[PATCH net-next 12/15] net: netcp: Remove usage of list iterator for list_add() after loop body

From: Jakob Koschel <hidden>
Date: 2022-04-07 10:32:42
Also in: linux-arm-kernel, lkml, netdev
Reply to: Jakob Koschel, 2022-04-07

In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Before, the code implicitly used the head when no element was found
when using &pos->list. Since the new variable is only set if an
element was found, the list_add() is performed within the loop
and only done after the loop if it is done on the list head directly.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ (local) [1]
Signed-off-by: Jakob Koschel <redacted>
---
 drivers/net/ethernet/ti/netcp_core.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index 16507bff652a..7f89fd82ecc8 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c

@@ -471,8 +471,8 @@ struct netcp_hook_list {
 int netcp_register_txhook(struct netcp_intf *netcp_priv, int order,
 			  netcp_hook_rtn *hook_rtn, void *hook_data)
 {
+	struct netcp_hook_list *next = NULL, *iter;
 	struct netcp_hook_list *entry;
-	struct netcp_hook_list *next;
 	unsigned long flags;
 
 	entry = devm_kzalloc(netcp_priv->dev, sizeof(*entry), GFP_KERNEL);

@@ -484,11 +484,15 @@ int netcp_register_txhook(struct netcp_intf *netcp_priv, int order,
 	entry->order     = order;
 
 	spin_lock_irqsave(&netcp_priv->lock, flags);
-	list_for_each_entry(next, &netcp_priv->txhook_list_head, list) {
-		if (next->order > order)
+	list_for_each_entry(iter, &netcp_priv->txhook_list_head, list) {
+		if (iter->order > order) {
+			next = iter;
+			list_add_tail(&entry->list, &iter->list);
 			break;
+		}
 	}
-	__list_add(&entry->list, next->list.prev, &next->list);
+	if (!next)
+		list_add_tail(&entry->list, &netcp_priv->txhook_list_head);
 	spin_unlock_irqrestore(&netcp_priv->lock, flags);
 
 	return 0;

@@ -520,8 +524,8 @@ EXPORT_SYMBOL_GPL(netcp_unregister_txhook);
 int netcp_register_rxhook(struct netcp_intf *netcp_priv, int order,
 			  netcp_hook_rtn *hook_rtn, void *hook_data)
 {
+	struct netcp_hook_list *next = NULL, *iter;
 	struct netcp_hook_list *entry;
-	struct netcp_hook_list *next;
 	unsigned long flags;
 
 	entry = devm_kzalloc(netcp_priv->dev, sizeof(*entry), GFP_KERNEL);

@@ -533,11 +537,15 @@ int netcp_register_rxhook(struct netcp_intf *netcp_priv, int order,
 	entry->order     = order;
 
 	spin_lock_irqsave(&netcp_priv->lock, flags);
-	list_for_each_entry(next, &netcp_priv->rxhook_list_head, list) {
-		if (next->order > order)
+	list_for_each_entry(iter, &netcp_priv->rxhook_list_head, list) {
+		if (iter->order > order) {
+			next = iter;
+			list_add_tail(&entry->list, &iter->list);
 			break;
+		}
 	}
-	__list_add(&entry->list, next->list.prev, &next->list);
+	if (!next)
+		list_add_tail(&entry->list, &netcp_priv->rxhook_list_head);
 	spin_unlock_irqrestore(&netcp_priv->lock, flags);
 
 	return 0;

-- 
2.25.1

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