--- //depot/vendor/freebsd/src/sys/kern/subr_sleepqueue.c	2007/06/12 23:32:21
+++ //depot/user/attilio/attilio_smpng/kern/subr_sleepqueue.c	2007/09/11 15:43:42
@@ -328,6 +328,7 @@
 		MPASS((flags & SLEEPQ_TYPE) == sq->sq_type);
 		LIST_INSERT_HEAD(&sq->sq_free, td->td_sleepqueue, sq_hash);
 	}
+	thread_lock(td);
 	TAILQ_INSERT_TAIL(&sq->sq_blocked[queue], td, td_slpq);
 	td->td_sleepqueue = NULL;
 	td->td_sqqueue = queue;
@@ -337,6 +338,7 @@
 		td->td_flags |= TDF_SINTR;
 		td->td_flags &= ~TDF_SLEEPABORT;
 	}
+	thread_unlock(td);
 }
 
 /*