USB: EHCI & UHCI: fix race between root-hub suspend and port resume

commit cec3a53c7fe794237b582e8e77fc0e48465e65ee upstream.

This patch (as1321) fixes a problem with EHCI and UHCI root-hub
suspends: If the suspend occurs while a port is trying to resume, the
resume doesn't finish and simply gets lost.  When remote wakeup is
enabled, this is undesirable behavior.

The patch checks first to see if any port resumes are in progress, and
if they are then it fails the root-hub suspend with -EBUSY.

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

diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index f46ad27c9a90e2cda2e8bbb8b9b45c861af765c5..e3d5cc1d8ae16e400a4a0f931a21e5de3591217f 100644 (file)
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -119,9 +119,26 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
        del_timer_sync(&ehci->watchdog);
        del_timer_sync(&ehci->iaa_watchdog);
 
-       port = HCS_N_PORTS (ehci->hcs_params);
        spin_lock_irq (&ehci->lock);
 
+       /* Once the controller is stopped, port resumes that are already
+        * in progress won't complete.  Hence if remote wakeup is enabled
+        * for the root hub and any ports are in the middle of a resume or
+        * remote wakeup, we must fail the suspend.
+        */
+       if (hcd->self.root_hub->do_remote_wakeup) {
+               port = HCS_N_PORTS(ehci->hcs_params);
+               while (port--) {
+                       if (ehci->reset_done[port] != 0) {
+                               spin_unlock_irq(&ehci->lock);
+                               ehci_dbg(ehci, "suspend failed because "
+                                               "port %d is resuming\n",
+                                               port + 1);
+                               return -EBUSY;
+                       }
+               }
+       }
+
        /* stop schedules, clean any completed work */
        if (HC_IS_RUNNING(hcd->state)) {
                ehci_quiesce (ehci);
@@ -137,6 +154,7 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
         */
        ehci->bus_suspended = 0;
        ehci->owned_ports = 0;
+       port = HCS_N_PORTS(ehci->hcs_params);
        while (port--) {
                u32 __iomem     *reg = &ehci->regs->port_status [port];
                u32             t1 = ehci_readl(ehci, reg) & ~PORT_RWC_BITS;

diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c
index 274751b4409c2bc2f71b7ea17a49a374d4494190..eb37d86bafef980606ab164dfd9eaf847df57659 100644 (file)
--- a/drivers/usb/host/uhci-hcd.c
+++ b/drivers/usb/host/uhci-hcd.c
@@ -749,7 +749,20 @@ static int uhci_rh_suspend(struct usb_hcd *hcd)
        spin_lock_irq(&uhci->lock);
        if (!test_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags))
                rc = -ESHUTDOWN;
-       else if (!uhci->dead)
+       else if (uhci->dead)
+               ;               /* Dead controllers tell no tales */
+
+       /* Once the controller is stopped, port resumes that are already
+        * in progress won't complete.  Hence if remote wakeup is enabled
+        * for the root hub and any ports are in the middle of a resume or
+        * remote wakeup, we must fail the suspend.
+        */
+       else if (hcd->self.root_hub->do_remote_wakeup &&
+                       uhci->resuming_ports) {
+               dev_dbg(uhci_dev(uhci), "suspend failed because a port "
+                               "is resuming\n");
+               rc = -EBUSY;
+       } else
                suspend_rh(uhci, UHCI_RH_SUSPENDED);
        spin_unlock_irq(&uhci->lock);
        return rc;