[PATCH] USB: Fix USB suspend/resume crasher (#2)

This patch closes the IRQ race and makes various other OHCI & EHCI code
path safer vs. suspend/resume.
I've been able to (finally !) successfully suspend and resume various
Mac models, with or without USB mouse plugged, or plugging while asleep,
or unplugging while asleep etc... all without a crash.

Alan, please verify the UHCI bit I did, I only verified that it builds.
It's very simple so I wouldn't expect any issue there. If you aren't
confident, then just drop the hunks that change uhci-hcd.c

I also made the patch a little bit more "safer" by making sure the store
to the interrupt register that disables interrupts is not posted before
I set the flag and drop the spinlock.

Without this patch, you cannot reliably sleep/wakeup any recent Mac, and
I suspect PCs have some more sneaky issues too (they don't frankly crash
with machine checks because x86 tend to silently swallow PCI errors but
that won't last afaik, at least PCI Express will blow up in those
situations, but the USB code may still misbehave).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/ohci-hcd.c

@@ -115,7 +115,7 @@
 
 /*-------------------------------------------------------------------------*/
 
-// #define OHCI_VERBOSE_DEBUG	/* not always helpful */
+#undef OHCI_VERBOSE_DEBUG	/* not always helpful */
 
 /* For initializing controller (mask in an HCFS mode too) */
 #define	OHCI_CONTROL_INIT 	OHCI_CTRL_CBSR
@@ -253,6 +253,10 @@ static int ohci_urb_enqueue (
 	spin_lock_irqsave (&ohci->lock, flags);
 
 	/* don't submit to a dead HC */
+	if (!test_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags)) {
+		retval = -ENODEV;
+		goto fail;
+	}
 	if (!HC_IS_RUNNING(hcd->state)) {
 		retval = -ENODEV;
 		goto fail;