only one cosmetic nit...

On 01/22, Srivatsa S. Bhat wrote:

+#define READER_PRESENT		(1UL << 16)
+#define READER_REFCNT_MASK	(READER_PRESENT - 1)
+
 #define reader_uses_percpu_refcnt(pcpu_rwlock, cpu)			\
 		(ACCESS_ONCE(per_cpu(*((pcpu_rwlock)->reader_refcnt), cpu)))

 #define reader_nested_percpu(pcpu_rwlock)				\
-			(__this_cpu_read(*((pcpu_rwlock)->reader_refcnt)) > 1)
+	(__this_cpu_read(*((pcpu_rwlock)->reader_refcnt)) & READER_REFCNT_MASK)

 #define writer_active(pcpu_rwlock)					\
 			(__this_cpu_read(*((pcpu_rwlock)->writer_signal)))

I think this all can go to lib/percpu-rwlock.c. Nobody needs to know
these implementation details.

Oleg.