On Thu, May 10, 2018 at 06:12:53AM +0000, Vallish Vaidyeshwara wrote:
> Seemingly innocent optimization related to xs_bind() broke TCP port
> reuse by making non-reserved ephermal socket port to not be saved
> in "struct sock_xprt (srcport)". In case of non-reserved port,
> allocation happens as part of kernel_connect() inside of
> xs_tcp_finish_connecting(). kernel_connect() returns EINPROGRESS
> and the code skips stashing srcport in sock_xprt for reconnects.
> This affects servers DRC in case of network partition where client's
> RPC recovery would try reconnecting with a different port.
>
> Reported-by: Alexey Kuznetsov <alexeyk@xxxxxxxxxx>
> Reviewed-by: Jacob Strauss <jsstraus@xxxxxxxxxx>
> Reviewed-by: Alakesh Haloi <alakeshh@xxxxxxxxxx>
> Signed-off-by: Vallish Vaidyeshwara <vallish@xxxxxxxxxx>
> Fixes: 0f7a622c ("rpc: xs_bind - do not bind when requesting a random ephemeral port")
> ---
> net/sunrpc/xprtsock.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> index c8902f1..5bf75b3 100644
> --- a/net/sunrpc/xprtsock.c
> +++ b/net/sunrpc/xprtsock.c
> @@ -2393,9 +2393,11 @@ static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
> ret = kernel_connect(sock, xs_addr(xprt), xprt->addrlen, O_NONBLOCK);
> switch (ret) {
> case 0:
> - xs_set_srcport(transport, sock);
> /* fall through */
> case -EINPROGRESS:
> + /* Allocated port saved for reconnect */
> + xs_set_srcport(transport, sock);
> +
> /* SYN_SENT! */
> if (xprt->reestablish_timeout < XS_TCP_INIT_REEST_TO)
> xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
> --
> 2.7.3.AMZN
>
Hello Trond and Bruce,
This patch is actually restoring existing broken DRC behavior. Can you folks
let me know your feedback on this patch as well.
Thanks.
-Vallish
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