kernek: use struct_group to wipe ar8216 volatile priv data

Instead of reference vlan and do strange subtraction, use the handy
struct_group() to create a virtual struct of the same size of the
members. This permits to have a more secure memset and fix compilation
warning in 6.1 where additional checks are done.

Signed-off-by: Christian Marangi <[email protected]>

target/linux/generic/files/drivers/net/phy/ar8216.c

@@ -1419,8 +1419,7 @@ ar8xxx_sw_reset_switch(struct switch_dev *dev)
 	int i;
 
 	mutex_lock(&priv->reg_mutex);
-	memset(&priv->vlan, 0, sizeof(struct ar8xxx_priv) -
-		offsetof(struct ar8xxx_priv, vlan));
+	memset(&priv->ar8xxx_priv_volatile, 0, sizeof(priv->ar8xxx_priv_volatile));
 
 	for (i = 0; i < dev->vlans; i++)
 		priv->vlan_id[i] = i;
@@ -2461,7 +2460,7 @@ ar8xxx_phy_config_init(struct phy_device *phydev)
 		dev->phy_ptr = priv;
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(6,1,0)
 		dev->priv_flags |= IFF_NO_IP_ALIGN;
-#else LINUX_VERSION_CODE >= KERNEL_VERSION(5,15,0)
+#else
 		dev->extra_priv_flags |= IFF_NO_IP_ALIGN;
 #endif
 		dev->eth_mangle_rx = ar8216_mangle_rx;
@@ -2700,7 +2699,7 @@ ar8xxx_phy_detach(struct phy_device *phydev)
 	dev->phy_ptr = NULL;
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(6,1,0)
 	dev->priv_flags &= ~IFF_NO_IP_ALIGN;
-#else LINUX_VERSION_CODE >= KERNEL_VERSION(5,15,0)
+#else
 	dev->extra_priv_flags &= ~IFF_NO_IP_ALIGN;
 #endif
 	dev->eth_mangle_rx = NULL;

target/linux/generic/files/drivers/net/phy/ar8216.h

@@ -506,20 +506,22 @@ struct ar8xxx_priv {
 	unsigned int use_count;
 
 	/* all fields below are cleared on reset */
-	bool vlan;
-
-	u16 vlan_id[AR8XXX_MAX_VLANS];
-	u8 vlan_table[AR8XXX_MAX_VLANS];
-	u8 vlan_tagged;
-	u16 pvid[AR8X16_MAX_PORTS];
-	int arl_age_time;
-
-	/* mirroring */
-	bool mirror_rx;
-	bool mirror_tx;
-	int source_port;
-	int monitor_port;
-	u8 port_vlan_prio[AR8X16_MAX_PORTS];
+	struct_group(ar8xxx_priv_volatile,
+		bool vlan;
+
+		u16 vlan_id[AR8XXX_MAX_VLANS];
+		u8 vlan_table[AR8XXX_MAX_VLANS];
+		u8 vlan_tagged;
+		u16 pvid[AR8X16_MAX_PORTS];
+		int arl_age_time;
+
+		/* mirroring */
+		bool mirror_rx;
+		bool mirror_tx;
+		int source_port;
+		int monitor_port;
+		u8 port_vlan_prio[AR8X16_MAX_PORTS];
+	);
 };
 
 u32