Thread (31 messages) 31 messages, 4 authors, 2017-08-24

[V3 PATCH net-next 4/5] xdp: remove net_device names from xdp_redirect tracepoint

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STALE3347d REVIEWED: 1 (1M)

From: Jesper Dangaard Brouer <hidden>
Date: 2017-08-24 10:33:21
Subsystem: bpf [general] (safe dynamic programs and tools), bpf [networking] (tcx & tc bpf, sock_addr), networking [general], the rest, tracing, xdp (express data path) · Maintainers: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Steven Rostedt, Masami Hiramatsu, Jesper Dangaard Brouer, John Fastabend

Revision v3 of 3 in this series; 1 review trailer (1 from subsystem maintainers).

Revisions (3)
  1. v1 [diff vs current]
  2. v2 [diff vs current]
  3. v3 current
There is too much overhead in the current trace_xdp_redirect
tracepoint as it does strcpy and strlen on the net_device names.

Besides, exposing the ifindex/index is actually the information that
is needed in the tracepoint to diagnose issues.  When a lookup fails
(either ifindex or devmap index) then there is a need for saying which
to_index that have issues.

V2: Adjust args to be aligned with trace_xdp_exception.

Signed-off-by: Jesper Dangaard Brouer <redacted>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
---
 include/trace/events/xdp.h |   24 ++++++++++++------------
 net/core/filter.c          |    6 +++---
 2 files changed, 15 insertions(+), 15 deletions(-)
diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h
index 0e42e69f773b..cd37706c6f55 100644
--- a/include/trace/events/xdp.h
+++ b/include/trace/events/xdp.h
@@ -51,33 +51,33 @@ TRACE_EVENT(xdp_exception,
 
 TRACE_EVENT(xdp_redirect,
 
-	TP_PROTO(const struct net_device *from,
-		 const struct net_device *to,
-		 const struct bpf_prog *xdp, u32 act, int err),
+	TP_PROTO(const struct net_device *dev,
+		 const struct bpf_prog *xdp, u32 act,
+		 int to_index, int err),
 
-	TP_ARGS(from, to, xdp, act, err),
+	TP_ARGS(dev, xdp, act, to_index, err),
 
 	TP_STRUCT__entry(
-		__string(name_from, from->name)
-		__string(name_to, to->name)
 		__array(u8, prog_tag, 8)
 		__field(u32, act)
+		__field(int, ifindex)
+		__field(int, to_index)
 		__field(int, err)
 	),
 
 	TP_fast_assign(
 		BUILD_BUG_ON(sizeof(__entry->prog_tag) != sizeof(xdp->tag));
 		memcpy(__entry->prog_tag, xdp->tag, sizeof(xdp->tag));
-		__assign_str(name_from, from->name);
-		__assign_str(name_to, to->name);
-		__entry->act = act;
-		__entry->err = err;
+		__entry->act		= act;
+		__entry->ifindex	= dev->ifindex;
+		__entry->to_index	= to_index;
+		__entry->err		= err;
 	),
 
-	TP_printk("prog=%s from=%s to=%s action=%s err=%d",
+	TP_printk("prog=%s action=%s ifindex=%d to_index=%d 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),
+		  __entry->ifindex, __entry->to_index,
 		  __entry->err)
 );
 #endif /* _TRACE_XDP_H */
diff --git a/net/core/filter.c b/net/core/filter.c
index a04680331033..4bcd6baa80c9 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2524,7 +2524,7 @@ static int xdp_do_redirect_map(struct net_device *dev, struct xdp_buff *xdp,
 	if (likely(!err))
 		ri->map_to_flush = map;
 out:
-	trace_xdp_redirect(dev, fwd, xdp_prog, XDP_REDIRECT, err);
+	trace_xdp_redirect(dev, xdp_prog, XDP_REDIRECT, index, err);
 	return err;
 }
 
@@ -2548,7 +2548,7 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 
 	err = __bpf_tx_xdp(fwd, NULL, xdp, 0);
 out:
-	trace_xdp_redirect(dev, fwd, xdp_prog, XDP_REDIRECT, err);
+	trace_xdp_redirect(dev, xdp_prog, XDP_REDIRECT, index, err);
 	return err;
 }
 EXPORT_SYMBOL_GPL(xdp_do_redirect);
@@ -2582,7 +2582,7 @@ int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb,
 
 	skb->dev = fwd;
 out:
-	trace_xdp_redirect(dev, fwd, xdp_prog, XDP_REDIRECT, err);
+	trace_xdp_redirect(dev, xdp_prog, XDP_REDIRECT, index, err);
 	return err;
 }
 EXPORT_SYMBOL_GPL(xdp_do_generic_redirect);
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