USB: EHCI: resolve some unlikely races

This patch (as1589) resolves some unlikely races involving system
shutdown or controller death in ehci-hcd:

	Shutdown races with both root-hub resume and controller
	resume.

	Controller death races with root-hub suspend.

A new bitflag is added to indicate that the controller has been shut
down (whether for system shutdown or because it died).  Tests are
added in the suspend and resume pathways to avoid reactivating the
controller after any sort of shutdown.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 23 insertions, 4 deletions

diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index ffc5f27..c788022 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -221,6 +221,8 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
 	ehci_quiesce(ehci);
 
 	spin_lock_irq (&ehci->lock);
+	if (ehci->rh_state < EHCI_RH_RUNNING)
+		goto done;
 
 	/* Once the controller is stopped, port resumes that are already
 	 * in progress won't complete.  Hence if remote wakeup is enabled
@@ -306,6 +308,10 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
 	ehci_halt (ehci);
 
 	spin_lock_irq(&ehci->lock);
+	if (ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_POLL_DEAD))
+		ehci_handle_controller_death(ehci);
+	if (ehci->rh_state != EHCI_RH_RUNNING)
+		goto done;
 	ehci->rh_state = EHCI_RH_SUSPENDED;
 
 	end_unlink_async(ehci);
@@ -320,6 +326,7 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
 	ehci_writel(ehci, mask, &ehci->regs->intr_enable);
 	ehci_readl(ehci, &ehci->regs->intr_enable);
 
+ done:
 	ehci->next_statechange = jiffies + msecs_to_jiffies(10);
 	ehci->enabled_hrtimer_events = 0;
 	ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
@@ -342,10 +349,8 @@ static int ehci_bus_resume (struct usb_hcd *hcd)
 	if (time_before (jiffies, ehci->next_statechange))
 		msleep(5);
 	spin_lock_irq (&ehci->lock);
-	if (!HCD_HW_ACCESSIBLE(hcd)) {
-		spin_unlock_irq(&ehci->lock);
-		return -ESHUTDOWN;
-	}
+	if (!HCD_HW_ACCESSIBLE(hcd) || ehci->shutdown)
+		goto shutdown;
 
 	if (unlikely(ehci->debug)) {
 		if (!dbgp_reset_prep())
@@ -384,6 +389,8 @@ static int ehci_bus_resume (struct usb_hcd *hcd)
 	spin_unlock_irq(&ehci->lock);
 	msleep(8);
 	spin_lock_irq(&ehci->lock);
+	if (ehci->shutdown)
+		goto shutdown;
 
 	/* clear phy low-power mode before resume */
 	if (ehci->bus_suspended && ehci->has_hostpc) {
@@ -401,6 +408,8 @@ static int ehci_bus_resume (struct usb_hcd *hcd)
 		spin_unlock_irq(&ehci->lock);
 		msleep(5);
 		spin_lock_irq(&ehci->lock);
+		if (ehci->shutdown)
+			goto shutdown;
 	}
 
 	/* manually resume the ports we suspended during bus_suspend() */
@@ -421,6 +430,8 @@ static int ehci_bus_resume (struct usb_hcd *hcd)
 		spin_unlock_irq(&ehci->lock);
 		msleep(20);
 		spin_lock_irq(&ehci->lock);
+		if (ehci->shutdown)
+			goto shutdown;
 	}
 
 	i = HCS_N_PORTS (ehci->hcs_params);
@@ -439,10 +450,18 @@ static int ehci_bus_resume (struct usb_hcd *hcd)
 	ehci_handover_companion_ports(ehci);
 
 	/* Now we can safely re-enable irqs */
+	spin_lock_irq(&ehci->lock);
+	if (ehci->shutdown)
+		goto shutdown;
 	ehci_writel(ehci, INTR_MASK, &ehci->regs->intr_enable);
 	(void) ehci_readl(ehci, &ehci->regs->intr_enable);
+	spin_unlock_irq(&ehci->lock);
 
 	return 0;
+
+ shutdown:
+	spin_unlock_irq(&ehci->lock);
+	return -ESHUTDOWN;
 }
 
 #else