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