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([2620:15c:2c1:200:55c7:81e6:c7d8:94b]) by smtp.gmail.com with ESMTPSA id e127sm4115291pfe.37.2019.10.03.09.32.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 03 Oct 2019 09:32:35 -0700 (PDT) Subject: Re: [PATCH net v2] ipv6: Handle race in addrconf_dad_work To: David Ahern , David Ahern , davem@davemloft.net, jakub.kicinski@netronome.com Cc: netdev@vger.kernel.org, rajendra.dendukuri@broadcom.com References: <20191001032834.5330-1-dsahern@kernel.org> <1ab3e0d0-fb37-d367-fd5f-c6b3262b6583@gmail.com> <18c18892-3f1c-6eb8-abbb-00fd6c9c64d3@gmail.com> <146a2f8a-8ee9-65f3-1013-ef60a96aa27b@gmail.com> <4c896029-882f-1a4f-c0cc-4553a9429da3@gmail.com> From: Eric Dumazet Message-ID: <43e2c04f-a601-3363-1f98-26fd007be960@gmail.com> Date: Thu, 3 Oct 2019 09:32:34 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <4c896029-882f-1a4f-c0cc-4553a9429da3@gmail.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 On 10/3/19 8:50 AM, David Ahern wrote: > On 10/2/19 3:23 PM, Eric Dumazet wrote: >> >> It seems we need to allow the code to do some changes if IF_READY is not set. >> > > That statement was correct. Prior to the patch in question ifp->state is > bumped to INET6_IFADDR_STATE_DAD in addrconf_dad_work. When > NETDEV_CHANGE event happens, addrconf_notify calls addrconf_dad_run > which calls addrconf_dad_kick to restart dad after the dad process > (applies even if nodad is set -- yes, odd). > > With the patch, IF_READY is not set when the bond device is created and > dad_work skips bumping the state. When the CHANGE event comes through > the state is not INET6_IFADDR_STATE_DAD (and the restart argument is not > set), so addrconf_dad_run does not call addrconf_dad_kick. > > Bottom line, regardless of IF_READY we need the state change to happen > in dad_work, we just need to skip the call to addconf_dad_begin. > > Can you test the change below on your boxes? It applies on current net. > > Rajendra: can you test as well and make sure your problem is still > resolved? > > Thanks, > > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c > index dd3be06d5a06..fce0d0dca7bb 100644 > --- a/net/ipv6/addrconf.c > +++ b/net/ipv6/addrconf.c > @@ -4032,12 +4032,6 @@ static void addrconf_dad_work(struct work_struct *w) > > rtnl_lock(); > > - /* check if device was taken down before this delayed work > - * function could be canceled > - */ > - if (idev->dead || !(idev->if_flags & IF_READY)) > - goto out; > - > spin_lock_bh(&ifp->lock); > if (ifp->state == INET6_IFADDR_STATE_PREDAD) { > action = DAD_BEGIN; > @@ -4068,6 +4062,12 @@ static void addrconf_dad_work(struct work_struct *w) > } > spin_unlock_bh(&ifp->lock); > > + /* check if device was taken down before this delayed work > + * function could be canceled > + */ > + if (idev->dead || !(idev->if_flags & IF_READY)) > + goto out; > + > if (action == DAD_BEGIN) { > addrconf_dad_begin(ifp); > goto out; > Still no luck for me :/