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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: Tom Zanussi <zanussi@comcast.net>
Cc: Satyam Sharma <satyam.sharma@gmail.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Tom Zanussi 2007-05-09 02:34:01 -07:00 committed by Linus Torvalds
parent d0758bc334
commit 7c9cb38302
2 changed files with 18 additions and 20 deletions
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3
include/linux/relay.h
View File

@ -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 */

35
kernel/relay.c
View File

@ -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 @@ end:
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;