Re: [REGRESSION] NFS is creating a hidden port (left over from xs_bind() )

From: Steven Rostedt
Date: Fri Jun 19 2015 - 17:56:54 EST


On Fri, 19 Jun 2015 16:30:18 -0400
Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> wrote:

> Steven, how about something like the following patch?

Building it now. Will let you know in a bit.


>
> 8<-----------------------------------------------------------------
> >From 9a0bcfdbdbc793eae1ed6d901a6396b6c66f9513 Mon Sep 17 00:00:00 2001
> From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> Date: Fri, 19 Jun 2015 16:17:57 -0400
> Subject: [PATCH] SUNRPC: Ensure we release the TCP socket once it has been
> closed
>
> This fixes a regression introduced by commit caf4ccd4e88cf2 ("SUNRPC:
> Make xs_tcp_close() do a socket shutdown rather than a sock_release").
> Prior to that commit, the autoclose feature would ensure that an
> idle connection would result in the socket being both disconnected and
> released, whereas now only gets disconnected.
>
> While the current behaviour is harmless, it does leave the port bound
> until either RPC traffic resumes or the RPC client is shut down.

Hmm, is this true? The port is bound, but the socket has been freed.
That is sk->sk_socket points to garbage. As my portlist.c module
verified.

It doesn't seem that anything can attach to that port again that I
know of. Is there a way to verify that something can attach to it again?

-- Steve


>
> Reported-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> net/sunrpc/xprt.c | 2 +-
> net/sunrpc/xprtsock.c | 8 ++++++--
> 2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
> index 3ca31f20b97c..ab5dd621ae0c 100644
> --- a/net/sunrpc/xprt.c
> +++ b/net/sunrpc/xprt.c
> @@ -611,8 +611,8 @@ static void xprt_autoclose(struct work_struct *work)
> struct rpc_xprt *xprt =
> container_of(work, struct rpc_xprt, task_cleanup);
>
> - xprt->ops->close(xprt);
> clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
> + xprt->ops->close(xprt);
> xprt_release_write(xprt, NULL);
> }
>
> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> index fda8ec8c74c0..75dcdadf0269 100644
> --- a/net/sunrpc/xprtsock.c
> +++ b/net/sunrpc/xprtsock.c
> @@ -634,10 +634,13 @@ static void xs_tcp_shutdown(struct rpc_xprt *xprt)
> struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
> struct socket *sock = transport->sock;
>
> - if (sock != NULL) {
> + if (sock == NULL)
> + return;
> + if (xprt_connected(xprt)) {
> kernel_sock_shutdown(sock, SHUT_RDWR);
> trace_rpc_socket_shutdown(xprt, sock);
> - }
> + } else
> + xs_reset_transport(transport);
> }
>
> /**
> @@ -786,6 +789,7 @@ static void xs_sock_mark_closed(struct rpc_xprt *xprt)
> xs_sock_reset_connection_flags(xprt);
> /* Mark transport as closed and wake up all pending tasks */
> xprt_disconnect_done(xprt);
> + xprt_force_disconnect(xprt);
> }
>
> /**

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