| Message ID | 20230801142621.7925-2-hffilwlqm@gmail.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | bpf, xdp: Add tracepoint to xdp attaching failure | expand |
On Tue, 1 Aug 2023 22:26:20 +0800 Leon Hwang wrote: > 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. Whatevered-by: Jakub Kicinski <kuba@kernel.org> ?
On 2/8/23 06:08, Jakub Kicinski wrote: > On Tue, 1 Aug 2023 22:26:20 +0800 Leon Hwang wrote: >> 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. > > Whatevered-by: Jakub Kicinski <kuba@kernel.org> ? Oh, it's not responsible for libraries to retrieve the error message. It should be users' responsibility. Sorry for the misguiding text. In the previous patch[0], which changes uapi, it's able to back-propagate the error message from dev_xdp_attach() to userspace through BPF syscall. Then, tracepoint idea is suggested to avoid changing uapi. I do agree to implement a tracepoint to avoid changing uapi. [0] bpf: Introduce user log https://lore.kernel.org/bpf/20230708040750.72570-1-hffilwlqm@gmail.com/ Thanks, Leon
diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h index c40fc97f94171..cd89f1d5ce7b8 100644 --- a/include/trace/events/xdp.h +++ b/include/trace/events/xdp.h @@ -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> diff --git a/net/core/dev.c b/net/core/dev.c index 8e7d0cb540cdb..002fec07de739 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -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; }
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: Leon Hwang <hffilwlqm@gmail.com> --- include/trace/events/xdp.h | 17 +++++++++++++++++ net/core/dev.c | 5 ++++- 2 files changed, 21 insertions(+), 1 deletion(-)