From 2ba043d04468261cc767a3b91cec6df4b2238950 Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Sat, 11 Jul 2015 13:27:58 +0200
Subject: kern: make sure the queue macros are only used on queues

This turns mistakes as the one corrected in e59f05e9 into compile-time
errors.

* kern/queue.h: Add a new macro, queue_assert, and use it to assert
that all arguments given to the queue macros have the correct type.
* device/net_io.c (ENQUEUE_DEAD): Adapt to the fact that
`queue_next(q)' is no longer an lvalue.
---
 device/net_io.c |  2 +-
 kern/queue.h    | 31 ++++++++++++++++++++++++++-----
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/device/net_io.c b/device/net_io.c
index d2928cc..47ef2ea 100644
--- a/device/net_io.c
+++ b/device/net_io.c
@@ -353,7 +353,7 @@ decl_simple_lock_data(,net_hash_header_lock)
 
 /* entry_p must be net_rcv_port_t or net_hash_entry_t */
 #define ENQUEUE_DEAD(dead, entry_p, chain) {			\
-	queue_next(&(entry_p)->chain) = (queue_entry_t) (dead);	\
+	(entry_p)->chain.next = (queue_entry_t) (dead);		\
 	(dead) = (queue_entry_t)(entry_p);			\
 }
 
diff --git a/kern/queue.h b/kern/queue.h
index 518084d..f0b4002 100644
--- a/kern/queue.h
+++ b/kern/queue.h
@@ -86,6 +86,14 @@ queue_entry_t	dequeue_tail(queue_t);
 void		remqueue(queue_t, queue_entry_t);
 void		insque(queue_entry_t, queue_entry_t);
 
+/*
+ *	Macro:		queue_assert
+ *	Function:
+ *		Used by macros to assert that the given argument is a
+ *		queue.
+ */
+#define queue_assert(q)	(void) ((void) (q)->next, (q)->prev)
+
 /*
  *	Macro:		queue_init
  *	Function:
@@ -104,7 +112,7 @@ void		insque(queue_entry_t, queue_entry_t);
  *		queue_entry_t queue_first(q)
  *			queue_t	q;		*IN*
  */
-#define	queue_first(q)	((q)->next)
+#define	queue_first(q)	(queue_assert(q), (q)->next)
 
 /*
  *	Macro:		queue_next
@@ -114,7 +122,7 @@ void		insque(queue_entry_t, queue_entry_t);
  *		queue_entry_t queue_next(qc)
  *			queue_t qc;
  */
-#define	queue_next(qc)	((qc)->next)
+#define	queue_next(qc)	(queue_assert(qc), (qc)->next)
 
 /*
  *	Macro:		queue_last
@@ -124,7 +132,7 @@ void		insque(queue_entry_t, queue_entry_t);
  *		queue_entry_t queue_last(q)
  *			queue_t	q;		 *IN*
  */
-#define	queue_last(q)	((q)->prev)
+#define	queue_last(q)	(queue_assert(q), (q)->prev)
 
 /*
  *	Macro:		queue_prev
@@ -134,7 +142,7 @@ void		insque(queue_entry_t, queue_entry_t);
  *		queue_entry_t queue_prev(qc)
  *			queue_t qc;
  */
-#define	queue_prev(qc)	((qc)->prev)
+#define	queue_prev(qc)	(queue_assert(qc), (qc)->prev)
 
 /*
  *	Macro:		queue_end
@@ -146,7 +154,8 @@ void		insque(queue_entry_t, queue_entry_t);
  *			queue_t q;
  *			queue_entry_t qe;
  */
-#define	queue_end(q, qe)	((q) == (qe))
+#define	queue_end(q, qe)	(queue_assert(q), queue_assert(qe), \
+				 (q) == (qe))
 
 /*
  *	Macro:		queue_empty
@@ -179,6 +188,8 @@ void		insque(queue_entry_t, queue_entry_t);
  */
 #define queue_enter(head, elt, type, field)			\
 { 								\
+	queue_assert(head);					\
+	queue_assert(&(elt)->field);				\
 	queue_entry_t prev;					\
 								\
 	prev = (head)->prev;					\
@@ -206,6 +217,8 @@ void		insque(queue_entry_t, queue_entry_t);
  */
 #define queue_enter_first(head, elt, type, field)		\
 { 								\
+	queue_assert(head);					\
+	queue_assert(&(elt)->field);				\
 	queue_entry_t next;					\
 								\
 	next = (head)->next;					\
@@ -239,6 +252,8 @@ void		insque(queue_entry_t, queue_entry_t);
  */
 #define	queue_remove(head, elt, type, field)			\
 {								\
+	queue_assert(head);					\
+	queue_assert(&(elt)->field);				\
 	queue_entry_t	next, prev;				\
 								\
 	next = (elt)->field.next;				\
@@ -266,6 +281,8 @@ void		insque(queue_entry_t, queue_entry_t);
  */
 #define	queue_remove_first(head, entry, type, field)		\
 {								\
+	queue_assert(head);					\
+	queue_assert(&(entry)->field);				\
 	queue_entry_t	next;					\
 								\
 	(entry) = (type) ((head)->next);			\
@@ -289,6 +306,8 @@ void		insque(queue_entry_t, queue_entry_t);
  */
 #define	queue_remove_last(head, entry, type, field)		\
 {								\
+	queue_assert(head);					\
+	queue_assert(&(entry)->field);				\
 	queue_entry_t	prev;					\
 								\
 	(entry) = (type) ((head)->prev);			\
@@ -306,6 +325,8 @@ void		insque(queue_entry_t, queue_entry_t);
  */
 #define	queue_assign(to, from, type, field)			\
 {								\
+	queue_assert(&(to)->field);				\
+	queue_assert(&(from)->field);				\
 	((type)((from)->prev))->field.next = (to);		\
 	((type)((from)->next))->field.prev = (to);		\
 	*to = *from;						\
-- 
cgit v1.2.3