[PATCH 0/2] selftests/bpf: make probe_user safe for parallel runs

[Sun Jian <sun.jian.kdev@gmail.com>]

The probe_user selftest attaches ksyscall hooks for connect() (and
socketcall() on s390). Historically this could corrupt other tests
calling connect(), which is why the test was marked as serial and
carried a TODO warning about cross-test corruption.

This series makes the test safe for parallel execution by filtering the
BPF-side instrumentation to the current test process only, and then
drops the serial restriction and the stale TODO comment.

Patch 1/2 adds a single-entry pid_map and checks current tgid (process
ID) before calling bpf_probe_read_user()/bpf_probe_write_user(). The
userspace test writes its PID into the map after loading the object.

Patch 2/2 drops the serial_ prefix and removes the outdated TODO, since
cross-test interference is no longer possible.

Tested on x86_64 (clang):
  ./test_progs -t probe_user -v
  ./test_progs -j$(nproc) -t probe_user

Sun Jian (2):
  selftests/bpf: probe_user: filter by pid to avoid cross-test
    interference
  selftests/bpf: probe_user: drop serial restriction

 .../selftests/bpf/prog_tests/probe_user.c     | 16 +++++++++++---
 .../selftests/bpf/progs/test_probe_user.c     | 22 +++++++++++++++++++
 2 files changed, 35 insertions(+), 3 deletions(-)


base-commit: 7dff99b354601dd01829e1511711846e04340a69
-- 
2.43.0