flow indr dev offload

驱动加载的时候会调用
flow_indr_dev_register(mlx5e_rep_indr_setup_cb, rpriv)
这样就把数据结构struct flow_indr_dev放到链表flow_block_indr_dev_list中。

*(struct flow_indr_dev *)0xffff9230d9b07240 = {

        .list = (struct list_head){

                .next = (struct list_head *)flow_block_indr_dev_list+0x0 = 0xffffffffbdab9d10,
                .prev = (struct list_head *)flow_block_indr_dev_list+0x0 = 0xffffffffbdab9d10,
        },
        .cb = (flow_indr_block_bind_cb_t *)mlx5e_rep_indr_setup_cb+0x0 = 0xffffffffc05878a0,
        .cb_priv = (void *)0xffff9230ddbf2800,
        .refcnt = (refcount_t){

                .refs = (atomic_t){

                        .counter = (int)1,
                },
        },
}

这样的话，在创建vxlan设备qdisc的时候就会调到

flow_indr_dev_setup_offload        <- 遍历flow_block_indr_dev_list
    mlx5e_rep_indr_setup_cb
        mlx5e_rep_indr_setup_block

14.40499 24260   24260   tc              mlx5e_rep_indr_setup_block
        b’mlx5e_rep_indr_setup_block+0x1 [mlx5_core]’
        b’flow_indr_dev_setup_offload+0x6a [kernel]’
        b’tcf_block_offload_cmd.isra.0+0xf7 [kernel]’
        b’tcf_block_get_ext+0x150 [kernel]’
        b’ingress_init+0x75 [sch_ingress]’
        b’qdisc_create+0x18f [kernel]’
        b’tc_modify_qdisc+0x14d [kernel]’
        b’rtnetlink_rcv_msg+0x184 [kernel]’
        b’netlink_rcv_skb+0x55 [kernel]’
        b’rtnetlink_rcv+0x15 [kernel]’
        b’netlink_unicast+0x24f [kernel]’
        b’netlink_sendmsg+0x233 [kernel]’
        b’sock_sendmsg+0x65 [kernel]’
    
然后分配
*(struct flow_block_cb *)0xffff92295ee5fe00 = {

        .driver_list = (struct list_head){

                .next = (struct list_head *)mlx5e_block_cb_list+0x0 = 0xffffffffc062aff0,
                .prev = (struct list_head *)mlx5e_block_cb_list+0x0 = 0xffffffffc062aff0,
        },
        .list = (struct list_head){

                .next = (struct list_head *)0xffff9230ccd7b178,
                .prev = (struct list_head *)0xffff9230ccd7b178,
        },
        .cb = (flow_setup_cb_t *)mlx5e_setup_tc_block_cb+0x0 = 0xffffffffc05869d0,
        .cb_ident = (void *)0xffff9230cfbe0cc0,
        .cb_priv = (void *)0xffff9230cfbe0cc0,
        .release = (void (*)(void *))0x0,
        .indr = (struct flow_block_indr){

                .list = (struct list_head){

                        .next = (struct list_head *)0x0,
                        .prev = (struct list_head *)0x0,
                },
                .dev = (struct net_device *)0x0,
                .sch = (struct Qdisc *)0x0,
                .binder_type = (enum flow_block_binder_type)FLOW_BLOCK_BINDER_TYPE_UNSPEC,
                .data = (void *)0x0,
                .cb_priv = (void *)0x0,
                .cleanup = (void (*)(struct flow_block_cb *))0x0,
        },
        .refcnt = (unsigned int)0,
}

下流表的时候，mlx5e_rep_indr_setup_tc_cb/mlx5e_configure_flower就会被掉到

5.822219 23244   23244   tc              mlx5e_rep_indr_setup_tc_cb
        b’mlx5e_rep_indr_setup_tc_cb+0x1 [mlx5_core]’
        b’fl_hw_replace_filter+0x184 [cls_flower]’
        b’fl_change+0x6ee [cls_flower]’
        b’tc_new_tfilter+0x68f [kernel]’
        b’rtnetlink_rcv_msg+0x33d [kernel]’
        b’netlink_rcv_skb+0x55 [kernel]’
        b’rtnetlink_rcv+0x15 [kernel]’
        b’netlink_unicast+0x24f [kernel]’
        b’netlink_sendmsg+0x233 [kernel]’
        
但是这样有一个bug，如果先创建vxlan设备，再加载驱动，驱动就调不到了。
所以有下面这个fix：

commit 74fc4f828769cca1c3be89ea92cb88feaa27ef52
Author: Eli Cohen <elic@nvidia.com>
Date:   Tue Aug 17 20:05:18 2021 +0300

    net: Fix offloading indirect devices dependency on qdisc order creation

    Currently, when creating an ingress qdisc on an indirect device before
    the driver registered for callbacks, the driver will not have a chance
    to register its filter configuration callbacks.

    To fix that, modify the code such that it keeps track of all the ingress
    qdiscs that call flow_indr_dev_setup_offload(). When a driver calls
    flow_indr_dev_register(),  go through the list of tracked ingress qdiscs
    and call the driver callback entry point so as to give it a chance to
    register its callback.

    Reviewed-by: Jiri Pirko <jiri@nvidia.com>
    Signed-off-by: Eli Cohen <elic@nvidia.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    
改commit引入了一个新链表flow_indir_dev_list，保存了所有indr dev，例如：
(char [16])”vxlan1″
(char [16])”br”
(char [16])”br”
(char [16])”ovs-system”
(char [16])”ovs-system”

这样驱动在加载的时候，会调用existing_qdiscs_register，然后遍历链表flow_indir_dev_list，
调用flow_indr_dev_setup_offload。

今天的文章flow indr dev offload分享到此就结束了，感谢您的阅读，如果确实帮到您，您可以动动手指转发给其他人。