netdev - Re: [PATCH net-next] bpf: add show

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Message-Id: <1447963950.3032383.444676081.5CE47461@webmail.messagingengine.com>
Date:	Thu, 19 Nov 2015 21:12:30 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:	Daniel Borkmann <daniel@...earbox.net>, davem@...emloft.net,
	netdev@...r.kernel.org
Subject: Re: [PATCH net-next] bpf: add show_fdinfo handler for maps

On Thu, Nov 19, 2015, at 19:32, Alexei Starovoitov wrote:
> On Thu, Nov 19, 2015 at 07:19:24PM +0100, Hannes Frederic Sowa wrote:
> > On Thu, Nov 19, 2015, at 11:56, Daniel Borkmann wrote:
> > > Add a handler for show_fdinfo() to be used by the anon-inodes
> > > backend for eBPF maps, and dump the map specification there. Not
> > > only useful for admins, but also it provides a minimal way to
> > > compare specs from ELF vs pinned object.
> > > 
> > > Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> > 
> > Acked-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
> > 
> > Does it make sense to include bpf_htab->count in case of a hashmap?
> 
> no. user space should not rely on such things. It can only be misused.

Sorry, I don't get it. How can it be misused? As an admin it would
certainly be interesting to know the pressure on the map? Do you expect
kmsg messages from the eBPF program?

Thanks,
Hannes
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