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([2601:282:800:fd80:b559:3352:82ff:93d8]) by smtp.googlemail.com with ESMTPSA id p3sm37105934iom.7.2019.07.19.09.55.50 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Jul 2019 09:55:50 -0700 (PDT) Subject: Re: [PATCH v2 net-next 03/11] net/ipv4: Plumb support for filtering route dumps To: Hangbin Liu , David Ahern Cc: netdev@vger.kernel.org, Jianlin Shi References: <20181016015651.22696-1-dsahern@kernel.org> <20181016015651.22696-4-dsahern@kernel.org> <20190719041700.GO18865@dhcp-12-139.nay.redhat.com> From: David Ahern Message-ID: <147df36b-75df-5e71-3d74-9454db676bce@gmail.com> Date: Fri, 19 Jul 2019 10:55:49 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190719041700.GO18865@dhcp-12-139.nay.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi: On 7/18/19 10:17 PM, Hangbin Liu wrote: > Hi David, > > Before commit 18a8021a7be3 ("net/ipv4: Plumb support for filtering route > dumps"), when we dump a non-exist table, ip cmd exits silently. > > # ip -4 route list table 1 > # echo $? > 0 > > After commit 18a8021a7be3 ("net/ipv4: Plumb support for filtering route > dumps"). When we dump a non-exist table, as we returned -ENOENT, ip route > shows: > > # ip -4 route show table 1 > Error: ipv4: FIB table does not exist. > Dump terminated > # echo $? > 2 > > For me it looks make sense to return -ENOENT if we do not have the route > table. But this changes the userspace behavior. Do you think if we need to > keep backward compatible or just let it do as it is right now? > It is not change in userspace behavior; ip opted into the strict checking. The impact is to 'ip' users. A couple of people have asked about this, and I am curious as to why people run a route dump for a table that does not exist and do not like being told that it does not exist.