On Thu, 5 Oct 2017 09:57:04 +0200 Ingo Molnar <mi...@kernel.org> wrote:
> > * Masami Hiramatsu <mhira...@kernel.org> wrote: > > > On Wed, 4 Oct 2017 12:41:01 +0200 > > Ingo Molnar <mi...@kernel.org> wrote: > > > > > > > > * Masami Hiramatsu <mhira...@kernel.org> wrote: > > > > > > > Hmm, actually we can not disable jprobe, that has no separate Kconfig. > > > > So we need to introduce new kconfig for that. > > > > > > > > And, there are several network protocols using jprobe to trace events. > > > > (e.g. NET_DCCPPROBE and NET_TCPPROBE) > > > > I think they need to migrate to trace-event at first. > > > > > > > > So, how about below idea? > > > > > > > > 1. Introduce CONFIG_JPROBE_API which only separate jprobe general parts > > > > (no arch dependent code involves) and make it default n. > > > > 2. Mark break_handler and jprobe APIs deprecated so that no new user > > > > comes up. > > > > 3. migrate in-kernel jprobe user to trace-event or ftrace. > > > > (may take some time) > > > > > > So my suggestion would be to just return from register_jprobe() and don't > > > register > > > anything. > > > > with CONFIG_JPROBE_API=n, is that right? > > No, unconditionally off with a WARN_ON_ONCE() warning in the registry > function and > the deactivation of all in-kernel uses (such as self-tests). > > The point is to make people that _truly_ rely on it complain - not just make > them > silently turn on a Kconfig option ... Hmm, but in that case, anyway we have to remove or rename the function like register_jprobe. Or would that "unconditionally" mean "#if 0"? > > > Yes, there are usecases of jprobes in the kernel, but they all look > > > pretty ancient and unused. > > > > Hmm, in that case, should we also remove those users? If we disable such way > > those features are just useless. > > My hypothesis is that those features are not used (hence useless), but we > should > first test whether there's any reliance before we remove code. Agreed. Thank you, > > Thanks, > > Ingo -- Masami Hiramatsu <mhira...@kernel.org>
