Fix a second potential rpc_wakeup race...

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

4 files changed, 58 insertions, 44 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index dfeea4fea95..a323abc7ea8 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -466,10 +466,9 @@ int rpc_call_sync(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
 
 	BUG_ON(flags & RPC_TASK_ASYNC);
 
-	status = -ENOMEM;
 	task = rpc_new_task(clnt, flags, &rpc_default_ops, NULL);
 	if (task == NULL)
-		goto out;
+		return -ENOMEM;
 
 	/* Mask signals on RPC calls _and_ GSS_AUTH upcalls */
 	rpc_task_sigmask(task, &oldset);
@@ -478,15 +477,17 @@ int rpc_call_sync(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
 
 	/* Set up the call info struct and execute the task */
 	status = task->tk_status;
-	if (status == 0) {
-		atomic_inc(&task->tk_count);
-		status = rpc_execute(task);
-		if (status == 0)
-			status = task->tk_status;
+	if (status != 0) {
+		rpc_release_task(task);
+		goto out;
 	}
-	rpc_restore_sigmask(&oldset);
-	rpc_release_task(task);
+	atomic_inc(&task->tk_count);
+	status = rpc_execute(task);
+	if (status == 0)
+		status = task->tk_status;
+	rpc_put_task(task);
 out:
+	rpc_restore_sigmask(&oldset);
 	return status;
 }
 
diff --git a/net/sunrpc/pmap_clnt.c b/net/sunrpc/pmap_clnt.c
index e52afab413d..8d2e10fc3df 100644
--- a/net/sunrpc/pmap_clnt.c
+++ b/net/sunrpc/pmap_clnt.c
@@ -134,7 +134,7 @@ void rpc_getport(struct rpc_task *task)
 	child = rpc_run_task(pmap_clnt, RPC_TASK_ASYNC, &pmap_getport_ops, map);
 	if (IS_ERR(child))
 		goto bailout;
-	rpc_release_task(child);
+	rpc_put_task(child);
 
 	task->tk_xprt->stat.bind_count++;
 	return;
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index b57d4062d42..66d01365f3a 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -266,12 +266,28 @@ static int rpc_wait_bit_interruptible(void *word)
 	return 0;
 }
 
+static void rpc_set_active(struct rpc_task *task)
+{
+	if (test_and_set_bit(RPC_TASK_ACTIVE, &task->tk_runstate) != 0)
+		return;
+	spin_lock(&rpc_sched_lock);
+#ifdef RPC_DEBUG
+	task->tk_magic = RPC_TASK_MAGIC_ID;
+	task->tk_pid = rpc_task_id++;
+#endif
+	/* Add to global list of all tasks */
+	list_add_tail(&task->tk_task, &all_tasks);
+	spin_unlock(&rpc_sched_lock);
+}
+
 /*
  * Mark an RPC call as having completed by clearing the 'active' bit
  */
-static inline void rpc_mark_complete_task(struct rpc_task *task)
+static void rpc_mark_complete_task(struct rpc_task *task)
 {
-	rpc_clear_active(task);
+	smp_mb__before_clear_bit();
+	clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
+	smp_mb__after_clear_bit();
 	wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
 }
 
@@ -335,9 +351,6 @@ static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 		return;
 	}
 
-	/* Mark the task as being activated if so needed */
-	rpc_set_active(task);
-
 	__rpc_add_wait_queue(q, task);
 
 	BUG_ON(task->tk_callback != NULL);
@@ -348,6 +361,9 @@ static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 				rpc_action action, rpc_action timer)
 {
+	/* Mark the task as being activated if so needed */
+	rpc_set_active(task);
+
 	/*
 	 * Protect the queue operations.
 	 */
@@ -673,8 +689,6 @@ static int __rpc_execute(struct rpc_task *task)
 	}
 
 	dprintk("RPC: %4d, return %d, status %d\n", task->tk_pid, status, task->tk_status);
-	/* Wake up anyone who is waiting for task completion */
-	rpc_mark_complete_task(task);
 	/* Release all resources associated with the task */
 	rpc_release_task(task);
 	return status;
@@ -788,15 +802,6 @@ void rpc_init_task(struct rpc_task *task, struct rpc_clnt *clnt, int flags, cons
 			task->tk_flags |= RPC_TASK_NOINTR;
 	}
 
-#ifdef RPC_DEBUG
-	task->tk_magic = RPC_TASK_MAGIC_ID;
-	task->tk_pid = rpc_task_id++;
-#endif
-	/* Add to global list of all tasks */
-	spin_lock(&rpc_sched_lock);
-	list_add_tail(&task->tk_task, &all_tasks);
-	spin_unlock(&rpc_sched_lock);
-
 	BUG_ON(task->tk_ops == NULL);
 
 	/* starting timestamp */
@@ -849,16 +854,35 @@ cleanup:
 	goto out;
 }
 
-void rpc_release_task(struct rpc_task *task)
+
+void rpc_put_task(struct rpc_task *task)
 {
 	const struct rpc_call_ops *tk_ops = task->tk_ops;
 	void *calldata = task->tk_calldata;
 
+	if (!atomic_dec_and_test(&task->tk_count))
+		return;
+	/* Release resources */
+	if (task->tk_rqstp)
+		xprt_release(task);
+	if (task->tk_msg.rpc_cred)
+		rpcauth_unbindcred(task);
+	if (task->tk_client) {
+		rpc_release_client(task->tk_client);
+		task->tk_client = NULL;
+	}
+	if (task->tk_flags & RPC_TASK_DYNAMIC)
+		rpc_free_task(task);
+	if (tk_ops->rpc_release)
+		tk_ops->rpc_release(calldata);
+}
+EXPORT_SYMBOL(rpc_put_task);
+
+void rpc_release_task(struct rpc_task *task)
+{
 #ifdef RPC_DEBUG
 	BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 #endif
-	if (!atomic_dec_and_test(&task->tk_count))
-		return;
 	dprintk("RPC: %4d release task\n", task->tk_pid);
 
 	/* Remove from global task list */
@@ -871,23 +895,13 @@ void rpc_release_task(struct rpc_task *task)
 	/* Synchronously delete any running timer */
 	rpc_delete_timer(task);
 
-	/* Release resources */
-	if (task->tk_rqstp)
-		xprt_release(task);
-	if (task->tk_msg.rpc_cred)
-		rpcauth_unbindcred(task);
-	if (task->tk_client) {
-		rpc_release_client(task->tk_client);
-		task->tk_client = NULL;
-	}
-
 #ifdef RPC_DEBUG
 	task->tk_magic = 0;
 #endif
-	if (task->tk_flags & RPC_TASK_DYNAMIC)
-		rpc_free_task(task);
-	if (tk_ops->rpc_release)
-		tk_ops->rpc_release(calldata);
+	/* Wake up anyone who is waiting for task completion */
+	rpc_mark_complete_task(task);
+
+	rpc_put_task(task);
 }
 
 /**
diff --git a/net/sunrpc/sunrpc_syms.c b/net/sunrpc/sunrpc_syms.c
index 192dff5dabc..faaf81e9772 100644
--- a/net/sunrpc/sunrpc_syms.c
+++ b/net/sunrpc/sunrpc_syms.c
@@ -33,7 +33,6 @@ EXPORT_SYMBOL(rpciod_down);
 EXPORT_SYMBOL(rpciod_up);
 EXPORT_SYMBOL(rpc_new_task);
 EXPORT_SYMBOL(rpc_wake_up_status);
-EXPORT_SYMBOL(rpc_release_task);
 
 /* RPC client functions */
 EXPORT_SYMBOL(rpc_clone_client);