tcp: fix a panic on UP machines in reqsk_fastopen_remove

From: Eric Dumazet <edumazet@google.com>

spin_is_locked() on a non !SMP build is kind of useless.

BUG_ON(!spin_is_locked(xx)) is guaranteed to crash.

Just remove this check in reqsk_fastopen_remove() as
the callers do hold the socket lock.

Reported-by: Ketan Kulkarni <ketkulka@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jerry Chu <hkchu@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Dave Taht <dave.taht@gmail.com>
---
 net/core/request_sock.c |    2 --
 1 file changed, 2 deletions(-)



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On Sun, Jan 13, 2013 at 8:21 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> spin_is_locked() on a non !SMP build is kind of useless.
>
> BUG_ON(!spin_is_locked(xx)) is guaranteed to crash.
>
> Just remove this check in reqsk_fastopen_remove() as
> the callers do hold the socket lock.
>
> Reported-by: Ketan Kulkarni <ketkulka@gmail.com>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Jerry Chu <hkchu@google.com>
> Cc: Yuchung Cheng <ycheng@google.com>
> Cc: Dave Taht <dave.taht@gmail.com>
> ---
>  net/core/request_sock.c |    2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/net/core/request_sock.c b/net/core/request_sock.c
> index c31d9e8..4425148 100644
> --- a/net/core/request_sock.c
> +++ b/net/core/request_sock.c
> @@ -186,8 +186,6 @@ void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
>         struct fastopen_queue *fastopenq =
>             inet_csk(lsk)->icsk_accept_queue.fastopenq;
>
> -       BUG_ON(!spin_is_locked(&sk->sk_lock.slock) && !sock_owned_by_user(sk));
> -
>         tcp_sk(sk)->fastopen_rsk = NULL;
>         spin_lock_bh(&fastopenq->lock);
>         fastopenq->qlen--;
>
>

Thanks, Eric. (I thought the assertion would be transparent to UP...)

Acked-by: H.K. Jerry Chu <hkchu@google.com>
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From: Jerry Chu <hkchu@google.com>
Date: Mon, 14 Jan 2013 00:26:26 -0800

> On Sun, Jan 13, 2013 at 8:21 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>> From: Eric Dumazet <edumazet@google.com>
>>
>> spin_is_locked() on a non !SMP build is kind of useless.
>>
>> BUG_ON(!spin_is_locked(xx)) is guaranteed to crash.
>>
>> Just remove this check in reqsk_fastopen_remove() as
>> the callers do hold the socket lock.
>>
>> Reported-by: Ketan Kulkarni <ketkulka@gmail.com>
>> Signed-off-by: Eric Dumazet <edumazet@google.com>
 ...
> Thanks, Eric. (I thought the assertion would be transparent to UP...)
> 
> Acked-by: H.K. Jerry Chu <hkchu@google.com>
> 

Applied, thanks.
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