On Wed, Oct 23, 2024 at 2:33 PM Yafang Shao [off-list ref] wrote:

We previously hooked the tcp_drop_reason() function using BPF to monitor
TCP drop reasons. However, after upgrading our compiler from GCC 9 to GCC
11, tcp_drop_reason() is now inlined, preventing us from hooking into it.
To address this, it would be beneficial to introduce a dedicated tracepoint
for monitoring.

This patch would require changes in user space tracers.
I am surprised no one came up with a noinline variant.

__bpf_kfunc is using

#define __bpf_kfunc __used __retain noinline

I would rather not have include/trace/events/tcp.h becoming the
biggest file in TCP stack...