netdev - [PATCH v5 bpf-next 0/5] bpf: Introduce minimal support for sleepable progs

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Message-Id: <20200630043343.53195-1-alexei.starovoitov@gmail.com>
Date:   Mon, 29 Jun 2020 21:33:38 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     davem@...emloft.net
Cc:     daniel@...earbox.net, paulmck@...nel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, kernel-team@...com
Subject: [PATCH v5 bpf-next 0/5] bpf: Introduce minimal support for sleepable progs

From: Alexei Starovoitov <ast@...nel.org>

v4->v5:
- addressed Andrii's feedback.

v3->v4:
- fixed synchronize_rcu_tasks_trace() usage and accelerated with synchronize_rcu_mult().
- removed redundant synchronize_rcu(). Otherwise it won't be clear why
  synchronize_rcu_tasks_trace() is not needed in free_map callbacks.
- improved test coverage.

v2->v3:
- switched to rcu_trace
- added bpf_copy_from_user

Here is 'perf report' differences:
sleepable with SRCU:
   3.86%  bench     [k] __srcu_read_unlock
   3.22%  bench     [k] __srcu_read_lock
   0.92%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep
   0.50%  bench     [k] bpf_trampoline_10297
   0.26%  bench     [k] __bpf_prog_exit_sleepable
   0.21%  bench     [k] __bpf_prog_enter_sleepable

sleepable with RCU_TRACE:
   0.79%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep
   0.72%  bench     [k] bpf_trampoline_10381
   0.31%  bench     [k] __bpf_prog_exit_sleepable
   0.29%  bench     [k] __bpf_prog_enter_sleepable

non-sleepable with RCU:
   0.88%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry
   0.84%  bench     [k] bpf_trampoline_10297
   0.13%  bench     [k] __bpf_prog_enter
   0.12%  bench     [k] __bpf_prog_exit

Happy to confirm that rcu_trace overhead is negligible.

v1->v2:
- split fmod_ret fix into separate patch
- added blacklist

v1:
This patch set introduces the minimal viable support for sleepable bpf programs.
In this patch only fentry/fexit/fmod_ret and lsm progs can be sleepable.
Only array and pre-allocated hash and lru maps allowed.

Alexei Starovoitov (5):
  bpf: Remove redundant synchronize_rcu.
  bpf: Introduce sleepable BPF programs
  bpf: Add bpf_copy_from_user() helper.
  libbpf: support sleepable progs
  selftests/bpf: Add sleepable tests

 arch/x86/net/bpf_jit_comp.c                   | 32 +++++----
 include/linux/bpf.h                           |  4 ++
 include/uapi/linux/bpf.h                      | 19 +++++-
 init/Kconfig                                  |  1 +
 kernel/bpf/arraymap.c                         | 10 +--
 kernel/bpf/hashtab.c                          | 20 +++---
 kernel/bpf/helpers.c                          | 22 +++++++
 kernel/bpf/lpm_trie.c                         |  5 --
 kernel/bpf/queue_stack_maps.c                 |  7 --
 kernel/bpf/reuseport_array.c                  |  2 -
 kernel/bpf/ringbuf.c                          |  7 --
 kernel/bpf/stackmap.c                         |  3 -
 kernel/bpf/syscall.c                          | 13 +++-
 kernel/bpf/trampoline.c                       | 28 +++++++-
 kernel/bpf/verifier.c                         | 62 ++++++++++++++++-
 kernel/trace/bpf_trace.c                      |  2 +
 tools/include/uapi/linux/bpf.h                | 19 +++++-
 tools/lib/bpf/libbpf.c                        | 25 ++++++-
 tools/testing/selftests/bpf/bench.c           |  2 +
 .../selftests/bpf/benchs/bench_trigger.c      | 17 +++++
 .../selftests/bpf/prog_tests/test_lsm.c       |  9 +++
 tools/testing/selftests/bpf/progs/lsm.c       | 66 ++++++++++++++++++-
 .../selftests/bpf/progs/trigger_bench.c       |  7 ++
 23 files changed, 315 insertions(+), 67 deletions(-)

-- 
2.23.0