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>

8 files changed, 20 insertions, 15 deletions

diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c
index 78e5bfc454ae..493775f4f2f1 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 c3d0ffeac243..8569310268ab 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 43f5676b1af4..d80b8192e0d4 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 2a8b83af7c47..ab82f145f689 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 23a167670fd5..d5798e17a832 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 7597fe146866..12b2fb04b29b 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 362c2811b2df..dad0144423da 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 88cd02626621..ec4d46399d59 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 */