Commit dee42870 authored by Changli Gao's avatar Changli Gao Committed by David S. Miller
Browse files

net: fix softnet_stat 



Per cpu variable softnet_data.total was shared between IRQ and SoftIRQ context
without any protection. And enqueue_to_backlog should update the netdev_rx_stat
of the target CPU.

This patch renames softnet_data.total to softnet_data.processed: the number of
packets processed in uppper levels(IP stacks).

softnet_stat data is moved into softnet_data.

Signed-off-by: default avatarChangli Gao <xiaosuo@gmail.com>
----
 include/linux/netdevice.h |   17 +++++++----------
 net/core/dev.c            |   26 ++++++++++++--------------
 net/sched/sch_generic.c   |    2 +-
 3 files changed, 20 insertions(+), 25 deletions(-)
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7ef52737

include/linux/netdevice.h

+7 −10
Original line number Diff line number Diff line
@@ -218,16 +218,6 @@ struct neighbour; 
struct neigh_parms;

struct sk_buff;



struct netif_rx_stats {

	unsigned total;

	unsigned dropped;

	unsigned time_squeeze;

	unsigned cpu_collision;

	unsigned received_rps;

};



DECLARE_PER_CPU(struct netif_rx_stats, netdev_rx_stat);



struct netdev_hw_addr {

	struct list_head	list;

	unsigned char		addr[MAX_ADDR_LEN];
@@ -1390,6 +1380,12 @@ struct softnet_data { 
	struct sk_buff		*completion_queue;

	struct sk_buff_head	process_queue;



	/* stats */

	unsigned		processed;

	unsigned		time_squeeze;

	unsigned		cpu_collision;

	unsigned		received_rps;



#ifdef CONFIG_RPS

	struct softnet_data	*rps_ipi_list;
@@ -1399,6 +1395,7 @@ struct softnet_data { 
	unsigned int		cpu;

	unsigned int		input_queue_head;

#endif

	unsigned		dropped;

	struct sk_buff_head	input_pkt_queue;

	struct napi_struct	backlog;

};

net/core/dev.c

+12 −14
Original line number Diff line number Diff line
@@ -2205,8 +2205,6 @@ int netdev_max_backlog __read_mostly = 1000; 
int netdev_budget __read_mostly = 300;

int weight_p __read_mostly = 64;            /* old backlog weight */



DEFINE_PER_CPU(struct netif_rx_stats, netdev_rx_stat) = { 0, };



#ifdef CONFIG_RPS



/* One global table that all flow-based protocols share. */
@@ -2366,7 +2364,7 @@ static void rps_trigger_softirq(void *data) 
	struct softnet_data *sd = data;



	__napi_schedule(&sd->backlog);

	__get_cpu_var(netdev_rx_stat).received_rps++;

	sd->received_rps++;

}



#endif /* CONFIG_RPS */
@@ -2405,7 +2403,6 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu, 
	sd = &per_cpu(softnet_data, cpu);



	local_irq_save(flags);

	__get_cpu_var(netdev_rx_stat).total++;



	rps_lock(sd);

	if (skb_queue_len(&sd->input_pkt_queue) <= netdev_max_backlog) {
@@ -2429,9 +2426,9 @@ enqueue: 
		goto enqueue;

	}



	sd->dropped++;

	rps_unlock(sd);



	__get_cpu_var(netdev_rx_stat).dropped++;

	local_irq_restore(flags);



	kfree_skb(skb);
@@ -2806,7 +2803,7 @@ static int __netif_receive_skb(struct sk_buff *skb) 
			skb->dev = master;

	}



	__get_cpu_var(netdev_rx_stat).total++;

	__get_cpu_var(softnet_data).processed++;



	skb_reset_network_header(skb);

	skb_reset_transport_header(skb);
@@ -3490,7 +3487,7 @@ out: 
	return;



softnet_break:

	__get_cpu_var(netdev_rx_stat).time_squeeze++;

	sd->time_squeeze++;

	__raise_softirq_irqoff(NET_RX_SOFTIRQ);

	goto out;

}
@@ -3691,17 +3688,17 @@ static int dev_seq_show(struct seq_file *seq, void *v) 
	return 0;

}



static struct netif_rx_stats *softnet_get_online(loff_t *pos)

static struct softnet_data *softnet_get_online(loff_t *pos)

{

	struct netif_rx_stats *rc = NULL;

	struct softnet_data *sd = NULL;



	while (*pos < nr_cpu_ids)

		if (cpu_online(*pos)) {

			rc = &per_cpu(netdev_rx_stat, *pos);

			sd = &per_cpu(softnet_data, *pos);

			break;

		} else

			++*pos;

	return rc;

	return sd;

}



static void *softnet_seq_start(struct seq_file *seq, loff_t *pos)
@@ -3721,12 +3718,12 @@ static void softnet_seq_stop(struct seq_file *seq, void *v) 


static int softnet_seq_show(struct seq_file *seq, void *v)

{

	struct netif_rx_stats *s = v;

	struct softnet_data *sd = v;



	seq_printf(seq, "%08x %08x %08x %08x %08x %08x %08x %08x %08x %08x\n",

		   s->total, s->dropped, s->time_squeeze, 0,

		   sd->processed, sd->dropped, sd->time_squeeze, 0,

		   0, 0, 0, 0, /* was fastroute */

		   s->cpu_collision, s->received_rps);

		   sd->cpu_collision, sd->received_rps);

	return 0;

}
@@ -5869,6 +5866,7 @@ static int __init net_dev_init(void) 
	for_each_possible_cpu(i) {

		struct softnet_data *sd = &per_cpu(softnet_data, i);



		memset(sd, 0, sizeof(*sd));

		skb_queue_head_init(&sd->input_pkt_queue);

		skb_queue_head_init(&sd->process_queue);

		sd->completion_queue = NULL;

net/sched/sch_generic.c

+1 −1
Original line number Diff line number Diff line
@@ -94,7 +94,7 @@ static inline int handle_dev_cpu_collision(struct sk_buff *skb, 
		 * Another cpu is holding lock, requeue & delay xmits for

		 * some time.

		 */

		__get_cpu_var(netdev_rx_stat).cpu_collision++;

		__get_cpu_var(softnet_data).cpu_collision++;

		ret = dev_requeue_skb(skb, q);

	}

CRA Git | Maintained and supported by SUSTech CRA and CCSE