net: restore gnet_stats_basic to previous definition

In 5e140dfc1fe87eae27846f193086724806b33c7d "net: reorder struct Qdisc
for better SMP performance" the definition of struct gnet_stats_basic
changed incompatibly, as copies of this struct are shipped to
userland via netlink.

Restoring old behavior is not welcome, for performance reason.

Fix is to use a private structure for kernel, and
teach gnet_stats_copy_basic() to convert from kernel to user land,
using legacy structure (struct gnet_stats_basic)

Based on a report and initial patch from Michael Spang.

Reported-by: Michael Spang <mspang@csclub.uwaterloo.ca>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

13 files changed, 33 insertions, 23 deletions

diff --git a/include/linux/gen_stats.h b/include/linux/gen_stats.h
index 0ffa41df0ee..710e901085d 100644
--- a/include/linux/gen_stats.h
+++ b/include/linux/gen_stats.h
@@ -22,6 +22,11 @@ struct gnet_stats_basic
 {
         __u64   bytes;
         __u32   packets;
+};
+struct gnet_stats_basic_packed
+{
+        __u64   bytes;
+        __u32   packets;
 } __attribute__ ((packed));
 
 /**
diff --git a/include/net/act_api.h b/include/net/act_api.h
index 565eed8fe49..c05fd717c58 100644
--- a/include/net/act_api.h
+++ b/include/net/act_api.h
@@ -16,7 +16,7 @@ struct tcf_common {
         u32                             tcfc_capab;
         int                             tcfc_action;
         struct tcf_t                    tcfc_tm;
-        struct gnet_stats_basic         tcfc_bstats;
+        struct gnet_stats_basic_packed  tcfc_bstats;
         struct gnet_stats_queue         tcfc_qstats;
         struct gnet_stats_rate_est      tcfc_rate_est;
         spinlock_t                      tcfc_lock;
diff --git a/include/net/gen_stats.h b/include/net/gen_stats.h
index d136b5240ef..c1488553e34 100644
--- a/include/net/gen_stats.h
+++ b/include/net/gen_stats.h
@@ -28,7 +28,7 @@ extern int gnet_stats_start_copy_compat(struct sk_buff *skb, int type,
                                         spinlock_t *lock, struct gnet_dump *d);
 
 extern int gnet_stats_copy_basic(struct gnet_dump *d,
-                                 struct gnet_stats_basic *b);
+                                 struct gnet_stats_basic_packed *b);
 extern int gnet_stats_copy_rate_est(struct gnet_dump *d,
                                     struct gnet_stats_rate_est *r);
 extern int gnet_stats_copy_queue(struct gnet_dump *d,
@@ -37,14 +37,14 @@ extern int gnet_stats_copy_app(struct gnet_dump *d, void *st, int len);
 
 extern int gnet_stats_finish_copy(struct gnet_dump *d);
 
-extern int gen_new_estimator(struct gnet_stats_basic *bstats,
+extern int gen_new_estimator(struct gnet_stats_basic_packed *bstats,
                              struct gnet_stats_rate_est *rate_est,
                              spinlock_t *stats_lock, struct nlattr *opt);
-extern void gen_kill_estimator(struct gnet_stats_basic *bstats,
+extern void gen_kill_estimator(struct gnet_stats_basic_packed *bstats,
                                struct gnet_stats_rate_est *rate_est);
-extern int gen_replace_estimator(struct gnet_stats_basic *bstats,
+extern int gen_replace_estimator(struct gnet_stats_basic_packed *bstats,
                                  struct gnet_stats_rate_est *rate_est,
                                  spinlock_t *stats_lock, struct nlattr *opt);
-extern bool gen_estimator_active(const struct gnet_stats_basic *bstats,
+extern bool gen_estimator_active(const struct gnet_stats_basic_packed *bstats,
                                  const struct gnet_stats_rate_est *rate_est);
 #endif
diff --git a/include/net/netfilter/xt_rateest.h b/include/net/netfilter/xt_rateest.h
index 65d594dffbf..ddbf37e1961 100644
--- a/include/net/netfilter/xt_rateest.h
+++ b/include/net/netfilter/xt_rateest.h
@@ -8,7 +8,7 @@ struct xt_rateest {
         spinlock_t                      lock;
         struct gnet_estimator           params;
         struct gnet_stats_rate_est      rstats;
-        struct gnet_stats_basic         bstats;
+        struct gnet_stats_basic_packed  bstats;
 };
 
 extern struct xt_rateest *xt_rateest_lookup(const char *name);
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 964ffa0d881..5482e9582f5 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -72,7 +72,7 @@ struct Qdisc
          */
         unsigned long           state;
         struct sk_buff_head     q;
-        struct gnet_stats_basic bstats;
+        struct gnet_stats_basic_packed bstats;
         struct gnet_stats_queue qstats;
 };
 
diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c
index 78e5bfc454a..493775f4f2f 100644
--- a/net/core/gen_estimator.c
+++ b/net/core/gen_estimator.c
@@ -81,7 +81,7 @@
 struct gen_estimator
 {
         struct list_head        list;
-        struct gnet_stats_basic *bstats;
+        struct gnet_stats_basic_packed  *bstats;
         struct gnet_stats_rate_est      *rate_est;
         spinlock_t              *stats_lock;
         int                     ewma_log;
@@ -165,7 +165,7 @@ static void gen_add_node(struct gen_estimator *est)
 }
 
 static
-struct gen_estimator *gen_find_node(const struct gnet_stats_basic *bstats,
+struct gen_estimator *gen_find_node(const struct gnet_stats_basic_packed *bstats,
                                     const struct gnet_stats_rate_est *rate_est)
 {
         struct rb_node *p = est_root.rb_node;
@@ -202,7 +202,7 @@ struct gen_estimator *gen_find_node(const struct gnet_stats_basic *bstats,
  *
  * NOTE: Called under rtnl_mutex
  */
-int gen_new_estimator(struct gnet_stats_basic *bstats,
+int gen_new_estimator(struct gnet_stats_basic_packed *bstats,
                       struct gnet_stats_rate_est *rate_est,
                       spinlock_t *stats_lock,
                       struct nlattr *opt)
@@ -262,7 +262,7 @@ static void __gen_kill_estimator(struct rcu_head *head)
  *
  * NOTE: Called under rtnl_mutex
  */
-void gen_kill_estimator(struct gnet_stats_basic *bstats,
+void gen_kill_estimator(struct gnet_stats_basic_packed *bstats,
                         struct gnet_stats_rate_est *rate_est)
 {
         struct gen_estimator *e;
@@ -292,7 +292,7 @@ EXPORT_SYMBOL(gen_kill_estimator);
  *
  * Returns 0 on success or a negative error code.
  */
-int gen_replace_estimator(struct gnet_stats_basic *bstats,
+int gen_replace_estimator(struct gnet_stats_basic_packed *bstats,
                           struct gnet_stats_rate_est *rate_est,
                           spinlock_t *stats_lock, struct nlattr *opt)
 {
@@ -308,7 +308,7 @@ EXPORT_SYMBOL(gen_replace_estimator);
  *
  * Returns true if estimator is active, and false if not.
  */
-bool gen_estimator_active(const struct gnet_stats_basic *bstats,
+bool gen_estimator_active(const struct gnet_stats_basic_packed *bstats,
                           const struct gnet_stats_rate_est *rate_est)
 {
         ASSERT_RTNL();
diff --git a/net/core/gen_stats.c b/net/core/gen_stats.c
index c3d0ffeac24..8569310268a 100644
--- a/net/core/gen_stats.c
+++ b/net/core/gen_stats.c
@@ -106,16 +106,21 @@ gnet_stats_start_copy(struct sk_buff *skb, int type, spinlock_t *lock,
  * if the room in the socket buffer was not sufficient.
  */
 int
-gnet_stats_copy_basic(struct gnet_dump *d, struct gnet_stats_basic *b)
+gnet_stats_copy_basic(struct gnet_dump *d, struct gnet_stats_basic_packed *b)
 {
         if (d->compat_tc_stats) {
                 d->tc_stats.bytes = b->bytes;
                 d->tc_stats.packets = b->packets;
         }
 
-        if (d->tail)
-                return gnet_stats_copy(d, TCA_STATS_BASIC, b, sizeof(*b));
+        if (d->tail) {
+                struct gnet_stats_basic sb;
 
+                memset(&sb, 0, sizeof(sb));
+                sb.bytes = b->bytes;
+                sb.packets = b->packets;
+                return gnet_stats_copy(d, TCA_STATS_BASIC, &sb, sizeof(sb));
+        }
         return 0;
 }
 
diff --git a/net/netfilter/xt_RATEEST.c b/net/netfilter/xt_RATEEST.c
index 43f5676b1af..d80b8192e0d 100644
--- a/net/netfilter/xt_RATEEST.c
+++ b/net/netfilter/xt_RATEEST.c
@@ -74,7 +74,7 @@ static unsigned int
 xt_rateest_tg(struct sk_buff *skb, const struct xt_target_param *par)
 {
         const struct xt_rateest_target_info *info = par->targinfo;
-        struct gnet_stats_basic *stats = &info->est->bstats;
+        struct gnet_stats_basic_packed *stats = &info->est->bstats;
 
         spin_lock_bh(&info->est->lock);
         stats->bytes += skb->len;
diff --git a/net/sched/sch_atm.c b/net/sched/sch_atm.c
index 2a8b83af7c4..ab82f145f68 100644
--- a/net/sched/sch_atm.c
+++ b/net/sched/sch_atm.c
@@ -49,7 +49,7 @@ struct atm_flow_data {
         struct socket           *sock;          /* for closing */
         u32                     classid;        /* x:y type ID */
         int                     ref;            /* reference count */
-        struct gnet_stats_basic bstats;
+        struct gnet_stats_basic_packed  bstats;
         struct gnet_stats_queue qstats;
         struct atm_flow_data    *next;
         struct atm_flow_data    *excess;        /* flow for excess traffic;
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 23a167670fd..d5798e17a83 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -128,7 +128,7 @@ struct cbq_class
         long                    avgidle;
         long                    deficit;        /* Saved deficit for WRR */
         psched_time_t           penalized;
-        struct gnet_stats_basic bstats;
+        struct gnet_stats_basic_packed bstats;
         struct gnet_stats_queue qstats;
         struct gnet_stats_rate_est rate_est;
         struct tc_cbq_xstats    xstats;
diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c
index 7597fe14686..12b2fb04b29 100644
--- a/net/sched/sch_drr.c
+++ b/net/sched/sch_drr.c
@@ -22,7 +22,7 @@ struct drr_class {
         unsigned int                    refcnt;
         unsigned int                    filter_cnt;
 
-        struct gnet_stats_basic         bstats;
+        struct gnet_stats_basic_packed          bstats;
         struct gnet_stats_queue         qstats;
         struct gnet_stats_rate_est      rate_est;
         struct list_head                alist;
diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index 362c2811b2d..dad0144423d 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -116,7 +116,7 @@ struct hfsc_class
         struct Qdisc_class_common cl_common;
         unsigned int    refcnt;         /* usage count */
 
-        struct gnet_stats_basic bstats;
+        struct gnet_stats_basic_packed bstats;
         struct gnet_stats_queue qstats;
         struct gnet_stats_rate_est rate_est;
         unsigned int    level;          /* class level in hierarchy */
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 88cd0262662..ec4d46399d5 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -74,7 +74,7 @@ enum htb_cmode {
 struct htb_class {
         struct Qdisc_class_common common;
         /* general class parameters */
-        struct gnet_stats_basic bstats;
+        struct gnet_stats_basic_packed bstats;
         struct gnet_stats_queue qstats;
         struct gnet_stats_rate_est rate_est;
         struct tc_htb_xstats xstats;    /* our special stats */