[PATCH v4 0/1] lockdep: add support for queued rwlock

[Waiman Long]

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 addes code to the lockdep subsystem to catch this kind of
recursive read_lock calls in kernel code.

Waiman Long (1):
  lockdep: restrict the use of recursive read_lock with qrwlock

 include/linux/lockdep.h  |   12 ++++++++++++
 kernel/locking/lockdep.c |    6 ++++++
 2 files changed, 18 insertions(+), 0 deletions(-)

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