* [PATCH v2 net-next] net: make dev_set_mtu() honor notification return code
@ 2014-01-10 15:56 Veaceslav Falico
2014-01-10 16:21 ` Jiri Pirko
0 siblings, 1 reply; 2+ messages in thread
From: Veaceslav Falico @ 2014-01-10 15:56 UTC (permalink / raw)
To: netdev
Cc: Veaceslav Falico, Jiri Pirko, David S. Miller, Eric Dumazet,
Alexander Duyck, Nicolas Dichtel
Currently, after changing the MTU for a device, dev_set_mtu() calls
NETDEV_CHANGEMTU notification, however doesn't verify it's return code -
which can be NOTIFY_BAD - i.e. some of the net notifier blocks refused this
change, and continues nevertheless.
To fix this, verify the return code, and if it's an error - then revert the
MTU to the original one, notify again and pass the error code.
CC: Jiri Pirko <jiri@resnulli.us>
CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Alexander Duyck <alexander.h.duyck@intel.com>
CC: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
---
Notes:
v1 -> v2:
Notify again after we've reverted the MTU back to the original, so that
everyone has a chance to change its MTU back.
net/core/dev.c | 34 +++++++++++++++++++++++++---------
1 file changed, 25 insertions(+), 9 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index ce01847..0991d94 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5287,6 +5287,17 @@ int dev_change_flags(struct net_device *dev, unsigned int flags)
}
EXPORT_SYMBOL(dev_change_flags);
+static int __dev_set_mtu(struct net_device *dev, int new_mtu)
+{
+ const struct net_device_ops *ops = dev->netdev_ops;
+
+ if (ops->ndo_change_mtu)
+ return ops->ndo_change_mtu(dev, new_mtu);
+
+ dev->mtu = new_mtu;
+ return 0;
+}
+
/**
* dev_set_mtu - Change maximum transfer unit
* @dev: device
@@ -5296,8 +5307,7 @@ EXPORT_SYMBOL(dev_change_flags);
*/
int dev_set_mtu(struct net_device *dev, int new_mtu)
{
- const struct net_device_ops *ops = dev->netdev_ops;
- int err;
+ int err, orig_mtu;
if (new_mtu == dev->mtu)
return 0;
@@ -5309,14 +5319,20 @@ int dev_set_mtu(struct net_device *dev, int new_mtu)
if (!netif_device_present(dev))
return -ENODEV;
- err = 0;
- if (ops->ndo_change_mtu)
- err = ops->ndo_change_mtu(dev, new_mtu);
- else
- dev->mtu = new_mtu;
+ orig_mtu = dev->mtu;
+ err = __dev_set_mtu(dev, new_mtu);
- if (!err)
- call_netdevice_notifiers(NETDEV_CHANGEMTU, dev);
+ if (!err) {
+ err = call_netdevice_notifiers(NETDEV_CHANGEMTU, dev);
+ err = notifier_to_errno(err);
+ if (err) {
+ /* setting mtu back and notifying everyone again,
+ * so that they have a chance to revert changes.
+ */
+ __dev_set_mtu(dev, orig_mtu);
+ call_netdevice_notifiers(NETDEV_CHANGEMTU, dev);
+ }
+ }
return err;
}
EXPORT_SYMBOL(dev_set_mtu);
--
1.8.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2 net-next] net: make dev_set_mtu() honor notification return code
2014-01-10 15:56 [PATCH v2 net-next] net: make dev_set_mtu() honor notification return code Veaceslav Falico
@ 2014-01-10 16:21 ` Jiri Pirko
0 siblings, 0 replies; 2+ messages in thread
From: Jiri Pirko @ 2014-01-10 16:21 UTC (permalink / raw)
To: Veaceslav Falico
Cc: netdev, David S. Miller, Eric Dumazet, Alexander Duyck, Nicolas Dichtel
Fri, Jan 10, 2014 at 04:56:25PM CET, vfalico@redhat.com wrote:
>Currently, after changing the MTU for a device, dev_set_mtu() calls
>NETDEV_CHANGEMTU notification, however doesn't verify it's return code -
>which can be NOTIFY_BAD - i.e. some of the net notifier blocks refused this
>change, and continues nevertheless.
>
>To fix this, verify the return code, and if it's an error - then revert the
>MTU to the original one, notify again and pass the error code.
>
>CC: Jiri Pirko <jiri@resnulli.us>
>CC: "David S. Miller" <davem@davemloft.net>
>CC: Eric Dumazet <edumazet@google.com>
>CC: Alexander Duyck <alexander.h.duyck@intel.com>
>CC: Nicolas Dichtel <nicolas.dichtel@6wind.com>
>Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Reviewed-by: Jiri Pirko <jiri@resnulli.us>
^ permalink raw reply [flat|nested] 2+ messages in thread
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