bpf, xdp: Maintain info on attached XDP BPF programs in net_device
Instead of delegating to drivers, maintain information about which BPF programs are attached in which XDP modes (generic/skb, driver, or hardware) locally in net_device. This effectively obsoletes XDP_QUERY_PROG command. Such re-organization simplifies existing code already. But it also allows to further add bpf_link-based XDP attachments without drivers having to know about any of this at all, which seems like a good setup. XDP_SETUP_PROG/XDP_SETUP_PROG_HW are just low-level commands to driver to install/uninstall active BPF program. All the higher-level concerns about prog/link interaction will be contained within generic driver-agnostic logic. All the XDP_QUERY_PROG calls to driver in dev_xdp_uninstall() were removed. It's not clear for me why dev_xdp_uninstall() were passing previous prog_flags when resetting installed programs. That seems unnecessary, plus most drivers don't populate prog_flags anyways. Having XDP_SETUP_PROG vs XDP_SETUP_PROG_HW should be enough of an indicator of what is required of driver to correctly reset active BPF program. dev_xdp_uninstall() is also generalized as an iteration over all three supported mode. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200722064603.3350758-3-andriin@fb.com
This commit is contained in:
Andrii Nakryiko
Alexei Starovoitov
Родитель
6cc7d1e8e9
Коммит
7f0a838254
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@ -889,6 +889,17 @@ struct netlink_ext_ack;
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struct xdp_umem;
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struct xdp_dev_bulk_queue;
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enum bpf_xdp_mode {
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XDP_MODE_SKB = 0,
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XDP_MODE_DRV = 1,
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XDP_MODE_HW = 2,
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__MAX_XDP_MODE
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};
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struct bpf_xdp_entity {
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struct bpf_prog *prog;
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};
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struct netdev_bpf {
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enum bpf_netdev_command command;
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union {
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@ -2142,6 +2153,9 @@ struct net_device {
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#endif
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const struct udp_tunnel_nic_info *udp_tunnel_nic_info;
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struct udp_tunnel_nic *udp_tunnel_nic;
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/* protected by rtnl_lock */
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struct bpf_xdp_entity xdp_state[__MAX_XDP_MODE];
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};
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#define to_net_dev(d) container_of(d, struct net_device, dev)
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@ -3817,8 +3831,7 @@ struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
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typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf);
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int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
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int fd, int expected_fd, u32 flags);
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u32 __dev_xdp_query(struct net_device *dev, bpf_op_t xdp_op,
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enum bpf_netdev_command cmd);
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u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode);
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int xdp_umem_query(struct net_device *dev, u16 queue_id);
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int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb);
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166
net/core/dev.c
166
net/core/dev.c
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@ -8716,84 +8716,103 @@ int dev_change_proto_down_generic(struct net_device *dev, bool proto_down)
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}
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EXPORT_SYMBOL(dev_change_proto_down_generic);
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u32 __dev_xdp_query(struct net_device *dev, bpf_op_t bpf_op,
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enum bpf_netdev_command cmd)
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static enum bpf_xdp_mode dev_xdp_mode(u32 flags)
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{
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struct netdev_bpf xdp;
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if (!bpf_op)
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return 0;
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memset(&xdp, 0, sizeof(xdp));
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xdp.command = cmd;
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/* Query must always succeed. */
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WARN_ON(bpf_op(dev, &xdp) < 0 && cmd == XDP_QUERY_PROG);
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return xdp.prog_id;
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if (flags & XDP_FLAGS_HW_MODE)
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return XDP_MODE_HW;
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if (flags & XDP_FLAGS_DRV_MODE)
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return XDP_MODE_DRV;
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return XDP_MODE_SKB;
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}
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static int dev_xdp_install(struct net_device *dev, bpf_op_t bpf_op,
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struct netlink_ext_ack *extack, u32 flags,
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static bpf_op_t dev_xdp_bpf_op(struct net_device *dev, enum bpf_xdp_mode mode)
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{
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switch (mode) {
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case XDP_MODE_SKB:
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return generic_xdp_install;
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case XDP_MODE_DRV:
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case XDP_MODE_HW:
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return dev->netdev_ops->ndo_bpf;
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default:
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return NULL;
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};
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}
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static struct bpf_prog *dev_xdp_prog(struct net_device *dev,
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enum bpf_xdp_mode mode)
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{
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return dev->xdp_state[mode].prog;
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}
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u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode)
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{
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struct bpf_prog *prog = dev_xdp_prog(dev, mode);
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return prog ? prog->aux->id : 0;
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}
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static void dev_xdp_set_prog(struct net_device *dev, enum bpf_xdp_mode mode,
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struct bpf_prog *prog)
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{
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bool non_hw = !(flags & XDP_FLAGS_HW_MODE);
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struct bpf_prog *prev_prog = NULL;
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dev->xdp_state[mode].prog = prog;
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}
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static int dev_xdp_install(struct net_device *dev, enum bpf_xdp_mode mode,
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bpf_op_t bpf_op, struct netlink_ext_ack *extack,
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u32 flags, struct bpf_prog *prog)
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{
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struct netdev_bpf xdp;
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int err;
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if (non_hw) {
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prev_prog = bpf_prog_by_id(__dev_xdp_query(dev, bpf_op,
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XDP_QUERY_PROG));
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if (IS_ERR(prev_prog))
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prev_prog = NULL;
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}
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memset(&xdp, 0, sizeof(xdp));
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if (flags & XDP_FLAGS_HW_MODE)
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xdp.command = XDP_SETUP_PROG_HW;
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else
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xdp.command = XDP_SETUP_PROG;
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xdp.command = mode == XDP_MODE_HW ? XDP_SETUP_PROG_HW : XDP_SETUP_PROG;
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xdp.extack = extack;
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xdp.flags = flags;
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xdp.prog = prog;
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/* Drivers assume refcnt is already incremented (i.e, prog pointer is
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* "moved" into driver), so they don't increment it on their own, but
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* they do decrement refcnt when program is detached or replaced.
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* Given net_device also owns link/prog, we need to bump refcnt here
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* to prevent drivers from underflowing it.
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*/
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if (prog)
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bpf_prog_inc(prog);
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err = bpf_op(dev, &xdp);
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if (!err && non_hw)
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bpf_prog_change_xdp(prev_prog, prog);
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if (prev_prog)
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bpf_prog_put(prev_prog);
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if (err) {
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if (prog)
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bpf_prog_put(prog);
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return err;
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}
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if (mode != XDP_MODE_HW)
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bpf_prog_change_xdp(dev_xdp_prog(dev, mode), prog);
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return 0;
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}
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static void dev_xdp_uninstall(struct net_device *dev)
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{
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struct netdev_bpf xdp;
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bpf_op_t ndo_bpf;
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struct bpf_prog *prog;
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enum bpf_xdp_mode mode;
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bpf_op_t bpf_op;
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/* Remove generic XDP */
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WARN_ON(dev_xdp_install(dev, generic_xdp_install, NULL, 0, NULL));
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ASSERT_RTNL();
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/* Remove from the driver */
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ndo_bpf = dev->netdev_ops->ndo_bpf;
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if (!ndo_bpf)
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return;
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for (mode = XDP_MODE_SKB; mode < __MAX_XDP_MODE; mode++) {
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prog = dev_xdp_prog(dev, mode);
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if (!prog)
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continue;
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memset(&xdp, 0, sizeof(xdp));
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xdp.command = XDP_QUERY_PROG;
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WARN_ON(ndo_bpf(dev, &xdp));
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if (xdp.prog_id)
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WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags,
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NULL));
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bpf_op = dev_xdp_bpf_op(dev, mode);
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if (!bpf_op)
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continue;
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/* Remove HW offload */
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memset(&xdp, 0, sizeof(xdp));
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xdp.command = XDP_QUERY_PROG_HW;
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if (!ndo_bpf(dev, &xdp) && xdp.prog_id)
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WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags,
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NULL));
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WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL));
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bpf_prog_put(prog);
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dev_xdp_set_prog(dev, mode, NULL);
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}
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}
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/**
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@ -8810,29 +8829,22 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
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int fd, int expected_fd, u32 flags)
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{
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const struct net_device_ops *ops = dev->netdev_ops;
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enum bpf_netdev_command query;
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enum bpf_xdp_mode mode = dev_xdp_mode(flags);
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bool offload = mode == XDP_MODE_HW;
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u32 prog_id, expected_id = 0;
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bpf_op_t bpf_op, bpf_chk;
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struct bpf_prog *prog;
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bool offload;
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bpf_op_t bpf_op;
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int err;
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ASSERT_RTNL();
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offload = flags & XDP_FLAGS_HW_MODE;
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query = offload ? XDP_QUERY_PROG_HW : XDP_QUERY_PROG;
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bpf_op = bpf_chk = ops->ndo_bpf;
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if (!bpf_op && (flags & (XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE))) {
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bpf_op = dev_xdp_bpf_op(dev, mode);
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if (!bpf_op) {
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NL_SET_ERR_MSG(extack, "underlying driver does not support XDP in native mode");
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return -EOPNOTSUPP;
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}
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if (!bpf_op || (flags & XDP_FLAGS_SKB_MODE))
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bpf_op = generic_xdp_install;
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if (bpf_op == bpf_chk)
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bpf_chk = generic_xdp_install;
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prog_id = __dev_xdp_query(dev, bpf_op, query);
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prog_id = dev_xdp_prog_id(dev, mode);
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if (flags & XDP_FLAGS_REPLACE) {
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if (expected_fd >= 0) {
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prog = bpf_prog_get_type_dev(expected_fd,
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@ -8850,8 +8862,11 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
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}
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}
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if (fd >= 0) {
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if (!offload && __dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG)) {
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NL_SET_ERR_MSG(extack, "native and generic XDP can't be active at the same time");
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enum bpf_xdp_mode other_mode = mode == XDP_MODE_SKB
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? XDP_MODE_DRV : XDP_MODE_SKB;
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if (!offload && dev_xdp_prog_id(dev, other_mode)) {
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NL_SET_ERR_MSG(extack, "Native and generic XDP can't be active at the same time");
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return -EEXIST;
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}
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@ -8866,7 +8881,7 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
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return PTR_ERR(prog);
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if (!offload && bpf_prog_is_dev_bound(prog->aux)) {
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NL_SET_ERR_MSG(extack, "using device-bound program without HW_MODE flag is not supported");
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NL_SET_ERR_MSG(extack, "Using device-bound program without HW_MODE flag is not supported");
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bpf_prog_put(prog);
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return -EINVAL;
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}
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@ -8895,12 +8910,15 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
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prog = NULL;
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}
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err = dev_xdp_install(dev, bpf_op, extack, flags, prog);
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if (err < 0 && prog)
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err = dev_xdp_install(dev, mode, bpf_op, extack, flags, prog);
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if (err < 0 && prog) {
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bpf_prog_put(prog);
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return err;
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}
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dev_xdp_set_prog(dev, mode, prog);
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return 0;
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}
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/**
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* dev_new_index - allocate an ifindex
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@ -1416,13 +1416,12 @@ static u32 rtnl_xdp_prog_skb(struct net_device *dev)
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static u32 rtnl_xdp_prog_drv(struct net_device *dev)
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{
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return __dev_xdp_query(dev, dev->netdev_ops->ndo_bpf, XDP_QUERY_PROG);
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return dev_xdp_prog_id(dev, XDP_MODE_DRV);
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}
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static u32 rtnl_xdp_prog_hw(struct net_device *dev)
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{
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return __dev_xdp_query(dev, dev->netdev_ops->ndo_bpf,
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XDP_QUERY_PROG_HW);
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return dev_xdp_prog_id(dev, XDP_MODE_HW);
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}
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static int rtnl_xdp_report_one(struct sk_buff *skb, struct net_device *dev,
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