v2 of the capacity-rollback fix was correct for bpf_stream_push_str(),
but review asked to:

1. refactor bpf_stream_release_capacity() to take a length;
2. fix the staging-path capacity leak and use vscnprintf();
3. return partial bpf_stream_read() progress on copy_to_user() fault;
4. reject truncated bpf_stream_vprintk() output with -E2BIG before
   charging capacity;
5. add selftests for the oversize and straddling-buffer cases.

This series addresses those points.

Tested locally:
  stream_oversize and stream_partial_read (equivalent to
  ./test_progs -t stream_oversize,stream_partial_read).

v2: https://lore.kernel.org/bpf/tencent_C919BB32458A4DAD645A68F441345B971E05@qq.com/
v1: https://lore.kernel.org/bpf/tencent_E69EAE29327E25B3548A9AF3F4FA289A6806@qq.com/

Jianlin Shi (5):
  bpf: roll back stream capacity when allocation fails
  bpf: fix stream capacity leak in staging path
  bpf: return partial progress from bpf_stream_read on fault
  bpf: reject oversized bpf_stream_vprintk output with -E2BIG
  selftests/bpf: cover stream capacity and partial read edge cases

 kernel/bpf/stream.c                           | 54 ++++++++------
 .../testing/selftests/bpf/prog_tests/stream.c | 70 +++++++++++++++++++
 tools/testing/selftests/bpf/progs/stream.c    | 12 ++++
 3 files changed, 116 insertions(+), 20 deletions(-)

-- 
2.43.0