netdev - Re: [PATCH net-next v2] Configure bridge FDB ageing time using netlink.

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Message-ID: <CA+CtxLQXOqO6FvB4=8YzXmUDDhEa1HmoNYbMyOwnOB=xBxZ4WQ@mail.gmail.com>
Date:	Sun, 15 Mar 2015 05:06:27 +0530
From:	Siva Mannem <siva.mannem.lnx@...il.com>
To:	Scott Feldman <sfeldma@...il.com>
Cc:	Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v2] Configure bridge FDB ageing time using netlink.

On Sun, Mar 15, 2015 at 3:47 AM, Scott Feldman <sfeldma@...il.com> wrote:
> On Fri, Mar 13, 2015 at 6:40 PM, Siva Mannem <siva.mannem.lnx@...il.com> wrote:
>> This patch allows user to configure bridge's FDB ageing using
>> netlink(for ex, iproute2). Allowed range is 10 seconds to 1000000 seconds
>> as per ieee8021QBridgeFdbAgingTime.
>>
>> Signed-off-by: Siva Mannem <siva.mannem.lnx@...il.com>
>> ---
>> Changes in v2:
>>  - Added commit message.
>>  - Fix style problems reported by checkpatch.pl.
>
>
>> +
>> +int br_set_ageing_time(struct net_bridge *br, unsigned long val)
>> +{
>> +       unsigned long t = clock_t_to_jiffies(val);
>> +
>> +       if (t < BR_MIN_AGEING_TIME || t > BR_MAX_AGEING_TIME)
>> +               return -ERANGE;
>> +
>> +       spin_lock_bh(&br->lock);
>> +       br->ageing_time = t;
>
> I wonder if you need to call mod_timer(&br->gc_timer, jiffies) after
> adjusting the time, to make new ageing_time effective?  The worst-case
> scenario I'm thinking about is if the initial br->ageing_time is the
> max value (1000000 seconds) and the user changes it the min value (10
> seconds), will the original 1000000 seconds need to expire before the
> gc_timer is called again and reset to 10 seconds?
>
Yes, the new ageing_time becomes effective only after the current timer expires.
The behavior when ageing_time is set via netlink  is similar to setting it using
sysfs and brctl. I want to keep the behavior same when the ageing_time is
configured using any of the existing mechanisms.

If this needs to become effective immediately, I will work on it via
another patch/RFC.

>> +       spin_unlock_bh(&br->lock);
>> +       return 0;
>> +}
>> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
>> index 8bc6b67..d80e802 100644



-- 
Regards,
Siva Mannem.
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