272 lines
6.6 KiB
C
272 lines
6.6 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/* XSKMAP used for AF_XDP sockets
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* Copyright(c) 2018 Intel Corporation.
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*/
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#include <linux/bpf.h>
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#include <linux/capability.h>
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#include <net/xdp_sock.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include "xsk.h"
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static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map,
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struct xdp_sock __rcu **map_entry)
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{
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struct xsk_map_node *node;
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node = bpf_map_kzalloc(&map->map, sizeof(*node),
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GFP_ATOMIC | __GFP_NOWARN);
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if (!node)
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return ERR_PTR(-ENOMEM);
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bpf_map_inc(&map->map);
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node->map = map;
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node->map_entry = map_entry;
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return node;
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}
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static void xsk_map_node_free(struct xsk_map_node *node)
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{
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bpf_map_put(&node->map->map);
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kfree(node);
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}
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static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node)
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{
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spin_lock_bh(&xs->map_list_lock);
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list_add_tail(&node->node, &xs->map_list);
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spin_unlock_bh(&xs->map_list_lock);
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}
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static void xsk_map_sock_delete(struct xdp_sock *xs,
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struct xdp_sock __rcu **map_entry)
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{
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struct xsk_map_node *n, *tmp;
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spin_lock_bh(&xs->map_list_lock);
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list_for_each_entry_safe(n, tmp, &xs->map_list, node) {
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if (map_entry == n->map_entry) {
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list_del(&n->node);
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xsk_map_node_free(n);
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}
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}
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spin_unlock_bh(&xs->map_list_lock);
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}
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static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
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{
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struct xsk_map *m;
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int numa_node;
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u64 size;
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if (!capable(CAP_NET_ADMIN))
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return ERR_PTR(-EPERM);
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if (attr->max_entries == 0 || attr->key_size != 4 ||
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attr->value_size != 4 ||
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attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY))
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return ERR_PTR(-EINVAL);
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numa_node = bpf_map_attr_numa_node(attr);
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size = struct_size(m, xsk_map, attr->max_entries);
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m = bpf_map_area_alloc(size, numa_node);
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if (!m)
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return ERR_PTR(-ENOMEM);
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bpf_map_init_from_attr(&m->map, attr);
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spin_lock_init(&m->lock);
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return &m->map;
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}
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static void xsk_map_free(struct bpf_map *map)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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synchronize_net();
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bpf_map_area_free(m);
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}
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static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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u32 index = key ? *(u32 *)key : U32_MAX;
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u32 *next = next_key;
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if (index >= m->map.max_entries) {
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*next = 0;
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return 0;
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}
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if (index == m->map.max_entries - 1)
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return -ENOENT;
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*next = index + 1;
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return 0;
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}
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static int xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
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{
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const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2;
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struct bpf_insn *insn = insn_buf;
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*insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
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*insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
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*insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *)));
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*insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map));
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*insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp);
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*insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0);
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*insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
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*insn++ = BPF_MOV64_IMM(ret, 0);
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return insn - insn_buf;
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}
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/* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
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* by local_bh_disable() (from XDP calls inside NAPI). The
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* rcu_read_lock_bh_held() below makes lockdep accept both.
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*/
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static void *__xsk_map_lookup_elem(struct bpf_map *map, u32 key)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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if (key >= map->max_entries)
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return NULL;
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return rcu_dereference_check(m->xsk_map[key], rcu_read_lock_bh_held());
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}
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static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
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{
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return __xsk_map_lookup_elem(map, *(u32 *)key);
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}
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static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
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u64 map_flags)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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struct xdp_sock __rcu **map_entry;
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struct xdp_sock *xs, *old_xs;
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u32 i = *(u32 *)key, fd = *(u32 *)value;
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struct xsk_map_node *node;
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struct socket *sock;
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int err;
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if (unlikely(map_flags > BPF_EXIST))
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return -EINVAL;
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if (unlikely(i >= m->map.max_entries))
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return -E2BIG;
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sock = sockfd_lookup(fd, &err);
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if (!sock)
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return err;
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if (sock->sk->sk_family != PF_XDP) {
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sockfd_put(sock);
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return -EOPNOTSUPP;
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}
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xs = (struct xdp_sock *)sock->sk;
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map_entry = &m->xsk_map[i];
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node = xsk_map_node_alloc(m, map_entry);
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if (IS_ERR(node)) {
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sockfd_put(sock);
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return PTR_ERR(node);
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}
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spin_lock_bh(&m->lock);
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old_xs = rcu_dereference_protected(*map_entry, lockdep_is_held(&m->lock));
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if (old_xs == xs) {
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err = 0;
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goto out;
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} else if (old_xs && map_flags == BPF_NOEXIST) {
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err = -EEXIST;
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goto out;
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} else if (!old_xs && map_flags == BPF_EXIST) {
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err = -ENOENT;
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goto out;
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}
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xsk_map_sock_add(xs, node);
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rcu_assign_pointer(*map_entry, xs);
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if (old_xs)
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xsk_map_sock_delete(old_xs, map_entry);
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spin_unlock_bh(&m->lock);
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sockfd_put(sock);
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return 0;
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out:
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spin_unlock_bh(&m->lock);
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sockfd_put(sock);
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xsk_map_node_free(node);
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return err;
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}
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static int xsk_map_delete_elem(struct bpf_map *map, void *key)
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{
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struct xsk_map *m = container_of(map, struct xsk_map, map);
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struct xdp_sock __rcu **map_entry;
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struct xdp_sock *old_xs;
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int k = *(u32 *)key;
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if (k >= map->max_entries)
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return -EINVAL;
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spin_lock_bh(&m->lock);
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map_entry = &m->xsk_map[k];
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old_xs = unrcu_pointer(xchg(map_entry, NULL));
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if (old_xs)
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xsk_map_sock_delete(old_xs, map_entry);
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spin_unlock_bh(&m->lock);
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return 0;
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}
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static int xsk_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
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{
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return __bpf_xdp_redirect_map(map, ifindex, flags, 0,
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__xsk_map_lookup_elem);
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}
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void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
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struct xdp_sock __rcu **map_entry)
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{
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spin_lock_bh(&map->lock);
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if (rcu_access_pointer(*map_entry) == xs) {
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rcu_assign_pointer(*map_entry, NULL);
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xsk_map_sock_delete(xs, map_entry);
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}
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spin_unlock_bh(&map->lock);
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}
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static bool xsk_map_meta_equal(const struct bpf_map *meta0,
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const struct bpf_map *meta1)
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{
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return meta0->max_entries == meta1->max_entries &&
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bpf_map_meta_equal(meta0, meta1);
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}
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static int xsk_map_btf_id;
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const struct bpf_map_ops xsk_map_ops = {
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.map_meta_equal = xsk_map_meta_equal,
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.map_alloc = xsk_map_alloc,
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.map_free = xsk_map_free,
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.map_get_next_key = xsk_map_get_next_key,
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.map_lookup_elem = xsk_map_lookup_elem,
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.map_gen_lookup = xsk_map_gen_lookup,
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.map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
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.map_update_elem = xsk_map_update_elem,
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.map_delete_elem = xsk_map_delete_elem,
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.map_check_btf = map_check_no_btf,
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.map_btf_name = "xsk_map",
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.map_btf_id = &xsk_map_btf_id,
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.map_redirect = xsk_map_redirect,
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};
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