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c42b7cddea
While reading sysctl_net_busy_poll, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.
Fixes: 0602129286 ("net: add low latency socket poll")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
177 lines
4.3 KiB
C
177 lines
4.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* net busy poll support
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* Copyright(c) 2013 Intel Corporation.
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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_BUSY_POLL_H
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#define _LINUX_NET_BUSY_POLL_H
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#include <linux/netdevice.h>
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#include <linux/sched/clock.h>
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#include <linux/sched/signal.h>
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#include <net/ip.h>
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/* 0 - Reserved to indicate value not set
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* 1..NR_CPUS - Reserved for sender_cpu
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* NR_CPUS+1..~0 - Region available for NAPI IDs
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*/
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#define MIN_NAPI_ID ((unsigned int)(NR_CPUS + 1))
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#define BUSY_POLL_BUDGET 8
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#ifdef CONFIG_NET_RX_BUSY_POLL
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struct napi_struct;
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extern unsigned int sysctl_net_busy_read __read_mostly;
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extern unsigned int sysctl_net_busy_poll __read_mostly;
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static inline bool net_busy_loop_on(void)
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{
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return READ_ONCE(sysctl_net_busy_poll);
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}
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static inline bool sk_can_busy_loop(const struct sock *sk)
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{
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return READ_ONCE(sk->sk_ll_usec) && !signal_pending(current);
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}
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bool sk_busy_loop_end(void *p, unsigned long start_time);
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void napi_busy_loop(unsigned int napi_id,
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bool (*loop_end)(void *, unsigned long),
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void *loop_end_arg, bool prefer_busy_poll, u16 budget);
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#else /* CONFIG_NET_RX_BUSY_POLL */
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static inline unsigned long net_busy_loop_on(void)
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{
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return 0;
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}
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static inline bool sk_can_busy_loop(struct sock *sk)
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{
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return false;
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}
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#endif /* CONFIG_NET_RX_BUSY_POLL */
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static inline unsigned long busy_loop_current_time(void)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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return (unsigned long)(local_clock() >> 10);
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#else
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return 0;
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#endif
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}
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/* in poll/select we use the global sysctl_net_ll_poll value */
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static inline bool busy_loop_timeout(unsigned long start_time)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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unsigned long bp_usec = READ_ONCE(sysctl_net_busy_poll);
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if (bp_usec) {
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unsigned long end_time = start_time + bp_usec;
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unsigned long now = busy_loop_current_time();
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return time_after(now, end_time);
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}
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#endif
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return true;
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}
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static inline bool sk_busy_loop_timeout(struct sock *sk,
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unsigned long start_time)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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unsigned long bp_usec = READ_ONCE(sk->sk_ll_usec);
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if (bp_usec) {
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unsigned long end_time = start_time + bp_usec;
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unsigned long now = busy_loop_current_time();
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return time_after(now, end_time);
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}
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#endif
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return true;
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}
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static inline void sk_busy_loop(struct sock *sk, int nonblock)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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unsigned int napi_id = READ_ONCE(sk->sk_napi_id);
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if (napi_id >= MIN_NAPI_ID)
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napi_busy_loop(napi_id, nonblock ? NULL : sk_busy_loop_end, sk,
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READ_ONCE(sk->sk_prefer_busy_poll),
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READ_ONCE(sk->sk_busy_poll_budget) ?: BUSY_POLL_BUDGET);
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#endif
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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_napi_id(struct sk_buff *skb,
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struct napi_struct *napi)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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/* If the skb was already marked with a valid NAPI ID, avoid overwriting
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* it.
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*/
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if (skb->napi_id < MIN_NAPI_ID)
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skb->napi_id = napi->napi_id;
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#endif
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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_napi_id(struct sock *sk, const struct sk_buff *skb)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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if (unlikely(READ_ONCE(sk->sk_napi_id) != skb->napi_id))
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WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
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#endif
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sk_rx_queue_update(sk, skb);
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}
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/* Variant of sk_mark_napi_id() for passive flow setup,
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* as sk->sk_napi_id and sk->sk_rx_queue_mapping content
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* needs to be set.
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*/
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static inline void sk_mark_napi_id_set(struct sock *sk,
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const struct sk_buff *skb)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
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#endif
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sk_rx_queue_set(sk, skb);
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}
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static inline void __sk_mark_napi_id_once(struct sock *sk, unsigned int napi_id)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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if (!READ_ONCE(sk->sk_napi_id))
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WRITE_ONCE(sk->sk_napi_id, napi_id);
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#endif
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}
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/* variant used for unconnected sockets */
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static inline void sk_mark_napi_id_once(struct sock *sk,
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const struct sk_buff *skb)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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__sk_mark_napi_id_once(sk, skb->napi_id);
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#endif
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}
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static inline void sk_mark_napi_id_once_xdp(struct sock *sk,
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const struct xdp_buff *xdp)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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__sk_mark_napi_id_once(sk, xdp->rxq->napi_id);
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#endif
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}
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#endif /* _LINUX_NET_BUSY_POLL_H */
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