From: Allan Stephens <allan.stephens@windriver.com>
Date: Wed, 26 Mar 2008 23:48:21 +0000 (-0700)
Subject: [TIPC]: Cosmetic cleanup of TIPC polling logic
X-Git-Tag: MMI-PSA29.97-13-9~35608^2~307
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=9b674e82b73a61844967b32e1b4ecaf8eb9d1805;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git

[TIPC]: Cosmetic cleanup of TIPC polling logic

This patch eliminates an unnecessary poll-related routine
by merging it into TIPC's main polling routine, and updates
the comments associated with this code.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index ae45df060e3a..1b5fb6103ded 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -101,44 +101,6 @@ static void sock_unlock(struct tipc_sock* tsock)
 	spin_unlock_bh(tsock->p->lock);
 }
 
-/**
- * pollmask - determine the current set of poll() events for a socket
- * @sock: socket structure
- *
- * TIPC sets the returned events as follows:
- * a) POLLRDNORM and POLLIN are set if the socket's receive queue is non-empty
- *    or if a connection-oriented socket is does not have an active connection
- *    (i.e. a read operation will not block).
- * b) POLLOUT is set except when a socket's connection has been terminated
- *    (i.e. a write operation will not block).
- * c) POLLHUP is set when a socket's connection has been terminated.
- *
- * IMPORTANT: The fact that a read or write operation will not block does NOT
- * imply that the operation will succeed!
- *
- * Returns pollmask value
- */
-
-static u32 pollmask(struct socket *sock)
-{
-	u32 mask;
-
-	if ((skb_queue_len(&sock->sk->sk_receive_queue) != 0) ||
-	    (sock->state == SS_UNCONNECTED) ||
-	    (sock->state == SS_DISCONNECTING))
-		mask = (POLLRDNORM | POLLIN);
-	else
-		mask = 0;
-
-	if (sock->state == SS_DISCONNECTING)
-		mask |= POLLHUP;
-	else
-		mask |= POLLOUT;
-
-	return mask;
-}
-
-
 /**
  * advance_queue - discard first buffer in queue
  * @tsock: TIPC socket
@@ -390,15 +352,47 @@ static int get_name(struct socket *sock, struct sockaddr *uaddr,
  * @sock: socket for which to calculate the poll bits
  * @wait: ???
  *
- * Returns the pollmask
+ * Returns pollmask value
+ *
+ * COMMENTARY:
+ * It appears that the usual socket locking mechanisms are not useful here
+ * since the pollmask info is potentially out-of-date the moment this routine
+ * exits.  TCP and other protocols seem to rely on higher level poll routines
+ * to handle any preventable race conditions, so TIPC will do the same ...
+ *
+ * TIPC sets the returned events as follows:
+ * a) POLLRDNORM and POLLIN are set if the socket's receive queue is non-empty
+ *    or if a connection-oriented socket is does not have an active connection
+ *    (i.e. a read operation will not block).
+ * b) POLLOUT is set except when a socket's connection has been terminated
+ *    (i.e. a write operation will not block).
+ * c) POLLHUP is set when a socket's connection has been terminated.
+ *
+ * IMPORTANT: The fact that a read or write operation will not block does NOT
+ * imply that the operation will succeed!
  */
 
 static unsigned int poll(struct file *file, struct socket *sock,
 			 poll_table *wait)
 {
-	poll_wait(file, sock->sk->sk_sleep, wait);
-	/* NEED LOCK HERE? */
-	return pollmask(sock);
+	struct sock *sk = sock->sk;
+	u32 mask;
+
+	poll_wait(file, sk->sk_sleep, wait);
+
+	if (!skb_queue_empty(&sk->sk_receive_queue) ||
+	    (sock->state == SS_UNCONNECTED) ||
+	    (sock->state == SS_DISCONNECTING))
+		mask = (POLLRDNORM | POLLIN);
+	else
+		mask = 0;
+
+	if (sock->state == SS_DISCONNECTING)
+		mask |= POLLHUP;
+	else
+		mask |= POLLOUT;
+
+	return mask;
 }
 
 /**