From: Ding Tianhong <dingtianhong@huawei•com>
To: Veaceslav Falico <vfalico@redhat•com>
Cc: Jay Vosburgh <fubar@us•ibm.com>, Netdev <netdev@vger•kernel.org>,
"David S. Miller" <davem@davemloft•net>
Subject: Re: [PATCH net] bonding: reset the slave's mtu when its be changed
Date: Sun, 12 Jan 2014 13:18:26 +0800 [thread overview]
Message-ID: <52D225A2.3070208@huawei.com> (raw)
In-Reply-To: <20140110121932.GC4132@redhat.com>
On 2014/1/10 20:19, Veaceslav Falico wrote:
> On Fri, Jan 10, 2014 at 07:32:51PM +0800, Ding Tianhong wrote:
>> All slave should have the same mtu with mastet's, and the bond do it when
>> enslave the slave, but the user could change the slave's mtu, it will cause
>> the master and slave have different mtu, althrough in AB mode, it does not
>> matter if the slave is not the current slave, but in other mode, it is incorrect,
>> so reset the slave's mtu like the master set.
>
> Why "net"? It's not a bugfix, it's a feature, and really discussable.
>
> Also, wrt the actual change - why do you think it's incorrect for slaves in
> bonding mode other than AB to have different MTU values? I don't see any
> reason for it, from the top of the head.
>
Ok, I will test more situation for every mode when slave's mtu changed, I am not sure
what will happened yet, if some links was interrupt, I thinks it is a bug.
>>
>> Cc: Jay Vosburgh <fubar@us•ibm.com>
>> Cc: Veaceslav Falico <vfalico@redhat•com>
>> Signed-off-by: Ding Tianhong <dingtianhong@huawei•com>
>> ---
>> drivers/net/bonding/bond_main.c | 21 ++++++++++-----------
>> 1 file changed, 10 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index 398e299..e7b5bcf 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -2882,18 +2882,17 @@ static int bond_slave_netdev_event(unsigned long event,
>> */
>> break;
>> case NETDEV_CHANGEMTU:
>> - /*
>> - * TODO: Should slaves be allowed to
>> - * independently alter their MTU? For
>> - * an active-backup bond, slaves need
>> - * not be the same type of device, so
>> - * MTUs may vary. For other modes,
>> - * slaves arguably should have the
>> - * same MTUs. To do this, we'd need to
>> - * take over the slave's change_mtu
>> - * function for the duration of their
>> - * servitude.
>> + /* All slave should have the same mtu
>> + * as master.
>> */
>> + if (slave->dev->mtu != bond->dev->mtu) {
>
> If we've got the event then it means it was changed to something different.
> No need to verify.
>
>> + int res;
>> + slave->original_mtu = slave->dev->mtu;
>
> If we're refusing to apply the *new* mtu, then why should we save it as the
> original? The original_mtu is the mtu that the slave had before it was
> enslaved.
>
the bond always save the slave's old mtu and set new one, so I did it again,
pls miss it, I think we should forbidden to change the mtu.
>> + res = dev_set_mtu(slave->dev, bond->dev->mtu);
>> + if (res)
>> + pr_debug("Error %d calling dev_set_mtu for slave %s\n",
>> + res, slave->dev->name);
>> + }
>
> Also, bonding should be vocal about changing forcibly the mtu - otherwise
> we'd end up with silently dropping the changes:
>
> ifconfig eth0 mtu 9000
> echo $?
> -> 0
> ifconfig eth0
> MTU: 1500
>
> or something like that, it will pass it up, refusing changes:
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index e06c445..0b36045 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -2846,19 +2846,8 @@ static int bond_slave_netdev_event(unsigned long event,
> */
> break;
> case NETDEV_CHANGEMTU:
> - /*
> - * TODO: Should slaves be allowed to
> - * independently alter their MTU? For
> - * an active-backup bond, slaves need
> - * not be the same type of device, so
> - * MTUs may vary. For other modes,
> - * slaves arguably should have the
> - * same MTUs. To do this, we'd need to
> - * take over the slave's change_mtu
> - * function for the duration of their
> - * servitude.
> - */
> - break;
> + /* don't permit slaves to change their MTU */
> + return NOTIFY_BAD;
> case NETDEV_CHANGENAME:
> /*
> * TODO: handle changing the primary's name
>
>> break;
>> case NETDEV_CHANGENAME:
>> /*
>> --
>> 1.8.0
>>
Yes, no problem.
Regards
Ding
>>
>
> .
>
next prev parent reply other threads:[~2014-01-12 5:18 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-10 11:32 [PATCH net] bonding: reset the slave's mtu when its be changed Ding Tianhong
2014-01-10 12:19 ` Veaceslav Falico
2014-01-12 5:18 ` Ding Tianhong [this message]
2014-01-14 2:11 ` Ding Tianhong
2014-01-14 6:03 ` Veaceslav Falico
2014-01-10 18:33 ` David Miller
2014-01-10 19:41 ` Sergei Shtylyov
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