[PATCH 00/14] Stop lockdep_assert_held*() from assuming lock ownership

[Bart Van Assche]

Hi Peter and Marco,

Since commit 7c451541743c ("lockdep: Annotate lockdep assertions for
context analysis"), lockdep_assert_held*() and lockdep_assert_in_rcu_*()
not only verify at runtime that a lock is held but also instruct Clang
context analysis to assume that the lock is held. This has the following
disadvantages:
- These assertions silence context analysis warnings in functions that
  lack a __must_hold*() annotation. Hence, the compiler neither reports
  the missing function annotation nor checks at compile time whether
  callers hold the lock.
- lockdep_assert_held() makes context analysis assume exclusive lock
  ownership, even if a reader-writer lock is held in shared mode.
- lockdep_assert_held*() can only be used with lock types that are
  defined with context_lock_struct().

This patch series removes the context assumptions from the lockdep and
RCU assertion macros and introduces separate macros for code that needs
to inform context analysis that a lock is held:
- lockdep_assume_ctx_held() and lockdep_assume_shared_ctx_held().
- lockdep_assume_in_rcu_read_lock(), lockdep_assume_in_rcu_read_lock_bh(),
  lockdep_assume_in_rcu_read_lock_sched() and
  lockdep_assume_in_rcu_reader().
Unlike the __assume_*() macros, which only inform context analysis, the
new lockdep_assume_*() macros also verify the assumption at runtime.

This patch series is organized as follows:
- Patches 1-4 fix issues in the existing context analysis support:
  __bitlock() operator precedence, false positives for __free() helpers,
  enabling WARN_CONTEXT_ANALYSIS_ALL for allmodconfig and allyesconfig
  builds, and a too strict SRCU reader requirement in
  srcu_dereference_check().
- Patches 5-7 add __must_hold*() annotations to functions that currently
  rely on lockdep_assert_held() for context analysis.
- Patch 8 introduces lockdep_assume_ctx_held() and
  lockdep_assume_shared_ctx_held().
- Patches 9-11 convert code that accesses locks through pointer aliases
  or that uses __assume_ctx_lock() to lockdep_assume_ctx_held().
- Patch 12 removes the context assumptions from lockdep_assert_held*().
- Patches 13-14 do the same for the RCU assertions and introduce the
  lockdep_assume_in_rcu_*() macros.

Please consider this patch series for the next merge window.

Thanks,

Bart.

Bart Van Assche (14):
  bit_spinlock: Fix the __bitlock() definition
  cleanup: Disable context analysis for __free() helpers
  tracing: Disable branch profiling for COMPILE_TEST builds
  srcu: Remove check from srcu_dereference_check()
  futex: Annotate __attach_to_pi_owner() and fixup_pi_*owner()
  locking/rwsem: Annotate rwsem internal functions with __must_hold()
  nvme-fabrics: Annotate nvmf_lookup_transport() with
    __must_hold_shared()
  lockdep: Introduce lockdep_assume_ctx_held()
  kfence: Use lockdep_assume_ctx_held() in kfence_report_error()
  Bluetooth: Add lock context annotations for connection aliases
  futex: Verify exit_mutex ownership in futex_exit_recursive()
  lockdep: Stop lockdep_assert_held*() from assuming lock ownership
  compiler-context-analysis: Split the RCU assertion tests
  rcu: Introduce lockdep_assume_in_rcu_*()

 Documentation/dev-tools/context-analysis.rst | 20 +++--
 drivers/nvme/host/fabrics.c                  |  1 +
 include/linux/bit_spinlock.h                 |  2 +-
 include/linux/cleanup.h                      |  6 +-
 include/linux/lockdep.h                      | 77 ++++++++++++++++--
 include/linux/rcupdate.h                     | 82 +++++++++++++++++---
 include/linux/srcu.h                         | 20 +++--
 kernel/futex/core.c                          |  2 +-
 kernel/futex/futex.h                         |  3 +-
 kernel/futex/pi.c                            |  3 +
 kernel/locking/rtmutex.c                     |  7 +-
 kernel/locking/rwsem.c                       |  3 +
 kernel/trace/Kconfig                         |  3 +-
 lib/test_context-analysis.c                  | 38 +++++++--
 mm/kfence/report.c                           |  2 +-
 net/bluetooth/6lowpan.c                      |  2 +-
 net/bluetooth/iso.c                          |  8 +-
 net/bluetooth/l2cap_core.c                   | 48 ++++++------
 net/bluetooth/mgmt.c                         |  2 +-
 net/bluetooth/smp.c                          |  2 +-
 20 files changed, 256 insertions(+), 75 deletions(-)