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>
diff --git a/kernel/relay.c b/kernel/relay.c
index 577f251..e804589 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -310,16 +310,13 @@
/**
* 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 @@
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 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 @@
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;