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authorAllan Stephens <allan.stephens@windriver.com>2010-08-17 11:00:06 +0000
committerDavid S. Miller <davem@davemloft.net>2010-08-17 17:31:53 -0700
commitf662c07058f7e6365ae65080d772f9122f6f50a9 (patch)
tree17a8ad3e5e432998d42b25891569f17025cf2b41 /net/tipc
parent35997e3157eba16c6124d440bdf9272087129b2a (diff)
downloadlinux-f662c07058f7e6365ae65080d772f9122f6f50a9.tar.bz2
tipc: correct problems with misleading flags returned using poll()
Prevent TIPC from incorrectly setting returned flags to poll() in the following cases: - an unconnected socket no longer indicates that it is always readable - an unconnected, connecting, or listening socket no longer indicates that it is always writable Signed-off-by: Allan Stephens <allan.stephens@windriver.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc')
-rw-r--r--net/tipc/socket.c61
1 files changed, 40 insertions, 21 deletions
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index b89c7b1a0d09..7b81fdd4f6d6 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -429,36 +429,55 @@ static int get_name(struct socket *sock, struct sockaddr *uaddr,
* 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!
+ *
+ * socket state flags set
+ * ------------ ---------
+ * unconnected no read flags
+ * no write flags
+ *
+ * connecting POLLIN/POLLRDNORM if ACK/NACK in rx queue
+ * no write flags
+ *
+ * connected POLLIN/POLLRDNORM if data in rx queue
+ * POLLOUT if port is not congested
+ *
+ * disconnecting POLLIN/POLLRDNORM/POLLHUP
+ * no write flags
+ *
+ * listening POLLIN if SYN in rx queue
+ * no write flags
+ *
+ * ready POLLIN/POLLRDNORM if data in rx queue
+ * [connectionless] POLLOUT (since port cannot be congested)
+ *
+ * IMPORTANT: The fact that a read or write operation is indicated does NOT
+ * imply that the operation will succeed, merely that it should be performed
+ * and will not block.
*/
static unsigned int poll(struct file *file, struct socket *sock,
poll_table *wait)
{
struct sock *sk = sock->sk;
- u32 mask;
+ u32 mask = 0;
poll_wait(file, sk_sleep(sk), 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;
+ switch ((int)sock->state) {
+ case SS_READY:
+ case SS_CONNECTED:
+ if (!tipc_sk_port(sk)->congested)
+ mask |= POLLOUT;
+ /* fall thru' */
+ case SS_CONNECTING:
+ case SS_LISTENING:
+ if (!skb_queue_empty(&sk->sk_receive_queue))
+ mask |= (POLLIN | POLLRDNORM);
+ break;
+ case SS_DISCONNECTING:
+ mask = (POLLIN | POLLRDNORM | POLLHUP);
+ break;
+ }
return mask;
}