• Vlad Buslov's avatar
    net: sched: refactor block offloads counter usage · 40119211
    Vlad Buslov authored
    Without rtnl lock protection filters can no longer safely manage block
    offloads counter themselves. Refactor cls API to protect block offloadcnt
    with tcf_block->cb_lock that is already used to protect driver callback
    list and nooffloaddevcnt counter. The counter can be modified by concurrent
    tasks by new functions that execute block callbacks (which is safe with
    previous patch that changed its type to atomic_t), however, block
    bind/unbind code that checks the counter value takes cb_lock in write mode
    to exclude any concurrent modifications. This approach prevents race
    conditions between bind/unbind and callback execution code but allows for
    concurrency for tc rule update path.
    
    Move block offload counter, filter in hardware counter and filter flags
    management from classifiers into cls hardware offloads API. Make functions
    tcf_block_offload_{inc|dec}() and tc_cls_offload_cnt_update() to be cls API
    private. Implement following new cls API to be used instead:
    
      tc_setup_cb_add() - non-destructive filter add. If filter that wasn't
      already in hardware is successfully offloaded, increment block offloads
      counter, set filter in hardware counter and flag. On failure, previously
      offloaded filter is considered to be intact and offloads counter is not
      decremented.
    
      tc_setup_cb_replace() - destructive filter replace. Release existing
      filter block offload counter and reset its in hardware counter and flag.
      Set new filter in hardware counter and flag. On failure, previously
      offloaded filter is considered to be destroyed and offload counter is
      decremented.
    
      tc_setup_cb_destroy() - filter destroy. Unconditionally decrement block
      offloads counter.
    
      tc_setup_cb_reoffload() - reoffload filter to single cb. Execute cb() and
      call tc_cls_offload_cnt_update() if cb() didn't return an error.
    
    Refactor all offload-capable classifiers to atomically offload filters to
    hardware, change block offload counter, and set filter in hardware counter
    and flag by means of the new cls API functions.
    Signed-off-by: default avatarVlad Buslov <vladbu@mellanox.com>
    Acked-by: default avatarJiri Pirko <jiri@mellanox.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    40119211
sch_generic.h 31.4 KB