txhash: Make rethinking txhash behavior configurable via sysctl

Add a per ns sysctl that controls the txhash rethink behavior:
net.core.txrehash. When enabled, the same behavior is retained,
when disabled, rethink is not performed. Sysctl is enabled by default.

Signed-off-by: Akhmat Karakotov <hmukos@yandex-team.ru>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/netns/core.h b/include/net/netns/core.h
index 552bc25..388244e 100644 (file)
--- a/include/net/netns/core.h
+++ b/include/net/netns/core.h
@@ -10,6 +10,7 @@ struct netns_core {
        struct ctl_table_header *sysctl_hdr;
 
        int     sysctl_somaxconn;
+       u8      sysctl_txrehash;
 
 #ifdef CONFIG_PROC_FS
        struct prot_inuse __percpu *prot_inuse;

diff --git a/include/net/sock.h b/include/net/sock.h
index ff9b508..0540e1b 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -587,6 +587,18 @@ static inline bool sk_user_data_is_nocopy(const struct sock *sk)
                           __tmp | SK_USER_DATA_NOCOPY);                \
 })
 
+static inline
+struct net *sock_net(const struct sock *sk)
+{
+       return read_pnet(&sk->sk_net);
+}
+
+static inline
+void sock_net_set(struct sock *sk, struct net *net)
+{
+       write_pnet(&sk->sk_net, net);
+}
+
 /*
  * SK_CAN_REUSE and SK_NO_REUSE on a socket mean that the socket is OK
  * or not whether his port will be reused by someone else. SK_FORCE_REUSE
@@ -2054,10 +2066,18 @@ static inline void sk_set_txhash(struct sock *sk)
 
 static inline bool sk_rethink_txhash(struct sock *sk)
 {
-       if (sk->sk_txhash) {
+       u8 rehash;
+
+       if (!sk->sk_txhash)
+               return false;
+
+       rehash = READ_ONCE(sock_net(sk)->core.sysctl_txrehash);
+
+       if (rehash) {
                sk_set_txhash(sk);
                return true;
        }
+
        return false;
 }
 
@@ -2704,18 +2724,6 @@ static inline void sk_eat_skb(struct sock *sk, struct sk_buff *skb)
        __kfree_skb(skb);
 }
 
-static inline
-struct net *sock_net(const struct sock *sk)
-{
-       return read_pnet(&sk->sk_net);
-}
-
-static inline
-void sock_net_set(struct sock *sk, struct net *net)
-{
-       write_pnet(&sk->sk_net, net);
-}
-
 static inline bool
 skb_sk_is_prefetched(struct sk_buff *skb)
 {

diff --git a/include/uapi/linux/socket.h b/include/uapi/linux/socket.h
index eb0a9a5..0accd61 100644 (file)
--- a/include/uapi/linux/socket.h
+++ b/include/uapi/linux/socket.h
@@ -31,4 +31,7 @@ struct __kernel_sockaddr_storage {
 
 #define SOCK_BUF_LOCK_MASK (SOCK_SNDBUF_LOCK | SOCK_RCVBUF_LOCK)
 
+#define SOCK_TXREHASH_DISABLED 0
+#define SOCK_TXREHASH_ENABLED  1
+
 #endif /* _UAPI_LINUX_SOCKET_H */

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index c53d9aa..8711350 100644 (file)
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -364,6 +364,8 @@ out_undo:
 static int __net_init net_defaults_init_net(struct net *net)
 {
        net->core.sysctl_somaxconn = SOMAXCONN;
+       net->core.sysctl_txrehash = SOCK_TXREHASH_ENABLED;
+
        return 0;
 }
 

diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 7b4d485..dbeb8ec 100644 (file)
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -593,6 +593,15 @@ static struct ctl_table netns_core_table[] = {
                .extra1         = SYSCTL_ZERO,
                .proc_handler   = proc_dointvec_minmax
        },
+       {
+               .procname       = "txrehash",
+               .data           = &init_net.core.sysctl_txrehash,
+               .maxlen         = sizeof(u8),
+               .mode           = 0644,
+               .extra1         = SYSCTL_ZERO,
+               .extra2         = SYSCTL_ONE,
+               .proc_handler   = proc_dou8vec_minmax,
+       },
        { }
 };
 
@@ -611,7 +620,7 @@ __setup("fb_tunnels=", fb_tunnels_only_for_init_net_sysctl_setup);
 
 static __net_init int sysctl_core_net_init(struct net *net)
 {
-       struct ctl_table *tbl;
+       struct ctl_table *tbl, *tmp;
 
        tbl = netns_core_table;
        if (!net_eq(net, &init_net)) {
@@ -619,7 +628,8 @@ static __net_init int sysctl_core_net_init(struct net *net)
                if (tbl == NULL)
                        goto err_dup;
 
-               tbl[0].data = &net->core.sysctl_somaxconn;
+               for (tmp = tbl; tmp->procname; tmp++)
+                       tmp->data += (char *)net - (char *)&init_net;
 
                /* Don't export any sysctls to unprivileged users */
                if (net->user_ns != &init_user_ns) {