netdev - Re: [bpf-next PATCH 3/3] bpf: add sample program to trace map events

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Message-ID: <20180423222238.2636bdc8@redhat.com>
Date:   Mon, 23 Apr 2018 22:22:38 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Sebastiano Miano <sebastiano.miano@...ito.it>,
        netdev@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        mingo@...hat.com, rostedt@...dmis.org, fulvio.risso@...ito.it,
        "David S. Miller" <davem@...emloft.net>, brouer@...hat.com
Subject: Re: [bpf-next PATCH 3/3] bpf: add sample program to trace map
 events

On Mon, 23 Apr 2018 14:08:02 -0600
Alexei Starovoitov <alexei.starovoitov@...il.com> wrote:

> On Mon, Apr 23, 2018 at 04:08:36PM +0200, Sebastiano Miano wrote:
> > 
> > That's in fact the real use case for the first two patches. Since bpf
> > tracepoints are still a rather common (and easy to use) troubleshooting and
> > monitoring tool why shouldn't we "enhance" their support with the newly
> > added map/prog IDs?  
> 
> because these tracepoints can be abused in the way that this patch demonstrated.
> Whether to keep this patch in the series or not is irrelevant.

I don't understand your abuse use-case, can you explain what you mean?

You do realize that these tracepoints can _only_ monitor the userspace
map activity (not kernel map changes) ... and we _do_ need a way to
debug this (and without the map_id I can tell which map).

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer