From: Alexei Starovoitov <ast-uqk4Ao+rVK5Wk0Htik3J/w@public•gmane.org>
To: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public•gmane.org>
Cc: Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public•gmane.org>,
Namhyung Kim <namhyung-DgEjT+Ai2ygdnm+yROfE0A@public•gmane.org>,
Arnaldo Carvalho de Melo
<acme-wEGCiKHe2LqWVfeAwA7xHQ@public•gmane.org>,
Jiri Olsa <jolsa-H+wXaHxf7aLQT0dZR+AlfA@public•gmane.org>,
Masami Hiramatsu
<masami.hiramatsu.pt-FCd8Q96Dh0JBDgjK7y7TUQ@public•gmane.org>,
"David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public•gmane.org>,
Daniel Borkmann <daniel-FeC+5ew28dpmcu3hnIyYJQ@public•gmane.org>,
Peter Zijlstra
<a.p.zijlstra-/NLkJaSkS4VmR6Xm/wNWPw@public•gmane.org>,
linux-api-u79uwXL29TY76Z2rM5mHXA@public•gmane.org,
netdev-u79uwXL29TY76Z2rM5mHXA@public•gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public•gmane.org
Subject: Re: [PATCH v9 tip 6/9] samples: bpf: simple non-portable kprobe filter example
Date: Mon, 23 Mar 2015 10:23:04 -0700 [thread overview]
Message-ID: <55104BF8.8000606@plumgrid.com> (raw)
In-Reply-To: <20150323072929.GB25184-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
On 3/23/15 12:29 AM, Ingo Molnar wrote:
>
>> ** **
>> ** This means that this is a DEBUG kernel and it is **
>> ** unsafe for production use. **
>
> But I think printing that it's unsafe for production use is over the
> top: it's up to the admin whether it's safe or unsafe, just like
> inserting a kprobe can be safe or unsafe.
>
> Informing that something happened is enough.
Well that is Steven's banner and I agree that it's a bit extreme.
I think it's done on purpose to scary people away from using
trace_printk() for anything other than debug.
It applies to both native trace_printk() for kernel debugging and
for bpf_trace_printk() for debugging of bpf programs.
I don't have a strong opinion about native case, but for bpf I do want
this banner to be scary. Otherwise it's too easy to start using
bpf_trace_printk() to pass event notifications to user space.
bpf_trace_printk and trace_pipe parsing shouldn't be used as a way
to communicate between programs and user space.
At the end, in actual production use, bpf programs won't be using it
and no banner will be seen.
Anyway, I don't think I can change this banner in this patch set.
If we decide to relax it, it should be done via Steven's tree.
next prev parent reply other threads:[~2015-03-23 17:23 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-20 23:30 [PATCH v9 tip 0/9] tracing: attach eBPF programs to kprobes Alexei Starovoitov
2015-03-20 23:30 ` [PATCH v9 tip 1/9] bpf: make internal bpf API independent of CONFIG_BPF_SYSCALL ifdefs Alexei Starovoitov
2015-03-21 12:16 ` Masami Hiramatsu
2015-03-20 23:30 ` [PATCH v9 tip 2/9] tracing: add kprobe flag Alexei Starovoitov
[not found] ` <1426894210-27441-3-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-03-21 12:16 ` Masami Hiramatsu
2015-03-20 23:30 ` [PATCH v9 tip 3/9] tracing: attach BPF programs to kprobes Alexei Starovoitov
[not found] ` <1426894210-27441-4-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-03-21 12:14 ` Masami Hiramatsu
2015-03-21 16:02 ` Alexei Starovoitov
[not found] ` <550D962E.7010400-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-03-22 10:06 ` Masami Hiramatsu
2015-03-22 18:03 ` Alexei Starovoitov
[not found] ` <550F0402.80900-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-03-23 2:17 ` Masami Hiramatsu
2015-03-23 4:57 ` bpf+tracing next steps. Was: " Alexei Starovoitov
[not found] ` <550F9D20.7070006-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-03-23 9:27 ` Masami Hiramatsu
2015-03-25 0:40 ` Alexei Starovoitov
[not found] ` <5512040B.3020605-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-03-25 12:07 ` Masami Hiramatsu
[not found] ` <1426894210-27441-1-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-03-20 23:30 ` [PATCH v9 tip 4/9] tracing: allow BPF programs to call bpf_ktime_get_ns() Alexei Starovoitov
2015-03-20 23:30 ` [PATCH v9 tip 5/9] tracing: allow BPF programs to call bpf_trace_printk() Alexei Starovoitov
[not found] ` <1426894210-27441-6-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-03-22 11:10 ` Ingo Molnar
[not found] ` <20150322111040.GA18695-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-03-22 18:05 ` Alexei Starovoitov
2015-03-20 23:30 ` [PATCH v9 tip 9/9] samples: bpf: kmem_alloc/free tracker Alexei Starovoitov
2015-03-20 23:30 ` [PATCH v9 tip 6/9] samples: bpf: simple non-portable kprobe filter example Alexei Starovoitov
[not found] ` <1426894210-27441-7-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-03-23 7:29 ` Ingo Molnar
[not found] ` <20150323072929.GB25184-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-03-23 17:23 ` Alexei Starovoitov [this message]
2015-03-23 7:35 ` Ingo Molnar
[not found] ` <20150323073506.GC25184-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-03-23 17:32 ` Alexei Starovoitov
2015-03-20 23:30 ` [PATCH v9 tip 7/9] samples: bpf: counting example for kfree_skb and write syscall Alexei Starovoitov
2015-03-20 23:30 ` [PATCH v9 tip 8/9] samples: bpf: IO latency analysis (iosnoop/heatmap) Alexei Starovoitov
2015-03-23 7:40 ` Ingo Molnar
2015-03-23 17:41 ` Alexei Starovoitov
2015-03-21 4:08 ` [PATCH v9 tip 0/9] tracing: attach eBPF programs to kprobes Steven Rostedt
[not found] ` <20150321000812.606ef8cb-2kNGR76GQU9OHLTnHDQRgA@public.gmane.org>
2015-03-23 7:36 ` Ingo Molnar
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