netdevice: check for net_device::priv_flags bitfield overflow

We almost ran out of unsigned int bitwidth. Define priv flags and
check for potential overflow in the fashion of netdev_features_t.
Defined this way, priv_flags can be easily expanded later with
just changing its typedef.

Signed-off-by: Alexander Lobakin <alobakin@pm.me>

include/linux/netdevice.h

@@ -1527,70 +1527,79 @@ struct net_device_ops {
  * @IFF_LIVE_RENAME_OK: rename is allowed while device is up and running
  */
 enum netdev_priv_flags {
-	IFF_802_1Q_VLAN			= 1<<0,
-	IFF_EBRIDGE			= 1<<1,
-	IFF_BONDING			= 1<<2,
-	IFF_ISATAP			= 1<<3,
-	IFF_WAN_HDLC			= 1<<4,
-	IFF_XMIT_DST_RELEASE		= 1<<5,
-	IFF_DONT_BRIDGE			= 1<<6,
-	IFF_DISABLE_NETPOLL		= 1<<7,
-	IFF_MACVLAN_PORT		= 1<<8,
-	IFF_BRIDGE_PORT			= 1<<9,
-	IFF_OVS_DATAPATH		= 1<<10,
-	IFF_TX_SKB_SHARING		= 1<<11,
-	IFF_UNICAST_FLT			= 1<<12,
-	IFF_TEAM_PORT			= 1<<13,
-	IFF_SUPP_NOFCS			= 1<<14,
-	IFF_LIVE_ADDR_CHANGE		= 1<<15,
-	IFF_MACVLAN			= 1<<16,
-	IFF_XMIT_DST_RELEASE_PERM	= 1<<17,
-	IFF_L3MDEV_MASTER		= 1<<18,
-	IFF_NO_QUEUE			= 1<<19,
-	IFF_OPENVSWITCH			= 1<<20,
-	IFF_L3MDEV_SLAVE		= 1<<21,
-	IFF_TEAM			= 1<<22,
-	IFF_RXFH_CONFIGURED		= 1<<23,
-	IFF_PHONY_HEADROOM		= 1<<24,
-	IFF_MACSEC			= 1<<25,
-	IFF_NO_RX_HANDLER		= 1<<26,
-	IFF_FAILOVER			= 1<<27,
-	IFF_FAILOVER_SLAVE		= 1<<28,
-	IFF_L3MDEV_RX_HANDLER		= 1<<29,
-	IFF_LIVE_RENAME_OK		= 1<<30,
+	IFF_802_1Q_VLAN_BIT,
+	IFF_EBRIDGE_BIT,
+	IFF_BONDING_BIT,
+	IFF_ISATAP_BIT,
+	IFF_WAN_HDLC_BIT,
+	IFF_XMIT_DST_RELEASE_BIT,
+	IFF_DONT_BRIDGE_BIT,
+	IFF_DISABLE_NETPOLL_BIT,
+	IFF_MACVLAN_PORT_BIT,
+	IFF_BRIDGE_PORT_BIT,
+	IFF_OVS_DATAPATH_BIT,
+	IFF_TX_SKB_SHARING_BIT,
+	IFF_UNICAST_FLT_BIT,
+	IFF_TEAM_PORT_BIT,
+	IFF_SUPP_NOFCS_BIT,
+	IFF_LIVE_ADDR_CHANGE_BIT,
+	IFF_MACVLAN_BIT,
+	IFF_XMIT_DST_RELEASE_PERM_BIT,
+	IFF_L3MDEV_MASTER_BIT,
+	IFF_NO_QUEUE_BIT,
+	IFF_OPENVSWITCH_BIT,
+	IFF_L3MDEV_SLAVE_BIT,
+	IFF_TEAM_BIT,
+	IFF_RXFH_CONFIGURED_BIT,
+	IFF_PHONY_HEADROOM_BIT,
+	IFF_MACSEC_BIT,
+	IFF_NO_RX_HANDLER_BIT,
+	IFF_FAILOVER_BIT,
+	IFF_FAILOVER_SLAVE_BIT,
+	IFF_L3MDEV_RX_HANDLER_BIT,
+	IFF_LIVE_RENAME_OK_BIT,
+
+	NETDEV_PRIV_FLAG_COUNT,
 };
 
-#define IFF_802_1Q_VLAN			IFF_802_1Q_VLAN
-#define IFF_EBRIDGE			IFF_EBRIDGE
-#define IFF_BONDING			IFF_BONDING
-#define IFF_ISATAP			IFF_ISATAP
-#define IFF_WAN_HDLC			IFF_WAN_HDLC
-#define IFF_XMIT_DST_RELEASE		IFF_XMIT_DST_RELEASE
-#define IFF_DONT_BRIDGE			IFF_DONT_BRIDGE
-#define IFF_DISABLE_NETPOLL		IFF_DISABLE_NETPOLL
-#define IFF_MACVLAN_PORT		IFF_MACVLAN_PORT
-#define IFF_BRIDGE_PORT			IFF_BRIDGE_PORT
-#define IFF_OVS_DATAPATH		IFF_OVS_DATAPATH
-#define IFF_TX_SKB_SHARING		IFF_TX_SKB_SHARING
-#define IFF_UNICAST_FLT			IFF_UNICAST_FLT
-#define IFF_TEAM_PORT			IFF_TEAM_PORT
-#define IFF_SUPP_NOFCS			IFF_SUPP_NOFCS
-#define IFF_LIVE_ADDR_CHANGE		IFF_LIVE_ADDR_CHANGE
-#define IFF_MACVLAN			IFF_MACVLAN
-#define IFF_XMIT_DST_RELEASE_PERM	IFF_XMIT_DST_RELEASE_PERM
-#define IFF_L3MDEV_MASTER		IFF_L3MDEV_MASTER
-#define IFF_NO_QUEUE			IFF_NO_QUEUE
-#define IFF_OPENVSWITCH			IFF_OPENVSWITCH
-#define IFF_L3MDEV_SLAVE		IFF_L3MDEV_SLAVE
-#define IFF_TEAM			IFF_TEAM
-#define IFF_RXFH_CONFIGURED		IFF_RXFH_CONFIGURED
-#define IFF_PHONY_HEADROOM		IFF_PHONY_HEADROOM
-#define IFF_MACSEC			IFF_MACSEC
-#define IFF_NO_RX_HANDLER		IFF_NO_RX_HANDLER
-#define IFF_FAILOVER			IFF_FAILOVER
-#define IFF_FAILOVER_SLAVE		IFF_FAILOVER_SLAVE
-#define IFF_L3MDEV_RX_HANDLER		IFF_L3MDEV_RX_HANDLER
-#define IFF_LIVE_RENAME_OK		IFF_LIVE_RENAME_OK
+typedef u32 netdev_priv_flags_t;
+static_assert(sizeof(netdev_priv_flags_t) * BITS_PER_BYTE <=
+	      NETDEV_PRIV_FLAG_COUNT);
+
+#define __IFF_BIT(bit)			((netdev_priv_flags_t)1 << (bit))
+#define __IFF(name)			__IFF_BIT(IFF_##name##_BIT)
+
+#define IFF_802_1Q_VLAN			__IFF(802_1Q_VLAN)
+#define IFF_EBRIDGE			__IFF(EBRIDGE)
+#define IFF_BONDING			__IFF(BONDING)
+#define IFF_ISATAP			__IFF(ISATAP)
+#define IFF_WAN_HDLC			__IFF(WAN_HDLC)
+#define IFF_XMIT_DST_RELEASE		__IFF(XMIT_DST_RELEASE)
+#define IFF_DONT_BRIDGE			__IFF(DONT_BRIDGE)
+#define IFF_DISABLE_NETPOLL		__IFF(DISABLE_NETPOLL)
+#define IFF_MACVLAN_PORT		__IFF(MACVLAN_PORT)
+#define IFF_BRIDGE_PORT			__IFF(BRIDGE_PORT)
+#define IFF_OVS_DATAPATH		__IFF(OVS_DATAPATH)
+#define IFF_TX_SKB_SHARING		__IFF(TX_SKB_SHARING)
+#define IFF_UNICAST_FLT			__IFF(UNICAST_FLT)
+#define IFF_TEAM_PORT			__IFF(TEAM_PORT)
+#define IFF_SUPP_NOFCS			__IFF(SUPP_NOFCS)
+#define IFF_LIVE_ADDR_CHANGE		__IFF(LIVE_ADDR_CHANGE)
+#define IFF_MACVLAN			__IFF(MACVLAN)
+#define IFF_XMIT_DST_RELEASE_PERM	__IFF(XMIT_DST_RELEASE_PERM)
+#define IFF_L3MDEV_MASTER		__IFF(L3MDEV_MASTER)
+#define IFF_NO_QUEUE			__IFF(NO_QUEUE)
+#define IFF_OPENVSWITCH			__IFF(OPENVSWITCH)
+#define IFF_L3MDEV_SLAVE		__IFF(L3MDEV_SLAVE)
+#define IFF_TEAM			__IFF(TEAM)
+#define IFF_RXFH_CONFIGURED		__IFF(RXFH_CONFIGURED)
+#define IFF_PHONY_HEADROOM		__IFF(PHONY_HEADROOM)
+#define IFF_MACSEC			__IFF(MACSEC)
+#define IFF_NO_RX_HANDLER		__IFF(NO_RX_HANDLER)
+#define IFF_FAILOVER			__IFF(FAILOVER)
+#define IFF_FAILOVER_SLAVE		__IFF(FAILOVER_SLAVE)
+#define IFF_L3MDEV_RX_HANDLER		__IFF(L3MDEV_RX_HANDLER)
+#define IFF_LIVE_RENAME_OK		__IFF(LIVE_RENAME_OK)
 
 /**
  *	struct net_device - The DEVICE structure.
@@ -1925,7 +1934,7 @@ struct net_device {
 	const struct header_ops *header_ops;
 
 	unsigned int		flags;
-	unsigned int		priv_flags;
+	netdev_priv_flags_t	priv_flags;
 
 	unsigned short		gflags;
 	unsigned short		padded;