Oops. config error. please ignore that.
On Thu, Sep 29, 2016 at 2:52 PM, Olga Kornievskaia <aglo@xxxxxxxxx> wrote:
> Hi Trond,
>
> Have you tried nfsv3 mount with this patch?
>
> Currently with this patch upstream kernel hangs.
>
> On Mon, Feb 9, 2015 at 5:48 PM, Trond Myklebust
> <trond.myklebust@xxxxxxxxxxxxxxx> wrote:
>> The socket lock is currently held by the task that is requesting the
>> connection be established. While that is efficient in the case where
>> the connection happens quickly, it is racy in the case where it doesn't.
>> What we really want is for the connect helper to be able to block access
>> to the socket while it is being set up.
>>
>> This patch does so by arranging to transfer the socket lock from the
>> task that is requesting the connect attempt, and then releasing that
>> lock once everything is done.
>> This scheme also gives us automatic protection against collisions with
>> the RPC close code, so we can kill the cancel_delayed_work_sync()
>> call in xs_close().
>>
>> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
>> ---
>> include/linux/sunrpc/xprt.h | 3 +++
>> net/sunrpc/xprt.c | 37 +++++++++++++++++++++++++++++++++----
>> net/sunrpc/xprtsock.c | 7 +++++--
>> 3 files changed, 41 insertions(+), 6 deletions(-)
>>
>> diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
>> index 9d27ac45b909..2926e618dbc6 100644
>> --- a/include/linux/sunrpc/xprt.h
>> +++ b/include/linux/sunrpc/xprt.h
>> @@ -347,6 +347,9 @@ void xprt_force_disconnect(struct rpc_xprt *xprt);
>> void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie);
>> int xs_swapper(struct rpc_xprt *xprt, int enable);
>>
>> +bool xprt_lock_connect(struct rpc_xprt *, struct rpc_task *, void *);
>> +void xprt_unlock_connect(struct rpc_xprt *, void *);
>> +
>> /*
>> * Reserved bit positions in xprt->state
>> */
>> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
>> index ebbefad21a37..ff3574df8344 100644
>> --- a/net/sunrpc/xprt.c
>> +++ b/net/sunrpc/xprt.c
>> @@ -690,6 +690,37 @@ out_abort:
>> spin_unlock(&xprt->transport_lock);
>> }
>>
>> +bool xprt_lock_connect(struct rpc_xprt *xprt,
>> + struct rpc_task *task,
>> + void *cookie)
>> +{
>> + bool ret = false;
>> +
>> + spin_lock_bh(&xprt->transport_lock);
>> + if (!test_bit(XPRT_LOCKED, &xprt->state))
>> + goto out;
>> + if (xprt->snd_task != task)
>> + goto out;
>> + xprt->snd_task = cookie;
>> + ret = true;
>> +out:
>> + spin_unlock_bh(&xprt->transport_lock);
>> + return ret;
>> +}
>> +
>> +void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
>> +{
>> + spin_lock_bh(&xprt->transport_lock);
>> + if (xprt->snd_task != cookie)
>> + goto out;
>> + if (!test_bit(XPRT_LOCKED, &xprt->state))
>> + goto out;
>> + xprt->snd_task =NULL;
>> + xprt->ops->release_xprt(xprt, NULL);
>> +out:
>> + spin_unlock_bh(&xprt->transport_lock);
>> +}
>> +
>> /**
>> * xprt_connect - schedule a transport connect operation
>> * @task: RPC task that is requesting the connect
>> @@ -712,9 +743,7 @@ void xprt_connect(struct rpc_task *task)
>> if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
>> xprt->ops->close(xprt);
>>
>> - if (xprt_connected(xprt))
>> - xprt_release_write(xprt, task);
>> - else {
>> + if (!xprt_connected(xprt)) {
>> task->tk_rqstp->rq_bytes_sent = 0;
>> task->tk_timeout = task->tk_rqstp->rq_timeout;
>> rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
>> @@ -726,6 +755,7 @@ void xprt_connect(struct rpc_task *task)
>> xprt->stat.connect_start = jiffies;
>> xprt->ops->connect(xprt, task);
>> }
>> + xprt_release_write(xprt, task);
>> }
>>
>> static void xprt_connect_status(struct rpc_task *task)
>> @@ -758,7 +788,6 @@ static void xprt_connect_status(struct rpc_task *task)
>> dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
>> "server %s\n", task->tk_pid, -task->tk_status,
>> xprt->servername);
>> - xprt_release_write(xprt, task);
>> task->tk_status = -EIO;
>> }
>> }
>> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
>> index 0fa7ed93dc20..e57d8ed2c4d8 100644
>> --- a/net/sunrpc/xprtsock.c
>> +++ b/net/sunrpc/xprtsock.c
>> @@ -852,8 +852,6 @@ static void xs_close(struct rpc_xprt *xprt)
>>
>> dprintk("RPC: xs_close xprt %p\n", xprt);
>>
>> - cancel_delayed_work_sync(&transport->connect_worker);
>> -
>> xs_reset_transport(transport);
>> xprt->reestablish_timeout = 0;
>>
>> @@ -2101,6 +2099,7 @@ 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_wake_pending_tasks(xprt, status);
>> }
>> @@ -2286,6 +2285,7 @@ static void xs_tcp_setup_socket(struct work_struct *work)
>> case 0:
>> case -EINPROGRESS:
>> case -EALREADY:
>> + xprt_unlock_connect(xprt, transport);
>> xprt_clear_connecting(xprt);
>> return;
>> case -EINVAL:
>> @@ -2303,6 +2303,7 @@ static void xs_tcp_setup_socket(struct work_struct *work)
>> out_eagain:
>> status = -EAGAIN;
>> out:
>> + xprt_unlock_connect(xprt, transport);
>> xprt_clear_connecting(xprt);
>> xprt_wake_pending_tasks(xprt, status);
>> }
>> @@ -2325,6 +2326,8 @@ static void xs_connect(struct rpc_xprt *xprt, struct rpc_task *task)
>> {
>> struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
>>
>> + WARN_ON_ONCE(!xprt_lock_connect(xprt, task, transport));
>> +
>> if (transport->sock != NULL && !RPC_IS_SOFTCONN(task)) {
>> dprintk("RPC: xs_connect delayed xprt %p for %lu "
>> "seconds\n",
>> --
>> 2.1.0
>>
>> --
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