list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
task->tk_waitqueue = queue;
queue->qlen++;
+ /* barrier matches the read in rpc_wake_up_task_queue_locked() */
+ smp_wmb();
rpc_set_queued(task);
dprintk("RPC: %5u added to queue %p \"%s\"\n",
/*
* Make an RPC task runnable.
*
- * Note: If the task is ASYNC, this must be called with
- * the spinlock held to protect the wait queue operation.
+ * Note: If the task is ASYNC, and is being made runnable after sitting on an
+ * rpc_wait_queue, this must be called with the queue spinlock held to protect
+ * the wait queue operation.
+ * Note the ordering of rpc_test_and_set_running() and rpc_clear_queued(),
+ * which is needed to ensure that __rpc_execute() doesn't loop (due to the
+ * lockless RPC_IS_QUEUED() test) before we've had a chance to test
+ * the RPC_TASK_RUNNING flag.
*/
static void rpc_make_runnable(struct rpc_task *task)
{
+ bool need_wakeup = !rpc_test_and_set_running(task);
+
rpc_clear_queued(task);
- if (rpc_test_and_set_running(task))
+ if (!need_wakeup)
return;
if (RPC_IS_ASYNC(task)) {
INIT_WORK(&task->u.tk_work, rpc_async_schedule);
*/
static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
{
- if (RPC_IS_QUEUED(task) && task->tk_waitqueue == queue)
- __rpc_do_wake_up_task(queue, task);
+ if (RPC_IS_QUEUED(task)) {
+ smp_rmb();
+ if (task->tk_waitqueue == queue)
+ __rpc_do_wake_up_task(queue, task);
+ }
}
/*
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;