[net,2/3] sctp: update the netstamp_needed counter when copying sockets

Dmitry Vyukov reported that SCTP was triggering a WARN on socket destroy
related to disabling sock timestamp.

When SCTP accepts an association or peel one off, it copies sock flags
but forgot to call net_enable_timestamp() if a packet timestamping flag
was copied, leading to extra calls to net_disable_timestamp() whenever
such clones were closed.

The fix is to call net_enable_timestamp() whenever we copy a sock with
that flag on, like tcp does.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
---
 include/net/sock.h | 2 ++
 net/core/sock.c    | 2 --
 net/sctp/socket.c  | 3 +++
 3 files changed, 5 insertions(+), 2 deletions(-)

On 12/04/2015 12:14 PM, Marcelo Ricardo Leitner wrote:
> Dmitry Vyukov reported that SCTP was triggering a WARN on socket destroy
> related to disabling sock timestamp.
> 
> When SCTP accepts an association or peel one off, it copies sock flags
> but forgot to call net_enable_timestamp() if a packet timestamping flag
> was copied, leading to extra calls to net_disable_timestamp() whenever
> such clones were closed.
> 
> The fix is to call net_enable_timestamp() whenever we copy a sock with
> that flag on, like tcp does.
> 
> Reported-by: Dmitry Vyukov <dvyukov@google.com>
> Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

Acked-by: Vlad Yasevich <vyasevich@gmail.com>

-vlad

> ---
>  include/net/sock.h | 2 ++
>  net/core/sock.c    | 2 --
>  net/sctp/socket.c  | 3 +++
>  3 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 52d27ee924f47867026d8f65c65551a9137219d3..b1d475b5db6825e13df3e3e147fed8654e1cf086 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -740,6 +740,8 @@ enum sock_flags {
>  	SOCK_SELECT_ERR_QUEUE, /* Wake select on error queue */
>  };
>  
> +#define SK_FLAGS_TIMESTAMP ((1UL << SOCK_TIMESTAMP) | (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE))
> +
>  static inline void sock_copy_flags(struct sock *nsk, struct sock *osk)
>  {
>  	nsk->sk_flags = osk->sk_flags;
> diff --git a/net/core/sock.c b/net/core/sock.c
> index e31dfcee1729aa23bdd2ed692fda1b90bd75afb8..d01c8f42dbb2f040fd48009b2767bd4e80aea8ab 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -433,8 +433,6 @@ static bool sock_needs_netstamp(const struct sock *sk)
>  	}
>  }
>  
> -#define SK_FLAGS_TIMESTAMP ((1UL << SOCK_TIMESTAMP) | (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE))
> -
>  static void sock_disable_timestamp(struct sock *sk, unsigned long flags)
>  {
>  	if (sk->sk_flags & flags) {
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 03c8256063ec6355fcce034366aa5d005d75b5f7..4c9282bdd06790a0cca7f7c33986e7eb6c541398 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -7199,6 +7199,9 @@ void sctp_copy_sock(struct sock *newsk, struct sock *sk,
>  	newinet->mc_ttl = 1;
>  	newinet->mc_index = 0;
>  	newinet->mc_list = NULL;
> +
> +	if (newsk->sk_flags & SK_FLAGS_TIMESTAMP)
> +		net_enable_timestamp();
>  }
>  
>  static inline void sctp_copy_descendant(struct sock *sk_to,
> 

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