netdev - [PATCH v2 3/5] net: devres: define a separate devres structure for devm_alloc

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Message-Id: <20200523132711.30617-4-brgl@bgdev.pl>
Date:   Sat, 23 May 2020 15:27:09 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Jonathan Corbet <corbet@....net>,
        "David S . Miller" <davem@...emloft.net>,
        Matthias Brugger <matthias.bgg@...il.com>,
        John Crispin <john@...ozen.org>,
        Sean Wang <sean.wang@...iatek.com>,
        Mark Lee <Mark-MC.Lee@...iatek.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Fabien Parent <fparent@...libre.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Edwin Peer <edwin.peer@...adcom.com>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Stephane Le Provost <stephane.leprovost@...iatek.com>,
        Pedro Tsai <pedro.tsai@...iatek.com>,
        Andrew Perepech <andrew.perepech@...iatek.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: [PATCH v2 3/5] net: devres: define a separate devres structure for devm_alloc_etherdev()

From: Bartosz Golaszewski <bgolaszewski@...libre.com>

Not using a proxy structure to store struct net_device doesn't save
anything in terms of compiled code size or memory usage but significantly
decreases the readability of the code with all the pointer casting.

Define struct net_device_devres and use it in devm_alloc_etherdev_mqs().

Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
---
 net/devres.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/net/devres.c b/net/devres.c
index c1465d9f9019..b97b0c5a8216 100644
--- a/net/devres.c
+++ b/net/devres.c
@@ -7,30 +7,34 @@
 #include <linux/etherdevice.h>
 #include <linux/netdevice.h>
 
-static void devm_free_netdev(struct device *dev, void *res)
+struct net_device_devres {
+	struct net_device *ndev;
+};
+
+static void devm_free_netdev(struct device *dev, void *this)
 {
-	free_netdev(*(struct net_device **)res);
+	struct net_device_devres *res = this;
+
+	free_netdev(res->ndev);
 }
 
 struct net_device *devm_alloc_etherdev_mqs(struct device *dev, int sizeof_priv,
 					   unsigned int txqs, unsigned int rxqs)
 {
-	struct net_device **dr;
-	struct net_device *netdev;
+	struct net_device_devres *dr;
 
 	dr = devres_alloc(devm_free_netdev, sizeof(*dr), GFP_KERNEL);
 	if (!dr)
 		return NULL;
 
-	netdev = alloc_etherdev_mqs(sizeof_priv, txqs, rxqs);
-	if (!netdev) {
+	dr->ndev = alloc_etherdev_mqs(sizeof_priv, txqs, rxqs);
+	if (!dr->ndev) {
 		devres_free(dr);
 		return NULL;
 	}
 
-	*dr = netdev;
 	devres_add(dev, dr);
 
-	return netdev;
+	return dr->ndev;
 }
 EXPORT_SYMBOL(devm_alloc_etherdev_mqs);
-- 
2.25.0