/*
* Add new request to a priority queue.
*/
-static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
+static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
+ struct rpc_task *task,
+ unsigned char queue_priority)
{
struct list_head *q;
struct rpc_task *t;
INIT_LIST_HEAD(&task->u.tk_wait.links);
- q = &queue->tasks[task->tk_priority];
- if (unlikely(task->tk_priority > queue->maxpriority))
+ q = &queue->tasks[queue_priority];
+ if (unlikely(queue_priority > queue->maxpriority))
q = &queue->tasks[queue->maxpriority];
list_for_each_entry(t, q, u.tk_wait.list) {
if (t->tk_owner == task->tk_owner) {
* improve overall performance.
* Everyone else gets appended to the queue to ensure proper FIFO behavior.
*/
-static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
+static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
+ struct rpc_task *task,
+ unsigned char queue_priority)
{
BUG_ON (RPC_IS_QUEUED(task));
if (RPC_IS_PRIORITY(queue))
- __rpc_add_wait_queue_priority(queue, task);
+ __rpc_add_wait_queue_priority(queue, task, queue_priority);
else if (RPC_IS_SWAPPER(task))
list_add(&task->u.tk_wait.list, &queue->tasks[0]);
else
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);
* NB: An RPC task will only receive interrupt-driven events as long
* as it's on a wait queue.
*/
-static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
- rpc_action action)
+static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
+ struct rpc_task *task,
+ rpc_action action,
+ unsigned char queue_priority)
{
dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
task->tk_pid, rpc_qname(q), jiffies);
- __rpc_add_wait_queue(q, task);
+ __rpc_add_wait_queue(q, task, queue_priority);
BUG_ON(task->tk_callback != NULL);
task->tk_callback = action;
* Protect the queue operations.
*/
spin_lock_bh(&q->lock);
- __rpc_sleep_on(q, task, action);
+ __rpc_sleep_on_priority(q, task, action, task->tk_priority);
spin_unlock_bh(&q->lock);
}
EXPORT_SYMBOL_GPL(rpc_sleep_on);
+void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
+ rpc_action action, int priority)
+{
+ /* We shouldn't ever put an inactive task to sleep */
+ BUG_ON(!RPC_IS_ACTIVATED(task));
+
+ /*
+ * Protect the queue operations.
+ */
+ spin_lock_bh(&q->lock);
+ __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
+ spin_unlock_bh(&q->lock);
+}
+
/**
* __rpc_do_wake_up_task - wake up a single rpc_task
* @queue: wait queue
*/
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);
+ }
}
/*
*/
void rpc_wake_up(struct rpc_wait_queue *queue)
{
- struct rpc_task *task, *next;
struct list_head *head;
spin_lock_bh(&queue->lock);
head = &queue->tasks[queue->maxpriority];
for (;;) {
- list_for_each_entry_safe(task, next, head, u.tk_wait.list)
+ while (!list_empty(head)) {
+ struct rpc_task *task;
+ task = list_first_entry(head,
+ struct rpc_task,
+ u.tk_wait.list);
rpc_wake_up_task_queue_locked(queue, task);
+ }
if (head == &queue->tasks[0])
break;
head--;
*/
void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
{
- struct rpc_task *task, *next;
struct list_head *head;
spin_lock_bh(&queue->lock);
head = &queue->tasks[queue->maxpriority];
for (;;) {
- list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
+ while (!list_empty(head)) {
+ struct rpc_task *task;
+ task = list_first_entry(head,
+ struct rpc_task,
+ u.tk_wait.list);
task->tk_status = status;
rpc_wake_up_task_queue_locked(queue, task);
}
task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
}
+static void
+rpc_init_task_statistics(struct rpc_task *task)
+{
+ /* Initialize retry counters */
+ task->tk_garb_retry = 2;
+ task->tk_cred_retry = 2;
+ task->tk_rebind_retry = 2;
+
+ /* starting timestamp */
+ task->tk_start = ktime_get();
+}
+
+static void
+rpc_reset_task_statistics(struct rpc_task *task)
+{
+ task->tk_timeouts = 0;
+ task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
+
+ rpc_init_task_statistics(task);
+}
+
/*
* Helper that calls task->tk_ops->rpc_call_done if it exists
*/
WARN_ON(RPC_ASSASSINATED(task));
/* Always release the RPC slot and buffer memory */
xprt_release(task);
+ rpc_reset_task_statistics(task);
}
}
}
static void rpc_async_schedule(struct work_struct *work)
{
+ current->flags |= PF_FSTRANS;
__rpc_execute(container_of(work, struct rpc_task, u.tk_work));
+ current->flags &= ~PF_FSTRANS;
}
/**
task->tk_calldata = task_setup_data->callback_data;
INIT_LIST_HEAD(&task->tk_task);
- /* Initialize retry counters */
- task->tk_garb_retry = 2;
- task->tk_cred_retry = 2;
- task->tk_rebind_retry = 2;
-
task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
task->tk_owner = current->tgid;
if (task->tk_ops->rpc_call_prepare != NULL)
task->tk_action = rpc_prepare_task;
- /* starting timestamp */
- task->tk_start = ktime_get();
+ rpc_init_task_statistics(task);
dprintk("RPC: new task initialized, procpid %u\n",
task_pid_nr(current));
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)
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;