From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: lars.persson@axis.com, netdev@vger.kernel.org
Subject: Re: [PATCH] tcp: tcp_release_cb() should release socket ownership
Date: Wed, 05 Mar 2014 20:59:38 -0500 (EST) [thread overview]
Message-ID: <20140305.205938.287751582220842351.davem@davemloft.net> (raw)
In-Reply-To: <1393972752.26794.145.camel@edumazet-glaptop2.roam.corp.google.com>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 04 Mar 2014 14:39:12 -0800
> @@ -767,6 +767,17 @@ void tcp_release_cb(struct sock *sk)
> if (flags & (1UL << TCP_TSQ_DEFERRED))
> tcp_tsq_handler(sk);
>
> + /* Here begins the tricky part :
> + * We are called from release_sock() with :
> + * 1) BH disabled
> + * 2) sk_lock.slock spinlock held
> + * 3) socket owned by us (sk->sk_lock.owned == 1)
> + *
> + * But following code is meant to be called from BH handlers,
> + * so we should keep BH disabled, but early release socket ownership
> + */
> + sock_release_ownership(sk);
> +
It really means that sk_lock.owned cannot ever be accessed without the
sk_lock spinlock held.
Most of this is easy to hand audit, except sock_owned_by_user() which
has call sites everywhere.
Consider adding a locking assertion to it.
next prev parent reply other threads:[~2014-03-06 1:59 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-04 8:59 [BUG] Deadlock on sk->sk_lock.slock Lars Persson
2014-03-04 14:16 ` Eric Dumazet
2014-03-04 18:48 ` David Miller
2014-03-04 22:39 ` [PATCH] tcp: tcp_release_cb() should release socket ownership Eric Dumazet
2014-03-06 1:59 ` David Miller [this message]
2014-03-06 2:06 ` Eric Dumazet
2014-03-06 2:15 ` David Miller
2014-03-06 2:20 ` Eric Dumazet
2014-03-07 15:45 ` Lars Persson
2014-03-07 16:01 ` Eric Dumazet
2014-03-10 16:43 ` Eric Dumazet
2014-03-10 20:40 ` David Miller
2014-03-10 16:50 ` [PATCH resend] " Eric Dumazet
2014-03-11 20:46 ` David Miller
2014-03-05 15:01 ` [BUG] Deadlock on sk->sk_lock.slock Lars Persson
2014-03-05 17:34 ` Eric Dumazet
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