net_sched: add 64bit rate estimators

struct gnet_stats_rate_est contains u32 fields, so the bytes per second
field can wrap at 34360Mbit.

Add a new gnet_stats_rate_est64 structure to get 64bit bps/pps fields,
and switch the kernel to use this structure natively.

This structure is dumped to user space as a new attribute :

TCA_STATS_RATE_EST64

Old tc command will now display the capped bps (to 34360Mbit), instead
of wrapped values, and updated tc command will display correct
information.

Old tc command output, after patch :

eric:~# tc -s -d qd sh dev lo
qdisc pfifo 8001: root refcnt 2 limit 1000p
 Sent 80868245400 bytes 1978837 pkt (dropped 0, overlimits 0 requeues 0)
 rate 34360Mbit 189696pps backlog 0b 0p requeues 0

This patch carefully reorganizes "struct Qdisc" layout to get optimal
performance on SMP.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/gen_stats.h b/include/net/gen_stats.h
index a79b6cf..cf8439b 100644
--- a/include/net/gen_stats.h
+++ b/include/net/gen_stats.h
@@ -30,7 +30,7 @@
 				 struct gnet_stats_basic_packed *b);
 extern int gnet_stats_copy_rate_est(struct gnet_dump *d,
 				    const struct gnet_stats_basic_packed *b,
-				    struct gnet_stats_rate_est *r);
+				    struct gnet_stats_rate_est64 *r);
 extern int gnet_stats_copy_queue(struct gnet_dump *d,
 				 struct gnet_stats_queue *q);
 extern int gnet_stats_copy_app(struct gnet_dump *d, void *st, int len);
@@ -38,13 +38,13 @@
 extern int gnet_stats_finish_copy(struct gnet_dump *d);
 
 extern int gen_new_estimator(struct gnet_stats_basic_packed *bstats,
-			     struct gnet_stats_rate_est *rate_est,
+			     struct gnet_stats_rate_est64 *rate_est,
 			     spinlock_t *stats_lock, struct nlattr *opt);
 extern void gen_kill_estimator(struct gnet_stats_basic_packed *bstats,
-			       struct gnet_stats_rate_est *rate_est);
+			       struct gnet_stats_rate_est64 *rate_est);
 extern int gen_replace_estimator(struct gnet_stats_basic_packed *bstats,
-				 struct gnet_stats_rate_est *rate_est,
+				 struct gnet_stats_rate_est64 *rate_est,
 				 spinlock_t *stats_lock, struct nlattr *opt);
 extern bool gen_estimator_active(const struct gnet_stats_basic_packed *bstats,
-				 const struct gnet_stats_rate_est *rate_est);
+				 const struct gnet_stats_rate_est64 *rate_est);
 #endif