bpf: Remove redundant synchronize_rcu.

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bpf_free_used_maps() or close(map_fd) will trigger map_free callback.
bpf_free_used_maps() is called after bpf prog is no longer executing:
bpf_prog_put->call_rcu->bpf_prog_free->bpf_free_used_maps.
Hence there is no need to call synchronize_rcu() to protect map elements.

Note that hash_of_maps and array_of_maps update/delete inner maps via
sys_bpf() that calls maybe_wait_bpf_programs() and synchronize_rcu().

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/bpf/20200630043343.53195-2-alexei.starovoitov@gmail.com

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This commit is contained in:

Alexei Starovoitov 2020-06-29 21:33:39 -07:00

parent 8c18311067

commit bba1dc0b55

7 changed files with 3 additions and 38 deletions

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9

kernel/bpf/arraymap.c

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8

kernel/bpf/hashtab.c

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5

kernel/bpf/lpm_trie.c

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7

kernel/bpf/queue_stack_maps.c

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2

kernel/bpf/reuseport_array.c

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7

kernel/bpf/ringbuf.c

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3

kernel/bpf/stackmap.c

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