net: remove support for per driver ndo_busy_poll()

We added generic support for busy polling in NAPI layer in linux-4.5

No network driver uses ndo_busy_poll() anymore, we can get rid
of the pointer in struct net_device_ops, and its use in sk_busy_loop()

Saves NETIF_F_BUSY_POLL features bit.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdev_features.h

@@ -71,7 +71,6 @@ enum {
 	NETIF_F_HW_VLAN_STAG_RX_BIT,	/* Receive VLAN STAG HW acceleration */
 	NETIF_F_HW_VLAN_STAG_FILTER_BIT,/* Receive filtering on VLAN STAGs */
 	NETIF_F_HW_L2FW_DOFFLOAD_BIT,	/* Allow L2 Forwarding in Hardware */
-	NETIF_F_BUSY_POLL_BIT,		/* Busy poll */
 
 	NETIF_F_HW_TC_BIT,		/* Offload TC infrastructure */
 
@@ -134,7 +133,6 @@ enum {
 #define NETIF_F_HW_VLAN_STAG_RX	__NETIF_F(HW_VLAN_STAG_RX)
 #define NETIF_F_HW_VLAN_STAG_TX	__NETIF_F(HW_VLAN_STAG_TX)
 #define NETIF_F_HW_L2FW_DOFFLOAD	__NETIF_F(HW_L2FW_DOFFLOAD)
-#define NETIF_F_BUSY_POLL	__NETIF_F(BUSY_POLL)
 #define NETIF_F_HW_TC		__NETIF_F(HW_TC)
 
 #define for_each_netdev_feature(mask_addr, bit)	\

include/linux/netdevice.h

@@ -1184,9 +1184,6 @@ struct net_device_ops {
 	int			(*ndo_netpoll_setup)(struct net_device *dev,
 						     struct netpoll_info *info);
 	void			(*ndo_netpoll_cleanup)(struct net_device *dev);
-#endif
-#ifdef CONFIG_NET_RX_BUSY_POLL
-	int			(*ndo_busy_poll)(struct napi_struct *dev);
 #endif
 	int			(*ndo_set_vf_mac)(struct net_device *dev,
 						  int queue, u8 *mac);

net/core/dev.c

@@ -4978,7 +4978,6 @@ bool sk_busy_loop(struct sock *sk, int nonblock)
 {
 	unsigned long end_time = !nonblock ? sk_busy_loop_end_time(sk) : 0;
 	int (*napi_poll)(struct napi_struct *napi, int budget);
-	int (*busy_poll)(struct napi_struct *dev);
 	void *have_poll_lock = NULL;
 	struct napi_struct *napi;
 	int rc;
@@ -4993,17 +4992,10 @@ bool sk_busy_loop(struct sock *sk, int nonblock)
 	if (!napi)
 		goto out;
 
-	/* Note: ndo_busy_poll method is optional in linux-4.5 */
-	busy_poll = napi->dev->netdev_ops->ndo_busy_poll;
-
 	preempt_disable();
 	for (;;) {
 		rc = 0;
 		local_bh_disable();
-		if (busy_poll) {
-			rc = busy_poll(napi);
-			goto count;
-		}
 		if (!napi_poll) {
 			unsigned long val = READ_ONCE(napi->state);
 
@@ -6956,13 +6948,6 @@ static netdev_features_t netdev_fix_features(struct net_device *dev,
 		features &= ~dev->gso_partial_features;
 	}
 
-#ifdef CONFIG_NET_RX_BUSY_POLL
-	if (dev->netdev_ops->ndo_busy_poll)
-		features |= NETIF_F_BUSY_POLL;
-	else
-#endif
-		features &= ~NETIF_F_BUSY_POLL;
-
 	return features;
 }
 

net/core/ethtool.c

@@ -102,7 +102,6 @@ static const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN]
 	[NETIF_F_RXFCS_BIT] =            "rx-fcs",
 	[NETIF_F_RXALL_BIT] =            "rx-all",
 	[NETIF_F_HW_L2FW_DOFFLOAD_BIT] = "l2-fwd-offload",
-	[NETIF_F_BUSY_POLL_BIT] =        "busy-poll",
 	[NETIF_F_HW_TC_BIT] =		 "hw-tc-offload",
 };