> On Dec 17, 2018, at 3:05 PM, Trond Myklebust <trondmy@xxxxxxxxx> wrote:
>
> When the socket is closed, we need to call xprt_disconnect_done() in order
> to clean up the XPRT_WRITE_SPACE flag, and wake up the sleeping tasks.
>
> However, we also want to ensure that we don't wake them up before the socket
> is closed, since that would cause thundering herd issues with everyone
> piling up to retransmit before the TCP shutdown dance has completed.
> Only the task that holds XPRT_LOCKED needs to wake up early in order to
> allow the close to complete.
>
> Reported-by: Dave Wysochanski <dwysocha@xxxxxxxxxx>
> Reported-by: Scott Mayhew <smayhew@xxxxxxxxxx>
> Cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> net/sunrpc/xprt.c | 4 +++-
> net/sunrpc/xprtsock.c | 10 ++++------
> 2 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
> index ce927002862a..089e53a87379 100644
> --- a/net/sunrpc/xprt.c
> +++ b/net/sunrpc/xprt.c
> @@ -680,7 +680,9 @@ void xprt_force_disconnect(struct rpc_xprt *xprt)
> /* Try to schedule an autoclose RPC call */
> if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
> queue_work(xprtiod_workqueue, &xprt->task_cleanup);
> - xprt_wake_pending_tasks(xprt, -EAGAIN);
> + else if (xprt->snd_task)
> + rpc_wake_up_queued_task_set_status(&xprt->pending,
> + xprt->snd_task, -ENOTCONN);
> spin_unlock_bh(&xprt->transport_lock);
> }
> EXPORT_SYMBOL_GPL(xprt_force_disconnect);
Hrm, well I'm not sure xprt_connect_status is ready to deal with -ENOTCONN.
kworker/2:3-2342 [002] 3706.246289: rpc_task_wakeup: task:39992@5 flags=0001 state=001e status=-107 timeout=120000 queue=xprt_pending
kworker/0:7-2424 [000] 3706.246296: xprtrdma_reconnect: peer=[192.168.2.55]:20049 r_xprt=0xffff88886c465000
kworker/u25:28-2270 [004] 3706.246321: rpc_task_run_action: task:39992@5 flags=0001 state=001d status=-107 action=xprt_connect_status
kworker/u25:28-2270 [004] 3706.246323: rpc_task_run_action: task:39992@5 flags=0001 state=001d status=-5 action=call_connect_status
kworker/u25:28-2270 [004] 3706.246323: rpc_connect_status: task:39992@5 status=-5
kworker/u25:28-2270 [004] 3706.246324: rpc_task_run_action: task:39992@5 flags=0001 state=001d status=-5 action=rpc_exit_task
kworker/u25:28-2270 [004] 3706.246327: rpc_stats_latency: task:39992@5 xid=0x2f1ad350 nfsv3 READ backlog=0 rtt=0 execute=13028
kworker/u25:28-2270 [004] 3706.246333: xprtrdma_rpc_done: task:39992@5 req=0xffff88886a438000 rep=(nil)
static void xprt_connect_status(struct rpc_task *task)
{
switch (task->tk_status) {
case 0:
dprintk("RPC: %5u xprt_connect_status: connection established\n",
task->tk_pid);
break;
case -ECONNREFUSED:
case -ECONNRESET:
case -ECONNABORTED:
case -ENETUNREACH:
case -EHOSTUNREACH:
case -EPIPE:
case -EAGAIN:
dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
break;
case -ETIMEDOUT:
dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
"out\n", task->tk_pid);
break;
default:
dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
"server %s\n", task->tk_pid, -task->tk_status,
task->tk_rqstp->rq_xprt->servername);
task->tk_status = -EIO;
}
}
Maybe the wake-up status should remain -EAGAIN ?
> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> index 8a5e823e0b33..f0b3700cec95 100644
> --- a/net/sunrpc/xprtsock.c
> +++ b/net/sunrpc/xprtsock.c
> @@ -1217,6 +1217,8 @@ static void xs_reset_transport(struct sock_xprt *transport)
>
> trace_rpc_socket_close(xprt, sock);
> sock_release(sock);
> +
> + xprt_disconnect_done(xprt);
> }
>
> /**
> @@ -1237,8 +1239,6 @@ static void xs_close(struct rpc_xprt *xprt)
>
> xs_reset_transport(transport);
> xprt->reestablish_timeout = 0;
> -
> - xprt_disconnect_done(xprt);
> }
>
> static void xs_inject_disconnect(struct rpc_xprt *xprt)
> @@ -1489,8 +1489,6 @@ static void xs_tcp_state_change(struct sock *sk)
> &transport->sock_state))
> xprt_clear_connecting(xprt);
> clear_bit(XPRT_CLOSING, &xprt->state);
> - if (sk->sk_err)
> - xprt_wake_pending_tasks(xprt, -sk->sk_err);
> /* Trigger the socket release */
> xs_tcp_force_close(xprt);
> }
> @@ -2092,8 +2090,8 @@ static void xs_udp_setup_socket(struct work_struct *work)
> trace_rpc_socket_connect(xprt, sock, 0);
> status = 0;
> out:
> - xprt_unlock_connect(xprt, transport);
> xprt_clear_connecting(xprt);
> + xprt_unlock_connect(xprt, transport);
> xprt_wake_pending_tasks(xprt, status);
> }
>
> @@ -2329,8 +2327,8 @@ static void xs_tcp_setup_socket(struct work_struct *work)
> }
> status = -EAGAIN;
> out:
> - xprt_unlock_connect(xprt, transport);
> xprt_clear_connecting(xprt);
> + xprt_unlock_connect(xprt, transport);
> xprt_wake_pending_tasks(xprt, status);
> }
>
> --
> 2.19.2
>
--
Chuck Lever
