From: Hannes Frederic Sowa <hannes@stressinduktion•org>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: davem@davemloft•net, netdev@vger•kernel.org,
sasha.levin@oracle•com, daniel@iogearbox•net,
alexei.starovoitov@gmail•com, mkubecek@suse•cz
Subject: Re: [PATCH net 4/4] tcp: various missing rcu_read_lock around __sk_dst_get
Date: Fri, 1 Apr 2016 04:01:34 +0200 [thread overview]
Message-ID: <56FDD67E.2040904@stressinduktion.org> (raw)
In-Reply-To: <1459475124.6473.250.camel@edumazet-glaptop3.roam.corp.google.com>
On 01.04.2016 03:45, Eric Dumazet wrote:
> On Thu, 2016-03-31 at 18:39 -0700, Eric Dumazet wrote:
>> On Fri, 2016-04-01 at 03:36 +0200, Hannes Frederic Sowa wrote:
>>> On Fri, Apr 1, 2016, at 03:19, Eric Dumazet wrote:
>>>> Thanks.
>>>>
>>>> As you can see, release_sock() messes badly lockdep (once your other
>>>> patches are in )
>>>>
>>>> Once we properly fix release_sock() and/or __release_sock(), all these
>>>> false positives disappear.
>>>
>>> This was a loopback connection. I need to study release_sock and
>>> __release_sock more as I cannot currently see an issue with the lockdep
>>> handling.
>>
>> Okay, please try :
>>
>> diff --git a/net/core/sock.c b/net/core/sock.c
>> index b67b9aedb230..570dcd91d64e 100644
>> --- a/net/core/sock.c
>> +++ b/net/core/sock.c
>> @@ -2429,10 +2429,6 @@ EXPORT_SYMBOL(lock_sock_nested);
>>
>> void release_sock(struct sock *sk)
>> {
>> - /*
>> - * The sk_lock has mutex_unlock() semantics:
>> - */
>> - mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);
>>
>> spin_lock_bh(&sk->sk_lock.slock);
>> if (sk->sk_backlog.tail)
>> @@ -2445,6 +2441,10 @@ void release_sock(struct sock *sk)
>> sk->sk_prot->release_cb(sk);
>>
>> sock_release_ownership(sk);
>> + /*
>> + * The sk_lock has mutex_unlock() semantics:
>> + */
>> + mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);
>> if (waitqueue_active(&sk->sk_lock.wq))
>> wake_up(&sk->sk_lock.wq);
>> spin_unlock_bh(&sk->sk_lock.slock);
>
> Also take a look at commit c3f9b01849ef3bc69024990092b9f42e20df7797
>
> We might need to include the mutex_release() in sock_release_ownership()
I thought so first, as well. But given the double check for the
spin_lock and the "mutex" we end up with the same result for the
lockdep_sock_is_held check.
Do you see other consequences?
Thanks,
Hannes
next prev parent reply other threads:[~2016-04-01 2:01 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-31 23:29 [PATCH net 0/4] net: fix and tighten rcu dereference checks Hannes Frederic Sowa
2016-03-31 23:29 ` [PATCH net 1/4] tun: add socket locking around sk_{attach,detach}_filter Hannes Frederic Sowa
2016-03-31 23:29 ` [PATCH net 2/4] net: proper check if we hold the socket lock during dereference Hannes Frederic Sowa
2016-03-31 23:29 ` [PATCH net 3/4] sock: use lockdep_sock_is_held were appropriate Hannes Frederic Sowa
2016-03-31 23:29 ` [PATCH net 4/4] tcp: various missing rcu_read_lock around __sk_dst_get Hannes Frederic Sowa
2016-03-31 23:39 ` Eric Dumazet
2016-04-01 0:01 ` Hannes Frederic Sowa
2016-04-01 0:12 ` Eric Dumazet
2016-04-01 0:21 ` Hannes Frederic Sowa
2016-04-01 1:19 ` Eric Dumazet
2016-04-01 1:36 ` Hannes Frederic Sowa
2016-04-01 1:39 ` Eric Dumazet
2016-04-01 1:45 ` Eric Dumazet
2016-04-01 2:01 ` Hannes Frederic Sowa [this message]
2016-04-01 3:13 ` Eric Dumazet
2016-04-01 3:31 ` Hannes Frederic Sowa
2016-04-01 1:58 ` Hannes Frederic Sowa
2016-04-01 1:45 ` Alexei Starovoitov
2016-04-01 3:03 ` Eric Dumazet
2016-04-01 3:06 ` Hannes Frederic Sowa
2016-04-01 4:04 ` Alexei Starovoitov
2016-04-01 4:12 ` Hannes Frederic Sowa
2016-04-01 4:26 ` Alexei Starovoitov
2016-04-01 4:33 ` Hannes Frederic Sowa
2016-04-01 8:10 ` Daniel Borkmann
2016-04-01 18:33 ` David Miller
2016-04-01 18:36 ` Daniel Borkmann
2016-04-01 0:30 ` Hannes Frederic Sowa
2016-04-01 1:23 ` Eric Dumazet
2016-04-01 1:37 ` Hannes Frederic Sowa
2016-03-31 23:48 ` [PATCH net 5/4] tcp: fix rcu usage around __sk_dst_get in tcp_update_metrics Hannes Frederic Sowa
2016-03-31 23:56 ` [PATCH net 6/4] tcp: fix __sk_dst_get usage in tcp_current_mss Hannes Frederic Sowa
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