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From:   Jakob Koschel <jakobkoschel@gmail.com>
To:     "David S. Miller" <davem@davemloft.net>
Cc:     Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        Lars Povlsen <lars.povlsen@microchip.com>,
        Steen Hegelund <Steen.Hegelund@microchip.com>,
        UNGLinuxDriver@microchip.com, Ariel Elior <aelior@marvell.com>,
        Manish Chopra <manishc@marvell.com>,
        Edward Cree <ecree.xilinx@gmail.com>,
        Martin Habets <habetsm.xilinx@gmail.com>,
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        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
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        Jiri Pirko <jiri@resnulli.us>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Casper Andersson <casper.casan@gmail.com>,
        Jakob Koschel <jakobkoschel@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>, Jason Gunthorpe <jgg@ziepe.ca>,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        Colin Ian King <colin.king@intel.com>,
        Eric Dumazet <edumazet@google.com>,
        Xu Wang <vulab@iscas.ac.cn>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linuxppc-dev@lists.ozlabs.org, bpf@vger.kernel.org,
        Mike Rapoport <rppt@kernel.org>,
        "Brian Johannesmeyer" <bjohannesmeyer@gmail.com>,
        Cristiano Giuffrida <c.giuffrida@vu.nl>,
        "Bos, H.J." <h.j.bos@vu.nl>
Subject: [PATCH net-next v5 15/18] net: netcp: Remove usage of list iterator for list_add() after loop body
Date:   Wed, 27 Apr 2022 18:06:32 +0200
Message-Id: <20220427160635.420492-16-jakobkoschel@gmail.com>
In-Reply-To: <20220427160635.420492-1-jakobkoschel@gmail.com>
References: <20220427160635.420492-1-jakobkoschel@gmail.com>
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In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer pointing to the location
where the element should be inserted [1].

Before, the code implicitly used the head when no element was found
when using &next->list. The new 'pos' variable is set to the list head
by default and overwritten if the list exits early, marking the
insertion point for list_add().

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
---
 drivers/net/ethernet/ti/netcp_core.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index 16507bff652a..f25104b5a31b 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c
@@ -471,6 +471,7 @@ struct netcp_hook_list {
 int netcp_register_txhook(struct netcp_intf *netcp_priv, int order,
 			  netcp_hook_rtn *hook_rtn, void *hook_data)
 {
+	struct list_head *pos = &netcp_priv->txhook_list_head;
 	struct netcp_hook_list *entry;
 	struct netcp_hook_list *next;
 	unsigned long flags;
@@ -485,10 +486,12 @@ int netcp_register_txhook(struct netcp_intf *netcp_priv, int order,
 
 	spin_lock_irqsave(&netcp_priv->lock, flags);
 	list_for_each_entry(next, &netcp_priv->txhook_list_head, list) {
-		if (next->order > order)
+		if (next->order > order) {
+			pos = &next->list;
 			break;
+		}
 	}
-	__list_add(&entry->list, next->list.prev, &next->list);
+	list_add_tail(&entry->list, pos);
 	spin_unlock_irqrestore(&netcp_priv->lock, flags);
 
 	return 0;
@@ -520,6 +523,7 @@ 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 list_head *pos = &netcp_priv->rxhook_list_head;
 	struct netcp_hook_list *entry;
 	struct netcp_hook_list *next;
 	unsigned long flags;
@@ -534,10 +538,12 @@ int netcp_register_rxhook(struct netcp_intf *netcp_priv, int order,
 
 	spin_lock_irqsave(&netcp_priv->lock, flags);
 	list_for_each_entry(next, &netcp_priv->rxhook_list_head, list) {
-		if (next->order > order)
+		if (next->order > order) {
+			pos = &next->list;
 			break;
+		}
 	}
-	__list_add(&entry->list, next->list.prev, &next->list);
+	list_add_tail(&entry->list, pos);
 	spin_unlock_irqrestore(&netcp_priv->lock, flags);
 
 	return 0;
-- 
2.25.1