locking: Add rwsem_assert_held() and rwsem_assert_held_write()

Modelled after lockdep_assert_held() and lockdep_assert_held_write(),
but are always active, even when lockdep is disabled.  Of course, they
don't test that _this_ thread is the owner, but it's sufficient to catch
many bugs and doesn't incur the same performance penalty as lockdep.

Acked-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/include/linux/rwbase_rt.h b/include/linux/rwbase_rt.h
index 1d264dd08625..29c4e4f243e4 100644
--- a/include/linux/rwbase_rt.h
+++ b/include/linux/rwbase_rt.h
@@ -26,12 +26,17 @@ struct rwbase_rt {
 	} while (0)
 
 
-static __always_inline bool rw_base_is_locked(struct rwbase_rt *rwb)
+static __always_inline bool rw_base_is_locked(const struct rwbase_rt *rwb)
 {
 	return atomic_read(&rwb->readers) != READER_BIAS;
 }
 
-static __always_inline bool rw_base_is_contended(struct rwbase_rt *rwb)
+static inline void rw_base_assert_held_write(const struct rwbase_rt *rwb)
+{
+	WARN_ON(atomic_read(&rwb->readers) != WRITER_BIAS);
+}
+
+static __always_inline bool rw_base_is_contended(const struct rwbase_rt *rwb)
 {
 	return atomic_read(&rwb->readers) > 0;
 }