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: Changli 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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 20 insertions, 25 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 40d4c20d034b..c39938f8a8d8 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -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;
 };
diff --git a/net/core/dev.c b/net/core/dev.c
index 100dcbd29739..36d53be4fca6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -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;
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index aeddabfb8e4e..a969b111bd76 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -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);
         }