• WANG Cong's avatar
    net_sched: kill u32_node pointer in Qdisc · 3cd904ec
    WANG Cong authored
    It is ugly to hide a u32-filter-specific pointer inside Qdisc,
    this breaks the TC layers:
    
    1. Qdisc is a generic representation, should not have any specific
       data of any type
    
    2. Qdisc layer is above filter layer, should only save filters in
       the list of struct tcf_proto.
    
    This pointer is used as the head of the chain of u32 hash tables,
    that is struct tc_u_hnode, because u32 filter is very special,
    it allows to create multiple hash tables within one qdisc and
    across multiple u32 filters.
    
    Instead of using this ugly pointer, we can just save it in a global
    hash table key'ed by (dev ifindex, qdisc handle), therefore we can
    still treat it as a per qdisc basis data structure conceptually.
    
    Of course, because of network namespaces, this key is not unique
    at all, but it is fine as we already have a pointer to Qdisc in
    struct tc_u_common, we can just compare the pointers when collision.
    
    And this only affects slow paths, has no impact to fast path,
    thanks to the pointer ->tp_c.
    
    Cc: Jamal Hadi Salim <jhs@mojatatu.com>
    Cc: Jiri Pirko <jiri@resnulli.us>
    Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
    Acked-by: default avatarJiri Pirko <jiri@mellanox.com>
    Acked-by: default avatarJamal Hadi Salim <jhs@mojatatu.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    3cd904ec
sch_generic.h 21.2 KB