1 files changed, 98 insertions, 0 deletions
diff --git a/usb/usb-fix-race-between-root-hub-wakeup-controller-suspend.patch b/usb/usb-fix-race-between-root-hub-wakeup-controller-suspend.patch
new file mode 100644
index 00000000000000..b51d05c1839473
--- /dev/null
+++ b/usb/usb-fix-race-between-root-hub-wakeup-controller-suspend.patch
@@ -0,0 +1,98 @@
+From stern@rowland.harvard.edu  Wed Jul  7 14:55:46 2010
+From: Alan Stern <stern@rowland.harvard.edu>
+Date: Fri, 25 Jun 2010 14:02:35 -0400 (EDT)
+Subject: USB: fix race between root-hub wakeup & controller suspend
+To: Greg KH <greg@kroah.com>
+Message-ID: <Pine.LNX.4.44L0.1006251248220.1604-100000@iolanthe.rowland.org>
+
+
+This patch (as1395) adds code to hcd_pci_suspend() for handling wakeup
+races.  This is another general race pattern, similar to the "open
+vs. unregister" race we're all familiar with.  Here, the race is
+between suspending a device and receiving a wakeup request from one of
+the device's suspended children.
+
+In particular, if a root-hub wakeup is requested at about the same
+time as the corresponding USB controller is suspended, and if the
+controller is enabled for wakeup, then the controller should either
+fail to suspend or else wake right back up again.
+
+During system sleep this won't happen very much, especially since host
+controllers generally aren't enabled for wakeup during sleep.  However
+it is definitely an issue for runtime PM.  Something like this will be
+needed to prevent the controller from autosuspending while waiting for
+a root-hub resume to take place.  (That is, in fact, the common case,
+for which there is an extra test.)
+
+Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
+Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
+
+---
+ drivers/usb/core/hcd-pci.c |   12 ++++++++++++
+ drivers/usb/core/hcd.c     |    5 ++++-
+ include/linux/usb/hcd.h    |    2 ++
+ 3 files changed, 18 insertions(+), 1 deletion(-)
+
+--- a/drivers/usb/core/hcd-pci.c
++++ b/drivers/usb/core/hcd-pci.c
+@@ -388,8 +388,20 @@ static int hcd_pci_suspend(struct device
+ 	if (hcd->driver->pci_suspend) {
+ 		bool	do_wakeup = device_may_wakeup(dev);
+ 
++		/* Optimization: Don't suspend if a root-hub wakeup is
++		 * pending and it would cause the HCD to wake up anyway.
++		 */
++		if (do_wakeup && HCD_WAKEUP_PENDING(hcd))
++			return -EBUSY;
+ 		retval = hcd->driver->pci_suspend(hcd, do_wakeup);
+ 		suspend_report_result(hcd->driver->pci_suspend, retval);
++
++		/* Check again in case wakeup raced with pci_suspend */
++		if (retval == 0 && do_wakeup && HCD_WAKEUP_PENDING(hcd)) {
++			if (hcd->driver->pci_resume)
++				hcd->driver->pci_resume(hcd, false);
++			retval = -EBUSY;
++		}
+ 		if (retval)
+ 			return retval;
+ 	}
+--- a/drivers/usb/core/hcd.c
++++ b/drivers/usb/core/hcd.c
+@@ -1940,6 +1940,7 @@ int hcd_bus_resume(struct usb_device *rh
+ 
+ 	dev_dbg(&rhdev->dev, "usb %s%s\n",
+ 			(msg.event & PM_EVENT_AUTO ? "auto-" : ""), "resume");
++	clear_bit(HCD_FLAG_WAKEUP_PENDING, &hcd->flags);
+ 	if (!hcd->driver->bus_resume)
+ 		return -ENOENT;
+ 	if (hcd->state == HC_STATE_RUNNING)
+@@ -1993,8 +1994,10 @@ void usb_hcd_resume_root_hub (struct usb
+ 	unsigned long flags;
+ 
+ 	spin_lock_irqsave (&hcd_root_hub_lock, flags);
+-	if (hcd->rh_registered)
++	if (hcd->rh_registered) {
++		set_bit(HCD_FLAG_WAKEUP_PENDING, &hcd->flags);
+ 		queue_work(pm_wq, &hcd->wakeup_work);
++	}
+ 	spin_unlock_irqrestore (&hcd_root_hub_lock, flags);
+ }
+ EXPORT_SYMBOL_GPL(usb_hcd_resume_root_hub);
+--- a/include/linux/usb/hcd.h
++++ b/include/linux/usb/hcd.h
+@@ -98,6 +98,7 @@ struct usb_hcd {
+ #define HCD_FLAG_SAW_IRQ		1
+ #define HCD_FLAG_POLL_RH		2	/* poll for rh status? */
+ #define HCD_FLAG_POLL_PENDING		3	/* status has changed? */
++#define HCD_FLAG_WAKEUP_PENDING		4	/* root hub is resuming? */
+ 
+ 	/* The flags can be tested using these macros; they are likely to
+ 	 * be slightly faster than test_bit().
+@@ -106,6 +107,7 @@ struct usb_hcd {
+ #define HCD_SAW_IRQ(hcd)	((hcd)->flags & (1U << HCD_FLAG_SAW_IRQ))
+ #define HCD_POLL_RH(hcd)	((hcd)->flags & (1U << HCD_FLAG_POLL_RH))
+ #define HCD_POLL_PENDING(hcd)	((hcd)->flags & (1U << HCD_FLAG_POLL_PENDING))
++#define HCD_WAKEUP_PENDING(hcd)	((hcd)->flags & (1U << HCD_FLAG_WAKEUP_PENDING))
+ 
+ 	/* Flags that get set only during HCD registration or removal. */
+ 	unsigned		rh_registered:1;/* is root hub registered? */