Commit bf4ea1d0 authored by Leon Hwang's avatar Leon Hwang Committed by Alexei Starovoitov
Browse files

bpf, xdp: Add tracepoint to xdp attaching failure 



When error happens in dev_xdp_attach(), it should have a way to tell
users the error message like the netlink approach.

To avoid breaking uapi, adding a tracepoint in bpf_xdp_link_attach() is
an appropriate way to notify users the error message.

Hence, bpf libraries are able to retrieve the error message by this
tracepoint, and then report the error message to users.

Signed-off-by: default avatarLeon Hwang <hffilwlqm@gmail.com>
Link: https://lore.kernel.org/r/20230801142621.7925-2-hffilwlqm@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 416c6d01

include/trace/events/xdp.h

+17 −0
Original line number Diff line number Diff line
@@ -404,6 +404,23 @@ TRACE_EVENT(mem_return_failed, 
	)

);



TRACE_EVENT(bpf_xdp_link_attach_failed,



	TP_PROTO(const char *msg),



	TP_ARGS(msg),



	TP_STRUCT__entry(

		__string(msg, msg)

	),



	TP_fast_assign(

		__assign_str(msg, msg);

	),



	TP_printk("errmsg=%s", __get_str(msg))

);



#endif /* _TRACE_XDP_H */



#include <trace/define_trace.h>

net/core/dev.c

+4 −1
Original line number Diff line number Diff line
@@ -133,6 +133,7 @@ 
#include <trace/events/net.h>

#include <trace/events/skb.h>

#include <trace/events/qdisc.h>

#include <trace/events/xdp.h>

#include <linux/inetdevice.h>

#include <linux/cpu_rmap.h>

#include <linux/static_key.h>
@@ -9470,6 +9471,7 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) 
{

	struct net *net = current->nsproxy->net_ns;

	struct bpf_link_primer link_primer;

	struct netlink_ext_ack extack = {};

	struct bpf_xdp_link *link;

	struct net_device *dev;

	int err, fd;
@@ -9497,12 +9499,13 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) 
		goto unlock;

	}



	err = dev_xdp_attach_link(dev, NULL, link);

	err = dev_xdp_attach_link(dev, &extack, link);

	rtnl_unlock();



	if (err) {

		link->dev = NULL;

		bpf_link_cleanup(&link_primer);

		trace_bpf_xdp_link_attach_failed(extack._msg);

		goto out_put_dev;

	}