Merge branch 'writeback-workqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq into for-3.10/core

Tejun writes:

-----

This is the pull request for the earlier patchset[1] with the same
name.  It's only three patches (the first one was committed to
workqueue tree) but the merge strategy is a bit involved due to the
dependencies.

* Because the conversion needs features from wq/for-3.10,
  block/for-3.10/core is based on rc3, and wq/for-3.10 has conflicts
  with rc3, I pulled mainline (rc5) into wq/for-3.10 to prevent those
  workqueue conflicts from flaring up in block tree.

* Resolving the issue that Jan and Dave raised about debugging
  requires arch-wide changes.  The patchset is being worked on[2] but
  it'll have to go through -mm after these changes show up in -next,
  and not included in this pull request.

The three commits are located in the following git branch.

  git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git writeback-workqueue

Pulling it into block/for-3.10/core produces a conflict in
drivers/md/raid5.c between the following two commits.

  e3620a3ad5 ("MD RAID5: Avoid accessing gendisk or queue structs when not available")
  2f6db2a707 ("raid5: use bio_reset()")

The conflict is trivial - one removes an "if ()" conditional while the
other removes "rbi->bi_next = NULL" right above it.  We just need to
remove both.  The merged branch is available at

  git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git block-test-merge

so that you can use it for verification.  The test merge commit has
proper merge description.

While these changes are a bit of pain to route, they make code simpler
and even have, while minute, measureable performance gain[3] even on a
workload which isn't particularly favorable to showing the benefits of
this conversion.

----

Fixed up the conflict.

Conflicts:
	drivers/md/raid5.c

Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index d255f66e708..07d4650a32a 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -80,7 +80,6 @@ MODULE_DEVICE_TABLE(usb, id_table);
 
 struct ch341_private {
 	spinlock_t lock; /* access lock */
-	wait_queue_head_t delta_msr_wait; /* wait queue for modem status */
 	unsigned baud_rate; /* set baud rate */
 	u8 line_control; /* set line control value RTS/DTR */
 	u8 line_status; /* active status of modem control inputs */
@@ -252,7 +251,6 @@ static int ch341_port_probe(struct usb_serial_port *port)
 		return -ENOMEM;
 
 	spin_lock_init(&priv->lock);
-	init_waitqueue_head(&priv->delta_msr_wait);
 	priv->baud_rate = DEFAULT_BAUD_RATE;
 	priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
 
@@ -298,7 +296,7 @@ static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 		priv->line_control &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 	spin_unlock_irqrestore(&priv->lock, flags);
 	ch341_set_handshake(port->serial->dev, priv->line_control);
-	wake_up_interruptible(&priv->delta_msr_wait);
+	wake_up_interruptible(&port->delta_msr_wait);
 }
 
 static void ch341_close(struct usb_serial_port *port)
@@ -491,7 +489,7 @@ static void ch341_read_int_callback(struct urb *urb)
 			tty_kref_put(tty);
 		}
 
-		wake_up_interruptible(&priv->delta_msr_wait);
+		wake_up_interruptible(&port->delta_msr_wait);
 	}
 
 exit:
@@ -517,11 +515,14 @@ static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 	spin_unlock_irqrestore(&priv->lock, flags);
 
 	while (!multi_change) {
-		interruptible_sleep_on(&priv->delta_msr_wait);
+		interruptible_sleep_on(&port->delta_msr_wait);
 		/* see if a signal did it */
 		if (signal_pending(current))
 			return -ERESTARTSYS;
 
+		if (port->serial->disconnected)
+			return -EIO;
+
 		spin_lock_irqsave(&priv->lock, flags);
 		status = priv->line_status;
 		multi_change = priv->multi_status_change;