Re: Regression: USB is nfg after suspend/resume(RAM) cycle on Intel chipset

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Alan Stern wrote:
On Tue, 29 May 2007, Mark Lord wrote:
Mark Lord wrote:
7ed92f1a149dddc3cb537ccd7441e98adac12c3e USB: make the autosuspend workqueue thread freezable
ef7f6c7084b333c7524dcd297e0578d43733a2a2 USB: more autosuspend timer stuff

I yanked them both, as they appeared to be releated based on the titles.
Reverting this pair of commits fixes the USB suspend/resume regression.
Okay, just to make it trivial,
I've narrowed it down to only this commit from Alan Stern:

7ed92f1a149dddc3cb537ccd7441e98adac12c3e USB: make the autosuspend workqueue thread freezable

I'm a little surprised; I would have expected the other patch to be the one responsible. Are you sure you got the right one?

Absolutely, 100% sure.

Your symptoms suggest that the ksuspend_usbd and khubd kernel threads
are in deadlock.
..
If this is indeed the case, the patch below ought to fix your problem. Essentially it replaces calls to flush_workqueue() with
cancel_sync_work().  I sent it to Andrew last week, but his problem
occurs only sporadically so it's hard to test.

I didn't re-break the kernel to do the alt-sysrq thing,
but I did reapply the b0rken commit plus your new patch (below).

So far, so good with that combination, thanks.
..

Index: 2.6.22-rc3/drivers/usb/core/hub.c
===================================================================
--- 2.6.22-rc3.orig/drivers/usb/core/hub.c
+++ 2.6.22-rc3/drivers/usb/core/hub.c
@@ -1158,6 +1158,30 @@ static void release_address(struct usb_d
 	}
 }
+#ifdef CONFIG_USB_SUSPEND
+
+static void usb_stop_pm(struct usb_device *udev)
+{
+	/* Synchronize with the ksuspend thread to prevent any more
+	 * autosuspend requests from being submitted, and decrement
+	 * the parent's count of unsuspended children.
+	 */
+	usb_pm_lock(udev);
+	if (udev->parent && !udev->discon_suspended)
+		usb_autosuspend_device(udev->parent);
+	usb_pm_unlock(udev);
+
+	/* Stop any autosuspend requests already submitted */
+	cancel_rearming_delayed_work(&udev->autosuspend);
+}
+
+#else
+
+static inline void usb_stop_pm(struct usb_device *udev)
+{ }
+
+#endif
+
 /**
  * usb_disconnect - disconnect a device (usbcore-internal)
  * @pdev: pointer to device being disconnected
@@ -1224,13 +1248,7 @@ void usb_disconnect(struct usb_device **
 	*pdev = NULL;
 	spin_unlock_irq(&device_state_lock);
- /* Decrement the parent's count of unsuspended children */
-	if (udev->parent) {
-		usb_pm_lock(udev);
-		if (!udev->discon_suspended)
-			usb_autosuspend_device(udev->parent);
-		usb_pm_unlock(udev);
-	}
+	usb_stop_pm(udev);
put_device(&udev->dev);
 }
Index: 2.6.22-rc3/drivers/usb/core/usb.c
===================================================================
--- 2.6.22-rc3.orig/drivers/usb/core/usb.c
+++ 2.6.22-rc3/drivers/usb/core/usb.c
@@ -184,10 +184,6 @@ static void usb_release_dev(struct devic
udev = to_usb_device(dev); -#ifdef CONFIG_USB_SUSPEND
-	cancel_delayed_work(&udev->autosuspend);
-	flush_workqueue(ksuspend_usb_wq);
-#endif
 	usb_destroy_configuration(udev);
 	usb_put_hcd(bus_to_hcd(udev->bus));
 	kfree(udev->product);
Index: 2.6.22-rc3/drivers/usb/core/hcd.c
===================================================================
--- 2.6.22-rc3.orig/drivers/usb/core/hcd.c
+++ 2.6.22-rc3/drivers/usb/core/hcd.c
@@ -1681,7 +1681,7 @@ void usb_remove_hcd(struct usb_hcd *hcd)
 	spin_unlock_irq (&hcd_root_hub_lock);
#ifdef CONFIG_PM
-	flush_workqueue(ksuspend_usb_wq);
+	cancel_work_sync(&hcd->wakeup_work);
 #endif
mutex_lock(&usb_bus_list_lock);

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