[PATCH v5 0/2] lockdep: add support for queued rwlock

[Waiman Long <Waiman.Long@hp.com>]

v4->v5:
 - Add patch 2 to update the locking selftest code to handle recursive
   read_lock correctly. Patch 1 has no change.

v3->v4:
 - Document the new read state and move the conditional compilation code
   to lockdep.h.

v2->v3:
 - Add a new read mode (3) for rwlock (used in
   lock_acquire_shared_cond_recursive()) to avoid conflict with other
   use cases of lock_acquire_shared_recursive().

v1->v2:
 - Use less conditional & make it easier to read

With the merging of qrwlock into 3.16, it was found that the btrfs
filesystem hanged readily. A fix was devised and merged into rc2 and
the use of recursive read_lock call was part of the problem.

This patch series addes code to the lockdep subsystem to catch this
kind of recursive read_lock calls in kernel code. It also updates
the locking selftest to handle recursive read_lock correctly so that
it won't complain about test failures whether or not queue rwlock
is configured.

Waiman Long (2):
  lockdep: restrict the use of recursive read_lock with qrwlock
  locking-selftest: Support queue rwlock

 include/linux/lockdep.h  |   12 ++++++++++++
 kernel/locking/lockdep.c |    6 ++++++
 lib/locking-selftest.c   |   16 +++++++++++++---
 3 files changed, 31 insertions(+), 3 deletions(-)