net: dev: Makes sure netif_rx() can be invoked in any context.

Dave suggested a while ago (eleven years by now) "Let's make netif_rx()
work in all contexts and get rid of netif_rx_ni()". Eric agreed and
pointed out that modern devices should use netif_receive_skb() to avoid
the overhead.
In the meantime someone added another variant, netif_rx_any_context(),
which behaves as suggested.

netif_rx() must be invoked with disabled bottom halves to ensure that
pending softirqs, which were raised within the function, are handled.
netif_rx_ni() can be invoked only from process context (bottom halves
must be enabled) because the function handles pending softirqs without
checking if bottom halves were disabled or not.
netif_rx_any_context() invokes on the former functions by checking
in_interrupts().

netif_rx() could be taught to handle both cases (disabled and enabled
bottom halves) by simply disabling bottom halves while invoking
netif_rx_internal(). The local_bh_enable() invocation will then invoke
pending softirqs only if the BH-disable counter drops to zero.

Eric is concerned about the overhead of BH-disable+enable especially in
regard to the loopback driver. As critical as this driver is, it will
receive a shortcut to avoid the additional overhead which is not needed.

Add a local_bh_disable() section in netif_rx() to ensure softirqs are
handled if needed.
Provide __netif_rx() which does not disable BH and has a lockdep assert
to ensure that interrupts are disabled. Use this shortcut in the
loopback driver and in drivers/net/*.c.
Make netif_rx_ni() and netif_rx_any_context() invoke netif_rx() so they
can be removed once they are no more users left.

Link: https://lkml.kernel.org/r/20100415.020246.218622820.davem@davemloft.net
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

13 files changed, 19 insertions, 19 deletions

diff --git a/drivers/net/amt.c b/drivers/net/amt.c
index f1a36d7e2151..10455c9b9da0 100644
--- a/drivers/net/amt.c
+++ b/drivers/net/amt.c
@@ -2373,7 +2373,7 @@ static bool amt_membership_query_handler(struct amt_dev *amt,
 	skb->pkt_type = PACKET_MULTICAST;
 	skb->ip_summed = CHECKSUM_NONE;
 	len = skb->len;
-	if (netif_rx(skb) == NET_RX_SUCCESS) {
+	if (__netif_rx(skb) == NET_RX_SUCCESS) {
 		amt_update_gw_status(amt, AMT_STATUS_RECEIVED_QUERY, true);
 		dev_sw_netstats_rx_add(amt->dev, len);
 	} else {
@@ -2470,7 +2470,7 @@ report:
 	skb->pkt_type = PACKET_MULTICAST;
 	skb->ip_summed = CHECKSUM_NONE;
 	len = skb->len;
-	if (netif_rx(skb) == NET_RX_SUCCESS) {
+	if (__netif_rx(skb) == NET_RX_SUCCESS) {
 		amt_update_relay_status(tunnel, AMT_STATUS_RECEIVED_UPDATE,
 					true);
 		dev_sw_netstats_rx_add(amt->dev, len);
diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index c1fdd721a730..a895ff756093 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -925,7 +925,7 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 		}
 
 		skb->protocol = eth_type_trans(skb, geneve->dev);
-		netif_rx(skb);
+		__netif_rx(skb);
 		dst_release(&rt->dst);
 		return -EMSGSIZE;
 	}
@@ -1021,7 +1021,7 @@ static int geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 		}
 
 		skb->protocol = eth_type_trans(skb, geneve->dev);
-		netif_rx(skb);
+		__netif_rx(skb);
 		dst_release(dst);
 		return -EMSGSIZE;
 	}
diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 24e5c54d06c1..bf087171bcf0 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -207,7 +207,7 @@ static int gtp_rx(struct pdp_ctx *pctx, struct sk_buff *skb,
 
 	dev_sw_netstats_rx_add(pctx->dev, skb->len);
 
-	netif_rx(skb);
+	__netif_rx(skb);
 	return 0;
 
 err:
diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index ed0edf5884ef..d05f86fe78c9 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -78,7 +78,7 @@ static netdev_tx_t loopback_xmit(struct sk_buff *skb,
 
 	skb_orphan(skb);
 
-	/* Before queueing this packet to netif_rx(),
+	/* Before queueing this packet to __netif_rx(),
 	 * make sure dst is refcounted.
 	 */
 	skb_dst_force(skb);
@@ -86,7 +86,7 @@ static netdev_tx_t loopback_xmit(struct sk_buff *skb,
 	skb->protocol = eth_type_trans(skb, dev);
 
 	len = skb->len;
-	if (likely(netif_rx(skb) == NET_RX_SUCCESS))
+	if (likely(__netif_rx(skb) == NET_RX_SUCCESS))
 		dev_lstats_add(dev, len);
 
 	return NETDEV_TX_OK;
diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index 3d0874331763..832f09ac075e 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -1033,7 +1033,7 @@ static enum rx_handler_result handle_not_macsec(struct sk_buff *skb)
 				else
 					nskb->pkt_type = PACKET_MULTICAST;
 
-				netif_rx(nskb);
+				__netif_rx(nskb);
 			}
 			continue;
 		}
@@ -1056,7 +1056,7 @@ static enum rx_handler_result handle_not_macsec(struct sk_buff *skb)
 
 		nskb->dev = ndev;
 
-		if (netif_rx(nskb) == NET_RX_SUCCESS) {
+		if (__netif_rx(nskb) == NET_RX_SUCCESS) {
 			u64_stats_update_begin(&secy_stats->syncp);
 			secy_stats->stats.InPktsUntagged++;
 			u64_stats_update_end(&secy_stats->syncp);
@@ -1288,7 +1288,7 @@ nosci:
 
 		macsec_reset_skb(nskb, macsec->secy.netdev);
 
-		ret = netif_rx(nskb);
+		ret = __netif_rx(nskb);
 		if (ret == NET_RX_SUCCESS) {
 			u64_stats_update_begin(&secy_stats->syncp);
 			secy_stats->stats.InPktsUnknownSCI++;
diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 6ef5f77be4d0..d87c06c317ed 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -410,7 +410,7 @@ static void macvlan_forward_source_one(struct sk_buff *skb,
 	if (ether_addr_equal_64bits(eth_hdr(skb)->h_dest, dev->dev_addr))
 		nskb->pkt_type = PACKET_HOST;
 
-	ret = netif_rx(nskb);
+	ret = __netif_rx(nskb);
 	macvlan_count_rx(vlan, len, ret == NET_RX_SUCCESS, false);
 }
 
@@ -468,7 +468,7 @@ static rx_handler_result_t macvlan_handle_frame(struct sk_buff **pskb)
 			/* forward to original port. */
 			vlan = src;
 			ret = macvlan_broadcast_one(skb, vlan, eth, 0) ?:
-			      netif_rx(skb);
+			      __netif_rx(skb);
 			handle_res = RX_HANDLER_CONSUMED;
 			goto out;
 		}
diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
index aaa628f859fd..0b1b6f650104 100644
--- a/drivers/net/mhi_net.c
+++ b/drivers/net/mhi_net.c
@@ -225,7 +225,7 @@ static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
 		u64_stats_inc(&mhi_netdev->stats.rx_packets);
 		u64_stats_add(&mhi_netdev->stats.rx_bytes, skb->len);
 		u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
-		netif_rx(skb);
+		__netif_rx(skb);
 	}
 
 	/* Refill if RX buffers queue becomes low */
diff --git a/drivers/net/ntb_netdev.c b/drivers/net/ntb_netdev.c
index 98ca6b18415e..80bdc07f2cd3 100644
--- a/drivers/net/ntb_netdev.c
+++ b/drivers/net/ntb_netdev.c
@@ -119,7 +119,7 @@ static void ntb_netdev_rx_handler(struct ntb_transport_qp *qp, void *qp_data,
 	skb->protocol = eth_type_trans(skb, ndev);
 	skb->ip_summed = CHECKSUM_NONE;
 
-	if (netif_rx(skb) == NET_RX_DROP) {
+	if (__netif_rx(skb) == NET_RX_DROP) {
 		ndev->stats.rx_errors++;
 		ndev->stats.rx_dropped++;
 	} else {
diff --git a/drivers/net/rionet.c b/drivers/net/rionet.c
index 1a95f3beb784..39e61e07e489 100644
--- a/drivers/net/rionet.c
+++ b/drivers/net/rionet.c
@@ -109,7 +109,7 @@ static int rionet_rx_clean(struct net_device *ndev)
 		skb_put(rnet->rx_skb[i], RIO_MAX_MSG_SIZE);
 		rnet->rx_skb[i]->protocol =
 		    eth_type_trans(rnet->rx_skb[i], ndev);
-		error = netif_rx(rnet->rx_skb[i]);
+		error = __netif_rx(rnet->rx_skb[i]);
 
 		if (error == NET_RX_DROP) {
 			ndev->stats.rx_dropped++;
diff --git a/drivers/net/sb1000.c b/drivers/net/sb1000.c
index 57a6d598467b..c3f8020571ad 100644
--- a/drivers/net/sb1000.c
+++ b/drivers/net/sb1000.c
@@ -872,7 +872,7 @@ printk("cm0: IP identification: %02x%02x  fragment offset: %02x%02x\n", buffer[3
 
 	/* datagram completed: send to upper level */
 	skb_trim(skb, dlen);
-	netif_rx(skb);
+	__netif_rx(skb);
 	stats->rx_bytes+=dlen;
 	stats->rx_packets++;
 	lp->rx_skb[ns] = NULL;
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index d29fb9759cc9..58b20ea171dd 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -287,7 +287,7 @@ static int veth_forward_skb(struct net_device *dev, struct sk_buff *skb,
 {
 	return __dev_forward_skb(dev, skb) ?: xdp ?
 		veth_xdp_rx(rq, skb) :
-		netif_rx(skb);
+		__netif_rx(skb);
 }
 
 /* return true if the specified skb has chances of GRO aggregation
diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index e0b1ab99a359..714cafcf6c6c 100644
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -418,7 +418,7 @@ static int vrf_local_xmit(struct sk_buff *skb, struct net_device *dev,
 
 	skb->protocol = eth_type_trans(skb, dev);
 
-	if (likely(netif_rx(skb) == NET_RX_SUCCESS))
+	if (likely(__netif_rx(skb) == NET_RX_SUCCESS))
 		vrf_rx_stats(dev, len);
 	else
 		this_cpu_inc(dev->dstats->rx_drps);
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 359d16780dbb..d0dc90d3dac2 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2541,7 +2541,7 @@ static void vxlan_encap_bypass(struct sk_buff *skb, struct vxlan_dev *src_vxlan,
 	tx_stats->tx_bytes += len;
 	u64_stats_update_end(&tx_stats->syncp);
 
-	if (netif_rx(skb) == NET_RX_SUCCESS) {
+	if (__netif_rx(skb) == NET_RX_SUCCESS) {
 		u64_stats_update_begin(&rx_stats->syncp);
 		rx_stats->rx_packets++;
 		rx_stats->rx_bytes += len;