From: Brian Haley <brian.haley@hp.com>
To: Pavel Emelyanov <xemul@parallels.com>
Cc: David Miller <davem@davemloft.net>,
Eric Dumazet <eric.dumazet@gmail.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [PATCH v2 net-next] sockopt: Change getsockopt() of SO_BINDTODEVICE to return an interface name
Date: Sat, 17 Nov 2012 16:58:05 -0500 [thread overview]
Message-ID: <50A8086D.80207@hp.com> (raw)
In-Reply-To: <50A71B50.3030603@parallels.com>
On 11/17/2012 12:06 AM, Pavel Emelyanov wrote:
>> @@ -4165,6 +4180,8 @@ static int dev_ifname(struct net *net, struct ifreq __user
>> *arg)
>>
>> strcpy(ifr.ifr_name, dev->name);
>> rcu_read_unlock();
>> + if (read_seqretry(&devnet_rename_seq, seq))
>> + goto retry;
>
> I believe it makes sense to make the seqcount protection as a separate patch
> with description of what may happen.
I asked about that before and Dave said he "wanted all the races resolved". At
best I could make this a series...
>> +retry:
>> + seq = read_seqbegin(&devnet_rename_seq);
>> + rcu_read_lock();
>> + dev = dev_get_by_index_rcu(net, sk->sk_bound_dev_if);
>
> The sk->sk_bound_dev_if might have changed to 0 while we did read_seqretry (or
> did the len check above, but the race window is smaller) and this code will
> report -ENODEV instead of zero lenght.
If there are two threads twiddling with the same socket like this the
application is broken in my mind.
-Brian
next prev parent reply other threads:[~2012-11-17 21:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-16 20:58 [PATCH v2 net-next] sockopt: Change getsockopt() of SO_BINDTODEVICE to return an interface name Brian Haley
2012-11-17 5:06 ` Pavel Emelyanov
2012-11-17 21:58 ` Brian Haley [this message]
2012-11-20 18:58 ` David Miller
2012-11-26 15:10 ` Brian Haley
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