USB: UHCI: fix IRQ race during initialization

This patch (as1644) fixes a race that occurs during startup in
uhci-hcd.  If the IRQ line is shared with other devices, it's possible
for the handler routine to be called before the data structures are
fully initialized.

The problem is fixed by adding a check to the IRQ handler routine.  If
the initialization hasn't finished yet, the routine will return
immediately.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Don Zickus <dzickus@redhat.com>
Tested-by: "Huang, Adrian (ISS Linux TW)" <adrian.huang@hp.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c
index 4b9e9aba2665..4f64d24eebc8 100644
--- a/drivers/usb/host/uhci-hcd.c
+++ b/drivers/usb/host/uhci-hcd.c
@@ -447,6 +447,10 @@ static irqreturn_t uhci_irq(struct usb_hcd *hcd)
                 return IRQ_NONE;
         uhci_writew(uhci, status, USBSTS);              /* Clear it */
 
+        spin_lock(&uhci->lock);
+        if (unlikely(!uhci->is_initialized))    /* not yet configured */
+                goto done;
+
         if (status & ~(USBSTS_USBINT | USBSTS_ERROR | USBSTS_RD)) {
                 if (status & USBSTS_HSE)
                         dev_err(uhci_dev(uhci), "host system error, "
@@ -455,7 +459,6 @@ static irqreturn_t uhci_irq(struct usb_hcd *hcd)
                         dev_err(uhci_dev(uhci), "host controller process "
                                         "error, something bad happened!\n");
                 if (status & USBSTS_HCH) {
-                        spin_lock(&uhci->lock);
                         if (uhci->rh_state >= UHCI_RH_RUNNING) {
                                 dev_err(uhci_dev(uhci),
                                         "host controller halted, "
@@ -473,15 +476,15 @@ static irqreturn_t uhci_irq(struct usb_hcd *hcd)
                                  * pending unlinks */
                                 mod_timer(&hcd->rh_timer, jiffies);
                         }
-                        spin_unlock(&uhci->lock);
                 }
         }
 
-        if (status & USBSTS_RD)
+        if (status & USBSTS_RD) {
+                spin_unlock(&uhci->lock);
                 usb_hcd_poll_rh_status(hcd);
-        else {
-                spin_lock(&uhci->lock);
+        } else {
                 uhci_scan_schedule(uhci);
+ done:
                 spin_unlock(&uhci->lock);
         }
 
@@ -662,9 +665,9 @@ static int uhci_start(struct usb_hcd *hcd)
          */
         mb();
 
+        spin_lock_irq(&uhci->lock);
         configure_hc(uhci);
         uhci->is_initialized = 1;
-        spin_lock_irq(&uhci->lock);
         start_rh(uhci);
         spin_unlock_irq(&uhci->lock);
         return 0;