On 11/16/20, Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
> When we write all cq items to tx, we have to wait for a new event based
> on poll to indicate that it is writable. But the current writability is
> triggered based on whether tx is full or not, and In fact, when tx is
> dissatisfied, the user of cq's item may not necessarily get it, because it
> may still be occupied by the network card. In this case, we need to know
> when cq is available, so this patch adds a socket option, When the user
> configures this option using setsockopt, when cq is available, a
> readable event is generated for all xsk bound to this umem.
>
> I can't find a better description of this event,
> I think it can also be 'readable', although it is indeed different from
> the 'readable' of the new data. But the overhead of xsk checking whether
> cq or rx is readable is small.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> ---
> include/net/xdp_sock.h | 1 +
> include/uapi/linux/if_xdp.h | 1 +
> net/xdp/xsk.c | 28 ++++++++++++++++++++++++++++
> 3 files changed, 30 insertions(+)
>
> diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
> index 1a9559c..faf5b1a 100644
> --- a/include/net/xdp_sock.h
> +++ b/include/net/xdp_sock.h
> @@ -49,6 +49,7 @@ struct xdp_sock {
> struct xsk_buff_pool *pool;
> u16 queue_id;
> bool zc;
> + bool cq_event;
> enum {
> XSK_READY = 0,
> XSK_BOUND,
> diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h
> index a78a809..2dba3cb 100644
> --- a/include/uapi/linux/if_xdp.h
> +++ b/include/uapi/linux/if_xdp.h
> @@ -63,6 +63,7 @@ struct xdp_mmap_offsets {
> #define XDP_UMEM_COMPLETION_RING 6
> #define XDP_STATISTICS 7
> #define XDP_OPTIONS 8
> +#define XDP_CQ_EVENT 9
>
> struct xdp_umem_reg {
> __u64 addr; /* Start of packet data area */
> diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
> index cfbec39..0c53403 100644
> --- a/net/xdp/xsk.c
> +++ b/net/xdp/xsk.c
> @@ -285,7 +285,16 @@ void __xsk_map_flush(void)
>
> void xsk_tx_completed(struct xsk_buff_pool *pool, u32 nb_entries)
> {
> + struct xdp_sock *xs;
> +
> xskq_prod_submit_n(pool->cq, nb_entries);
> +
> + rcu_read_lock();
> + list_for_each_entry_rcu(xs, &pool->xsk_tx_list, tx_list) {
> + if (xs->cq_event)
> + sock_def_readable(&xs->sk);
> + }
> + rcu_read_unlock();
> }
> EXPORT_SYMBOL(xsk_tx_completed);
>
> @@ -495,6 +504,9 @@ static __poll_t xsk_poll(struct file *file, struct
> socket *sock,
> __xsk_sendmsg(sk);
> }
>
> + if (xs->cq_event && pool->cq && !xskq_prod_is_empty(pool->cq))
> + mask |= EPOLLIN | EPOLLRDNORM;
> +
> if (xs->rx && !xskq_prod_is_empty(xs->rx))
> mask |= EPOLLIN | EPOLLRDNORM;
> if (xs->tx && !xskq_cons_is_full(xs->tx))
> @@ -882,6 +894,22 @@ static int xsk_setsockopt(struct socket *sock, int
> level, int optname,
> mutex_unlock(&xs->mutex);
> return err;
> }
> + case XDP_CQ_EVENT:
> + {
> + int cq_event;
> +
> + if (optlen < sizeof(cq_event))
> + return -EINVAL;
> + if (copy_from_sockptr(&cq_event, optval, sizeof(cq_event)))
> + return -EFAULT;
> +
> + if (cq_event)
> + xs->cq_event = true;
> + else
> + xs->cq_event = false;
It's false by default, isn't it?
> +
> + return 0;
> + }
> default:
> break;
> }
> --
> 1.8.3.1
>
>
