Re: [PATCH net-next 0/2] bpf/tracing: allow user space to query prog array on the same tp

[Alexei Starovoitov <ast@fb.com>]

On 11/28/17 11:20 PM, Yonghong Song wrote:
> Commit e87c6bc3852b ("bpf: permit multiple bpf attachments
> for a single perf event") added support to attach multiple
> bpf programs to a single perf event. Given a perf event
> (kprobe, uprobe, or kernel tracepoint), the perf ioctl interface
> is used to query bpf programs attached to the same trace event.
> The same ioctl interface is also used to attach bpf program.
> Patch #1 had the core implementation and patch #2 added
> a test case in tools bpf selftests suite.

We actually had an implementation of the same tracepoint+bpf
introspection via BPF_PROG_QUERY command that we use for cgroup+bpf,
but it looks cleaner to use ioctl() style of api here,
since attach to tracepoint/kuprobe is also done via ioctl.

For the set:
Acked-by: Alexei Starovoitov <ast@kernel.org>

The patch touches 3 lines in events/core.c but most likely
it won't conflict with anything in tip, so we plan to have
this set in bpf-next.git -> net-next.git only.

Thanks