net: rename low latency sockets functions to busy poll

Rename functions in include/net/ll_poll.h to busy wait.
Clarify documentation about expected power use increase.
Rename POLL_LL to POLL_BUSY_LOOP.
Add need_resched() testing to poll/select busy loops.

Note, that in select and poll can_busy_poll is dynamic and is
updated continuously to reflect the existence of supported
sockets with valid queue information.

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

3 files changed, 11 insertions, 10 deletions

diff --git a/net/core/datagram.c b/net/core/datagram.c
index 9cbaba98ce4c..6e9ab31e457e 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -208,7 +208,8 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
                 }
                 spin_unlock_irqrestore(&queue->lock, cpu_flags);
 
-                if (sk_valid_ll(sk) && sk_poll_ll(sk, flags & MSG_DONTWAIT))
+                if (sk_can_busy_loop(sk) &&
+                    sk_busy_loop(sk, flags & MSG_DONTWAIT))
                         continue;
 
                 /* User doesn't want to wait */
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 46ed9afd1f5e..15cbfa94bd8e 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1554,9 +1554,9 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
         struct sk_buff *skb;
         u32 urg_hole = 0;
 
-        if (sk_valid_ll(sk) && skb_queue_empty(&sk->sk_receive_queue)
-            && (sk->sk_state == TCP_ESTABLISHED))
-                sk_poll_ll(sk, nonblock);
+        if (sk_can_busy_loop(sk) && skb_queue_empty(&sk->sk_receive_queue) &&
+            (sk->sk_state == TCP_ESTABLISHED))
+                sk_busy_loop(sk, nonblock);
 
         lock_sock(sk);
 
diff --git a/net/socket.c b/net/socket.c
index 4da14cbd49b6..45afa648364a 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1148,7 +1148,7 @@ EXPORT_SYMBOL(sock_create_lite);
 /* No kernel lock held - perfect */
 static unsigned int sock_poll(struct file *file, poll_table *wait)
 {
-        unsigned int ll_flag = 0;
+        unsigned int busy_flag = 0;
         struct socket *sock;
 
         /*
@@ -1156,16 +1156,16 @@ static unsigned int sock_poll(struct file *file, poll_table *wait)
          */
         sock = file->private_data;
 
-        if (sk_valid_ll(sock->sk)) {
+        if (sk_can_busy_loop(sock->sk)) {
                 /* this socket can poll_ll so tell the system call */
-                ll_flag = POLL_LL;
+                busy_flag = POLL_BUSY_LOOP;
 
                 /* once, only if requested by syscall */
-                if (wait && (wait->_key & POLL_LL))
-                        sk_poll_ll(sock->sk, 1);
+                if (wait && (wait->_key & POLL_BUSY_LOOP))
+                        sk_busy_loop(sock->sk, 1);
         }
 
-        return ll_flag | sock->ops->poll(file, sock, wait);
+        return busy_flag | sock->ops->poll(file, sock, wait);
 }
 
 static int sock_mmap(struct file *file, struct vm_area_struct *vma)