If we fail to write to a vnode during a ktrace write, then we drop all

other references to that vnode as a trace vnode in other processes as well
as in any pending requests on the todo list.  Thus, it is possible for a
ktrace request structure to have a NULL ktr_vp when it is destroyed in
ktr_freerequest().  We shouldn't call vrele() on the vnode in that case.

Reported by:	bde

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/kern/subr_taskqueue.c b/sys/kern/subr_taskqueue.c
index 19a93ad..28fbe38 100644
--- a/sys/kern/subr_taskqueue.c
+++ b/sys/kern/subr_taskqueue.c
@@ -94,6 +94,7 @@ taskqueue_free(struct taskqueue *queue)
 {
 
 	mtx_lock(&queue->tq_mutex);
+	KASSERT(queue->tq_draining == 0, ("free'ing a draining taskqueue"));
 	queue->tq_draining = 1;
 	mtx_unlock(&queue->tq_mutex);