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

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>
Cc: stable <stable@kernel.org>
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 2c6571c05f35c99398d973382680137f56363dcb..c75d9270c752921ee8751e2106ce522c6db2ee85 100644 (file)
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -120,9 +120,26 @@ 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);
@@ -138,6 +155,7 @@ 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 5cd0e48f67fb13b3df18ed077cd72a76995ae10c..99cd00fd3514c7f25abb0b42977e14c61edbb6ca 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;