SUNRPC: Fix an RCU dereference in xprt_reserve

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index e1e439ea177f..7f3a01a8cae7 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -1093,7 +1093,7 @@ EXPORT_SYMBOL_GPL(xprt_free);
  */
 void xprt_reserve(struct rpc_task *task)
 {
-        struct rpc_xprt *xprt = task->tk_xprt;
+        struct rpc_xprt *xprt;
 
         task->tk_status = 0;
         if (task->tk_rqstp != NULL)
@@ -1101,7 +1101,10 @@ void xprt_reserve(struct rpc_task *task)
 
         task->tk_timeout = 0;
         task->tk_status = -EAGAIN;
+        rcu_read_lock();
+        xprt = rcu_dereference(task->tk_client->cl_xprt);
         xprt->ops->alloc_slot(xprt, task);
+        rcu_read_unlock();
 }
 
 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)