From 4c03bdd7b5c084c3c6973cb2419edac5363c051f Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Thu, 17 Aug 2017 18:22:37 +0200 Subject: [PATCH] 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: Jesper Dangaard Brouer Signed-off-by: David S. Miller --- include/trace/events/xdp.h | 11 +++++++---- net/core/filter.c | 19 ++++++++++++------- 2 files changed, 19 insertions(+), 11 deletions(-) diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h index 7b1eb7b4be41..0e42e69f773b 100644 --- a/include/trace/events/xdp.h +++ b/include/trace/events/xdp.h @@ -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 */ diff --git a/net/core/filter.c b/net/core/filter.c index 0f4df86d936a..fa2115695037 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -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); -- 2.34.1