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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>
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@ -12,6 +12,7 @@
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#include <linux/types.h>
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#include <linux/sched.h>
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#include <linux/timer.h>
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#include <linux/wait.h>
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#include <linux/list.h>
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#include <linux/fs.h>
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@ -38,7 +39,7 @@ struct rchan_buf
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size_t subbufs_consumed; /* count of sub-buffers consumed */
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struct rchan *chan; /* associated channel */
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wait_queue_head_t read_wait; /* reader wait queue */
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struct delayed_work wake_readers; /* reader wake-up work struct */
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struct timer_list timer; /* reader wake-up timer */
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struct dentry *dentry; /* channel file dentry */
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struct kref kref; /* channel buffer refcount */
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struct page **page_array; /* array of current buffer pages */
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@ -310,16 +310,13 @@ static struct rchan_callbacks default_channel_callbacks = {
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/**
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* wakeup_readers - wake up readers waiting on a channel
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* @work: work struct that contains the the channel buffer
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* @data: contains the the channel buffer
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*
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* This is the work function used to defer reader waking. The
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* reason waking is deferred is that calling directly from write
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* causes problems if you're writing from say the scheduler.
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* This is the timer function used to defer reader waking.
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*/
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static void wakeup_readers(struct work_struct *work)
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static void wakeup_readers(unsigned long data)
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{
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struct rchan_buf *buf =
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container_of(work, struct rchan_buf, wake_readers.work);
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struct rchan_buf *buf = (struct rchan_buf *)data;
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wake_up_interruptible(&buf->read_wait);
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}
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@ -337,11 +334,9 @@ static void __relay_reset(struct rchan_buf *buf, unsigned int init)
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if (init) {
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init_waitqueue_head(&buf->read_wait);
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kref_init(&buf->kref);
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INIT_DELAYED_WORK(&buf->wake_readers, NULL);
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} else {
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cancel_delayed_work(&buf->wake_readers);
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flush_scheduled_work();
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}
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setup_timer(&buf->timer, wakeup_readers, (unsigned long)buf);
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} else
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del_timer_sync(&buf->timer);
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buf->subbufs_produced = 0;
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buf->subbufs_consumed = 0;
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@ -447,8 +442,7 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
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static void relay_close_buf(struct rchan_buf *buf)
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{
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buf->finalized = 1;
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cancel_delayed_work(&buf->wake_readers);
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flush_scheduled_work();
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del_timer_sync(&buf->timer);
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kref_put(&buf->kref, relay_remove_buf);
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}
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@ -608,11 +602,14 @@ size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
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buf->dentry->d_inode->i_size += buf->chan->subbuf_size -
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buf->padding[old_subbuf];
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smp_mb();
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if (waitqueue_active(&buf->read_wait)) {
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PREPARE_DELAYED_WORK(&buf->wake_readers,
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wakeup_readers);
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schedule_delayed_work(&buf->wake_readers, 1);
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}
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if (waitqueue_active(&buf->read_wait))
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/*
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* Calling wake_up_interruptible() from here
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* will deadlock if we happen to be logging
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* from the scheduler (trying to re-grab
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* rq->lock), so defer it.
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*/
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__mod_timer(&buf->timer, jiffies + 1);
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}
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old = buf->data;
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