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SUNRPC: Add a new helper rpc_wake_up_queued_task()
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In all cases where we currently use rpc_wake_up_task(), we almost always
know on which waitqueue the rpc_task is actually sleeping. This will allows
us to simplify the queue locking in a future patch.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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Trond Myklebust authored and Trond Myklebust committed Feb 26, 2008
1 parent fde95c7 commit 96ef13b
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Showing 3 changed files with 34 additions and 36 deletions.
4 changes: 3 additions & 1 deletion include/linux/sunrpc/sched.h
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,6 @@ struct rpc_wait_queue;
struct rpc_wait {
struct list_head list; /* wait queue links */
struct list_head links; /* Links to related tasks */
struct rpc_wait_queue * rpc_waitq; /* RPC wait queue we're on */
};

/*
Expand Down Expand Up @@ -80,6 +79,7 @@ struct rpc_task {
struct workqueue_struct *tk_workqueue; /* Normally rpciod, but could
* be any workqueue
*/
struct rpc_wait_queue *tk_waitqueue; /* RPC wait queue we're on */
union {
struct work_struct tk_work; /* Async task work queue */
struct rpc_wait tk_wait; /* RPC wait */
Expand Down Expand Up @@ -233,6 +233,8 @@ void rpc_init_wait_queue(struct rpc_wait_queue *, const char *);
void rpc_sleep_on(struct rpc_wait_queue *, struct rpc_task *,
rpc_action action, rpc_action timer);
void rpc_wake_up_task(struct rpc_task *);
void rpc_wake_up_queued_task(struct rpc_wait_queue *,
struct rpc_task *);
void rpc_wake_up(struct rpc_wait_queue *);
struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *);
void rpc_wake_up_status(struct rpc_wait_queue *, int);
Expand Down
2 changes: 1 addition & 1 deletion net/sunrpc/clnt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1535,7 +1535,7 @@ void rpc_show_tasks(void)
proc = -1;

if (RPC_IS_QUEUED(t))
rpc_waitq = rpc_qname(t->u.tk_wait.rpc_waitq);
rpc_waitq = rpc_qname(t->tk_waitqueue);

printk("%5u %04d %04x %6d %8p %6d %8p %8ld %8s %8p %8p\n",
t->tk_pid, proc,
Expand Down
64 changes: 30 additions & 34 deletions net/sunrpc/sched.c
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Original file line number Diff line number Diff line change
Expand Up @@ -148,7 +148,7 @@ static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *
list_add(&task->u.tk_wait.list, &queue->tasks[0]);
else
list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
task->u.tk_wait.rpc_waitq = queue;
task->tk_waitqueue = queue;
queue->qlen++;
rpc_set_queued(task);

Expand All @@ -175,11 +175,8 @@ static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
* Remove request from queue.
* Note: must be called with spin lock held.
*/
static void __rpc_remove_wait_queue(struct rpc_task *task)
static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
{
struct rpc_wait_queue *queue;
queue = task->u.tk_wait.rpc_waitq;

if (RPC_IS_PRIORITY(queue))
__rpc_remove_wait_queue_priority(task);
else
Expand Down Expand Up @@ -364,11 +361,12 @@ EXPORT_SYMBOL_GPL(rpc_sleep_on);

/**
* __rpc_do_wake_up_task - wake up a single rpc_task
* @queue: wait queue
* @task: task to be woken up
*
* Caller must hold queue->lock, and have cleared the task queued flag.
*/
static void __rpc_do_wake_up_task(struct rpc_task *task)
static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
{
dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
task->tk_pid, jiffies);
Expand All @@ -383,44 +381,46 @@ static void __rpc_do_wake_up_task(struct rpc_task *task)
}

__rpc_disable_timer(task);
__rpc_remove_wait_queue(task);
__rpc_remove_wait_queue(queue, task);

rpc_make_runnable(task);

dprintk("RPC: __rpc_wake_up_task done\n");
}

/*
* Wake up the specified task
* Wake up a queued task while the queue lock is being held
*/
static void __rpc_wake_up_task(struct rpc_task *task)
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)
return;
if (rpc_start_wakeup(task)) {
if (RPC_IS_QUEUED(task))
__rpc_do_wake_up_task(task);
__rpc_do_wake_up_task(queue, task);
rpc_finish_wakeup(task);
}
}

/*
* Wake up the specified task
* Wake up a task on a specific queue
*/
void rpc_wake_up_task(struct rpc_task *task)
void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
{
rcu_read_lock_bh();
if (rpc_start_wakeup(task)) {
if (RPC_IS_QUEUED(task)) {
struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;

/* Note: we're already in a bh-safe context */
spin_lock(&queue->lock);
__rpc_do_wake_up_task(task);
spin_unlock(&queue->lock);
}
rpc_finish_wakeup(task);
}
spin_lock(&queue->lock);
rpc_wake_up_task_queue_locked(queue, task);
spin_unlock(&queue->lock);
rcu_read_unlock_bh();
}
EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);

/*
* Wake up the specified task
*/
void rpc_wake_up_task(struct rpc_task *task)
{
rpc_wake_up_queued_task(task->tk_waitqueue, task);
}
EXPORT_SYMBOL_GPL(rpc_wake_up_task);

/*
Expand Down Expand Up @@ -471,7 +471,7 @@ static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queu
new_owner:
rpc_set_waitqueue_owner(queue, task->tk_owner);
out:
__rpc_wake_up_task(task);
rpc_wake_up_task_queue_locked(queue, task);
return task;
}

Expand All @@ -490,7 +490,7 @@ struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
task = __rpc_wake_up_next_priority(queue);
else {
task_for_first(task, &queue->tasks[0])
__rpc_wake_up_task(task);
rpc_wake_up_task_queue_locked(queue, task);
}
spin_unlock(&queue->lock);
rcu_read_unlock_bh();
Expand All @@ -515,7 +515,7 @@ void rpc_wake_up(struct rpc_wait_queue *queue)
head = &queue->tasks[queue->maxpriority];
for (;;) {
list_for_each_entry_safe(task, next, head, u.tk_wait.list)
__rpc_wake_up_task(task);
rpc_wake_up_task_queue_locked(queue, task);
if (head == &queue->tasks[0])
break;
head--;
Expand Down Expand Up @@ -543,7 +543,7 @@ void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
for (;;) {
list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
task->tk_status = status;
__rpc_wake_up_task(task);
rpc_wake_up_task_queue_locked(queue, task);
}
if (head == &queue->tasks[0])
break;
Expand All @@ -562,22 +562,18 @@ static void rpc_run_timer(unsigned long ptr)
struct rpc_task *task = (struct rpc_task *)ptr;
void (*callback)(struct rpc_task *);

if (!rpc_start_wakeup(task))
goto out;
if (RPC_IS_QUEUED(task)) {
struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
struct rpc_wait_queue *queue = task->tk_waitqueue;
callback = task->tk_timeout_fn;

dprintk("RPC: %5u running timer\n", task->tk_pid);
if (callback != NULL)
callback(task);
/* Note: we're already in a bh-safe context */
spin_lock(&queue->lock);
__rpc_do_wake_up_task(task);
rpc_wake_up_task_queue_locked(queue, task);
spin_unlock(&queue->lock);
}
rpc_finish_wakeup(task);
out:
smp_mb__before_clear_bit();
clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
smp_mb__after_clear_bit();
Expand Down

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