bonding: convert to list API and replace bond's custom list

This patch aims to remove struct bonding's first_slave and struct
slave's next and prev pointers, and replace them with the standard Linux
list API. The old macros are converted to list API as well and some new
primitives are available now. The checks if there're slaves that used
slave_cnt have been replaced by the list_empty macro.
Also a few small style fixes, changing longest -> shortest line in local
variable declarations, leaving an empty line before return and removing
unnecessary brackets.
This is the first step to gradual RCU conversion.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 40 insertions, 31 deletions

diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 42d1c65..cfd9b49 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -71,6 +71,28 @@
 	set_fs(fs);			\
 	res; })
 
+/* slave list primitives */
+#define bond_to_slave(ptr) list_entry(ptr, struct slave, list)
+
+/* IMPORTANT: bond_first/last_slave can return NULL in case of an empty list */
+#define bond_first_slave(bond) \
+	list_first_entry_or_null(&(bond)->slave_list, struct slave, list)
+#define bond_last_slave(bond) \
+	(list_empty(&(bond)->slave_list) ? NULL : \
+					   bond_to_slave((bond)->slave_list.prev))
+
+#define bond_is_first_slave(bond, pos) ((pos)->list.prev == &(bond)->slave_list)
+#define bond_is_last_slave(bond, pos) ((pos)->list.next == &(bond)->slave_list)
+
+/* Since bond_first/last_slave can return NULL, these can return NULL too */
+#define bond_next_slave(bond, pos) \
+	(bond_is_last_slave(bond, pos) ? bond_first_slave(bond) : \
+					 bond_to_slave((pos)->list.next))
+
+#define bond_prev_slave(bond, pos) \
+	(bond_is_first_slave(bond, pos) ? bond_last_slave(bond) : \
+					  bond_to_slave((pos)->list.prev))
+
 /**
  * bond_for_each_slave_from - iterate the slaves list from a starting point
  * @bond:	the bond holding this list.
@@ -80,37 +102,29 @@
  *
  * Caller must hold bond->lock
  */
-#define bond_for_each_slave_from(bond, pos, cnt, start)	\
-	for (cnt = 0, pos = start;				\
-	     cnt < (bond)->slave_cnt;				\
-             cnt++, pos = (pos)->next)
+#define bond_for_each_slave_from(bond, pos, cnt, start) \
+	for (cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \
+	     cnt++, pos = bond_next_slave(bond, pos))
 
 /**
- * bond_for_each_slave_from_to - iterate the slaves list from start point to stop point
- * @bond:	the bond holding this list.
- * @pos:	current slave.
- * @cnt:	counter for number max of moves
- * @start:	start point.
- * @stop:	stop point.
+ * bond_for_each_slave - iterate over all slaves
+ * @bond:	the bond holding this list
+ * @pos:	current slave
  *
  * Caller must hold bond->lock
  */
-#define bond_for_each_slave_from_to(bond, pos, cnt, start, stop)	\
-	for (cnt = 0, pos = start;					\
-	     ((cnt < (bond)->slave_cnt) && (pos != (stop)->next));	\
-             cnt++, pos = (pos)->next)
+#define bond_for_each_slave(bond, pos) \
+	list_for_each_entry(pos, &(bond)->slave_list, list)
 
 /**
- * bond_for_each_slave - iterate the slaves list from head
- * @bond:	the bond holding this list.
- * @pos:	current slave.
- * @cnt:	counter for max number of moves
+ * bond_for_each_slave_reverse - iterate in reverse from a given position
+ * @bond:	the bond holding this list
+ * @pos:	slave to continue from
  *
  * Caller must hold bond->lock
  */
-#define bond_for_each_slave(bond, pos, cnt)	\
-		bond_for_each_slave_from(bond, pos, cnt, (bond)->first_slave)
-
+#define bond_for_each_slave_continue_reverse(bond, pos) \
+	list_for_each_entry_continue_reverse(pos, &(bond)->slave_list, list)
 
 #ifdef CONFIG_NET_POLL_CONTROLLER
 extern atomic_t netpoll_block_tx;
@@ -174,8 +188,7 @@ struct vlan_entry {
 
 struct slave {
 	struct net_device *dev; /* first - useful for panic debug */
-	struct slave *next;
-	struct slave *prev;
+	struct list_head list;
 	struct bonding *bond; /* our master */
 	int    delay;
 	unsigned long jiffies;
@@ -215,7 +228,7 @@ struct slave {
  */
 struct bonding {
 	struct   net_device *dev; /* first - useful for panic debug */
-	struct   slave *first_slave;
+	struct   list_head slave_list;
 	struct   slave *curr_active_slave;
 	struct   slave *current_arp_slave;
 	struct   slave *primary_slave;
@@ -270,13 +283,10 @@ static inline struct slave *bond_get_slave_by_dev(struct bonding *bond,
 						  struct net_device *slave_dev)
 {
 	struct slave *slave = NULL;
-	int i;
 
-	bond_for_each_slave(bond, slave, i) {
-		if (slave->dev == slave_dev) {
+	bond_for_each_slave(bond, slave)
+		if (slave->dev == slave_dev)
 			return slave;
-		}
-	}
 
 	return NULL;
 }
@@ -477,10 +487,9 @@ static inline void bond_destroy_proc_dir(struct bond_net *bn)
 static inline struct slave *bond_slave_has_mac(struct bonding *bond,
 					       const u8 *mac)
 {
-	int i = 0;
 	struct slave *tmp;
 
-	bond_for_each_slave(bond, tmp, i)
+	bond_for_each_slave(bond, tmp)
 		if (ether_addr_equal_64bits(mac, tmp->dev->dev_addr))
 			return tmp;