netdev - Re: [patch 1/2] qeth: new qeth device driver

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Date:	Mon, 11 Feb 2008 08:55:41 +0100
From:	Frank Blaschka <blaschka@...ux.vnet.ibm.com>
To:	paulmck@...ux.vnet.ibm.com
CC:	netdev@...r.kernel.org
Subject: Re: [patch 1/2] qeth: new qeth device driver

Paul E. McKenney schrieb:
> On Fri, Feb 08, 2008 at 03:10:00PM +0100, Frank.Blaschka@...ibm.com wrote:
>> From: Frank Blaschka <frank.blaschka@...ibm.com>
>>
>> List of major changes and improvements:
>>  no manipulation of the global ARP constructor
>>  clean code split into core, layer 2 and layer 3 functionality
>>  better exploitation of the ethtool interface
>>  better representation of the various hardware capabilities
>>  fix packet socket support (tcpdump), no fake_ll required
>>  osasnmpd notification via udev events
>>  coding style and beautification
> 
> One question below...
> 
>> Signed-off-by: Frank Blaschka <frank.blaschka@...ibm.com>
>> ---
> 
> [ . . . ]
> 
>> +static void qeth_l3_vlan_rx_add_vid(struct net_device *dev, unsigned short vid)
>> +{
>> +	struct net_device *vlandev;
>> +	struct qeth_card *card = (struct qeth_card *) dev->priv;
>> +	struct in_device *in_dev;
>> +
>> +	if (card->info.type == QETH_CARD_TYPE_IQD)
>> +		return;
>> +
>> +	vlandev = vlan_group_get_device(card->vlangrp, vid);
>> +	vlandev->neigh_setup = qeth_l3_neigh_setup;
>> +
>> +	in_dev = __in_dev_get_rcu(vlandev);
> 
> Is this really in an RCU read-side critical section?  Or is this just
> using common code?
> 
> 						Thanx, Paul
> --
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Hi Paul,

thanks for pointing at this. Using __in_dev_get_rcu without the rcu lock
is probably a bug at this place (right?). Using in_dev_get/in_dev_put
would be more appropriate. Same for qeth_l3_free_vlan_addresses4(), here
we take the rcu read lock, but in_dev_get/in_dev_put would be the better
choice. What do you think?

Best regards,
		Frank

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