Merge branch 'xdp-more-work-on-xdp-tracepoints'

Jesper Dangaard Brouer says:

====================
xdp: more work on xdp tracepoints

More work on streamlining and performance optimizing the tracepoints
for XDP.

I've created a simple xdp_monitor application that uses this
tracepoint, and prints statistics. Available at github:

https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/samples/bpf/xdp_monitor_kern.c
https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/samples/bpf/xdp_monitor_user.c

The improvement over tracepoint with strcpy: 9810372 - 8428762 = +1381610 pps faster
 - (1/9810372 - 1/8428762)*10^9 = -16.7 nanosec
 - 100-(8428762/9810372*100) = strcpy-trace is 14.08% slower
 - 981037/8428762*100 = removing strcpy made it 11.64% faster

V3: Fix merge conflict with commit e4a8e817 ("bpf: misc xdp redirect cleanups")
V2: Change trace_xdp_redirect() to align with args of trace_xdp_exception()
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -9849,14 +9849,14 @@ static int ixgbe_xdp_xmit(struct net_device *dev, struct xdp_buff *xdp)
 	int err;
 
 	if (unlikely(test_bit(__IXGBE_DOWN, &adapter->state)))
-		return -EINVAL;
+		return -ENETDOWN;
 
 	/* During program transitions its possible adapter->xdp_prog is assigned
 	 * but ring has not been configured yet. In this case simply abort xmit.
 	 */
 	ring = adapter->xdp_prog ? adapter->xdp_ring[smp_processor_id()] : NULL;
 	if (unlikely(!ring))
-		return -EINVAL;
+		return -ENXIO;
 
 	err = ixgbe_xmit_xdp_ring(adapter, xdp);
 	if (err != IXGBE_XDP_TX)

include/linux/filter.h

@@ -718,7 +718,8 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
  * because we only track one map and force a flush when the map changes.
  * This does not appear to be a real limitation for existing software.
  */
-int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb);
+int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb,
+			    struct bpf_prog *prog);
 int xdp_do_redirect(struct net_device *dev,
 		    struct xdp_buff *xdp,
 		    struct bpf_prog *prog);

include/trace/events/xdp.h

@@ -31,53 +31,53 @@ TRACE_EVENT(xdp_exception,
 	TP_ARGS(dev, xdp, act),
 
 	TP_STRUCT__entry(
-		__string(name, dev->name)
 		__array(u8, prog_tag, 8)
 		__field(u32, act)
+		__field(int, ifindex)
 	),
 
 	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, dev->name);
 		__entry->act		= act;
+		__entry->ifindex	= dev->ifindex;
 	),
 
-	TP_printk("prog=%s device=%s action=%s",
+	TP_printk("prog=%s action=%s ifindex=%d",
 		  __print_hex_str(__entry->prog_tag, 8),
-		  __get_str(name),
-		  __print_symbolic(__entry->act, __XDP_ACT_SYM_TAB))
+		  __print_symbolic(__entry->act, __XDP_ACT_SYM_TAB),
+		  __entry->ifindex)
 );
 
 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->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 */

net/core/dev.c

@@ -3953,7 +3953,8 @@ int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb)
 		if (act != XDP_PASS) {
 			switch (act) {
 			case XDP_REDIRECT:
-				err = xdp_do_generic_redirect(skb->dev, skb);
+				err = xdp_do_generic_redirect(skb->dev, skb,
+							      xdp_prog);
 				if (err)
 					goto out_redir;
 			/* fallthru to submit skb */
@@ -3966,7 +3967,6 @@ int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb)
 	}
 	return XDP_PASS;
 out_redir:
-	trace_xdp_exception(skb->dev, xdp_prog, XDP_REDIRECT);
 	kfree_skb(skb);
 	return XDP_DROP;
 }

net/core/filter.c

@@ -2476,7 +2476,6 @@ static int __bpf_tx_xdp(struct net_device *dev,
 	int err;
 
 	if (!dev->netdev_ops->ndo_xdp_xmit) {
-		bpf_warn_invalid_xdp_redirect(dev->ifindex);
 		return -EOPNOTSUPP;
 	}
 
@@ -2525,7 +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;
 }
 
@@ -2543,39 +2542,48 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 	fwd = dev_get_by_index_rcu(dev_net(dev), index);
 	ri->ifindex = 0;
 	if (unlikely(!fwd)) {
-		bpf_warn_invalid_xdp_redirect(index);
 		err = -EINVAL;
 		goto out;
 	}
 
 	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);
 
-int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb)
+int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb,
+			    struct bpf_prog *xdp_prog)
 {
 	struct redirect_info *ri = this_cpu_ptr(&redirect_info);
-	unsigned int len;
 	u32 index = ri->ifindex;
+	struct net_device *fwd;
+	unsigned int len;
+	int err = 0;
 
-	dev = dev_get_by_index_rcu(dev_net(dev), index);
+	fwd = dev_get_by_index_rcu(dev_net(dev), index);
 	ri->ifindex = 0;
-	if (unlikely(!dev)) {
-		bpf_warn_invalid_xdp_redirect(index);
-		return -EINVAL;
+	if (unlikely(!fwd)) {
+		err = -EINVAL;
+		goto out;
 	}
 
-	if (unlikely(!(dev->flags & IFF_UP)))
-		return -ENETDOWN;
-	len = dev->mtu + dev->hard_header_len + VLAN_HLEN;
-	if (skb->len > len)
-		return -E2BIG;
+	if (unlikely(!(fwd->flags & IFF_UP))) {
+		err = -ENETDOWN;
+		goto out;
+	}
 
-	skb->dev = dev;
-	return 0;
+	len = fwd->mtu + fwd->hard_header_len + VLAN_HLEN;
+	if (skb->len > len) {
+		err = -EMSGSIZE;
+		goto out;
+	}
+
+	skb->dev = fwd;
+out:
+	trace_xdp_redirect(dev, xdp_prog, XDP_REDIRECT, index, err);
+	return err;
 }
 EXPORT_SYMBOL_GPL(xdp_do_generic_redirect);
 
@@ -3565,11 +3573,6 @@ void bpf_warn_invalid_xdp_action(u32 act)
 }
 EXPORT_SYMBOL_GPL(bpf_warn_invalid_xdp_action);
 
-void bpf_warn_invalid_xdp_redirect(u32 ifindex)
-{
-	WARN_ONCE(1, "Illegal XDP redirect to unsupported device ifindex(%i)\n", ifindex);
-}
-
 static bool __is_valid_sock_ops_access(int off, int size)
 {
 	if (off < 0 || off >= sizeof(struct bpf_sock_ops))