Commit 7e0a0e38 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

SUNRPC: Replace the queue timer with a delayed work function 



The queue timer function, which walks the RPC queue in order to locate
candidates for waking up is one of the current constraints against
removing the bh-safe queue spin locks. Replace it with a delayed
work queue, so that we can do the actual rpc task wake ups from an
ordinary process context.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 44942b4e

include/linux/sunrpc/sched.h

+2 −1
Original line number Diff line number Diff line
@@ -183,8 +183,9 @@ struct rpc_task_setup { 
#define RPC_NR_PRIORITY		(1 + RPC_PRIORITY_PRIVILEGED - RPC_PRIORITY_LOW)



struct rpc_timer {

	struct timer_list timer;

	struct list_head list;

	unsigned long expires;

	struct delayed_work dwork;

};



/*

net/sunrpc/sched.c

+20 −10
Original line number Diff line number Diff line
@@ -46,7 +46,7 @@ static mempool_t *rpc_buffer_mempool __read_mostly; 


static void			rpc_async_schedule(struct work_struct *);

static void			 rpc_release_task(struct rpc_task *task);

static void __rpc_queue_timer_fn(struct timer_list *t);

static void __rpc_queue_timer_fn(struct work_struct *);



/*

 * RPC tasks sit here while waiting for conditions to improve.
@@ -87,13 +87,19 @@ __rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task) 
	task->tk_timeout = 0;

	list_del(&task->u.tk_wait.timer_list);

	if (list_empty(&queue->timer_list.list))

		del_timer(&queue->timer_list.timer);

		cancel_delayed_work(&queue->timer_list.dwork);

}



static void

rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)

{

	timer_reduce(&queue->timer_list.timer, expires);

	unsigned long now = jiffies;

	queue->timer_list.expires = expires;

	if (time_before_eq(expires, now))

		expires = 0;

	else

		expires -= now;

	mod_delayed_work(rpciod_workqueue, &queue->timer_list.dwork, expires);

}



/*
@@ -107,6 +113,7 @@ __rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task, 
		task->tk_pid, jiffies_to_msecs(timeout - jiffies));



	task->tk_timeout = timeout;

	if (list_empty(&queue->timer_list.list) || time_before(timeout, queue->timer_list.expires))

		rpc_set_queue_timer(queue, timeout);

	list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);

}
@@ -250,7 +257,8 @@ static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const c 
	queue->maxpriority = nr_queues - 1;

	rpc_reset_waitqueue_priority(queue);

	queue->qlen = 0;

	timer_setup(&queue->timer_list.timer, __rpc_queue_timer_fn, 0);

	queue->timer_list.expires = 0;

	INIT_DEFERRABLE_WORK(&queue->timer_list.dwork, __rpc_queue_timer_fn);

	INIT_LIST_HEAD(&queue->timer_list.list);

	rpc_assign_waitqueue_name(queue, qname);

}
@@ -269,7 +277,7 @@ EXPORT_SYMBOL_GPL(rpc_init_wait_queue); 


void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)

{

	del_timer_sync(&queue->timer_list.timer);

	cancel_delayed_work_sync(&queue->timer_list.dwork);

}

EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
@@ -759,13 +767,15 @@ void rpc_wake_up_status(struct rpc_wait_queue *queue, int status) 
}

EXPORT_SYMBOL_GPL(rpc_wake_up_status);



static void __rpc_queue_timer_fn(struct timer_list *t)

static void __rpc_queue_timer_fn(struct work_struct *work)

{

	struct rpc_wait_queue *queue = from_timer(queue, t, timer_list.timer);

	struct rpc_wait_queue *queue = container_of(work,

			struct rpc_wait_queue,

			timer_list.dwork.work);

	struct rpc_task *task, *n;

	unsigned long expires, now, timeo;



	spin_lock(&queue->lock);

	spin_lock_bh(&queue->lock);

	expires = now = jiffies;

	list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {

		timeo = task->tk_timeout;
@@ -780,7 +790,7 @@ static void __rpc_queue_timer_fn(struct timer_list *t) 
	}

	if (!list_empty(&queue->timer_list.list))

		rpc_set_queue_timer(queue, expires);

	spin_unlock(&queue->lock);

	spin_unlock_bh(&queue->lock);

}



static void __rpc_atrun(struct rpc_task *task)

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