On Wed, Aug 30, 2023 at 02:14:21PM +1000, NeilBrown wrote:
>
> sunrpc/xprtsock.c has an XPRT_SOCK_CONNECTING flag which is used only on
> TCP xprts while connecting.
> The purpose appears to be to protect against delayed TCP_CLOSE
> transitions from calling xprt_clear_connecting() asynchronously.
>
> Normally it is set after calling xprt_set_connecting() and before
> calling kernel_connect(), and cleared before calling
> xprt_clear_connecting(). It is only tested on a state change to
> TCP_CLOSE.
>
> Unfortunately there is one time that it is *not* explicitly cleared
> before calling xprt_clear_connecting(). I don't know what all to
> consequences of this are. It may well relate to the underlying problem
> that resulted in
> Commit 3be232f11a3c ("SUNRPC: Prevent immediate close+reconnect")
> That close/reconnect pattern can happen if a TCP_CLOSE is seen
> while XPRT_SOCK_CONNECTING is set but shouldn't be.
>
> local and udp connections don't use XPRT_SOCK_CONNECTING.
>
> tcp_tls connection don't *appear* to set the flag but do sometimes clear
> it.
Note: At this early stage, don't assume that code is 100% complete
and consistent. ;-)
> I don't understand all of the tls code, so I added what might be a
> missing clear of XPRT_SOCK_CONNECTING there.
>
> Signed-off-by: NeilBrown <neilb@xxxxxxx>
> ---
> net/sunrpc/xprtsock.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> index 268a2cc61acd..9426b1051b09 100644
> --- a/net/sunrpc/xprtsock.c
> +++ b/net/sunrpc/xprtsock.c
> @@ -2425,6 +2425,7 @@ static void xs_tcp_setup_socket(struct work_struct *work)
> */
> xprt_wake_pending_tasks(xprt, status);
> xs_tcp_force_close(xprt);
> + clear_bit(XPRT_SOCK_CONNECTING, &transport->sock_state);
> out:
> xprt_clear_connecting(xprt);
> out_unlock:
> @@ -2689,6 +2690,7 @@ static void xs_tcp_tls_setup_socket(struct work_struct *work)
> */
> xprt_wake_pending_tasks(upper_xprt, status);
> xs_tcp_force_close(upper_xprt);
> + clear_bit(XPRT_SOCK_CONNECTING, &upper_transport->sock_state);
> xprt_clear_connecting(upper_xprt);
> goto out_unlock;
> }
> --
> 2.41.0
>
--
Chuck Lever
