Re: [PATCH bpf-next v4 05/14] xsk: move queue_id, dev and need_wakeup to buffer pool

From: "Björn Töpel" <bjorn.topel@intel.com>
To: Magnus Karlsson <magnus.karlsson@intel.com>,
	ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org,
	jonathan.lemon@gmail.com, maximmi@mellanox.com
Cc: bpf@vger.kernel.org, jeffrey.t.kirsher@intel.com,
	anthony.l.nguyen@intel.com, maciej.fijalkowski@intel.com,
	maciejromanfijalkowski@gmail.com, cristian.dumitrescu@intel.com
Subject: Re: [PATCH bpf-next v4 05/14] xsk: move queue_id, dev and need_wakeup to buffer pool
Date: Tue, 28 Jul 2020 09:09:56 +0200	[thread overview]
Message-ID: <00afe3da-0d5e-18fe-b6cb-490faa3dd132@intel.com> (raw)
In-Reply-To: <1595307848-20719-6-git-send-email-magnus.karlsson@intel.com>

On 2020-07-21 07:03, Magnus Karlsson wrote:
> Move queue_id, dev, and need_wakeup from the umem to the
> buffer pool. This so that we in a later commit can share the umem
> between multiple HW queues. There is one buffer pool per dev and
> queue id, so these variables should belong to the buffer pool, not
> the umem. Need_wakeup is also something that is set on a per napi
> level, so there is usually one per device and queue id. So move
> this to the buffer pool too.
> 
> Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
> ---
>   include/net/xdp_sock.h      |  3 ---
>   include/net/xsk_buff_pool.h |  4 ++++
>   net/xdp/xdp_umem.c          | 19 +------------------
>   net/xdp/xdp_umem.h          |  4 ----
>   net/xdp/xsk.c               | 40 +++++++++++++++-------------------------
>   net/xdp/xsk_buff_pool.c     | 39 ++++++++++++++++++++++-----------------
>   net/xdp/xsk_diag.c          |  4 ++--
>   7 files changed, 44 insertions(+), 69 deletions(-)
> 
[...]
>   		}
> diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
> index 36287d2..436648a 100644
> --- a/net/xdp/xsk_buff_pool.c
> +++ b/net/xdp/xsk_buff_pool.c
> @@ -95,10 +95,9 @@ void xp_set_rxq_info(struct xsk_buff_pool *pool, struct xdp_rxq_info *rxq)
>   }
>   EXPORT_SYMBOL(xp_set_rxq_info);
>   
> -int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *dev,
> +int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *netdev,
>   		  u16 queue_id, u16 flags)
>   {
> -	struct xdp_umem *umem = pool->umem;
>   	bool force_zc, force_copy;
>   	struct netdev_bpf bpf;
>   	int err = 0;
> @@ -111,27 +110,30 @@ int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *dev,
>   	if (force_zc && force_copy)
>   		return -EINVAL;
>   
> -	if (xsk_get_pool_from_qid(dev, queue_id))
> +	if (xsk_get_pool_from_qid(netdev, queue_id))
>   		return -EBUSY;
>   
> -	err = xsk_reg_pool_at_qid(dev, pool, queue_id);
> +	err = xsk_reg_pool_at_qid(netdev, pool, queue_id);
>   	if (err)
>   		return err;
>   
>   	if (flags & XDP_USE_NEED_WAKEUP) {
> -		umem->flags |= XDP_UMEM_USES_NEED_WAKEUP;
> +		pool->uses_need_wakeup = true;
>   		/* Tx needs to be explicitly woken up the first time.
>   		 * Also for supporting drivers that do not implement this
>   		 * feature. They will always have to call sendto().
>   		 */
> -		umem->need_wakeup = XDP_WAKEUP_TX;
> +		pool->cached_need_wakeup = XDP_WAKEUP_TX;
>   	}
>   
> +	dev_hold(netdev);
> +

You have a reference leak here for the error case.

Björn