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>
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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