[PATCH] can: fix WARN_ON dump in net/core/rtnetlink.c:rtmsg_ifinfo()

[PATCH] can: fix WARN_ON dump in net/core/rtnetlink.c:rtmsg_ifinfo()

[Wolfgang Grandegger]

On older kernels, e.g. 2.6.27, a WARN_ON dump in rtmsg_ifinfo()
is thrown when the CAN device is registered due to insufficient
skb space, as reported by various users. This patch adds the
rtnl_link_ops "get_size" to fix the problem. I think this patch
is required for more recent kernels as well, even if no WARN_ON
dumps are triggered. Maybe we also need "get_xstats_size" for
the CAN xstats.

Signed-off-by: Wolfgang Grandegger <wg-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>

---
 drivers/net/can/dev.c |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)

Index: net-next-2.6/drivers/net/can/dev.c
===================================================================
--- net-next-2.6.orig/drivers/net/can/dev.c
+++ net-next-2.6/drivers/net/can/dev.c
@@ -637,6 +637,22 @@ static int can_changelink(struct net_dev
 	return 0;
 }
 
+static size_t can_get_size(const struct net_device *dev)
+{
+	struct can_priv *priv = netdev_priv(dev);
+	size_t size;
+
+	size = nla_total_size(sizeof(u32));   /* IFLA_CAN_STATE */
+	size += sizeof(struct can_ctrlmode);  /* IFLA_CAN_CTRLMODE */
+	size += nla_total_size(sizeof(u32));  /* IFLA_CAN_RESTART_MS */
+	size += sizeof(struct can_bittiming); /* IFLA_CAN_BITTIMING */
+	size += sizeof(struct can_clock);     /* IFLA_CAN_CLOCK */
+	if (priv->bittiming_const)	      /* IFLA_CAN_BITTIMING_CONST */
+		size += sizeof(struct can_bittiming_const);
+
+	return size;
+}
+
 static int can_fill_info(struct sk_buff *skb, const struct net_device *dev)
 {
 	struct can_priv *priv = netdev_priv(dev);
@@ -687,6 +703,7 @@ static struct rtnl_link_ops can_link_ops
 	.setup		= can_setup,
 	.newlink	= can_newlink,
 	.changelink	= can_changelink,
+	.get_size	= can_get_size,
 	.fill_info	= can_fill_info,
 	.fill_xstats	= can_fill_xstats,
 };

Re: [PATCH] can: fix WARN_ON dump in net/core/rtnetlink.c:rtmsg_ifinfo()

[David Miller]

From: Wolfgang Grandegger <wg@grandegger.com>
Date: Sat, 07 Nov 2009 10:53:13 +0100

> On older kernels, e.g. 2.6.27, a WARN_ON dump in rtmsg_ifinfo()
> is thrown when the CAN device is registered due to insufficient
> skb space, as reported by various users. This patch adds the
> rtnl_link_ops "get_size" to fix the problem. I think this patch
> is required for more recent kernels as well, even if no WARN_ON
> dumps are triggered. Maybe we also need "get_xstats_size" for
> the CAN xstats.
> 
> Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>

Applied to net-2.6, thanks Wolfgang.

Re: [PATCH] can: fix WARN_ON dump in net/core/rtnetlink.c:rtmsg_ifinfo()

[Wolfgang Grandegger]

David Miller wrote:
> From: Wolfgang Grandegger <wg-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>
> Date: Sat, 07 Nov 2009 10:53:13 +0100
> 
>> On older kernels, e.g. 2.6.27, a WARN_ON dump in rtmsg_ifinfo()
>> is thrown when the CAN device is registered due to insufficient
>> skb space, as reported by various users. This patch adds the
>> rtnl_link_ops "get_size" to fix the problem. I think this patch
>> is required for more recent kernels as well, even if no WARN_ON
>> dumps are triggered. Maybe we also need "get_xstats_size" for
>> the CAN xstats.
>>
>> Signed-off-by: Wolfgang Grandegger <wg-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>
> 
> Applied to net-2.6, thanks Wolfgang.

Thanks, the commit message included some questions. What is the rule
using the rtnl_link_ops "get_size" or "get_xstats_size". Are these
mandatory if the corresponding fill functions are used?

Wolfgang.

Re: [PATCH] can: fix WARN_ON dump in net/core/rtnetlink.c:rtmsg_ifinfo()

[Patrick McHardy]

Wolfgang Grandegger wrote:
> David Miller wrote:
>> From: Wolfgang Grandegger <wg@grandegger.com>
>> Date: Sat, 07 Nov 2009 10:53:13 +0100
>>
>>> On older kernels, e.g. 2.6.27, a WARN_ON dump in rtmsg_ifinfo()
>>> is thrown when the CAN device is registered due to insufficient
>>> skb space, as reported by various users. This patch adds the
>>> rtnl_link_ops "get_size" to fix the problem. I think this patch
>>> is required for more recent kernels as well, even if no WARN_ON
>>> dumps are triggered. Maybe we also need "get_xstats_size" for
>>> the CAN xstats.
>>>
>>> Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
>> Applied to net-2.6, thanks Wolfgang.
> 
> Thanks, the commit message included some questions. What is the rule
> using the rtnl_link_ops "get_size" or "get_xstats_size". Are these
> mandatory if the corresponding fill functions are used?

Yes. You also need a get_xstats_size() function.

Re: [PATCH] can: fix WARN_ON dump in net/core/rtnetlink.c:rtmsg_ifinfo()

[Wolfgang Grandegger]

Patrick McHardy wrote:
> Wolfgang Grandegger wrote:
>> David Miller wrote:
>>> From: Wolfgang Grandegger <wg-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>
>>> Date: Sat, 07 Nov 2009 10:53:13 +0100
>>>
>>>> On older kernels, e.g. 2.6.27, a WARN_ON dump in rtmsg_ifinfo()
>>>> is thrown when the CAN device is registered due to insufficient
>>>> skb space, as reported by various users. This patch adds the
>>>> rtnl_link_ops "get_size" to fix the problem. I think this patch
>>>> is required for more recent kernels as well, even if no WARN_ON
>>>> dumps are triggered. Maybe we also need "get_xstats_size" for
>>>> the CAN xstats.
>>>>
>>>> Signed-off-by: Wolfgang Grandegger <wg-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>
>>> Applied to net-2.6, thanks Wolfgang.
>> Thanks, the commit message included some questions. What is the rule
>> using the rtnl_link_ops "get_size" or "get_xstats_size". Are these
>> mandatory if the corresponding fill functions are used?
> 
> Yes. You also need a get_xstats_size() function.

Thanks for clarification. I will provide a patch a.s.a.p.

Wolfgang.