net: add socket option for low latency polling

adds a socket option for low latency polling.
This allows overriding the global sysctl value with a per-socket one.
Unexport sysctl_net_ll_poll since for now it's not needed in modules.

Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 20 insertions, 0 deletions

diff --git a/net/core/sock.c b/net/core/sock.c
index 788c0da5eed1..1e744b12fda3 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -913,6 +913,19 @@ set_rcvbuf:
                 sock_valbool_flag(sk, SOCK_SELECT_ERR_QUEUE, valbool);
                 break;
 
+#ifdef CONFIG_NET_LL_RX_POLL
+        case SO_LL:
+                /* allow unprivileged users to decrease the value */
+                if ((val > sk->sk_ll_usec) && !capable(CAP_NET_ADMIN))
+                        ret = -EPERM;
+                else {
+                        if (val < 0)
+                                ret = -EINVAL;
+                        else
+                                sk->sk_ll_usec = val;
+                }
+                break;
+#endif
         default:
                 ret = -ENOPROTOOPT;
                 break;
@@ -1170,6 +1183,12 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
                 v.val = sock_flag(sk, SOCK_SELECT_ERR_QUEUE);
                 break;
 
+#ifdef CONFIG_NET_LL_RX_POLL
+        case SO_LL:
+                v.val = sk->sk_ll_usec;
+                break;
+#endif
+
         default:
                 return -ENOPROTOOPT;
         }
@@ -2288,6 +2307,7 @@ void sock_init_data(struct socket *sock, struct sock *sk)
 
 #ifdef CONFIG_NET_LL_RX_POLL
         sk->sk_napi_id          =       0;
+        sk->sk_ll_usec          =       sysctl_net_ll_poll;
 #endif
 
         /*