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Commit 7c9cb383 authored by Tom Zanussi's avatar Tom Zanussi Committed by Linus Torvalds
Browse files

relay: use plain timer instead of delayed work 



relay doesn't need to use schedule_delayed_work() for waking readers
when a simple timer will do.

Signed-off-by: default avatarTom Zanussi <zanussi@comcast.net>
Cc: Satyam Sharma <satyam.sharma@gmail.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d0758bc3

include/linux/relay.h

+2 −1
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 


#include <linux/types.h>

#include <linux/sched.h>

#include <linux/timer.h>

#include <linux/wait.h>

#include <linux/list.h>

#include <linux/fs.h>
@@ -38,7 +39,7 @@ struct rchan_buf 
	size_t subbufs_consumed;	/* count of sub-buffers consumed */

	struct rchan *chan;		/* associated channel */

	wait_queue_head_t read_wait;	/* reader wait queue */

	struct delayed_work wake_readers; /* reader wake-up work struct */

	struct timer_list timer; 	/* reader wake-up timer */

	struct dentry *dentry;		/* channel file dentry */

	struct kref kref;		/* channel buffer refcount */

	struct page **page_array;	/* array of current buffer pages */

kernel/relay.c

+16 −19
Original line number Diff line number Diff line
@@ -310,16 +310,13 @@ static struct rchan_callbacks default_channel_callbacks = { 


/**

 *	wakeup_readers - wake up readers waiting on a channel

 *	@work: work struct that contains the the channel buffer

 *	@data: contains the the channel buffer

 *

 *	This is the work function used to defer reader waking.  The

 *	reason waking is deferred is that calling directly from write

 *	causes problems if you're writing from say the scheduler.

 *	This is the timer function used to defer reader waking.

 */

static void wakeup_readers(struct work_struct *work)

static void wakeup_readers(unsigned long data)

{

	struct rchan_buf *buf =

		container_of(work, struct rchan_buf, wake_readers.work);

	struct rchan_buf *buf = (struct rchan_buf *)data;

	wake_up_interruptible(&buf->read_wait);

}
@@ -337,11 +334,9 @@ static void __relay_reset(struct rchan_buf *buf, unsigned int init) 
	if (init) {

		init_waitqueue_head(&buf->read_wait);

		kref_init(&buf->kref);

		INIT_DELAYED_WORK(&buf->wake_readers, NULL);

	} else {

		cancel_delayed_work(&buf->wake_readers);

		flush_scheduled_work();

	}

		setup_timer(&buf->timer, wakeup_readers, (unsigned long)buf);

	} else

		del_timer_sync(&buf->timer);



	buf->subbufs_produced = 0;

	buf->subbufs_consumed = 0;
@@ -447,8 +442,7 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu) 
static void relay_close_buf(struct rchan_buf *buf)

{

	buf->finalized = 1;

	cancel_delayed_work(&buf->wake_readers);

	flush_scheduled_work();

	del_timer_sync(&buf->timer);

	kref_put(&buf->kref, relay_remove_buf);

}
@@ -608,11 +602,14 @@ size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) 
		buf->dentry->d_inode->i_size += buf->chan->subbuf_size -

			buf->padding[old_subbuf];

		smp_mb();

		if (waitqueue_active(&buf->read_wait)) {

			PREPARE_DELAYED_WORK(&buf->wake_readers,

					     wakeup_readers);

			schedule_delayed_work(&buf->wake_readers, 1);

		}

		if (waitqueue_active(&buf->read_wait))

			/*

			 * Calling wake_up_interruptible() from here

			 * will deadlock if we happen to be logging

			 * from the scheduler (trying to re-grab

			 * rq->lock), so defer it.

			 */

			__mod_timer(&buf->timer, jiffies + 1);

	}



	old = buf->data;