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Miller" Subject: Re: [PATCH net] sit: use ipv6_mod_enabled to check if ipv6 is disabled Message-ID: <20190226040759.GU10051@dhcp-12-139.nay.redhat.com> References: <20190225041243.9753-1-liuhangbin@gmail.com> <7c0f5c9c-d918-de27-643d-416509576be4@gmail.com> <20190225081759.GP10051@dhcp-12-139.nay.redhat.com> <1dd57d9d-fed2-67b8-ac28-7ef3681eeed2@gmail.com> <20190226015533.GR10051@dhcp-12-139.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi David, On Mon, Feb 25, 2019 at 07:15:26PM -0700, David Ahern wrote: > On 2/25/19 6:55 PM, Hangbin Liu wrote: > > Just as I said, this issue only occurs when IPv6 is disabled at boot time > > as there is no IPv6 route entry. Disable ipv6 on specific interface should > > not be affected(IPv6 route/fib has inited). So I think use ipv6_mod_enabled() > > would be more suitable in this scenario. Did I miss something? > > From a readability perspective the code path depends on whether ipv6 is > enabled on the device. I think it is better to leave that as it is. When I posted 173656accaf5 ("sit: check if IPv6 enabled before calling ip6_err_gen_icmpv6_unreach()"), my purpose is to check if IPv6 disabled at boot time. I didn't know we have ipv6_mod_enabled() at that time, so I just used __in6_dev_get() as a trick way/work around. A few days later I saw your commit e434863718d4 ("net: vrf: Fix crash when IPv6 is disabled at boot time") and I thought this would be a more clear way to tell people that we are checking if IPv6 disabled at boot time. So I posted these two follow up fixes. I don't know why you thought check IPv6 is enbled on the device is better. Because it's more strict? Maybe I missed something here. But if you feel it is better to leave as it it, then let's keep it. Thanks Hangbin