[NET]: Remove obsolete netif_rx congestion sensing mechanism.

Remove the congestion sensing mechanism from netif_rx, and always
return either full or empty.  Almost no driver checks the return value
from netif_rx, and those that do only use it for debug messages.

The original design of netif_rx was to do flow control based on the
receive queue, but NAPI has supplanted this and no driver uses the
feedback.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -558,8 +558,6 @@ static inline int unregister_gifconf(unsigned int family)
 struct softnet_data
 {
 	int			throttle;
-	int			cng_level;
-	int			avg_blog;
 	struct sk_buff_head	input_pkt_queue;
 	struct list_head	poll_list;
 	struct net_device	*output_queue;

net/core/dev.c

@@ -115,18 +115,6 @@
 #endif	/* CONFIG_NET_RADIO */
 #include <asm/current.h>
 
-/* This define, if set, will randomly drop a packet when congestion
- * is more than moderate.  It helps fairness in the multi-interface
- * case when one of them is a hog, but it kills performance for the
- * single interface case so it is off now by default.
- */
-#undef RAND_LIE
-
-/* Setting this will sample the queue lengths and thus congestion
- * via a timer instead of as each packet is received.
- */
-#undef OFFLINE_SAMPLE
-
 /*
  *	The list of packet types we will receive (as opposed to discard)
  *	and the routines to invoke.
@@ -159,11 +147,6 @@ static DEFINE_SPINLOCK(ptype_lock);
 static struct list_head ptype_base[16];	/* 16 way hashed list */
 static struct list_head ptype_all;		/* Taps */
 
-#ifdef OFFLINE_SAMPLE
-static void sample_queue(unsigned long dummy);
-static struct timer_list samp_timer = TIMER_INITIALIZER(sample_queue, 0, 0);
-#endif
-
 /*
  * The @dev_base list is protected by @dev_base_lock and the rtln
  * semaphore.
@@ -1365,69 +1348,10 @@ int dev_queue_xmit(struct sk_buff *skb)
 
 int netdev_max_backlog = 300;
 int weight_p = 64;            /* old backlog weight */
-/* These numbers are selected based on intuition and some
- * experimentatiom, if you have more scientific way of doing this
- * please go ahead and fix things.
- */
-int no_cong_thresh = 10;
-int no_cong = 20;
-int lo_cong = 100;
-int mod_cong = 290;
 
 DEFINE_PER_CPU(struct netif_rx_stats, netdev_rx_stat) = { 0, };
 
 
-static void get_sample_stats(int cpu)
-{
-#ifdef RAND_LIE
-	unsigned long rd;
-	int rq;
-#endif
-	struct softnet_data *sd = &per_cpu(softnet_data, cpu);
-	int blog = sd->input_pkt_queue.qlen;
-	int avg_blog = sd->avg_blog;
-
-	avg_blog = (avg_blog >> 1) + (blog >> 1);
-
-	if (avg_blog > mod_cong) {
-		/* Above moderate congestion levels. */
-		sd->cng_level = NET_RX_CN_HIGH;
-#ifdef RAND_LIE
-		rd = net_random();
-		rq = rd % netdev_max_backlog;
-		if (rq < avg_blog) /* unlucky bastard */
-			sd->cng_level = NET_RX_DROP;
-#endif
-	} else if (avg_blog > lo_cong) {
-		sd->cng_level = NET_RX_CN_MOD;
-#ifdef RAND_LIE
-		rd = net_random();
-		rq = rd % netdev_max_backlog;
-			if (rq < avg_blog) /* unlucky bastard */
-				sd->cng_level = NET_RX_CN_HIGH;
-#endif
-	} else if (avg_blog > no_cong)
-		sd->cng_level = NET_RX_CN_LOW;
-	else  /* no congestion */
-		sd->cng_level = NET_RX_SUCCESS;
-
-	sd->avg_blog = avg_blog;
-}
-
-#ifdef OFFLINE_SAMPLE
-static void sample_queue(unsigned long dummy)
-{
-/* 10 ms 0r 1ms -- i don't care -- JHS */
-	int next_tick = 1;
-	int cpu = smp_processor_id();
-
-	get_sample_stats(cpu);
-	next_tick += jiffies;
-	mod_timer(&samp_timer, next_tick);
-}
-#endif
-
-
 /**
  *	netif_rx	-	post buffer to the network code
  *	@skb: buffer to post
@@ -1476,11 +1400,8 @@ int netif_rx(struct sk_buff *skb)
 enqueue:
 			dev_hold(skb->dev);
 			__skb_queue_tail(&queue->input_pkt_queue, skb);
-#ifndef OFFLINE_SAMPLE
-			get_sample_stats(this_cpu);
-#endif
 			local_irq_restore(flags);
-			return queue->cng_level;
+			return NET_RX_SUCCESS;
 		}
 
 		if (queue->throttle)
@@ -3300,8 +3221,6 @@ static int __init net_dev_init(void)
 		queue = &per_cpu(softnet_data, i);
 		skb_queue_head_init(&queue->input_pkt_queue);
 		queue->throttle = 0;
-		queue->cng_level = 0;
-		queue->avg_blog = 10; /* arbitrary non-zero */
 		queue->completion_queue = NULL;
 		INIT_LIST_HEAD(&queue->poll_list);
 		set_bit(__LINK_STATE_START, &queue->backlog_dev.state);
@@ -3310,11 +3229,6 @@ static int __init net_dev_init(void)
 		atomic_set(&queue->backlog_dev.refcnt, 1);
 	}
 
-#ifdef OFFLINE_SAMPLE
-	samp_timer.expires = jiffies + (10 * HZ);
-	add_timer(&samp_timer);
-#endif
-
 	dev_boot_phase = 0;
 
 	open_softirq(NET_TX_SOFTIRQ, net_tx_action, NULL);

net/core/sysctl_net_core.c

@@ -14,10 +14,6 @@
 
 extern int netdev_max_backlog;
 extern int weight_p;
-extern int no_cong_thresh;
-extern int no_cong;
-extern int lo_cong;
-extern int mod_cong;
 extern int net_msg_cost;
 extern int net_msg_burst;
 
@@ -84,38 +80,6 @@ ctl_table core_table[] = {
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec
 	},
-	{
-		.ctl_name	= NET_CORE_NO_CONG_THRESH,
-		.procname	= "no_cong_thresh",
-		.data		= &no_cong_thresh,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec
-	},
-	{
-		.ctl_name	= NET_CORE_NO_CONG,
-		.procname	= "no_cong",
-		.data		= &no_cong,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec
-	},
-	{
-		.ctl_name	= NET_CORE_LO_CONG,
-		.procname	= "lo_cong",
-		.data		= &lo_cong,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec
-	},
-	{
-		.ctl_name	= NET_CORE_MOD_CONG,
-		.procname	= "mod_cong",
-		.data		= &mod_cong,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec
-	},
 	{
 		.ctl_name	= NET_CORE_MSG_COST,
 		.procname	= "message_cost",