Commit 4c03bdd7 authored by Jesper Dangaard Brouer's avatar Jesper Dangaard Brouer Committed by David S. Miller
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xdp: adjust xdp redirect tracepoint to include return error code 



The return error code need to be included in the tracepoint
xdp:xdp_redirect, else its not possible to distinguish successful or
failed XDP_REDIRECT transmits.

XDP have no queuing mechanism. Thus, it is fairly easily to overrun a
NIC transmit queue.  The eBPF program invoking helpers (bpf_redirect
or bpf_redirect_map) to redirect a packet doesn't get any feedback
whether the packet was actually transmitted.

Info on failed transmits in the tracepoint xdp:xdp_redirect, is
interesting as this opens for providing a feedback-loop to the
receiving XDP program.

Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d2cee2e5

include/trace/events/xdp.h

+7 −4
Original line number Diff line number Diff line
@@ -53,15 +53,16 @@ TRACE_EVENT(xdp_redirect, 


	TP_PROTO(const struct net_device *from,

		 const struct net_device *to,

		 const struct bpf_prog *xdp, u32 act),

		 const struct bpf_prog *xdp, u32 act, int err),



	TP_ARGS(from, to, xdp, act),

	TP_ARGS(from, to, xdp, act, err),



	TP_STRUCT__entry(

		__string(name_from, from->name)

		__string(name_to, to->name)

		__array(u8, prog_tag, 8)

		__field(u32, act)

		__field(int, err)

	),



	TP_fast_assign(
@@ -70,12 +71,14 @@ TRACE_EVENT(xdp_redirect, 
		__assign_str(name_from, from->name);

		__assign_str(name_to, to->name);

		__entry->act = act;

		__entry->err = err;

	),



	TP_printk("prog=%s from=%s to=%s action=%s",

	TP_printk("prog=%s from=%s to=%s action=%s err=%d",

		  __print_hex_str(__entry->prog_tag, 8),

		  __get_str(name_from), __get_str(name_to),

		  __print_symbolic(__entry->act, __XDP_ACT_SYM_TAB))

		  __print_symbolic(__entry->act, __XDP_ACT_SYM_TAB),

		  __entry->err)

);

#endif /* _TRACE_XDP_H */

net/core/filter.c

+12 −7
Original line number Diff line number Diff line
@@ -2535,14 +2535,16 @@ int xdp_do_redirect_map(struct net_device *dev, struct xdp_buff *xdp, 
	struct bpf_map *map = ri->map;

	u32 index = ri->ifindex;

	struct net_device *fwd;

	int err = -EINVAL;

	int err;



	ri->ifindex = 0;

	ri->map = NULL;



	fwd = __dev_map_lookup_elem(map, index);

	if (!fwd)

	if (!fwd) {

		err = -EINVAL;

		goto out;

	}



	if (ri->map_to_flush && (ri->map_to_flush != map))

		xdp_do_flush_map();
@@ -2552,7 +2554,7 @@ int xdp_do_redirect_map(struct net_device *dev, struct xdp_buff *xdp, 
		ri->map_to_flush = map;



out:

	trace_xdp_redirect(dev, fwd, xdp_prog, XDP_REDIRECT);

	trace_xdp_redirect(dev, fwd, xdp_prog, XDP_REDIRECT, err);

	return err;

}
@@ -2562,6 +2564,7 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp, 
	struct redirect_info *ri = this_cpu_ptr(&redirect_info);

	struct net_device *fwd;

	u32 index = ri->ifindex;

	int err;



	if (ri->map)

		return xdp_do_redirect_map(dev, xdp, xdp_prog);
@@ -2570,12 +2573,14 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp, 
	ri->ifindex = 0;

	if (unlikely(!fwd)) {

		bpf_warn_invalid_xdp_redirect(index);

		return -EINVAL;

		err = -EINVAL;

		goto out;

	}



	trace_xdp_redirect(dev, fwd, xdp_prog, XDP_REDIRECT);



	return __bpf_tx_xdp(fwd, NULL, xdp, 0);

	err = __bpf_tx_xdp(fwd, NULL, xdp, 0);

out:

	trace_xdp_redirect(dev, fwd, xdp_prog, XDP_REDIRECT, err);

	return err;

}

EXPORT_SYMBOL_GPL(xdp_do_redirect);

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