netdev - Re: [PATCH net] net: bridge: fix early call to br_stp_change_bridge

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Message-ID: <4b07ce51-177d-df6f-f5ac-321f85402b6c@cumulusnetworks.com>
Date:   Mon, 18 Dec 2017 16:22:19 +0200
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     Toshiaki Makita <makita.toshiaki@....ntt.co.jp>,
        netdev@...r.kernel.org
Cc:     roopa@...ulusnetworks.com, davem@...emloft.net,
        stephen@...workplumber.org, avagin@...il.com,
        bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net] net: bridge: fix early call to
 br_stp_change_bridge_id

On 12/18/2017 04:24 AM, Toshiaki Makita wrote:
> On 2017/12/16 20:31, Nikolay Aleksandrov wrote:
[snip]
> ...
>>  	err = br_changelink(dev, tb, data, extack);
>> -	if (err)
>> +	if (err) {
>> +		/* clean possible fdbs from br_stp_change_bridge_id above */
>> +		br_fdb_delete_by_port(br, NULL, 0, 1);
> 
> Don't we need to call br_dev_delete (br_link_ops.dellink) after
> successful register instead of br_fdb_delete?
> Particularly I'm wondering if not calling br_sysfs_delbr() is ok or not.
> 

Funny, that is actually the only reason we need to call it (br_sysfs_delbr). :-)

Good catch, that is another leak - the bridge sysfs entries are registered when
NETDEV_REGISTER event happens (register_netdevice) but are not properly cleaned up
on error there. This has also been present since the introduction of changelink
during newlink, commit:
 b6677449dff6 ("bridge: netlink: call br_changelink() during br_dev_newlink()")

I'll send v2 that does br_dev_delete(dev, NULL) instead of the current cleanup.
With kobject debug enabled and that I can see "brif" and the rest of the sysfs
files getting freed properly, while before they weren't.

Thanks,
 Nik