4 files changed, 53 insertions, 16 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 822f020..507b5e8 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -555,7 +555,7 @@ EXPORT_SYMBOL_GPL(rpc_clone_client);
  * rpc_clone_client_set_auth - Clone an RPC client structure and set its auth
  *
  * @clnt: RPC client whose parameters are copied
- * @auth: security flavor for new client
+ * @flavor: security flavor for new client
  *
  * Returns a fresh RPC client or an ERR_PTR.
  */
@@ -610,11 +610,6 @@ EXPORT_SYMBOL_GPL(rpc_killall_tasks);
  */
 void rpc_shutdown_client(struct rpc_clnt *clnt)
 {
-	/*
-	 * To avoid deadlock, never call rpc_shutdown_client from a
-	 * workqueue context!
-	 */
-	WARN_ON_ONCE(current->flags & PF_WQ_WORKER);
 	might_sleep();
 
 	dprintk_rcu("RPC:       shutting down %s client for %s\n",
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index d17a704..fb20f25 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -98,9 +98,25 @@ __rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
 	list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
 }
 
+static void rpc_rotate_queue_owner(struct rpc_wait_queue *queue)
+{
+	struct list_head *q = &queue->tasks[queue->priority];
+	struct rpc_task *task;
+
+	if (!list_empty(q)) {
+		task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
+		if (task->tk_owner == queue->owner)
+			list_move_tail(&task->u.tk_wait.list, q);
+	}
+}
+
 static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 {
-	queue->priority = priority;
+	if (queue->priority != priority) {
+		/* Fairness: rotate the list when changing priority */
+		rpc_rotate_queue_owner(queue);
+		queue->priority = priority;
+	}
 }
 
 static void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
@@ -934,16 +950,35 @@ struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
 	return task;
 }
 
+/*
+ * rpc_free_task - release rpc task and perform cleanups
+ *
+ * Note that we free up the rpc_task _after_ rpc_release_calldata()
+ * in order to work around a workqueue dependency issue.
+ *
+ * Tejun Heo states:
+ * "Workqueue currently considers two work items to be the same if they're
+ * on the same address and won't execute them concurrently - ie. it
+ * makes a work item which is queued again while being executed wait
+ * for the previous execution to complete.
+ *
+ * If a work function frees the work item, and then waits for an event
+ * which should be performed by another work item and *that* work item
+ * recycles the freed work item, it can create a false dependency loop.
+ * There really is no reliable way to detect this short of verifying
+ * every memory free."
+ *
+ */
 static void rpc_free_task(struct rpc_task *task)
 {
-	const struct rpc_call_ops *tk_ops = task->tk_ops;
-	void *calldata = task->tk_calldata;
+	unsigned short tk_flags = task->tk_flags;
+
+	rpc_release_calldata(task->tk_ops, task->tk_calldata);
 
-	if (task->tk_flags & RPC_TASK_DYNAMIC) {
+	if (tk_flags & RPC_TASK_DYNAMIC) {
 		dprintk("RPC: %5u freeing task\n", task->tk_pid);
 		mempool_free(task, rpc_task_mempool);
 	}
-	rpc_release_calldata(tk_ops, calldata);
 }
 
 static void rpc_async_release(struct work_struct *work)
@@ -953,8 +988,7 @@ static void rpc_async_release(struct work_struct *work)
 
 static void rpc_release_resources_task(struct rpc_task *task)
 {
-	if (task->tk_rqstp)
-		xprt_release(task);
+	xprt_release(task);
 	if (task->tk_msg.rpc_cred) {
 		put_rpccred(task->tk_msg.rpc_cred);
 		task->tk_msg.rpc_cred = NULL;
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 0a148c9..0f679df 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -465,7 +465,7 @@ static int svc_udp_get_dest_address4(struct svc_rqst *rqstp,
 }
 
 /*
- * See net/ipv6/datagram.c : datagram_recv_ctl
+ * See net/ipv6/datagram.c : ip6_datagram_recv_ctl
  */
 static int svc_udp_get_dest_address6(struct svc_rqst *rqstp,
 				     struct cmsghdr *cmh)
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index bd462a5..33811db 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -1136,10 +1136,18 @@ static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
 void xprt_release(struct rpc_task *task)
 {
 	struct rpc_xprt	*xprt;
-	struct rpc_rqst	*req;
+	struct rpc_rqst	*req = task->tk_rqstp;
 
-	if (!(req = task->tk_rqstp))
+	if (req == NULL) {
+		if (task->tk_client) {
+			rcu_read_lock();
+			xprt = rcu_dereference(task->tk_client->cl_xprt);
+			if (xprt->snd_task == task)
+				xprt_release_write(xprt, task);
+			rcu_read_unlock();
+		}
 		return;
+	}
 
 	xprt = req->rq_xprt;
 	if (task->tk_ops->rpc_count_stats != NULL)