[2.6] [2/2] hlist: remove IFs from hlist functions

diff -NuprX dontdiff linux-2.6.2/include/linux/list.h linux-2.6.2.hlist/include/linux/list.h
@@ -434,10 +434,12 @@ struct hlist_node {
 	struct hlist_node *next, **pprev;
 };
 
-#define HLIST_HEAD_INIT { .first = NULL }
-#define HLIST_HEAD(name) struct hlist_head name = {  .first = NULL }
-#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
-#define INIT_HLIST_NODE(ptr) ((ptr)->next = NULL, (ptr)->pprev = NULL)
+extern struct hlist_node hlist_null; /* shared tail sentinel */
+
+#define HLIST_HEAD_INIT { .first = &hlist_null }
+#define HLIST_HEAD(name) struct hlist_head name = {  .first = &hlist_null }
+#define INIT_HLIST_HEAD(ptr) ((ptr)->first = &hlist_null)
+#define INIT_HLIST_NODE(ptr) ((ptr)->next = &hlist_null, (ptr)->pprev = NULL)
 
 static __inline__ void hlist_node_init(struct hlist_node *h)
 {

@@ -446,7 +448,7 @@ static __inline__ void hlist_node_init(s
 
 static __inline__ int hlist_last(const struct hlist_node *h)
 {
-	return !h->next;
+	return h->next == &hlist_null;
 }
 
 static __inline__ int hlist_unhashed(const struct hlist_node *h)

@@ -456,7 +458,7 @@ static __inline__ int hlist_unhashed(con
 
 static __inline__ int hlist_empty(const struct hlist_head *h)
 {
-	return !h->first;
+	return h->first == &hlist_null;
 }
 
 static __inline__ void __hlist_del(struct hlist_node *n)

@@ -464,8 +466,7 @@ static __inline__ void __hlist_del(struc
 	struct hlist_node *next = n->next;
 	struct hlist_node **pprev = n->pprev;
 	*pprev = next;
-	if (next)
-		next->pprev = pprev;
+	next->pprev = pprev;
 }
 
 static __inline__ void hlist_del(struct hlist_node *n)

@@ -506,8 +507,7 @@ static __inline__ void hlist_add_head(st
 {
 	struct hlist_node *first = h->first;
 	n->next = first;
-	if (first)
-		first->pprev = &n->next;
+	first->pprev = &n->next;
 	h->first = n;
 	n->pprev = &h->first;
 }

@@ -518,8 +518,7 @@ static __inline__ void hlist_add_head_rc
 	n->next = first;
 	n->pprev = &h->first;
 	smp_wmb();
-	if (first)
-		first->pprev = &n->next;
+	first->pprev = &n->next;
 	h->first = n;
 }
 

@@ -542,16 +541,15 @@ static __inline__ void hlist_add_after(s
 
 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
 #define hlist_entry_safe(ptr, type, member) \
-	((ptr) == 0 ? NULL : container_of(ptr,type,member))
+	((ptr) == &hlist_null ? NULL : container_of(ptr,type,member))
 
-/* Cannot easily do prefetch unfortunately */
 #define hlist_for_each(pos, head) \
-	for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); \
-	     pos = pos->next)
+	for (pos = (head)->first, prefetch(pos->next); pos != &hlist_null; \
+	     pos = pos->next, prefetch(pos->next))
 
 #define hlist_for_each_safe(pos, n, head) \
-	for (pos = (head)->first; n = pos ? pos->next : 0, pos; \
-	     pos = n)
+	for (pos = (head)->first, n = pos->next; pos != &hlist_null; \
+	     pos = n, n = pos->next)
 
 /**
  * hlist_for_each_entry	- iterate over list of given type

@@ -561,10 +559,10 @@ static __inline__ void hlist_add_after(s
  * @member:	the name of the hlist_node within the struct.
  */
 #define hlist_for_each_entry(tpos, pos, head, member)			 \
-	for (pos = (head)->first;					 \
-	     pos && ({ prefetch(pos->next); 1;}) &&			 \
+	for (pos = (head)->first, prefetch(pos->next);			 \
+	     pos != &hlist_null &&					 \
 		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
-	     pos = pos->next)
+	     pos = pos->next, prefetch(pos->next))
 
 /**
  * hlist_for_each_entry_continue - iterate over a hlist continuing 

diff -NuprX dontdiff linux-2.6.2/lib/list.c linux-2.6.2.hlist/lib/list.c
@@ -0,0 +1,10 @@
+#include <linux/module.h>
+#include <linux/list.h>
+
+/*
+ *	shared tail sentinel for hlists
+ */
+struct hlist_node hlist_null;
+
+EXPORT_SYMBOL(hlist_null);
+