mbox series

[bpf-next,0/3] make bpf_task_storage_busy being preemption-safe

Message ID 20220829142752.330094-1-houtao@huaweicloud.com (mailing list archive)
Headers show
Series make bpf_task_storage_busy being preemption-safe | expand

Message

Hou Tao Aug. 29, 2022, 2:27 p.m. UTC 
From: Hou Tao <houtao1@huawei.com>

Hi,

The patchset aims to make the update of bpf_task_storage_busy being
preemption-safe. The problem is on same architectures (e.g. arm64),
__this_cpu_{inc|dec|inc_return} are neither preemption-safe nor
IRQ-safe, so the concurrent lookups or updates on the same task local
storage and the same CPU may make bpf_task_storage_busy be imbalanced,
and bpf_task_storage_trylock() on specific cpu will always fail.

Patch 1 fixes the problem by using preemption/IRQ-safe per-cpu helpers.
And patch 2 & patch 3 add a test case for the problem. Comments are
always welcome.

Regards,
Tao

Hou Tao (3):
  bpf: Use this_cpu_{inc|dec|inc_return} for bpf_task_storage_busy
  selftests/bpf: Move sys_pidfd_open() into test_progs.h
  selftests/bpf: Test concurrent updates on bpf_task_storage_busy

 kernel/bpf/bpf_local_storage.c                |  4 +-
 kernel/bpf/bpf_task_storage.c                 |  8 +-
 .../bpf/prog_tests/task_local_storage.c       | 91 +++++++++++++++++++
 .../selftests/bpf/prog_tests/test_bprm_opts.c |  9 --
 .../bpf/prog_tests/test_local_storage.c       |  9 --
 tools/testing/selftests/bpf/test_progs.h      |  9 ++
 6 files changed, 106 insertions(+), 24 deletions(-)