Re: [tipc-discussion] [PATCH v2] tipc: return POLLOUT for sockets in an unconnected state

[Paul G. <pau...@wi...>]

On 12-10-16 03:22 AM, eri...@er... wrote:
> From: Erik Hugne <eri...@er...>
> 
> If an implied connect is attempted on a nonblocking STREAM/SEQPACKET
> socket during link congestion, the connect message will be discarded
> and sendmsg will return EAGAIN.
> This is normal behavior, and the application is expected to poll
> the socket until POLLOUT is set, after which the connection
> attempt can be retried.
> However, the POLLOUT flag is never set for unconnected sockets
> and poll() always returns a zero mask.
> The application is then left without a trigger for when
> it can make another attempt at sending the message.
> 
> The solution is to check if we're poll'ing on an unconnected socket
> and set the POLLOUT flag if the TIPC port owned by this socket
> is not congested.
> The TIPC ports waiting on a specific link will be marked as
> 'not congested' when the link congestion have abated.

This seems much more informative and demonstrates a clearer
understanding of what is going on.  Lets get rid of the random
insertion of carriage returns after each sentence and reserve
their use for meaningful newlines between paragraphs, and
fix "poll'ing" to be just "polling" though.

Thanks,
Paul.
--

> 
> Signed-off-by: Erik Hugne <eri...@er...>
> ---
>  net/tipc/socket.c |    6 +++++-
>  1 files changed, 5 insertions(+), 1 deletions(-)
> 
> diff --git a/net/tipc/socket.c b/net/tipc/socket.c
> index 09dc5b9..e9a9dfd 100644
> --- a/net/tipc/socket.c
> +++ b/net/tipc/socket.c
> @@ -407,7 +407,7 @@ static int get_name(struct socket *sock, struct sockaddr *uaddr,
>   * socket state		flags set
>   * ------------		---------
>   * unconnected		no read flags
> - *			no write flags
> + *			POLLOUT if port is not congested
>   *
>   * connecting		POLLIN/POLLRDNORM if ACK/NACK in rx queue
>   *			no write flags
> @@ -437,6 +437,10 @@ static unsigned int poll(struct file *file, struct socket *sock,
>  	poll_wait(file, sk_sleep(sk), wait);
>  
>  	switch ((int)sock->state) {
> +	case SS_UNCONNECTED:
> +		if (!tipc_sk_port(sk)->congested)
> +			mask |= POLLOUT;
> +		break;
>  	case SS_READY:
>  	case SS_CONNECTED:
>  		if (!tipc_sk_port(sk)->congested)
>