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There are common instances of the following construct : if (n->confirmed != now) n->confirmed = now; A C compiler could legally remove the conditional. Use READ_ONCE()/WRITE_ONCE() to avoid this problem. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
83 lines
2.0 KiB
C
83 lines
2.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* linux/net/inet/arp.h */
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#ifndef _ARP_H
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#define _ARP_H
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#include <linux/if_arp.h>
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#include <linux/hash.h>
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#include <net/neighbour.h>
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extern struct neigh_table arp_tbl;
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static inline u32 arp_hashfn(const void *pkey, const struct net_device *dev, u32 *hash_rnd)
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{
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u32 key = *(const u32 *)pkey;
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u32 val = key ^ hash32_ptr(dev);
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return val * hash_rnd[0];
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}
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#ifdef CONFIG_INET
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static inline struct neighbour *__ipv4_neigh_lookup_noref(struct net_device *dev, u32 key)
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{
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if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
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key = INADDR_ANY;
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return ___neigh_lookup_noref(&arp_tbl, neigh_key_eq32, arp_hashfn, &key, dev);
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}
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#else
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static inline
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struct neighbour *__ipv4_neigh_lookup_noref(struct net_device *dev, u32 key)
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{
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return NULL;
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}
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#endif
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static inline struct neighbour *__ipv4_neigh_lookup(struct net_device *dev, u32 key)
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{
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struct neighbour *n;
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rcu_read_lock_bh();
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n = __ipv4_neigh_lookup_noref(dev, key);
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if (n && !refcount_inc_not_zero(&n->refcnt))
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n = NULL;
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rcu_read_unlock_bh();
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return n;
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}
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static inline void __ipv4_confirm_neigh(struct net_device *dev, u32 key)
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{
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struct neighbour *n;
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rcu_read_lock_bh();
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n = __ipv4_neigh_lookup_noref(dev, key);
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if (n) {
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unsigned long now = jiffies;
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/* avoid dirtying neighbour */
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if (READ_ONCE(n->confirmed) != now)
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WRITE_ONCE(n->confirmed, now);
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}
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rcu_read_unlock_bh();
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}
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void arp_init(void);
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int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg);
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void arp_send(int type, int ptype, __be32 dest_ip,
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struct net_device *dev, __be32 src_ip,
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const unsigned char *dest_hw,
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const unsigned char *src_hw, const unsigned char *th);
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int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir);
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void arp_ifdown(struct net_device *dev);
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struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
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struct net_device *dev, __be32 src_ip,
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const unsigned char *dest_hw,
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const unsigned char *src_hw,
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const unsigned char *target_hw);
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void arp_xmit(struct sk_buff *skb);
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#endif /* _ARP_H */
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