From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subject: Re: [PATCH bpf-next 0/6] Error handling when map lookup isn't
 supported
Date: Tue, 9 Oct 2018 21:55:28 -0700
Message-ID: <20181010045526.zdwc2awhcflpdqfr@ast-mbp.dhcp.thefacebook.com>
References: <20181009010454.6652-1-bhole_prashant_q7@lab.ntt.co.jp>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Jakub Kicinski <jakub.kicinski@netronome.com>,
        "David S . Miller" <davem@davemloft.net>,
        Quentin Monnet <quentin.monnet@netronome.com>,
        netdev@vger.kernel.org
To: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Return-path: <netdev-owner@vger.kernel.org>
Received: from mail-pl1-f196.google.com ([209.85.214.196]:44538 "EHLO
        mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1725813AbeJJMPv (ORCPT
        <rfc822;netdev@vger.kernel.org>); Wed, 10 Oct 2018 08:15:51 -0400
Received: by mail-pl1-f196.google.com with SMTP id p25-v6so1889931pli.11
        for <netdev@vger.kernel.org>; Tue, 09 Oct 2018 21:55:31 -0700 (PDT)
Content-Disposition: inline
In-Reply-To: <20181009010454.6652-1-bhole_prashant_q7@lab.ntt.co.jp>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

On Tue, Oct 09, 2018 at 10:04:48AM +0900, Prashant Bhole wrote:
> Currently when map a lookup fails, user space API can not make any
> distinction whether given key was not found or lookup is not supported
> by particular map.
> 
> In this series we modify return value of maps which do not support
> lookup. Lookup on such map implementation will return -EOPNOTSUPP.
> bpf() syscall with BPF_MAP_LOOKUP_ELEM command will set EOPNOTSUPP
> errno. We also handle this error in bpftool to print appropriate
> message.
> 
> Patch 1: adds handling of BPF_MAP_LOOKUP ELEM command of bpf syscall
> such that errno will set to EOPNOTSUPP when map doesn't support lookup
> 
> Patch 2: Modifies the return value of map_lookup_elem() to EOPNOTSUPP
> for maps which do not support lookup
> 
> Patch 3: Splits do_dump() in bpftool/map.c. Element printing code is
> moved out into new function dump_map_elem(). This was done in order to
> reduce deep indentation and accomodate further changes.
> 
> Patch 4: Changes in bpftool to print strerror() message when lookup
> error is occured. This will result in appropriate message like
> "Operation not supported" when map doesn't support lookup.
> 
> Patch 5: test_verifier: change fixup map naming convention as
> suggested by Alexei
> 
> Patch 6: Added verifier tests to check whether verifier rejects call 
> to bpf_map_lookup_elem from bpf program. For all map types those
> do not support map lookup.

Applied, Thanks