From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe Koziolek Subject: Re: [PATCH v4] net/bonding: send arp in interval if no active slave Date: Fri, 30 Oct 2015 19:59:12 +0100 Message-ID: <5633BE00.5090509@redknee.com> References: <56094137.9030206@redhat.com> <1444161197-38442-1-git-send-email-jarod@redhat.com> <56150A1B.10405@cumulusnetworks.com> <56151E4A.2000503@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15"; format=flowed Content-Transfer-Encoding: 7bit Cc: , Jay Vosburgh , Andy Gospodarek , Veaceslav Falico , To: Jarod Wilson , Nikolay Aleksandrov Return-path: In-Reply-To: <56151E4A.2000503@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org > Nikolay Aleksandrov wrote: >> On 10/06/2015 09:53 PM, Jarod Wilson wrote: >>> From: Uwe Koziolek >>> >>> With some very finicky switch hardware, active backup bonding can get into >>> a situation where we play ping-pong between interfaces, trying to get one >>> to come up as the active slave. There seems to be an issue with the >>> switch's arp replies either taking too long, or simply getting lost, so we >>> wind up unable to get any interface up and active. Sometimes, the issue >>> sorts itself out after a while, sometimes it doesn't. >>> >>> Testing with num_grat_arp has proven fruitless, but sending an additional >>> arp on curr_arp_slave if we're still in the arp_interval timeslice in >>> bond_ab_arp_probe(), has shown to produce 100% reliability in testing with >>> this hardware combination. >>> >>> [jarod: manufacturing of changelog, addition of modparam gating] >>> CC: Jay Vosburgh >>> CC: Andy Gospodarek >>> CC: Veaceslav Falico >>> CC: netdev@vger.kernel.org >>> Signed-off-by: Uwe Koziolek >>> Signed-off-by: Jarod Wilson >>> --- >>> v2: add code comment as to why change is needed >>> v3: fix wrapping of comments >>> v4: [jarod] add module parameter gating of code addition >>> >> Hi all, >> As Andy already stated I'm not a fan of such workarounds either but it's >> necessary sometimes so if this is going to be actually considered then a >> few things need to be fixed. Please make this a proper bonding option >> which can be changed at runtime and not only via a module parameter. > > Okay, I can give that a shot, however... > >> Now, I saw that you've only tested with 500 ms, can't this be fixed by using >> a different interval ? This seems like a very specific problem to have a >> whole new option for. > > ...I'll wait until we've heard confirmation from Uwe that intervals other than 500ms don't fix things. > A test with 5000 ms don't fix the problem. Tested with Cisco C3750, 4 bonds. >> I really want to say fix the switch but I know that's not an option. :-) > > Yeah, unfortunately not! > >> A few minor nits below, >> >>> drivers/net/bonding/bond_main.c | 24 ++++++++++++++++++++++++ >>> include/net/bonding.h | 1 + >>> 2 files changed, 25 insertions(+) >>> >>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c >>> index 90f2615..72ab512 100644 >>> --- a/drivers/net/bonding/bond_main.c >>> +++ b/drivers/net/bonding/bond_main.c >>> @@ -95,6 +95,7 @@ static int miimon; >>> static int updelay; >>> static int downdelay; >>> static int use_carrier = 1; >>> +static int arp_slow_switch; >>> static char *mode; >>> static char *primary; >>> static char *primary_reselect; >>> @@ -133,6 +134,10 @@ MODULE_PARM_DESC(downdelay, "Delay before considering link down, " >>> module_param(use_carrier, int, 0); >>> MODULE_PARM_DESC(use_carrier, "Use netif_carrier_ok (vs MII ioctls) in miimon; " >>> "0 for off, 1 for on (default)"); >>> +module_param(arp_slow_switch, int, 0); >>> +MODULE_PARM_DESC(arp_slow_switch, "Do extra arp checks for switches with arp " >>> + "caches that are slow to update; " >>> + "0 for off (default), 1 for on"); >>> module_param(mode, charp, 0); >>> MODULE_PARM_DESC(mode, "Mode of operation; 0 for balance-rr, " >>> "1 for active-backup, 2 for balance-xor, " >>> @@ -2793,6 +2798,18 @@ static bool bond_ab_arp_probe(struct bonding *bond) >>> return should_notify_rtnl; >>> } >>> >>> + /* Sometimes the forwarding tables of the switches are not update >> ^ s/update/updated/ > > D'oh. Fixed locally. > >>> @@ -4280,6 +4297,12 @@ static int bond_check_params(struct bond_params *params) >>> use_carrier = 1; >>> } >>> >>> + if ((arp_slow_switch != 0) && (arp_slow_switch != 1)) { >> ^^ no need for the extra () > > Copy-pasta from use_carrier checks right above it. Never quite sure if I should stick with the same possibly sub-optimal > formatting conventions already in the file, try to fix them while also fixing bugs, or just mix styles... > > >>> + pr_warn("Warning: arp_slow_switch module parameter (%d), not of valid value (0/1), so it was set to 1\n", >>> + arp_slow_switch); >>> + arp_slow_switch = 1; >> ^^ please default to old behaviour in this case (0) > > Will do. > Uwe Koziolek