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Date: Wed, 26 Mar 2008 17:02:39 -0400
From: Allan Stephens <allan.stephens@...driver.com>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org, allan.stephens@...driver.com
Subject: [PATCH net-2.6.26] [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@...driver.com>
---
net/tipc/socket.c | 78 ++++++++++++++++++++++++----------------------------
1 files changed, 36 insertions(+), 42 deletions(-)
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index ae45df0..1b5fb61 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -102,44 +102,6 @@ static void sock_unlock(struct tipc_sock* tsock)
}
/**
- * 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+ * since the pollmask info is potentially out-of-date the moment this routine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;
}
/**
--
1.5.3.2
--
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