On Wed, 2017-05-17 at 11:39 -0700, Andrei Vagin wrote:
> This function has to return NULL on a error case, because there is a
> separate error variable.
>
> The offset has to be changed only if skb is returned
>
> v2: fix udp code to not use an extra variable
>
> Cc: Paolo Abeni <pab...@redhat.com>
> Cc: Eric Dumazet <eduma...@google.com>
> Cc: David S. Miller <da...@davemloft.net>
> Fixes: 65101aeca522 ("net/sock: factor out dequeue/peek with offset cod")
> Signed-off-by: Andrei Vagin <ava...@openvz.org>
> ---
> net/core/datagram.c | 14 ++++++++------
> net/ipv4/udp.c | 12 +++---------
> 2 files changed, 11 insertions(+), 15 deletions(-)
>
> diff --git a/net/core/datagram.c b/net/core/datagram.c
> index a4592b4..bc46118 100644
> --- a/net/core/datagram.c
> +++ b/net/core/datagram.c
> @@ -170,20 +170,21 @@ struct sk_buff *__skb_try_recv_from_queue(struct sock
> *sk,
> struct sk_buff **last)
> {
> struct sk_buff *skb;
> + int _off = *off;
>
> *last = queue->prev;
> skb_queue_walk(queue, skb) {
> if (flags & MSG_PEEK) {
> - if (*off >= skb->len && (skb->len || *off ||
> + if (_off >= skb->len && (skb->len || _off ||
> skb->peeked)) {
> - *off -= skb->len;
> + _off -= skb->len;
> continue;
> }
> if (!skb->len) {
> skb = skb_set_peeked(skb);
> if (unlikely(IS_ERR(skb))) {
> *err = PTR_ERR(skb);
> - return skb;
> + return NULL;
> }
> }
> *peeked = 1;
> @@ -193,6 +194,7 @@ struct sk_buff *__skb_try_recv_from_queue(struct sock *sk,
> if (destructor)
> destructor(sk, skb);
> }
> + *off = _off;
> return skb;
> }
> return NULL;
> @@ -253,8 +255,6 @@ struct sk_buff *__skb_try_recv_datagram(struct sock *sk,
> unsigned int flags,
>
> *peeked = 0;
> do {
> - int _off = *off;
> -
> /* Again only user level code calls this function, so nothing
> * interrupt level will suddenly eat the receive_queue.
> *
> @@ -263,8 +263,10 @@ struct sk_buff *__skb_try_recv_datagram(struct sock *sk,
> unsigned int flags,
> */
> spin_lock_irqsave(&queue->lock, cpu_flags);
> skb = __skb_try_recv_from_queue(sk, queue, flags, destructor,
> - peeked, &_off, err, last);
> + peeked, off, &error, last);
> spin_unlock_irqrestore(&queue->lock, cpu_flags);
> + if (error)
> + goto no_packet;
> if (skb)
> return skb;
>
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 7bd56c9..278e707 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1465,16 +1465,13 @@ struct sk_buff *__skb_recv_udp(struct sock *sk,
> unsigned int flags,
> error = -EAGAIN;
> *peeked = 0;
> do {
> - int _off = *off;
> -
> spin_lock_bh(&queue->lock);
> skb = __skb_try_recv_from_queue(sk, queue, flags,
> udp_skb_destructor,
> - peeked, &_off, err,
> + peeked, off, err,
> &last);
> if (skb) {
> spin_unlock_bh(&queue->lock);
> - *off = _off;
> return skb;
> }
>
> @@ -1488,20 +1485,17 @@ struct sk_buff *__skb_recv_udp(struct sock *sk,
> unsigned int flags,
> * the sk_receive_queue lock if fwd memory scheduling
> * is needed.
> */
> - _off = *off;
> spin_lock(&sk_queue->lock);
> skb_queue_splice_tail_init(sk_queue, queue);
>
> skb = __skb_try_recv_from_queue(sk, queue, flags,
> udp_skb_dtor_locked,
> - peeked, &_off, err,
> + peeked, off, err,
> &last);
> spin_unlock(&sk_queue->lock);
> spin_unlock_bh(&queue->lock);
> - if (skb) {
> - *off = _off;
> + if (skb)
> return skb;
> - }
>
> busy_check:
> if (!sk_can_busy_loop(sk))
LGTM, thanks!
Acked-by: Paolo Abeni <pab...@redhat.com>
