On Tue, Nov 14, 2023 at 12:42 PM Pengcheng Yang <yangpc@xxxxxxxxxx> wrote:
>
> Currently we cannot get the data length in ingress_msg,
> we introduce sk_msg_queue_len() to do this.
>
> Signed-off-by: Pengcheng Yang <yangpc@xxxxxxxxxx>
> ---
> include/linux/skmsg.h | 24 ++++++++++++++++++++++--
> net/core/skmsg.c | 4 ++++
> 2 files changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
> index c1637515a8a4..3023a573859d 100644
> --- a/include/linux/skmsg.h
> +++ b/include/linux/skmsg.h
> @@ -82,6 +82,7 @@ struct sk_psock {
> u32 apply_bytes;
> u32 cork_bytes;
> u32 eval;
> + u32 msg_len;
> bool redir_ingress; /* undefined if sk_redir is null */
> struct sk_msg *cork;
> struct sk_psock_progs progs;
> @@ -131,6 +132,11 @@ int sk_msg_recvmsg(struct sock *sk, struct sk_psock *psock, struct msghdr *msg,
> int len, int flags);
> bool sk_msg_is_readable(struct sock *sk);
>
> +static inline void sk_msg_queue_consumed(struct sk_psock *psock, u32 len)
> +{
> + psock->msg_len -= len;
> +}
> +
> static inline void sk_msg_check_to_free(struct sk_msg *msg, u32 i, u32 bytes)
> {
> WARN_ON(i == msg->sg.end && bytes);
> @@ -311,9 +317,10 @@ static inline void sk_psock_queue_msg(struct sk_psock *psock,
> struct sk_msg *msg)
> {
> spin_lock_bh(&psock->ingress_lock);
> - if (sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED))
> + if (sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)) {
> list_add_tail(&msg->list, &psock->ingress_msg);
> - else {
> + psock->msg_len += msg->sg.size;
> + } else {
> sk_msg_free(psock->sk, msg);
> kfree(msg);
> }
> @@ -368,6 +375,19 @@ static inline void kfree_sk_msg(struct sk_msg *msg)
> kfree(msg);
> }
>
> +static inline u32 sk_msg_queue_len(struct sock *sk)
const struct sock *sk;
> +{
> + struct sk_psock *psock;
> + u32 len = 0;
> +
> + rcu_read_lock();
> + psock = sk_psock(sk);
> + if (psock)
> + len = psock->msg_len;
This is racy against writers.
You must use READ_ONCE() here, and WRITE_ONCE() on write sides.
> + rcu_read_unlock();
> + return len;
> +}
> +
> static inline void sk_psock_report_error(struct sk_psock *psock, int err)
> {
> struct sock *sk = psock->sk;
> diff --git a/net/core/skmsg.c b/net/core/skmsg.c
> index 6c31eefbd777..b3de17e99b67 100644
> --- a/net/core/skmsg.c
> +++ b/net/core/skmsg.c
> @@ -481,6 +481,8 @@ int sk_msg_recvmsg(struct sock *sk, struct sk_psock *psock, struct msghdr *msg,
> msg_rx = sk_psock_peek_msg(psock);
> }
> out:
> + if (likely(!peek) && copied > 0)
> + sk_msg_queue_consumed(psock, copied);
> return copied;
> }
> EXPORT_SYMBOL_GPL(sk_msg_recvmsg);
> @@ -771,9 +773,11 @@ static void __sk_psock_purge_ingress_msg(struct sk_psock *psock)
>
> list_for_each_entry_safe(msg, tmp, &psock->ingress_msg, list) {
> list_del(&msg->list);
> + sk_msg_queue_consumed(psock, msg->sg.size);
> sk_msg_free(psock->sk, msg);
> kfree(msg);
> }
> + WARN_ON_ONCE(psock->msg_len != 0);
> }
>
> static void __sk_psock_zap_ingress(struct sk_psock *psock)
> --
> 2.38.1
>
