk_buff *skb, 122 struct napi_struct *napi) 123 { 124 skb->napi_id = napi->napi_id; 125 } 126 127 /* used in the protocol hanlder to propagate the napi_id to the socket */ 128 static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb) 129 { 130 sk->sk_napi_id = skb->napi_id; 131 } 132 133 #else /* CONFIG_NET_RX_BUSY_POLL */ 134 static inline unsigned long net_busy_loop_on(void) 135 { 136 return 0; 137 } 138 139 static inline unsigned long busy_loop_end_time(void) 140 { 141 return 0; 142 } 143 144 static inline bool sk_can_busy_loop(struct sock *sk) 145 { 146 return false; 147 } 148 149 static inline void skb_mark_napi_id(struct sk_buff *skb, 150 struct napi_struct *napi) 151 { 152 } 153 154 static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb) 155 { 156 } 157 158 static inline bool busy_loop_timeout(unsigned long end_time) 159 { 160 return true; 161 } 162 163 static inline bool sk_busy_loop(struct sock *sk, int nonblock) 164 { 165 return false; 166 } 167 168 #endif /* CONFIG_NET_RX_BUSY_POLL */ 169 #endif /* _LINUX_NET_BUSY_POLL_H */ 170