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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
	davem@davemloft.net, daniel@iogearbox.net, peterz@infradead.org,
	x86@kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org,
	kernel-team@fb.com, Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH bpf-next 0/7] Introduce BPF trampoline
Date: Tue, 5 Nov 2019 07:47:11 -0800	[thread overview]
Message-ID: <20191105154709.utmzm6qvtlux4hww@ast-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <20191105104024.4e99a630@grimm.local.home>

On Tue, Nov 05, 2019 at 10:40:24AM -0500, Steven Rostedt wrote:
> On Tue, 5 Nov 2019 06:31:56 -0800
> Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:
> 
> > Steven,
> > look slike your branch hasn't been updated in 13 days.
> > Are you still planning to fix the bugs and send it in for the merge window?
> > I cannot afford to wait a full release, since I have my own follow for
> > XDP/networking based on this and other folks are building their stuff on top of
> > BPF trampoline too. So I'm thinking for v2 I will switch to using text_poke()
> > and add appropriate guard checks, so it will be safe out of the box without
> > ftrace dependency. If register_ftrace_direct() indeed comes in soon I'll
> > switch to that and will make bpf trampoline to co-operate with ftrace.
> > text_poke approach will make it such that what ever comes first to trace the
> > fentry (either bpf trampoline or ftrace) will grab the nop and the other system
> > will not be able to attach. That's safe and correct, but certainly not nice
> > long term. So the fix will be needed. The key point that switching to text_poke
> > will remove the register_ftrace_direct() dependency, unblock bpf developers and
> > will give you time to land your stuff at your pace.
> 
> Alexei,
> 
> I am still working on it, and if it seems stable enough I will submit
> it for this merge window, but there's no guarantees. It's ready when
> it's ready. I gave 5 talks last week (4 in Lyon, and one is Sofia,
> Bulgaria), thus I did not have time to work on it then. I'm currently
> in the Sofia office, and I got a version working that seems to be
> stable. But I still have to break it up into a patch series, and run it
> through more stress tests.
> 
> If you have to wait you may need to wait. The Linux kernel isn't
> something that is suppose to put in temporary hacks, just to satisfy
> someone's deadline.

Ok. I will switch to text_poke and will make it hack free.
ftrace mechanisms are being replaced by text_poke anyway.


  reply	other threads:[~2019-11-05 15:47 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-02 22:00 [PATCH bpf-next 0/7] Introduce BPF trampoline Alexei Starovoitov
2019-11-02 22:00 ` [PATCH bpf-next 1/7] bpf, ftrace: temporary workaround Alexei Starovoitov
2019-11-02 22:00 ` [PATCH bpf-next 2/7] bpf: refactor x86 JIT into helpers Alexei Starovoitov
2019-11-02 22:00 ` [PATCH bpf-next 3/7] bpf: Introduce BPF trampoline Alexei Starovoitov
2019-11-05 19:51   ` Andrii Nakryiko
2019-11-02 22:00 ` [PATCH bpf-next 4/7] libbpf: Add support to attach to fentry/fexit tracing progs Alexei Starovoitov
2019-11-05 21:17   ` Andrii Nakryiko
2019-11-05 23:17     ` Alexei Starovoitov
2019-11-02 22:00 ` [PATCH bpf-next 5/7] selftest/bpf: Simple test for fentry/fexit Alexei Starovoitov
2019-11-05 21:37   ` Andrii Nakryiko
2019-11-02 22:00 ` [PATCH bpf-next 6/7] bpf: Add kernel test functions for fentry testing Alexei Starovoitov
2019-11-02 22:00 ` [PATCH bpf-next 7/7] selftests/bpf: Add test for BPF trampoline Alexei Starovoitov
2019-11-05 21:50   ` Andrii Nakryiko
2019-11-05 14:31 ` [PATCH bpf-next 0/7] Introduce " Alexei Starovoitov
2019-11-05 15:40   ` Steven Rostedt
2019-11-05 15:47     ` Alexei Starovoitov [this message]
2019-11-05 16:00       ` Steven Rostedt
2019-11-05 16:28         ` Alexei Starovoitov
2019-11-05 17:26           ` Steven Rostedt
2019-11-05 17:59             ` Alexei Starovoitov

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