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Date: Tue, 13 Jan 2015 16:12:34 +0100
From: Daniel Borkmann <dborkman@...hat.com>
To: John Fastabend <john.fastabend@...il.com>
CC: netdev@...r.kernel.org, danny.zhou@...el.com,
nhorman@...driver.com, john.ronciak@...el.com,
hannes@...essinduktion.org, brouer@...hat.com
Subject: Re: [RFC PATCH v2 1/2] net: af_packet support for direct ring access
in user space
On 01/13/2015 05:35 AM, John Fastabend wrote:
...
> struct net_device_ops {
> int (*ndo_init)(struct net_device *dev);
> @@ -1190,6 +1240,35 @@ struct net_device_ops {
> int (*ndo_switch_port_stp_update)(struct net_device *dev,
> u8 state);
> #endif
> + int (*ndo_split_queue_pairs)(struct net_device *dev,
> + unsigned int qpairs_start_from,
> + unsigned int qpairs_num,
> + struct sock *sk);
...
> + int (*ndo_get_dma_region_info)
> + (struct net_device *dev,
> + struct tpacket_dma_mem_region *region,
> + struct sock *sk);
> };
Any slight chance these 8 ndo ops could be further reduced? ;)
> /**
> diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h
> index da2d668..eb7a727 100644
> --- a/include/uapi/linux/if_packet.h
> +++ b/include/uapi/linux/if_packet.h
...
> +struct tpacket_dev_qpair_map_region_info {
> + unsigned int tp_dev_bar_sz; /* size of BAR */
> + unsigned int tp_dev_sysm_sz; /* size of systerm memory */
> + /* number of contiguous memory on BAR mapping to user space */
> + unsigned int tp_num_map_regions;
> + /* number of contiguous memory on system mapping to user apce */
> + unsigned int tp_num_sysm_map_regions;
> + struct map_page_region {
> + unsigned page_offset; /* offset to start of region */
> + unsigned page_sz; /* size of page */
> + unsigned page_cnt; /* number of pages */
Please use unsigned int et al, or preferably __u* variants consistently
in the uapi structs.
> + } tp_regions[MAX_MAP_MEMORY_REGIONS];
> +};
...
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> index 6880f34..8cd17da 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
...
> @@ -2633,6 +2636,16 @@ static int packet_release(struct socket *sock)
> sock_prot_inuse_add(net, sk->sk_prot, -1);
> preempt_enable();
>
> + if (po->tp_owns_queue_pairs) {
> + struct net_device *dev;
> +
> + dev = __dev_get_by_index(sock_net(sk), po->ifindex);
> + if (dev) {
> + dev->netdev_ops->ndo_return_queue_pairs(dev, sk);
> + umem_release(dev, po);
> + }
> + }
> +
...
> +static int
> packet_setsockopt(struct socket *sock, int level, int optname, char __user *optval, unsigned int optlen)
> {
> struct sock *sk = sock->sk;
> @@ -3428,6 +3525,167 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
> po->xmit = val ? packet_direct_xmit : dev_queue_xmit;
> return 0;
> }
> + case PACKET_RXTX_QPAIRS_SPLIT:
> + {
...
> + /* This call only works after a bind call which calls a dev_hold
> + * operation so we do not need to increment dev ref counter
> + */
> + dev = __dev_get_by_index(sock_net(sk), po->ifindex);
> + if (!dev)
> + return -EINVAL;
> + ops = dev->netdev_ops;
> + if (!ops->ndo_split_queue_pairs)
> + return -EOPNOTSUPP;
> +
> + err = ops->ndo_split_queue_pairs(dev,
> + qpairs.tp_qpairs_start_from,
> + qpairs.tp_qpairs_num, sk);
> + if (!err)
> + po->tp_owns_queue_pairs = true;
When this is being set here, above test in packet_release() and the chunk
quoted below in packet_mmap() are not guaranteed to work since we don't
test if some ndos are actually implemented by the driver. Seems a bit
fragile, I'm wondering if we should test this capability as a _whole_,
iow if all necessary functions to make this work are being provided by the
driver, e.g. flag the netdev as such and test for that instead.
> + return err;
> + }
> + case PACKET_RXTX_QPAIRS_RETURN:
> + {
...
> + dev = __dev_get_by_index(sock_net(sk), po->ifindex);
> + if (!dev)
> + return -EINVAL;
> + ops = dev->netdev_ops;
> + if (!ops->ndo_split_queue_pairs)
> + return -EOPNOTSUPP;
Should test for ndo_return_queue_pairs.
> + err = dev->netdev_ops->ndo_return_queue_pairs(dev, sk);
> + if (!err)
> + po->tp_owns_queue_pairs = false;
> +
...
> + case PACKET_RXTX_QPAIRS_SPLIT:
> + {
...
> + /* This call only work after a bind call which calls a dev_hold
> + * operation so we do not need to increment dev ref counter
> + */
> + dev = __dev_get_by_index(sock_net(sk), po->ifindex);
> + if (!dev)
> + return -EINVAL;
> + if (!dev->netdev_ops->ndo_split_queue_pairs)
> + return -EOPNOTSUPP;
Copy-paste (although not quite, since here's no extra ops var). :)
Should be ndo_get_split_queue_pairs.
> + err = dev->netdev_ops->ndo_get_split_queue_pairs(dev,
> + &qpairs_info.tp_qpairs_start_from,
> + &qpairs_info.tp_qpairs_num, sk);
> +
...
> @@ -3927,8 +4309,20 @@ static int packet_mmap(struct file *file, struct socket *sock,
> if (vma->vm_pgoff)
> return -EINVAL;
>
> + dev = __dev_get_by_index(sock_net(sk), po->ifindex);
> + if (!dev)
> + return -EINVAL;
> +
> mutex_lock(&po->pg_vec_lock);
>
> + if (po->tp_owns_queue_pairs) {
> + ops = dev->netdev_ops;
> + err = ops->ndo_direct_qpair_page_map(vma, dev);
> + if (err)
> + goto out;
> + goto done;
> + }
> +
--
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