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Message-ID: <f6b54e3c-a4e6-afc1-86cc-48a19a1c7372@intel.com>
Date: Tue, 28 Jul 2020 09:15:27 +0200
From: Björn Töpel <bjorn.topel@...el.com>
To: Magnus Karlsson <magnus.karlsson@...el.com>, ast@...nel.org,
daniel@...earbox.net, netdev@...r.kernel.org,
jonathan.lemon@...il.com, maximmi@...lanox.com
Cc: bpf@...r.kernel.org, jeffrey.t.kirsher@...el.com,
anthony.l.nguyen@...el.com, maciej.fijalkowski@...el.com,
maciejromanfijalkowski@...il.com, cristian.dumitrescu@...el.com
Subject: Re: [PATCH bpf-next v4 10/14] xsk: add shared umem support between
queue ids
On 2020-07-21 07:04, Magnus Karlsson wrote:
> Add support to share a umem between queue ids on the same
> device. This mode can be invoked with the XDP_SHARED_UMEM bind
> flag. Previously, sharing was only supported within the same
> queue id and device, and you shared one set of fill and
> completion rings. However, note that when sharing a umem between
> queue ids, you need to create a fill ring and a completion ring
> and tie them to the socket before you do the bind with the
> XDP_SHARED_UMEM flag. This so that the single-producer
> single-consumer semantics can be upheld.
>
> Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>
Acked-by: Björn Töpel <bjorn.topel@...el.com>
> ---
> include/net/xsk_buff_pool.h | 2 ++
> net/xdp/xsk.c | 44 ++++++++++++++++++++++++++++++--------------
> net/xdp/xsk_buff_pool.c | 26 ++++++++++++++++++++++++--
> 3 files changed, 56 insertions(+), 16 deletions(-)
>
> diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
> index b4d6307..4d699dd 100644
> --- a/include/net/xsk_buff_pool.h
> +++ b/include/net/xsk_buff_pool.h
> @@ -75,6 +75,8 @@ struct xsk_buff_pool *xp_create_and_assign_umem(struct xdp_sock *xs,
> struct xdp_umem *umem);
> int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *dev,
> u16 queue_id, u16 flags);
> +int xp_assign_dev_shared(struct xsk_buff_pool *pool, struct xdp_umem *umem,
> + struct net_device *dev, u16 queue_id);
> void xp_destroy(struct xsk_buff_pool *pool);
> void xp_release(struct xdp_buff_xsk *xskb);
> void xp_get_pool(struct xsk_buff_pool *pool);
> diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
> index d0ff5e8..e897755 100644
> --- a/net/xdp/xsk.c
> +++ b/net/xdp/xsk.c
> @@ -689,12 +689,6 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
> goto out_unlock;
> }
>
> - if (xs->fq_tmp || xs->cq_tmp) {
> - /* Do not allow setting your own fq or cq. */
> - err = -EINVAL;
> - goto out_unlock;
> - }
> -
> sock = xsk_lookup_xsk_from_fd(sxdp->sxdp_shared_umem_fd);
> if (IS_ERR(sock)) {
> err = PTR_ERR(sock);
> @@ -707,15 +701,41 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
> sockfd_put(sock);
> goto out_unlock;
> }
> - if (umem_xs->dev != dev || umem_xs->queue_id != qid) {
> + if (umem_xs->dev != dev) {
> err = -EINVAL;
> sockfd_put(sock);
> goto out_unlock;
> }
>
> - /* Share the buffer pool with the other socket. */
> - xp_get_pool(umem_xs->pool);
> - xs->pool = umem_xs->pool;
> + if (umem_xs->queue_id != qid) {
> + /* Share the umem with another socket on another qid */
> + xs->pool = xp_create_and_assign_umem(xs,
> + umem_xs->umem);
> + if (!xs->pool) {
> + sockfd_put(sock);
> + goto out_unlock;
> + }
> +
> + err = xp_assign_dev_shared(xs->pool, umem_xs->umem,
> + dev, qid);
> + if (err) {
> + xp_destroy(xs->pool);
> + sockfd_put(sock);
> + goto out_unlock;
> + }
> + } else {
> + /* Share the buffer pool with the other socket. */
> + if (xs->fq_tmp || xs->cq_tmp) {
> + /* Do not allow setting your own fq or cq. */
> + err = -EINVAL;
> + sockfd_put(sock);
> + goto out_unlock;
> + }
> +
> + xp_get_pool(umem_xs->pool);
> + xs->pool = umem_xs->pool;
> + }
> +
> xdp_get_umem(umem_xs->umem);
> WRITE_ONCE(xs->umem, umem_xs->umem);
> sockfd_put(sock);
> @@ -847,10 +867,6 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
> mutex_unlock(&xs->mutex);
> return -EBUSY;
> }
> - if (!xs->umem) {
> - mutex_unlock(&xs->mutex);
> - return -EINVAL;
> - }
>
> q = (optname == XDP_UMEM_FILL_RING) ? &xs->fq_tmp :
> &xs->cq_tmp;
> diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
> index ca74a3e..688dc36 100644
> --- a/net/xdp/xsk_buff_pool.c
> +++ b/net/xdp/xsk_buff_pool.c
> @@ -123,8 +123,8 @@ static void xp_disable_drv_zc(struct xsk_buff_pool *pool)
> }
> }
>
> -int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *netdev,
> - u16 queue_id, u16 flags)
> +static int __xp_assign_dev(struct xsk_buff_pool *pool,
> + struct net_device *netdev, u16 queue_id, u16 flags)
> {
> bool force_zc, force_copy;
> struct netdev_bpf bpf;
> @@ -193,6 +193,28 @@ int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *netdev,
> return err;
> }
>
> +int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *dev,
> + u16 queue_id, u16 flags)
> +{
> + return __xp_assign_dev(pool, dev, queue_id, flags);
> +}
> +
> +int xp_assign_dev_shared(struct xsk_buff_pool *pool, struct xdp_umem *umem,
> + struct net_device *dev, u16 queue_id)
> +{
> + u16 flags;
> +
> + /* One fill and completion ring required for each queue id. */
> + if (!pool->fq || !pool->cq)
> + return -EINVAL;
> +
> + flags = umem->zc ? XDP_ZEROCOPY : XDP_COPY;
> + if (pool->uses_need_wakeup)
> + flags |= XDP_USE_NEED_WAKEUP;
> +
> + return __xp_assign_dev(pool, dev, queue_id, flags);
> +}
> +
> void xp_clear_dev(struct xsk_buff_pool *pool)
> {
> if (!pool->netdev)
>
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