- Assert for not leaking readers rw locks counter on userland return.

- Use a correct spin_cnt for KDTRACE_HOOK case in rw read lock.

Sponsored by:	EMC / Isilon storage division

sys/kern/kern_rwlock.c

@@ -440,6 +440,9 @@ __rw_rlock(volatile uintptr_t *c, const char *file, int line)
 					break;
 				cpu_spinwait();
 			}
+#ifdef KDTRACE_HOOKS
+			spin_cnt += rowner_loops - i;
+#endif
 			if (i != rowner_loops)
 				continue;
 		}

sys/kern/subr_trap.c

@@ -152,6 +152,9 @@ userret(struct thread *td, struct trapframe *frame)
 	    ("userret: Returning in a critical section"));
 	KASSERT(td->td_locks == 0,
 	    ("userret: Returning with %d locks held", td->td_locks));
+	KASSERT(td->td_rw_rlocks == 0,
+	    ("userret: Returning with %d rwlocks held in read mode",
+	    td->td_rw_rlocks));
 	KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
 	    ("userret: Returning with pagefaults disabled"));
 	KASSERT(td->td_no_sleeping == 0,