Subject: Re: [Patch bpf-next v4 02/11] skmsg: introduce a spinlock to protect ingress_msg

From: Jakub Sitnicki <[email-masked]>
Date: Thu, 11 Mar 2021 12:28:01 +0100

On Wed, Mar 10, 2021 at 06:32 AM CET, Cong Wang wrote:
> From: Cong Wang <[email-masked]>
>
> Currently we rely on lock_sock to protect ingress_msg,
> it is too big for this, we can actually just use a spinlock
> to protect this list like protecting other skb queues.
>
> __tcp_bpf_recvmsg() is still special because of peeking,
> it still has to use lock_sock.
>
> Cc: John Fastabend <[email-masked]>
> Cc: Daniel Borkmann <[email-masked]>
> Cc: Jakub Sitnicki <[email-masked]>
> Cc: Lorenz Bauer <[email-masked]>
> Signed-off-by: Cong Wang <[email-masked]>
> ---

One nit below.

Acked-by: Jakub Sitnicki <[email-masked]>

>  include/linux/skmsg.h | 46 +++++++++++++++++++++++++++++++++++++++++++
>  net/core/skmsg.c      |  3 +++
>  net/ipv4/tcp_bpf.c    | 18 ++++++-----------
>  3 files changed, 55 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
> index 6c09d94be2e9..7333bf881b81 100644
> --- a/include/linux/skmsg.h
> +++ b/include/linux/skmsg.h
> @@ -89,6 +89,7 @@ struct sk_psock {
>  #endif
>  	struct sk_buff_head		ingress_skb;
>  	struct list_head		ingress_msg;
> +	spinlock_t			ingress_lock;
>  	unsigned long			state;
>  	struct list_head		link;
>  	spinlock_t			link_lock;
> @@ -284,7 +285,45 @@ static inline struct sk_psock *sk_psock(const struct sock *sk)
>  static inline void sk_psock_queue_msg(struct sk_psock *psock,
>  				      struct sk_msg *msg)
>  {
> +	spin_lock_bh(&psock->ingress_lock);
>  	list_add_tail(&msg->list, &psock->ingress_msg);
> +	spin_unlock_bh(&psock->ingress_lock);
> +}
> +
> +static inline struct sk_msg *sk_psock_deque_msg(struct sk_psock *psock)

Should be sk_psock_deque*ue*_msg()?

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