tree 348cff60f15f3282e5489fba4dfd46b6c958e533
parent 3816199506c7826983096fc65ed46f2733a47bb8
author Peter Zijlstra <peterz@infradead.org> 1480476745 +1100
committer Dave Chinner <david@fromorbit.com> 1480476745 +1100

locking/lockdep: Provide a type check for lock_is_held

Christoph requested lockdep_assert_held() variants that distinguish
between held-for-read or held-for-write.

Provide:

  int lock_is_held_type(struct lockdep_map *lock, int read)

which takes the same argument as lock_acquire(.read) and matches it to
the held_lock instance.

Use of this function should be gated by the debug_locks variable. When
that is 0 the return value of the lock_is_held_type() function is
undefined. This is done to allow both negative and positive tests for
holding locks.

By default we provide (positive) lockdep_assert_held{,_exclusive,_read}()
macros.

Requested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>