Re: [PATCH bpf-next v1] bpf, sockmap: Introduce tracing capability for sockmap

[Cong Wang]

On Wed, Apr 09, 2025 at 06:29:33PM +0800, Jiayuan Chen wrote:
> Sockmap has the same high-performance forwarding capability as XDP, but
> operates at Layer 7.
> 
> Introduce tracing capability for sockmap, similar to XDP, to trace the
> execution results of BPF programs without modifying the programs
> themselves, similar to the existing trace_xdp_redirect{_map}.
> 
> It is crucial for debugging BPF programs, especially in production
> environments.
> 
> Additionally, a header file was added to bpf_trace.h to automatically
> generate tracepoints.
> 
> Test results:
> $ echo "1" > /sys/kernel/tracing/events/sockmap/enable
> 
> skb:
> sockmap_redirect: sk=00000000d3266a8d, type=skb, family=2, protocol=6, \
> prog_id=73, length=256, action=PASS
> 
> msg:
> sockmap_redirect: sk=00000000528c7614, type=msg, family=2, protocol=6, \
> prog_id=185, length=5, action=REDIRECT
> 
> tls:
> sockmap_redirect: sk=00000000d04d2224, type=skb, family=2, protocol=6, \
> prog_id=143, length=35, action=PASS
> 
> strparser:
> sockmap_skb_strp_parse: sk=00000000ecab0b30, family=2, protocol=6, \
> prog_id=170, size=5

Nice work!

While you are on it, could we also trace skb->_sk_redir bits too? It is
very useful to distinguish, at least, ingress from egress redirection.

Thanks!