linux-kernel - [PATCH net-next 12/15] net: netcp: Remove usage of list iterator for list

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Message-Id: <20220407102900.3086255-13-jakobkoschel@gmail.com>
Date:   Thu,  7 Apr 2022 12:28:57 +0200
From:   Jakob Koschel <jakobkoschel@...il.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Lars Povlsen <lars.povlsen@...rochip.com>,
        Steen Hegelund <Steen.Hegelund@...rochip.com>,
        UNGLinuxDriver@...rochip.com, Ariel Elior <aelior@...vell.com>,
        Manish Chopra <manishc@...vell.com>,
        Edward Cree <ecree.xilinx@...il.com>,
        Martin Habets <habetsm.xilinx@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Jiri Pirko <jiri@...nulli.us>,
        Casper Andersson <casper.casan@...il.com>,
        Bjarni Jonasson <bjarni.jonasson@...rochip.com>,
        Jakob Koschel <jakobkoschel@...il.com>,
        Colin Ian King <colin.king@...el.com>,
        Michael Walle <michael@...le.cc>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Arnd Bergmann <arnd@...db.de>,
        Eric Dumazet <edumazet@...gle.com>,
        Di Zhu <zhudi21@...wei.com>, Xu Wang <vulab@...as.ac.cn>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, Mike Rapoport <rppt@...nel.org>,
        "Brian Johannesmeyer" <bjohannesmeyer@...il.com>,
        Cristiano Giuffrida <c.giuffrida@...nl>,
        "Bos, H.J." <h.j.bos@...nl>
Subject: [PATCH net-next 12/15] net: netcp: Remove usage of list iterator for list_add() after loop body

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/ [1]
Signed-off-by: Jakob Koschel <jakobkoschel@...il.com>
---
 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