[PATCH 005/112] SUNRPC: Fix a race in xs_tcp_state_change()

[Trond Myklebust]

When scheduling the autoclose RPC call, we want to ensure that we don't
race against the test_bit() call in xprt_clear_locked().

Signed-off-by: Trond Myklebust <[EMAIL PROTECTED]>
---

 include/linux/sunrpc/xprt.h |    1 +
 net/sunrpc/xprt.c           |   20 ++++++++++++++++++++
 net/sunrpc/xprtsock.c       |    5 +----
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 30b17b3..6f524a9 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -246,6 +246,7 @@ struct rpc_rqst *   xprt_lookup_rqst(struct rpc_xprt *xprt, 
__be32 xid);
 void                   xprt_complete_rqst(struct rpc_task *task, int copied);
 void                   xprt_release_rqst_cong(struct rpc_task *task);
 void                   xprt_disconnect(struct rpc_xprt *xprt);
+void                   xprt_force_disconnect(struct rpc_xprt *xprt);
 
 /*
  * Reserved bit positions in xprt->state
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index cd641c8..8575bf4 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -570,6 +570,7 @@ static void xprt_autoclose(struct work_struct *work)
 
        xprt_disconnect(xprt);
        xprt->ops->close(xprt);
+       clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
        xprt_release_write(xprt, NULL);
 }
 
@@ -588,6 +589,25 @@ void xprt_disconnect(struct rpc_xprt *xprt)
 }
 EXPORT_SYMBOL_GPL(xprt_disconnect);
 
+/**
+ * xprt_force_disconnect - force a transport to disconnect
+ * @xprt: transport to disconnect
+ *
+ */
+void xprt_force_disconnect(struct rpc_xprt *xprt)
+{
+       /* Don't race with the test_bit() in xprt_clear_locked() */
+       spin_lock_bh(&xprt->transport_lock);
+       set_bit(XPRT_CLOSE_WAIT, &xprt->state);
+       /* Try to schedule an autoclose RPC call */
+       if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
+               queue_work(rpciod_workqueue, &xprt->task_cleanup);
+       else if (xprt->snd_task != NULL)
+               rpc_wake_up_task(xprt->snd_task);
+       spin_unlock_bh(&xprt->transport_lock);
+}
+EXPORT_SYMBOL_GPL(xprt_force_disconnect);
+
 static void
 xprt_init_autodisconnect(unsigned long data)
 {
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 2f630a5..29c5e6c 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1118,10 +1118,7 @@ static void xs_tcp_state_change(struct sock *sk)
        case TCP_SYN_RECV:
                break;
        case TCP_CLOSE_WAIT:
-               /* Try to schedule an autoclose RPC calls */
-               set_bit(XPRT_CLOSE_WAIT, &xprt->state);
-               if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
-                       queue_work(rpciod_workqueue, &xprt->task_cleanup);
+               xprt_force_disconnect(xprt);
        default:
                xprt_disconnect(xprt);
        }
-
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