xdp: Simplify cpumap cleanup

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After the RCU flavor consolidation [1], call_rcu() and
synchronize_rcu() waits for preempt-disable regions (NAPI) in addition
to the read-side critical sections. As a result of this, the cleanup
code in cpumap can be simplified

* There is no longer a need to flush in __cpu_map_entry_free, since we
  know that this has been done when the call_rcu() callback is
  triggered.

* When freeing the map, there is no need to explicitly wait for a
  flush. It's guaranteed to be done after the synchronize_rcu() call
  in cpu_map_free().

[1] https://lwn.net/Articles/777036/

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20191219061006.21980-3-bjorn.topel@gmail.com

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Björn Töpel 2019-12-19 07:10:00 +01:00 • committed by Alexei Starovoitov

parent 0536b85239

commit 4bc188c7f2

1 changed files with 5 additions and 29 deletions

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kernel/bpf/cpumap.c

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