net: Introduce sk_tx_queue_mapping

Introduce sk_tx_queue_mapping; and functions that set, test and
get this value. Reset sk_tx_queue_mapping to -1 whenever the dst
cache is set/reset, and in socket alloc. Setting txq to -1 and
using valid txq=<0 to n-1> allows the tx path to use the value
of sk_tx_queue_mapping directly instead of subtracting 1 on every
tx.

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 30 insertions, 1 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 1364428f53f2..55de3bd719a5 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -107,6 +107,7 @@ struct net;
  *      @skc_node: main hash linkage for various protocol lookup tables
  *      @skc_nulls_node: main hash linkage for UDP/UDP-Lite protocol
  *      @skc_refcnt: reference count
+ *      @skc_tx_queue_mapping: tx queue number for this connection
  *      @skc_hash: hash value used with various protocol lookup tables
  *      @skc_family: network address family
  *      @skc_state: Connection state
@@ -128,6 +129,7 @@ struct sock_common {
                 struct hlist_nulls_node skc_nulls_node;
         };
         atomic_t                skc_refcnt;
+        int                     skc_tx_queue_mapping;
 
         unsigned int            skc_hash;
         unsigned short          skc_family;
@@ -215,6 +217,7 @@ struct sock {
 #define sk_node                 __sk_common.skc_node
 #define sk_nulls_node           __sk_common.skc_nulls_node
 #define sk_refcnt               __sk_common.skc_refcnt
+#define sk_tx_queue_mapping     __sk_common.skc_tx_queue_mapping
 
 #define sk_copy_start           __sk_common.skc_hash
 #define sk_hash                 __sk_common.skc_hash
@@ -1094,8 +1097,29 @@ static inline void sock_put(struct sock *sk)
 extern int sk_receive_skb(struct sock *sk, struct sk_buff *skb,
                           const int nested);
 
+static inline void sk_tx_queue_set(struct sock *sk, int tx_queue)
+{
+        sk->sk_tx_queue_mapping = tx_queue;
+}
+
+static inline void sk_tx_queue_clear(struct sock *sk)
+{
+        sk->sk_tx_queue_mapping = -1;
+}
+
+static inline int sk_tx_queue_get(const struct sock *sk)
+{
+        return sk->sk_tx_queue_mapping;
+}
+
+static inline bool sk_tx_queue_recorded(const struct sock *sk)
+{
+        return (sk && sk->sk_tx_queue_mapping >= 0);
+}
+
 static inline void sk_set_socket(struct sock *sk, struct socket *sock)
 {
+        sk_tx_queue_clear(sk);
         sk->sk_socket = sock;
 }
 
@@ -1152,6 +1176,7 @@ __sk_dst_set(struct sock *sk, struct dst_entry *dst)
 {
         struct dst_entry *old_dst;
 
+        sk_tx_queue_clear(sk);
         old_dst = sk->sk_dst_cache;
         sk->sk_dst_cache = dst;
         dst_release(old_dst);
@@ -1170,6 +1195,7 @@ __sk_dst_reset(struct sock *sk)
 {
         struct dst_entry *old_dst;
 
+        sk_tx_queue_clear(sk);
         old_dst = sk->sk_dst_cache;
         sk->sk_dst_cache = NULL;
         dst_release(old_dst);
diff --git a/net/core/sock.c b/net/core/sock.c
index 38713aa3faf2..934d9673f084 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -357,6 +357,7 @@ struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie)
         struct dst_entry *dst = sk->sk_dst_cache;
 
         if (dst && dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
+                sk_tx_queue_clear(sk);
                 sk->sk_dst_cache = NULL;
                 dst_release(dst);
                 return NULL;
@@ -953,7 +954,8 @@ static void sock_copy(struct sock *nsk, const struct sock *osk)
         void *sptr = nsk->sk_security;
 #endif
         BUILD_BUG_ON(offsetof(struct sock, sk_copy_start) !=
-                     sizeof(osk->sk_node) + sizeof(osk->sk_refcnt));
+                     sizeof(osk->sk_node) + sizeof(osk->sk_refcnt) +
+                     sizeof(osk->sk_tx_queue_mapping));
         memcpy(&nsk->sk_copy_start, &osk->sk_copy_start,
                osk->sk_prot->obj_size - offsetof(struct sock, sk_copy_start));
 #ifdef CONFIG_SECURITY_NETWORK
@@ -997,6 +999,7 @@ static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority,
 
                 if (!try_module_get(prot->owner))
                         goto out_free_sec;
+                sk_tx_queue_clear(sk);
         }
 
         return sk;