net_sched: remove tcf_block_put_deferred()

In commit 7aa0045dadb6 ("net_sched: introduce a workqueue for RCU callbacks of tc filter")
I defer tcf_chain_flush() to a workqueue, this causes a use-after-free
because qdisc is already destroyed after we queue this work.

The tcf_block_put_deferred() is no longer necessary after we get RTNL
for each tc filter destroy work, no others could jump in at this point.
Same for tcf_chain_hold(), we are fully serialized now.

This also reduces one indirection therefore makes the code more
readable. Note this brings back a rcu_barrier(), however comparing
to the code prior to commit 7aa0045dadb6 we still reduced one
rcu_barrier(). For net-next, we can consider to refcnt tcf block to
avoid it.

Fixes: 7aa0045dadb6 ("net_sched: introduce a workqueue for RCU callbacks of tc filter")
Cc: Daniel Borkmann <[email protected]>
Cc: Jiri Pirko <[email protected]>
Cc: John Fastabend <[email protected]>
Cc: Jamal Hadi Salim <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

0 files changed, 0 insertions, 0 deletions